From 64cc20e49958d9e35bdc83246c4e9cbc9fda974e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Mon, 28 Jun 2021 11:53:19 -0400
Subject: [PATCH 01/35] refactor: inline pushComment

---
 packages/babel-parser/src/parser/comments.js  |  3 +-
 .../babel-parser/src/plugins/flow/index.js    |  4 +-
 packages/babel-parser/src/tokenizer/index.js  | 76 +++++++++----------
 packages/babel-parser/src/types.js            | 12 ++-
 4 files changed, 48 insertions(+), 47 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index c990c9e0e8a9..48c47cd6a2dc 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -34,6 +34,7 @@ function last<T>(stack: $ReadOnlyArray<T>): T {
 export default class CommentsParser extends BaseParser {
   addComment(comment: Comment): void {
     if (this.filename) comment.loc.filename = this.filename;
+    this.state.comments.push(comment);
     this.state.trailingComments.push(comment);
     this.state.leadingComments.push(comment);
   }
@@ -101,8 +102,6 @@ export default class CommentsParser extends BaseParser {
   }
 
   processComment(node: Node): void {
-    if (node.type === "Program" && node.body.length > 0) return;
-
     const stack = this.state.commentStack;
 
     let firstChild, lastChild, trailingComments, i, j;
diff --git a/packages/babel-parser/src/plugins/flow/index.js b/packages/babel-parser/src/plugins/flow/index.js
index 3bf6f4082d7e..d27aaaa0777c 100644
--- a/packages/babel-parser/src/plugins/flow/index.js
+++ b/packages/babel-parser/src/plugins/flow/index.js
@@ -3212,7 +3212,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       return fileNode;
     }
 
-    skipBlockComment(): void {
+    skipBlockComment(): N.CommentBlock | void {
       if (this.hasPlugin("flowComments") && this.skipFlowComment()) {
         if (this.state.hasFlowComment) {
           this.unexpected(null, FlowErrors.NestedFlowComment);
@@ -3232,7 +3232,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         return;
       }
 
-      super.skipBlockComment();
+      return super.skipBlockComment();
     }
 
     skipFlowComment(): number | boolean {
diff --git a/packages/babel-parser/src/tokenizer/index.js b/packages/babel-parser/src/tokenizer/index.js
index c1c9848b424d..0e1da5a29298 100644
--- a/packages/babel-parser/src/tokenizer/index.js
+++ b/packages/babel-parser/src/tokenizer/index.js
@@ -304,28 +304,7 @@ export default class Tokenizer extends ParserErrors {
     }
   }
 
-  pushComment(
-    block: boolean,
-    text: string,
-    start: number,
-    end: number,
-    startLoc: Position,
-    endLoc: Position,
-  ): void {
-    const comment = {
-      type: block ? "CommentBlock" : "CommentLine",
-      value: text,
-      start: start,
-      end: end,
-      loc: new SourceLocation(startLoc, endLoc),
-    };
-
-    if (this.options.tokens) this.pushToken(comment);
-    this.state.comments.push(comment);
-    this.addComment(comment);
-  }
-
-  skipBlockComment(): void {
+  skipBlockComment(): N.CommentBlock | void {
     let startLoc;
     if (!this.isLookahead) startLoc = this.state.curPosition();
     const start = this.state.pos;
@@ -348,17 +327,19 @@ export default class Tokenizer extends ParserErrors {
     if (this.isLookahead) return;
     /*:: invariant(startLoc) */
 
-    this.pushComment(
-      true,
-      this.input.slice(start + 2, end),
-      start,
-      this.state.pos,
-      startLoc,
-      this.state.curPosition(),
-    );
+    const value = this.input.slice(start + 2, end);
+    const comment = {
+      type: "CommentBlock",
+      value: value,
+      start: start,
+      end: end + 2,
+      loc: new SourceLocation(startLoc, this.state.curPosition()),
+    };
+    if (this.options.tokens) this.pushToken(comment);
+    return comment;
   }
 
-  skipLineComment(startSkip: number): void {
+  skipLineComment(startSkip: number): N.CommentLine | void {
     const start = this.state.pos;
     let startLoc;
     if (!this.isLookahead) startLoc = this.state.curPosition();
@@ -374,20 +355,25 @@ export default class Tokenizer extends ParserErrors {
     if (this.isLookahead) return;
     /*:: invariant(startLoc) */
 
-    this.pushComment(
-      false,
-      this.input.slice(start + startSkip, this.state.pos),
+    const end = this.state.pos;
+    const value = this.input.slice(start + startSkip, end);
+
+    const comment = {
+      type: "CommentLine",
+      value,
       start,
-      this.state.pos,
-      startLoc,
-      this.state.curPosition(),
-    );
+      end,
+      loc: new SourceLocation(startLoc, this.state.curPosition()),
+    };
+    if (this.options.tokens) this.pushToken(comment);
+    return comment;
   }
 
   // Called at the start of the parse and after every token. Skips
   // whitespace and comments, and.
 
   skipSpace(): void {
+    const comments = [];
     loop: while (this.state.pos < this.length) {
       const ch = this.input.charCodeAt(this.state.pos);
       switch (ch) {
@@ -414,11 +400,11 @@ export default class Tokenizer extends ParserErrors {
         case charCodes.slash:
           switch (this.input.charCodeAt(this.state.pos + 1)) {
             case charCodes.asterisk:
-              this.skipBlockComment();
+              comments.push(this.skipBlockComment());
               break;
 
             case charCodes.slash:
-              this.skipLineComment(2);
+              comments.push(this.skipLineComment(2));
               break;
 
             default:
@@ -434,6 +420,10 @@ export default class Tokenizer extends ParserErrors {
           }
       }
     }
+    for (let i = 0; i < comments.length; i++) {
+      const comment = comments[i];
+      if (comment !== undefined) this.addComment(comment);
+    }
   }
 
   // Called at the end of every token. Sets `end`, `val`, and
@@ -668,7 +658,8 @@ export default class Tokenizer extends ParserErrors {
         (this.state.lastTokEnd === 0 || this.hasPrecedingLineBreak())
       ) {
         // A `-->` line comment
-        this.skipLineComment(3);
+        const comment = this.skipLineComment(3);
+        if (comment !== undefined) this.addComment(comment);
         this.skipSpace();
         this.nextToken();
         return;
@@ -711,7 +702,8 @@ export default class Tokenizer extends ParserErrors {
       this.input.charCodeAt(this.state.pos + 3) === charCodes.dash
     ) {
       // `<!--`, an XML-style comment that should be interpreted as a line comment
-      this.skipLineComment(4);
+      const comment = this.skipLineComment(4);
+      if (comment !== undefined) this.addComment(comment);
       this.skipSpace();
       this.nextToken();
       return;
diff --git a/packages/babel-parser/src/types.js b/packages/babel-parser/src/types.js
index 4294833d510f..8f7e9f0b1c93 100644
--- a/packages/babel-parser/src/types.js
+++ b/packages/babel-parser/src/types.js
@@ -16,7 +16,7 @@ import type { ParsingError } from "./parser/error";
  *   - packages/babel-generators/src/generators
  */
 
-export type Comment = {
+type CommentBase = {
   type: "CommentBlock" | "CommentLine",
   value: string,
   start: number,
@@ -24,6 +24,16 @@ export type Comment = {
   loc: SourceLocation,
 };
 
+export type CommentBlock = CommentBase & {
+  type: "CommentBlock",
+};
+
+export type CommentLine = CommentBase & {
+  type: "CommentLine",
+};
+
+export type Comment = CommentBlock | CommentLine;
+
 export interface NodeBase {
   start: number;
   end: number;

From b20fffac832dc72a018a06fd260bce2e84d46840 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 12:27:14 -0400
Subject: [PATCH 02/35] chore: add benchmark cases

---
 .../benchmark/many-async-arrows/bench.mjs     | 22 +++++++++++++++++
 .../many-inner-comments-nested/bench.mjs      | 22 +++++++++++++++++
 .../many-leading-comments-nested/bench.mjs    | 24 +++++++++++++++++++
 .../benchmark/many-leading-comments/bench.mjs | 24 +++++++++++++++++++
 .../many-trailing-comments-nested/bench.mjs   | 22 +++++++++++++++++
 5 files changed, 114 insertions(+)
 create mode 100644 packages/babel-parser/benchmark/many-async-arrows/bench.mjs
 create mode 100644 packages/babel-parser/benchmark/many-inner-comments-nested/bench.mjs
 create mode 100644 packages/babel-parser/benchmark/many-leading-comments-nested/bench.mjs
 create mode 100644 packages/babel-parser/benchmark/many-leading-comments/bench.mjs
 create mode 100644 packages/babel-parser/benchmark/many-trailing-comments-nested/bench.mjs

diff --git a/packages/babel-parser/benchmark/many-async-arrows/bench.mjs b/packages/babel-parser/benchmark/many-async-arrows/bench.mjs
new file mode 100644
index 000000000000..030e52353501
--- /dev/null
+++ b/packages/babel-parser/benchmark/many-async-arrows/bench.mjs
@@ -0,0 +1,22 @@
+import Benchmark from "benchmark";
+import baseline from "@babel-baseline/parser";
+import current from "../../lib/index.js";
+import { report } from "../util.mjs";
+
+const suite = new Benchmark.Suite();
+function createInput(length) {
+  return "async () => {};".repeat(length);
+}
+function benchCases(name, implementation, options) {
+  for (const length of [256, 512, 1024, 2048]) {
+    const input = createInput(length);
+    suite.add(`${name} ${length} async arrow functions`, () => {
+      implementation.parse(input, options);
+    });
+  }
+}
+
+benchCases("baseline", baseline);
+benchCases("current", current);
+
+suite.on("cycle", report).run();
diff --git a/packages/babel-parser/benchmark/many-inner-comments-nested/bench.mjs b/packages/babel-parser/benchmark/many-inner-comments-nested/bench.mjs
new file mode 100644
index 000000000000..4159dc8125fb
--- /dev/null
+++ b/packages/babel-parser/benchmark/many-inner-comments-nested/bench.mjs
@@ -0,0 +1,22 @@
+import Benchmark from "benchmark";
+import baseline from "@babel-baseline/parser";
+import current from "../../lib/index.js";
+import { report } from "../util.mjs";
+
+const suite = new Benchmark.Suite();
+function createInput(length) {
+  return "[".repeat(length) + "/* c */,]".repeat(length);
+}
+function benchCases(name, implementation, options) {
+  for (const length of [128, 256, 512, 1024]) {
+    const input = createInput(length);
+    suite.add(`${name} ${length} nested inner comments`, () => {
+      implementation.parse(input, options);
+    });
+  }
+}
+
+benchCases("baseline", baseline);
+benchCases("current", current);
+
+suite.on("cycle", report).run();
diff --git a/packages/babel-parser/benchmark/many-leading-comments-nested/bench.mjs b/packages/babel-parser/benchmark/many-leading-comments-nested/bench.mjs
new file mode 100644
index 000000000000..55c7d2503304
--- /dev/null
+++ b/packages/babel-parser/benchmark/many-leading-comments-nested/bench.mjs
@@ -0,0 +1,24 @@
+import Benchmark from "benchmark";
+import baseline from "@babel-baseline/parser";
+import current from "../../lib/index.js";
+import { report } from "../util.mjs";
+
+const suite = new Benchmark.Suite();
+function createInput(length) {
+  return "// c\n{\n".repeat(length) + "}".repeat(length);
+}
+current.parse(createInput(256), {});
+function benchCases(name, implementation, options) {
+  for (const length of [128, 256, 512, 1024]) {
+    const input = createInput(length);
+    const { parse } = implementation;
+    suite.add(`${name} ${length} nested leading comments`, () => {
+      parse(input, options);
+    });
+  }
+}
+
+benchCases("baseline", baseline);
+benchCases("current", current);
+
+suite.on("cycle", report).run();
diff --git a/packages/babel-parser/benchmark/many-leading-comments/bench.mjs b/packages/babel-parser/benchmark/many-leading-comments/bench.mjs
new file mode 100644
index 000000000000..0adc4f427430
--- /dev/null
+++ b/packages/babel-parser/benchmark/many-leading-comments/bench.mjs
@@ -0,0 +1,24 @@
+import Benchmark from "benchmark";
+import baseline from "@babel-baseline/parser";
+import current from "../../lib/index.js";
+import { report } from "../util.mjs";
+
+const suite = new Benchmark.Suite();
+function createInput(length) {
+  return "// c\n".repeat(length) + "{}";
+}
+current.parse(createInput(256), {});
+function benchCases(name, implementation, options) {
+  for (const length of [128, 256, 512, 1024]) {
+    const input = createInput(length);
+    const { parse } = implementation;
+    suite.add(`${name} ${length} leading comments`, () => {
+      parse(input, options);
+    });
+  }
+}
+
+benchCases("baseline", baseline);
+benchCases("current", current);
+
+suite.on("cycle", report).run();
diff --git a/packages/babel-parser/benchmark/many-trailing-comments-nested/bench.mjs b/packages/babel-parser/benchmark/many-trailing-comments-nested/bench.mjs
new file mode 100644
index 000000000000..44c61d88cbf0
--- /dev/null
+++ b/packages/babel-parser/benchmark/many-trailing-comments-nested/bench.mjs
@@ -0,0 +1,22 @@
+import Benchmark from "benchmark";
+import baseline from "@babel-baseline/parser";
+import current from "../../lib/index.js";
+import { report } from "../util.mjs";
+
+const suite = new Benchmark.Suite();
+function createInput(length) {
+  return "{".repeat(length) + "} // c\n".repeat(length);
+}
+function benchCases(name, implementation, options) {
+  for (const length of [128, 256, 512, 1024]) {
+    const input = createInput(length);
+    suite.add(`${name} ${length} trailing comments`, () => {
+      implementation.parse(input, options);
+    });
+  }
+}
+
+benchCases("baseline", baseline);
+benchCases("current", current);
+
+suite.on("cycle", report).run();

From a557f5b4bb7beeb6697a3b9a6279c8a54c0062ab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 12:27:41 -0400
Subject: [PATCH 03/35] perf: overhaul comment attachment

---
 packages/babel-parser/src/parser/comments.js  | 112 +++++++++++++++++-
 .../babel-parser/src/parser/expression.js     |   1 +
 packages/babel-parser/src/parser/statement.js |   1 +
 packages/babel-parser/src/tokenizer/index.js  |  58 ++++++---
 packages/babel-parser/src/tokenizer/state.js  |   8 +-
 packages/babel-parser/src/types.js            |  10 ++
 6 files changed, 166 insertions(+), 24 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 48c47cd6a2dc..f867b51e95b6 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -26,17 +26,23 @@
 
 import BaseParser from "./base";
 import type { Comment, Node } from "../types";
+import * as charCodes from "charcodes";
 
 function last<T>(stack: $ReadOnlyArray<T>): T {
   return stack[stack.length - 1];
 }
 
+function setInnerComments(node, comments) {
+  if (node.innerComments === undefined) {
+    node.innerComments = comments;
+  } else {
+    node.innerComments.push(...comments);
+  }
+}
 export default class CommentsParser extends BaseParser {
   addComment(comment: Comment): void {
     if (this.filename) comment.loc.filename = this.filename;
     this.state.comments.push(comment);
-    this.state.trailingComments.push(comment);
-    this.state.leadingComments.push(comment);
   }
 
   adjustCommentsAfterTrailingComma(
@@ -101,7 +107,7 @@ export default class CommentsParser extends BaseParser {
     }
   }
 
-  processComment(node: Node): void {
+  processComment2(node: Node): void {
     const stack = this.state.commentStack;
 
     let firstChild, lastChild, trailingComments, i, j;
@@ -284,4 +290,104 @@ export default class CommentsParser extends BaseParser {
 
     stack.push(node);
   }
+
+  processComment(node: Node): void {
+    const { unattachedCommentStack } = this.state;
+    const commentStackLength = unattachedCommentStack.length;
+    if (commentStackLength === 0) return;
+    let i = commentStackLength - 1;
+    const lastComments = unattachedCommentStack[i];
+
+    if (lastComments.start === node.end) {
+      lastComments.leadingNode = node;
+      i--;
+    }
+    // invariant: for all 0 <= j <= i, c = commentStack[j] satisfies c.end < node.end
+    const nodeStart = node.start;
+    for (; i >= 0; i--) {
+      const commentWS = unattachedCommentStack[i];
+      const commentEnd = commentWS.end;
+      if (commentEnd > nodeStart) {
+        // by definition of commentWhiteSpace, this implies commentWS.start > nodeStart
+        // so node can be a containerNode candidate
+        const { containerNode } = commentWS;
+        if (containerNode === null) {
+          commentWS.containerNode = node;
+        } else {
+          if (containerNode.end - containerNode.start < node.end - nodeStart) {
+            unattachedCommentStack.splice(i, 1);
+          } else if (node.type !== "Program") {
+            // we have a node share the same length of containerNode, but its finishNode is invoked later
+            // than containerNode, so this node is the outer node. E.g. ExpressionStatement contains a VariableDeclaration
+            commentWS.containerNode = node;
+          }
+        }
+      } else if (commentEnd === nodeStart) {
+        commentWS.trailingNode = node;
+        break;
+      }
+    }
+  }
+
+  finalizeComment() {
+    const { commentStack } = this.state;
+    const commentStackLength = commentStack.length;
+    for (let i = 0; i < commentStackLength; i++) {
+      const commentWS = commentStack[i];
+      if (commentWS.leadingNode !== null || commentWS.trailingNode !== null) {
+        if (commentWS.leadingNode !== null) {
+          commentWS.leadingNode.trailingComments = commentWS.comments;
+        }
+        if (commentWS.trailingNode !== null) {
+          commentWS.trailingNode.leadingComments = commentWS.comments;
+        }
+      } else {
+        const {
+          containerNode: node,
+          comments,
+          start: commentStart,
+        } = commentWS;
+        if (this.input.charCodeAt(commentStart - 1) === charCodes.comma) {
+          switch (node.type) {
+            case "ObjectExpression":
+            case "ObjectPattern":
+              this.adjustInnerComments(node, node.properties, comments);
+              break;
+            case "CallExpression":
+              this.adjustInnerComments(node, node.arguments, comments);
+              break;
+            case "ArrayExpression":
+            case "ArrayPattern":
+              this.adjustInnerComments(node, node.elements, comments);
+              break;
+            case "ExportNamedDeclaration":
+            case "ImportDeclaration":
+              this.adjustInnerComments(node, node.specifiers, comments);
+              break;
+            default: {
+              setInnerComments(node, comments);
+            }
+          }
+        } else {
+          setInnerComments(node, comments);
+        }
+      }
+    }
+  }
+
+  adjustInnerComments(node, elements, comments) {
+    let lastElement = null;
+    let i = elements.length;
+    while (lastElement === null && i > 0) {
+      lastElement = elements[--i];
+    }
+    if (lastElement === null) {
+      setInnerComments(node, comments);
+    }
+    if (lastElement.trailingComments === undefined) {
+      lastElement.trailingComments = comments;
+    } else {
+      lastElement.trailingComments.push(...comments);
+    }
+  }
 }
diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index aaf4794f7724..1d4d583fca4d 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -161,6 +161,7 @@ export default class ExpressionParser extends LValParser {
     if (!this.match(tt.eof)) {
       this.unexpected();
     }
+    this.finalizeComment();
     expr.comments = this.state.comments;
     expr.errors = this.state.errors;
     if (this.options.tokens) {
diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
index 0f6ce71dcf31..56a21f452abc 100644
--- a/packages/babel-parser/src/parser/statement.js
+++ b/packages/babel-parser/src/parser/statement.js
@@ -99,6 +99,7 @@ export default class StatementParser extends ExpressionParser {
 
   parseTopLevel(file: N.File, program: N.Program): N.File {
     file.program = this.parseProgram(program);
+    this.finalizeComment();
     file.comments = this.state.comments;
 
     if (this.options.tokens) file.tokens = babel7CompatTokens(this.tokens);
diff --git a/packages/babel-parser/src/tokenizer/index.js b/packages/babel-parser/src/tokenizer/index.js
index 0e1da5a29298..5afdc2765142 100644
--- a/packages/babel-parser/src/tokenizer/index.js
+++ b/packages/babel-parser/src/tokenizer/index.js
@@ -4,7 +4,6 @@
 
 import type { Options } from "../options";
 import * as N from "../types";
-import type { Position } from "../util/location";
 import * as charCodes from "charcodes";
 import { isIdentifierStart, isIdentifierChar } from "../util/identifier";
 import { types as tt, keywords as keywordTypes, type TokenType } from "./types";
@@ -289,7 +288,7 @@ export default class Tokenizer extends ParserErrors {
 
   nextToken(): void {
     const curContext = this.curContext();
-    if (!curContext.preserveSpace) this.skipSpace();
+    if (!curContext.preserveSpace) this.skipSpace([], this.state.pos);
     this.state.start = this.state.pos;
     if (!this.isLookahead) this.state.startLoc = this.state.curPosition();
     if (this.state.pos >= this.length) {
@@ -372,8 +371,7 @@ export default class Tokenizer extends ParserErrors {
   // Called at the start of the parse and after every token. Skips
   // whitespace and comments, and.
 
-  skipSpace(): void {
-    const comments = [];
+  skipSpace(comments, spaceStart): void {
     loop: while (this.state.pos < this.length) {
       const ch = this.input.charCodeAt(this.state.pos);
       switch (ch) {
@@ -399,13 +397,23 @@ export default class Tokenizer extends ParserErrors {
 
         case charCodes.slash:
           switch (this.input.charCodeAt(this.state.pos + 1)) {
-            case charCodes.asterisk:
-              comments.push(this.skipBlockComment());
+            case charCodes.asterisk: {
+              const comment = this.skipBlockComment();
+              if (comment !== undefined) {
+                this.addComment(comment);
+                comments.push(comment);
+              }
               break;
+            }
 
-            case charCodes.slash:
-              comments.push(this.skipLineComment(2));
+            case charCodes.slash: {
+              const comment = this.skipLineComment(2);
+              if (comment !== undefined) {
+                this.addComment(comment);
+                comments.push(comment);
+              }
               break;
+            }
 
             default:
               break loop;
@@ -420,9 +428,19 @@ export default class Tokenizer extends ParserErrors {
           }
       }
     }
-    for (let i = 0; i < comments.length; i++) {
-      const comment = comments[i];
-      if (comment !== undefined) this.addComment(comment);
+
+    if (comments.length > 0) {
+      const end = this.state.pos;
+      const CommentWhitespace = {
+        start: spaceStart,
+        end,
+        comments,
+        leadingNode: null,
+        trailingNode: null,
+        containerNode: null,
+      };
+      this.state.commentStack.push(CommentWhitespace);
+      this.state.unattachedCommentStack.push(CommentWhitespace);
     }
   }
 
@@ -658,9 +676,14 @@ export default class Tokenizer extends ParserErrors {
         (this.state.lastTokEnd === 0 || this.hasPrecedingLineBreak())
       ) {
         // A `-->` line comment
+        const whitespaceStart = this.state.lastTokEnd;
         const comment = this.skipLineComment(3);
-        if (comment !== undefined) this.addComment(comment);
-        this.skipSpace();
+        const comments = [];
+        if (comment !== undefined) {
+          this.addComment(comment);
+          comments.push(comment);
+        }
+        this.skipSpace(comments, whitespaceStart);
         this.nextToken();
         return;
       }
@@ -702,9 +725,14 @@ export default class Tokenizer extends ParserErrors {
       this.input.charCodeAt(this.state.pos + 3) === charCodes.dash
     ) {
       // `<!--`, an XML-style comment that should be interpreted as a line comment
+      const whitespaceStart = this.state.lastTokEnd;
       const comment = this.skipLineComment(4);
-      if (comment !== undefined) this.addComment(comment);
-      this.skipSpace();
+      const comments = [];
+      if (comment !== undefined) {
+        this.addComment(comment);
+        comments.push(comment);
+      }
+      this.skipSpace(comments, whitespaceStart);
       this.nextToken();
       return;
     }
diff --git a/packages/babel-parser/src/tokenizer/state.js b/packages/babel-parser/src/tokenizer/state.js
index c6775ede56eb..23f9e31a8c56 100644
--- a/packages/babel-parser/src/tokenizer/state.js
+++ b/packages/babel-parser/src/tokenizer/state.js
@@ -95,12 +95,8 @@ export default class State {
   // Comment attachment store
   trailingComments: Array<N.Comment> = [];
   leadingComments: Array<N.Comment> = [];
-  commentStack: Array<{
-    start: number,
-    leadingComments: ?Array<N.Comment>,
-    trailingComments: ?Array<N.Comment>,
-    type: string,
-  }> = [];
+  unattachedCommentStack: Array<N.CommentWhitespace> = [];
+  commentStack: Array<N.CommentWhitespace> = [];
   // $FlowIgnore this is initialized when the parser starts.
   commentPreviousNode: N.Node = null;
 
diff --git a/packages/babel-parser/src/types.js b/packages/babel-parser/src/types.js
index 8f7e9f0b1c93..b65d58a9fcb7 100644
--- a/packages/babel-parser/src/types.js
+++ b/packages/babel-parser/src/types.js
@@ -34,6 +34,16 @@ export type CommentLine = CommentBase & {
 
 export type Comment = CommentBlock | CommentLine;
 
+// A whitespace containing comments
+export type CommentWhitespace = {
+  start: number,
+  end: number,
+  comments: Array<Comment>,
+  leadingNode: Node,
+  trailingNode: Node,
+  containerNode: Node,
+};
+
 export interface NodeBase {
   start: number;
   end: number;

From 555687b8015d38dcc8fb8a5b38e651ab0fdca7c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 12:42:22 -0400
Subject: [PATCH 04/35] cleanup

---
 packages/babel-parser/src/parser/comments.js | 326 ++-----------------
 packages/babel-parser/src/tokenizer/index.js |   2 +-
 packages/babel-parser/src/tokenizer/state.js |   6 +-
 packages/babel-parser/src/types.js           |   6 +-
 4 files changed, 35 insertions(+), 305 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index f867b51e95b6..e802c39c8d4a 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -1,296 +1,44 @@
 // @flow
 
-/**
- * Based on the comment attachment algorithm used in espree and estraverse.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * * Redistributions of source code must retain the above copyright
- *   notice, this list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above copyright
- *   notice, this list of conditions and the following disclaimer in the
- *   documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
- * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
+/*:: declare var invariant; */
 
 import BaseParser from "./base";
 import type { Comment, Node } from "../types";
 import * as charCodes from "charcodes";
 
-function last<T>(stack: $ReadOnlyArray<T>): T {
-  return stack[stack.length - 1];
-}
-
-function setInnerComments(node, comments) {
+function setInnerComments(node: Node, comments: Array<Comment>) {
   if (node.innerComments === undefined) {
     node.innerComments = comments;
   } else {
     node.innerComments.push(...comments);
   }
 }
+
+function adjustInnerComments(
+  node: Node,
+  elements: Array<Node>,
+  comments: Array<Comment>,
+) {
+  let lastElement = null;
+  let i = elements.length;
+  while (lastElement === null && i > 0) {
+    lastElement = elements[--i];
+  }
+  if (lastElement === null) {
+    setInnerComments(node, comments);
+  } else if (lastElement.trailingComments === undefined) {
+    lastElement.trailingComments = comments;
+  } else {
+    lastElement.trailingComments.push(...comments);
+  }
+}
+
 export default class CommentsParser extends BaseParser {
   addComment(comment: Comment): void {
     if (this.filename) comment.loc.filename = this.filename;
     this.state.comments.push(comment);
   }
 
-  adjustCommentsAfterTrailingComma(
-    node: Node,
-    elements: (Node | null)[],
-    // When the current node is followed by a token which hasn't a respective AST node, we
-    // need to take all the trailing comments to prevent them from being attached to an
-    // unrelated node. e.g. in
-    //     var { x } /* cmt */ = { y }
-    // we don't want /* cmt */ to be attached to { y }.
-    // On the other hand, in
-    //     fn(x) [new line] /* cmt */ [new line] y
-    // /* cmt */ is both a trailing comment of fn(x) and a leading comment of y
-    takeAllComments?: boolean,
-  ) {
-    if (this.state.leadingComments.length === 0) {
-      return;
-    }
-
-    let lastElement = null;
-    let i = elements.length;
-    while (lastElement === null && i > 0) {
-      lastElement = elements[--i];
-    }
-    if (lastElement === null) {
-      return;
-    }
-
-    for (let j = 0; j < this.state.leadingComments.length; j++) {
-      if (
-        this.state.leadingComments[j].end < this.state.commentPreviousNode.end
-      ) {
-        this.state.leadingComments.splice(j, 1);
-        j--;
-      }
-    }
-
-    const newTrailingComments = [];
-    for (let i = 0; i < this.state.leadingComments.length; i++) {
-      const leadingComment = this.state.leadingComments[i];
-      if (leadingComment.end < node.end) {
-        newTrailingComments.push(leadingComment);
-
-        // Perf: we don't need to splice if we are going to reset the array anyway
-        if (!takeAllComments) {
-          this.state.leadingComments.splice(i, 1);
-          i--;
-        }
-      } else {
-        if (node.trailingComments === undefined) {
-          node.trailingComments = [];
-        }
-        node.trailingComments.push(leadingComment);
-      }
-    }
-    if (takeAllComments) this.state.leadingComments = [];
-
-    if (newTrailingComments.length > 0) {
-      lastElement.trailingComments = newTrailingComments;
-    } else if (lastElement.trailingComments !== undefined) {
-      lastElement.trailingComments = [];
-    }
-  }
-
-  processComment2(node: Node): void {
-    const stack = this.state.commentStack;
-
-    let firstChild, lastChild, trailingComments, i, j;
-
-    if (this.state.trailingComments.length > 0) {
-      // If the first comment in trailingComments comes after the
-      // current node, then we're good - all comments in the array will
-      // come after the node and so it's safe to add them as official
-      // trailingComments.
-      if (this.state.trailingComments[0].start >= node.end) {
-        trailingComments = this.state.trailingComments;
-        this.state.trailingComments = [];
-      } else {
-        // Otherwise, if the first comment doesn't come after the
-        // current node, that means we have a mix of leading and trailing
-        // comments in the array and that leadingComments contains the
-        // same items as trailingComments. Reset trailingComments to
-        // zero items and we'll handle this by evaluating leadingComments
-        // later.
-        this.state.trailingComments.length = 0;
-      }
-    } else if (stack.length > 0) {
-      const lastInStack = last(stack);
-      if (
-        lastInStack.trailingComments &&
-        lastInStack.trailingComments[0].start >= node.end
-      ) {
-        trailingComments = lastInStack.trailingComments;
-        delete lastInStack.trailingComments;
-      }
-    }
-
-    // Eating the stack.
-    if (stack.length > 0 && last(stack).start >= node.start) {
-      firstChild = stack.pop();
-    }
-
-    while (stack.length > 0 && last(stack).start >= node.start) {
-      lastChild = stack.pop();
-    }
-
-    if (!lastChild && firstChild) lastChild = firstChild;
-
-    // Adjust comments that follow a trailing comma on the last element in a
-    // comma separated list of nodes to be the trailing comments on the last
-    // element
-    if (firstChild) {
-      switch (node.type) {
-        case "ObjectExpression":
-          this.adjustCommentsAfterTrailingComma(node, node.properties);
-          break;
-        case "ObjectPattern":
-          this.adjustCommentsAfterTrailingComma(node, node.properties, true);
-          break;
-        case "CallExpression":
-          this.adjustCommentsAfterTrailingComma(node, node.arguments);
-          break;
-        case "ArrayExpression":
-          this.adjustCommentsAfterTrailingComma(node, node.elements);
-          break;
-        case "ArrayPattern":
-          this.adjustCommentsAfterTrailingComma(node, node.elements, true);
-          break;
-      }
-    } else if (
-      this.state.commentPreviousNode &&
-      ((this.state.commentPreviousNode.type === "ImportSpecifier" &&
-        node.type !== "ImportSpecifier") ||
-        (this.state.commentPreviousNode.type === "ExportSpecifier" &&
-          node.type !== "ExportSpecifier"))
-    ) {
-      this.adjustCommentsAfterTrailingComma(node, [
-        this.state.commentPreviousNode,
-      ]);
-    }
-
-    if (lastChild) {
-      if (lastChild.leadingComments) {
-        if (
-          lastChild !== node &&
-          lastChild.leadingComments.length > 0 &&
-          last(lastChild.leadingComments).end <= node.start
-        ) {
-          node.leadingComments = lastChild.leadingComments;
-          delete lastChild.leadingComments;
-        } else {
-          // A leading comment for an anonymous class had been stolen by its first ClassMethod,
-          // so this takes back the leading comment.
-          // See also: https://github.com/eslint/espree/issues/158
-          for (i = lastChild.leadingComments.length - 2; i >= 0; --i) {
-            if (lastChild.leadingComments[i].end <= node.start) {
-              node.leadingComments = lastChild.leadingComments.splice(0, i + 1);
-              break;
-            }
-          }
-        }
-      }
-    } else if (this.state.leadingComments.length > 0) {
-      if (last(this.state.leadingComments).end <= node.start) {
-        if (this.state.commentPreviousNode) {
-          for (j = 0; j < this.state.leadingComments.length; j++) {
-            if (
-              this.state.leadingComments[j].end <
-              this.state.commentPreviousNode.end
-            ) {
-              this.state.leadingComments.splice(j, 1);
-              j--;
-            }
-          }
-        }
-        if (this.state.leadingComments.length > 0) {
-          node.leadingComments = this.state.leadingComments;
-          this.state.leadingComments = [];
-        }
-      } else {
-        // https://github.com/eslint/espree/issues/2
-        //
-        // In special cases, such as return (without a value) and
-        // debugger, all comments will end up as leadingComments and
-        // will otherwise be eliminated. This step runs when the
-        // commentStack is empty and there are comments left
-        // in leadingComments.
-        //
-        // This loop figures out the stopping point between the actual
-        // leading and trailing comments by finding the location of the
-        // first comment that comes after the given node.
-        for (i = 0; i < this.state.leadingComments.length; i++) {
-          if (this.state.leadingComments[i].end > node.start) {
-            break;
-          }
-        }
-
-        // Split the array based on the location of the first comment
-        // that comes after the node. Keep in mind that this could
-        // result in an empty array, and if so, the array must be
-        // deleted.
-        const leadingComments = this.state.leadingComments.slice(0, i);
-
-        if (leadingComments.length) {
-          node.leadingComments = leadingComments;
-        }
-
-        // Similarly, trailing comments are attached later. The variable
-        // must be reset to null if there are no trailing comments.
-        trailingComments = this.state.leadingComments.slice(i);
-        if (trailingComments.length === 0) {
-          trailingComments = null;
-        }
-      }
-    }
-
-    this.state.commentPreviousNode = node;
-
-    if (trailingComments) {
-      if (
-        trailingComments.length &&
-        trailingComments[0].start >= node.start &&
-        last(trailingComments).end <= node.end
-      ) {
-        node.innerComments = trailingComments;
-      } else {
-        // TrailingComments maybe contain innerComments
-        const firstTrailingCommentIndex = trailingComments.findIndex(
-          comment => comment.end >= node.end,
-        );
-
-        if (firstTrailingCommentIndex > 0) {
-          node.innerComments = trailingComments.slice(
-            0,
-            firstTrailingCommentIndex,
-          );
-          node.trailingComments = trailingComments.slice(
-            firstTrailingCommentIndex,
-          );
-        } else {
-          node.trailingComments = trailingComments;
-        }
-      }
-    }
-
-    stack.push(node);
-  }
-
   processComment(node: Node): void {
     const { unattachedCommentStack } = this.state;
     const commentStackLength = unattachedCommentStack.length;
@@ -317,8 +65,9 @@ export default class CommentsParser extends BaseParser {
           if (containerNode.end - containerNode.start < node.end - nodeStart) {
             unattachedCommentStack.splice(i, 1);
           } else if (node.type !== "Program") {
-            // we have a node share the same length of containerNode, but its finishNode is invoked later
-            // than containerNode, so this node is the outer node. E.g. ExpressionStatement contains a VariableDeclaration
+            // we have a node with the same length of containerNode, but its finishNode is invoked later
+            // than containerNode, so this node is the outer node and should replace the inner node.
+            // E.g. ExpressionStatement contains a VariableDeclaration
             commentWS.containerNode = node;
           }
         }
@@ -342,6 +91,7 @@ export default class CommentsParser extends BaseParser {
           commentWS.trailingNode.leadingComments = commentWS.comments;
         }
       } else {
+        /*:: invariant(commentWS.containerNode !== null) */
         const {
           containerNode: node,
           comments,
@@ -351,18 +101,18 @@ export default class CommentsParser extends BaseParser {
           switch (node.type) {
             case "ObjectExpression":
             case "ObjectPattern":
-              this.adjustInnerComments(node, node.properties, comments);
+              adjustInnerComments(node, node.properties, comments);
               break;
             case "CallExpression":
-              this.adjustInnerComments(node, node.arguments, comments);
+              adjustInnerComments(node, node.arguments, comments);
               break;
             case "ArrayExpression":
             case "ArrayPattern":
-              this.adjustInnerComments(node, node.elements, comments);
+              adjustInnerComments(node, node.elements, comments);
               break;
             case "ExportNamedDeclaration":
             case "ImportDeclaration":
-              this.adjustInnerComments(node, node.specifiers, comments);
+              adjustInnerComments(node, node.specifiers, comments);
               break;
             default: {
               setInnerComments(node, comments);
@@ -374,20 +124,4 @@ export default class CommentsParser extends BaseParser {
       }
     }
   }
-
-  adjustInnerComments(node, elements, comments) {
-    let lastElement = null;
-    let i = elements.length;
-    while (lastElement === null && i > 0) {
-      lastElement = elements[--i];
-    }
-    if (lastElement === null) {
-      setInnerComments(node, comments);
-    }
-    if (lastElement.trailingComments === undefined) {
-      lastElement.trailingComments = comments;
-    } else {
-      lastElement.trailingComments.push(...comments);
-    }
-  }
 }
diff --git a/packages/babel-parser/src/tokenizer/index.js b/packages/babel-parser/src/tokenizer/index.js
index 5afdc2765142..f30e67283981 100644
--- a/packages/babel-parser/src/tokenizer/index.js
+++ b/packages/babel-parser/src/tokenizer/index.js
@@ -371,7 +371,7 @@ export default class Tokenizer extends ParserErrors {
   // Called at the start of the parse and after every token. Skips
   // whitespace and comments, and.
 
-  skipSpace(comments, spaceStart): void {
+  skipSpace(comments: Array<N.Comment>, spaceStart: number): void {
     loop: while (this.state.pos < this.length) {
       const ch = this.input.charCodeAt(this.state.pos);
       switch (ch) {
diff --git a/packages/babel-parser/src/tokenizer/state.js b/packages/babel-parser/src/tokenizer/state.js
index 23f9e31a8c56..5c2b2979e93f 100644
--- a/packages/babel-parser/src/tokenizer/state.js
+++ b/packages/babel-parser/src/tokenizer/state.js
@@ -89,16 +89,12 @@ export default class State {
   // where @foo belongs to the outer class and @bar to the inner
   decoratorStack: Array<Array<N.Decorator>> = [[]];
 
-  // Comment store.
+  // Comment store for Program.comments
   comments: Array<N.Comment> = [];
 
   // Comment attachment store
-  trailingComments: Array<N.Comment> = [];
-  leadingComments: Array<N.Comment> = [];
   unattachedCommentStack: Array<N.CommentWhitespace> = [];
   commentStack: Array<N.CommentWhitespace> = [];
-  // $FlowIgnore this is initialized when the parser starts.
-  commentPreviousNode: N.Node = null;
 
   // The current position of the tokenizer in the input.
   pos: number = 0;
diff --git a/packages/babel-parser/src/types.js b/packages/babel-parser/src/types.js
index b65d58a9fcb7..825d6d29139a 100644
--- a/packages/babel-parser/src/types.js
+++ b/packages/babel-parser/src/types.js
@@ -39,9 +39,9 @@ export type CommentWhitespace = {
   start: number,
   end: number,
   comments: Array<Comment>,
-  leadingNode: Node,
-  trailingNode: Node,
-  containerNode: Node,
+  leadingNode: Node | null,
+  trailingNode: Node | null,
+  containerNode: Node | null,
 };
 
 export interface NodeBase {

From fc79aa57d0daa005d5a82d5526b325d6264f6b66 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 12:48:19 -0400
Subject: [PATCH 05/35] update test fixtures

They are all bugfixes.
---
 .../core/uncategorised/342/output.json        | 13 +---
 .../output.json                               | 34 ++++----
 .../output.json                               | 34 ++++----
 .../05-type-annotation/output.json            | 11 +--
 .../export/internal-comments/output.json      | 73 ++++++++---------
 .../import/internal-comments/output.json      | 78 +++++++------------
 6 files changed, 108 insertions(+), 135 deletions(-)

diff --git a/packages/babel-parser/test/fixtures/core/uncategorised/342/output.json b/packages/babel-parser/test/fixtures/core/uncategorised/342/output.json
index d6ad31a3e965..ec31bddc3af2 100644
--- a/packages/babel-parser/test/fixtures/core/uncategorised/342/output.json
+++ b/packages/babel-parser/test/fixtures/core/uncategorised/342/output.json
@@ -16,27 +16,20 @@
           "left": {
             "type": "Identifier",
             "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
-            "name": "foo",
             "trailingComments": [
               {
                 "type": "CommentLine",
                 "value": "bar",
                 "start":4,"end":11,"loc":{"start":{"line":1,"column":4},"end":{"line":1,"column":11}}
               }
-            ]
+            ],
+            "name": "foo"
           },
           "operator": "+",
           "right": {
             "type": "Identifier",
             "start":13,"end":16,"loc":{"start":{"line":2,"column":1},"end":{"line":2,"column":4},"identifierName":"baz"},
-            "name": "baz",
-            "leadingComments": [
-              {
-                "type": "CommentLine",
-                "value": "bar",
-                "start":4,"end":11,"loc":{"start":{"line":1,"column":4},"end":{"line":1,"column":11}}
-              }
-            ]
+            "name": "baz"
           }
         }
       }
diff --git a/packages/babel-parser/test/fixtures/es2015/modules/export-declaration-trailing-comma/output.json b/packages/babel-parser/test/fixtures/es2015/modules/export-declaration-trailing-comma/output.json
index bbffebd77d3d..c4477428d18b 100644
--- a/packages/babel-parser/test/fixtures/es2015/modules/export-declaration-trailing-comma/output.json
+++ b/packages/babel-parser/test/fixtures/es2015/modules/export-declaration-trailing-comma/output.json
@@ -10,20 +10,17 @@
       {
         "type": "ExportNamedDeclaration",
         "start":0,"end":76,"loc":{"start":{"line":1,"column":0},"end":{"line":5,"column":24}},
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": " Four ",
+            "start":54,"end":64,"loc":{"start":{"line":5,"column":2},"end":{"line":5,"column":12}}
+          }
+        ],
         "specifiers": [
           {
             "type": "ExportSpecifier",
             "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15}},
-            "local": {
-              "type": "Identifier",
-              "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15},"identifierName":"Foo"},
-              "name": "Foo"
-            },
-            "exported": {
-              "type": "Identifier",
-              "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15},"identifierName":"Foo"},
-              "name": "Foo"
-            },
             "leadingComments": [
               {
                 "type": "CommentBlock",
@@ -41,13 +38,18 @@
                 "type": "CommentBlock",
                 "value": " Three ",
                 "start":40,"end":51,"loc":{"start":{"line":4,"column":2},"end":{"line":4,"column":13}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": " Four ",
-                "start":54,"end":64,"loc":{"start":{"line":5,"column":2},"end":{"line":5,"column":12}}
               }
-            ]
+            ],
+            "local": {
+              "type": "Identifier",
+              "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15},"identifierName":"Foo"},
+              "name": "Foo"
+            },
+            "exported": {
+              "type": "Identifier",
+              "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15},"identifierName":"Foo"},
+              "name": "Foo"
+            }
           }
         ],
         "source": {
diff --git a/packages/babel-parser/test/fixtures/es2015/modules/import-declaration-trailing-comma/output.json b/packages/babel-parser/test/fixtures/es2015/modules/import-declaration-trailing-comma/output.json
index a968e0267d23..88113201c290 100644
--- a/packages/babel-parser/test/fixtures/es2015/modules/import-declaration-trailing-comma/output.json
+++ b/packages/babel-parser/test/fixtures/es2015/modules/import-declaration-trailing-comma/output.json
@@ -10,20 +10,17 @@
       {
         "type": "ImportDeclaration",
         "start":0,"end":76,"loc":{"start":{"line":1,"column":0},"end":{"line":5,"column":24}},
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": " Four ",
+            "start":54,"end":64,"loc":{"start":{"line":5,"column":2},"end":{"line":5,"column":12}}
+          }
+        ],
         "specifiers": [
           {
             "type": "ImportSpecifier",
             "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15}},
-            "imported": {
-              "type": "Identifier",
-              "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15},"identifierName":"Foo"},
-              "name": "Foo"
-            },
-            "local": {
-              "type": "Identifier",
-              "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15},"identifierName":"Foo"},
-              "name": "Foo"
-            },
             "leadingComments": [
               {
                 "type": "CommentBlock",
@@ -41,13 +38,18 @@
                 "type": "CommentBlock",
                 "value": " Three ",
                 "start":40,"end":51,"loc":{"start":{"line":4,"column":2},"end":{"line":4,"column":13}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": " Four ",
-                "start":54,"end":64,"loc":{"start":{"line":5,"column":2},"end":{"line":5,"column":12}}
               }
-            ]
+            ],
+            "imported": {
+              "type": "Identifier",
+              "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15},"identifierName":"Foo"},
+              "name": "Foo"
+            },
+            "local": {
+              "type": "Identifier",
+              "start":21,"end":24,"loc":{"start":{"line":2,"column":12},"end":{"line":2,"column":15},"identifierName":"Foo"},
+              "name": "Foo"
+            }
           }
         ],
         "source": {
diff --git a/packages/babel-parser/test/fixtures/flow/comment-disabled/05-type-annotation/output.json b/packages/babel-parser/test/fixtures/flow/comment-disabled/05-type-annotation/output.json
index 1735a998c005..9c7b8a84677b 100644
--- a/packages/babel-parser/test/fixtures/flow/comment-disabled/05-type-annotation/output.json
+++ b/packages/babel-parser/test/fixtures/flow/comment-disabled/05-type-annotation/output.json
@@ -34,20 +34,15 @@
         "body": {
           "type": "BlockStatement",
           "start":51,"end":54,"loc":{"start":{"line":1,"column":51},"end":{"line":2,"column":1}},
-          "body": [],
-          "directives": [],
           "leadingComments": [
-            {
-              "type": "CommentBlock",
-              "value": ": string ",
-              "start":22,"end":35,"loc":{"start":{"line":1,"column":22},"end":{"line":1,"column":35}}
-            },
             {
               "type": "CommentBlock",
               "value": ": number ",
               "start":37,"end":50,"loc":{"start":{"line":1,"column":37},"end":{"line":1,"column":50}}
             }
-          ]
+          ],
+          "body": [],
+          "directives": []
         }
       }
     ],
diff --git a/packages/babel-parser/test/fixtures/typescript/export/internal-comments/output.json b/packages/babel-parser/test/fixtures/typescript/export/internal-comments/output.json
index 3bea67d601ae..28d3759266d5 100644
--- a/packages/babel-parser/test/fixtures/typescript/export/internal-comments/output.json
+++ b/packages/babel-parser/test/fixtures/typescript/export/internal-comments/output.json
@@ -24,17 +24,24 @@
             "start":94,"end":99,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":5}}
           }
         ],
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": "2",
+            "start":13,"end":18,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":18}}
+          },
+          {
+            "type": "CommentBlock",
+            "value": "9",
+            "start":69,"end":74,"loc":{"start":{"line":1,"column":69},"end":{"line":1,"column":74}}
+          }
+        ],
         "exportKind": "value",
         "specifiers": [
           {
             "type": "ExportSpecifier",
             "start":27,"end":28,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":28}},
             "leadingComments": [
-              {
-                "type": "CommentBlock",
-                "value": "2",
-                "start":13,"end":18,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":18}}
-              },
               {
                 "type": "CommentBlock",
                 "value": "3",
@@ -46,11 +53,6 @@
                 "type": "CommentBlock",
                 "value": "4",
                 "start":29,"end":34,"loc":{"start":{"line":1,"column":29},"end":{"line":1,"column":34}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "5",
-                "start":36,"end":41,"loc":{"start":{"line":1,"column":36},"end":{"line":1,"column":41}}
               }
             ],
             "local": {
@@ -67,21 +69,18 @@
           {
             "type": "ExportSpecifier",
             "start":42,"end":60,"loc":{"start":{"line":1,"column":42},"end":{"line":1,"column":60}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": "5",
+                "start":36,"end":41,"loc":{"start":{"line":1,"column":36},"end":{"line":1,"column":41}}
+              }
+            ],
             "trailingComments": [
               {
                 "type": "CommentBlock",
                 "value": "8",
                 "start":61,"end":66,"loc":{"start":{"line":1,"column":61},"end":{"line":1,"column":66}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "9",
-                "start":69,"end":74,"loc":{"start":{"line":1,"column":69},"end":{"line":1,"column":74}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "10",
-                "start":80,"end":86,"loc":{"start":{"line":1,"column":80},"end":{"line":1,"column":86}}
               }
             ],
             "local": {
@@ -100,11 +99,6 @@
               "type": "Identifier",
               "start":59,"end":60,"loc":{"start":{"line":1,"column":59},"end":{"line":1,"column":60},"identifierName":"C"},
               "leadingComments": [
-                {
-                  "type": "CommentBlock",
-                  "value": "6",
-                  "start":44,"end":49,"loc":{"start":{"line":1,"column":44},"end":{"line":1,"column":49}}
-                },
                 {
                   "type": "CommentBlock",
                   "value": "7",
@@ -118,6 +112,13 @@
         "source": {
           "type": "StringLiteral",
           "start":87,"end":92,"loc":{"start":{"line":1,"column":87},"end":{"line":1,"column":92}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "10",
+              "start":80,"end":86,"loc":{"start":{"line":1,"column":80},"end":{"line":1,"column":86}}
+            }
+          ],
           "extra": {
             "rawValue": "foo",
             "raw": "\"foo\""
@@ -136,21 +137,23 @@
             "start":94,"end":99,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":5}}
           }
         ],
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": "2",
+            "start":107,"end":112,"loc":{"start":{"line":2,"column":13},"end":{"line":2,"column":18}}
+          },
+          {
+            "type": "CommentBlock",
+            "value": "3",
+            "start":115,"end":120,"loc":{"start":{"line":2,"column":21},"end":{"line":2,"column":26}}
+          }
+        ],
         "exportKind": "value",
         "source": {
           "type": "StringLiteral",
           "start":132,"end":137,"loc":{"start":{"line":2,"column":38},"end":{"line":2,"column":43}},
           "leadingComments": [
-            {
-              "type": "CommentBlock",
-              "value": "2",
-              "start":107,"end":112,"loc":{"start":{"line":2,"column":13},"end":{"line":2,"column":18}}
-            },
-            {
-              "type": "CommentBlock",
-              "value": "3",
-              "start":115,"end":120,"loc":{"start":{"line":2,"column":21},"end":{"line":2,"column":26}}
-            },
             {
               "type": "CommentBlock",
               "value": "4",
diff --git a/packages/babel-parser/test/fixtures/typescript/import/internal-comments/output.json b/packages/babel-parser/test/fixtures/typescript/import/internal-comments/output.json
index 909242f2af20..fbbb3ba324ab 100644
--- a/packages/babel-parser/test/fixtures/typescript/import/internal-comments/output.json
+++ b/packages/babel-parser/test/fixtures/typescript/import/internal-comments/output.json
@@ -24,6 +24,13 @@
             "start":111,"end":116,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":5}}
           }
         ],
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": "11",
+            "start":85,"end":91,"loc":{"start":{"line":1,"column":85},"end":{"line":1,"column":91}}
+          }
+        ],
         "importKind": "value",
         "specifiers": [
           {
@@ -53,26 +60,6 @@
             "type": "ImportSpecifier",
             "start":42,"end":43,"loc":{"start":{"line":1,"column":42},"end":{"line":1,"column":43}},
             "leadingComments": [
-              {
-                "type": "CommentBlock",
-                "value": "1",
-                "start":0,"end":5,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":5}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "2",
-                "start":13,"end":18,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":18}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "3",
-                "start":21,"end":26,"loc":{"start":{"line":1,"column":21},"end":{"line":1,"column":26}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "4",
-                "start":28,"end":33,"loc":{"start":{"line":1,"column":28},"end":{"line":1,"column":33}}
-              },
               {
                 "type": "CommentBlock",
                 "value": "5",
@@ -84,11 +71,6 @@
                 "type": "CommentBlock",
                 "value": "6",
                 "start":44,"end":49,"loc":{"start":{"line":1,"column":44},"end":{"line":1,"column":49}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "7",
-                "start":51,"end":56,"loc":{"start":{"line":1,"column":51},"end":{"line":1,"column":56}}
               }
             ],
             "imported": {
@@ -105,21 +87,18 @@
           {
             "type": "ImportSpecifier",
             "start":57,"end":75,"loc":{"start":{"line":1,"column":57},"end":{"line":1,"column":75}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": "7",
+                "start":51,"end":56,"loc":{"start":{"line":1,"column":51},"end":{"line":1,"column":56}}
+              }
+            ],
             "trailingComments": [
               {
                 "type": "CommentBlock",
                 "value": "10",
                 "start":76,"end":82,"loc":{"start":{"line":1,"column":76},"end":{"line":1,"column":82}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "11",
-                "start":85,"end":91,"loc":{"start":{"line":1,"column":85},"end":{"line":1,"column":91}}
-              },
-              {
-                "type": "CommentBlock",
-                "value": "12",
-                "start":97,"end":103,"loc":{"start":{"line":1,"column":97},"end":{"line":1,"column":103}}
               }
             ],
             "imported": {
@@ -138,11 +117,6 @@
               "type": "Identifier",
               "start":74,"end":75,"loc":{"start":{"line":1,"column":74},"end":{"line":1,"column":75},"identifierName":"C"},
               "leadingComments": [
-                {
-                  "type": "CommentBlock",
-                  "value": "8",
-                  "start":59,"end":64,"loc":{"start":{"line":1,"column":59},"end":{"line":1,"column":64}}
-                },
                 {
                   "type": "CommentBlock",
                   "value": "9",
@@ -156,6 +130,13 @@
         "source": {
           "type": "StringLiteral",
           "start":104,"end":109,"loc":{"start":{"line":1,"column":104},"end":{"line":1,"column":109}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "12",
+              "start":97,"end":103,"loc":{"start":{"line":1,"column":97},"end":{"line":1,"column":103}}
+            }
+          ],
           "extra": {
             "rawValue": "foo",
             "raw": "\"foo\""
@@ -192,15 +173,17 @@
                 "start":151,"end":156,"loc":{"start":{"line":2,"column":40},"end":{"line":2,"column":45}}
               }
             ],
+            "innerComments": [
+              {
+                "type": "CommentBlock",
+                "value": "3",
+                "start":132,"end":137,"loc":{"start":{"line":2,"column":21},"end":{"line":2,"column":26}}
+              }
+            ],
             "local": {
               "type": "Identifier",
               "start":147,"end":150,"loc":{"start":{"line":2,"column":36},"end":{"line":2,"column":39},"identifierName":"foo"},
               "leadingComments": [
-                {
-                  "type": "CommentBlock",
-                  "value": "3",
-                  "start":132,"end":137,"loc":{"start":{"line":2,"column":21},"end":{"line":2,"column":26}}
-                },
                 {
                   "type": "CommentBlock",
                   "value": "4",
@@ -215,11 +198,6 @@
           "type": "StringLiteral",
           "start":168,"end":173,"loc":{"start":{"line":2,"column":57},"end":{"line":2,"column":62}},
           "leadingComments": [
-            {
-              "type": "CommentBlock",
-              "value": "5",
-              "start":151,"end":156,"loc":{"start":{"line":2,"column":40},"end":{"line":2,"column":45}}
-            },
             {
               "type": "CommentBlock",
               "value": "6",

From add886e563bbd69e113ce4440e5d1d6f840a094e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 17:50:27 -0400
Subject: [PATCH 06/35] fix: merge HTMLComment parsing to skipSpace

---
 packages/babel-parser/src/tokenizer/index.js | 76 ++++++++++----------
 1 file changed, 36 insertions(+), 40 deletions(-)

diff --git a/packages/babel-parser/src/tokenizer/index.js b/packages/babel-parser/src/tokenizer/index.js
index f30e67283981..c3b868939e15 100644
--- a/packages/babel-parser/src/tokenizer/index.js
+++ b/packages/babel-parser/src/tokenizer/index.js
@@ -288,7 +288,7 @@ export default class Tokenizer extends ParserErrors {
 
   nextToken(): void {
     const curContext = this.curContext();
-    if (!curContext.preserveSpace) this.skipSpace([], this.state.pos);
+    if (!curContext.preserveSpace) this.skipSpace();
     this.state.start = this.state.pos;
     if (!this.isLookahead) this.state.startLoc = this.state.curPosition();
     if (this.state.pos >= this.length) {
@@ -371,7 +371,9 @@ export default class Tokenizer extends ParserErrors {
   // Called at the start of the parse and after every token. Skips
   // whitespace and comments, and.
 
-  skipSpace(comments: Array<N.Comment>, spaceStart: number): void {
+  skipSpace(): void {
+    const spaceStart = this.state.pos;
+    const comments = [];
     loop: while (this.state.pos < this.length) {
       const ch = this.input.charCodeAt(this.state.pos);
       switch (ch) {
@@ -423,6 +425,38 @@ export default class Tokenizer extends ParserErrors {
         default:
           if (isWhitespace(ch)) {
             ++this.state.pos;
+          } else if (ch === charCodes.dash && !this.inModule) {
+            const pos = this.state.pos;
+            if (
+              this.input.charCodeAt(pos + 1) === charCodes.dash &&
+              this.input.charCodeAt(pos + 2) === charCodes.greaterThan &&
+              (spaceStart === 0 || this.state.lineStart > spaceStart)
+            ) {
+              // A `-->` line comment
+              const comment = this.skipLineComment(3);
+              if (comment !== undefined) {
+                this.addComment(comment);
+                comments.push(comment);
+              }
+            } else {
+              break loop;
+            }
+          } else if (ch === charCodes.lessThan && !this.inModule) {
+            const pos = this.state.pos;
+            if (
+              this.input.charCodeAt(pos + 1) === charCodes.exclamationMark &&
+              this.input.charCodeAt(pos + 2) === charCodes.dash &&
+              this.input.charCodeAt(pos + 3) === charCodes.dash
+            ) {
+              // `<!--`, an XML-style comment that should be interpreted as a line comment
+              const comment = this.skipLineComment(4);
+              if (comment !== undefined) {
+                this.addComment(comment);
+                comments.push(comment);
+              }
+            } else {
+              break loop;
+            }
           } else {
             break loop;
           }
@@ -669,24 +703,6 @@ export default class Tokenizer extends ParserErrors {
     const next = this.input.charCodeAt(this.state.pos + 1);
 
     if (next === code) {
-      if (
-        next === charCodes.dash &&
-        !this.inModule &&
-        this.input.charCodeAt(this.state.pos + 2) === charCodes.greaterThan &&
-        (this.state.lastTokEnd === 0 || this.hasPrecedingLineBreak())
-      ) {
-        // A `-->` line comment
-        const whitespaceStart = this.state.lastTokEnd;
-        const comment = this.skipLineComment(3);
-        const comments = [];
-        if (comment !== undefined) {
-          this.addComment(comment);
-          comments.push(comment);
-        }
-        this.skipSpace(comments, whitespaceStart);
-        this.nextToken();
-        return;
-      }
       this.finishOp(tt.incDec, 2);
       return;
     }
@@ -717,26 +733,6 @@ export default class Tokenizer extends ParserErrors {
       return;
     }
 
-    if (
-      next === charCodes.exclamationMark &&
-      code === charCodes.lessThan &&
-      !this.inModule &&
-      this.input.charCodeAt(this.state.pos + 2) === charCodes.dash &&
-      this.input.charCodeAt(this.state.pos + 3) === charCodes.dash
-    ) {
-      // `<!--`, an XML-style comment that should be interpreted as a line comment
-      const whitespaceStart = this.state.lastTokEnd;
-      const comment = this.skipLineComment(4);
-      const comments = [];
-      if (comment !== undefined) {
-        this.addComment(comment);
-        comments.push(comment);
-      }
-      this.skipSpace(comments, whitespaceStart);
-      this.nextToken();
-      return;
-    }
-
     if (next === charCodes.equalsTo) {
       // <= | >=
       size = 2;

From d10e5839a2e71f80160c0754ff6519a38b58b3c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 18:08:50 -0400
Subject: [PATCH 07/35] perf: remove unattachedCommentStack
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

baseline 128 nested leading comments: 11_034 ops/sec ±50.64% (0.091ms)
baseline 256 nested leading comments: 6_037 ops/sec ±11.46% (0.166ms)
baseline 512 nested leading comments: 3_077 ops/sec ±2.31% (0.325ms)
baseline 1024 nested leading comments: 1_374 ops/sec ±3.22% (0.728ms)
current 128 nested leading comments: 11_027 ops/sec ±37.41% (0.091ms)
current 256 nested leading comments: 6_736 ops/sec ±1.39% (0.148ms)
current 512 nested leading comments: 3_306 ops/sec ±0.69% (0.302ms)
current 1024 nested leading comments: 1_579 ops/sec ±2.09% (0.633ms)

baseline 128 nested trailing comments: 10_073 ops/sec ±42.95% (0.099ms)
baseline 256 nested trailing comments: 6_294 ops/sec ±2.19% (0.159ms)
baseline 512 nested trailing comments: 3_041 ops/sec ±0.8% (0.329ms)
baseline 1024 nested trailing comments: 1_530 ops/sec ±1.18% (0.654ms)
current 128 nested trailing comments: 11_461 ops/sec ±44.89% (0.087ms)
current 256 nested trailing comments: 7_212 ops/sec ±1.6% (0.139ms)
current 512 nested trailing comments: 3_403 ops/sec ±1% (0.294ms)
current 1024 nested trailing comments: 1_539 ops/sec ±1.49% (0.65ms)
---
 .../many-trailing-comments-nested/bench.mjs   |   2 +-
 packages/babel-parser/src/parser/comments.js  | 186 ++++++++++++------
 .../babel-parser/src/parser/expression.js     |   2 +-
 packages/babel-parser/src/parser/statement.js |   2 +-
 packages/babel-parser/src/tokenizer/index.js  |   1 -
 packages/babel-parser/src/tokenizer/state.js  |   1 -
 .../import/internal-comments/output.json      |   7 +-
 7 files changed, 135 insertions(+), 66 deletions(-)

diff --git a/packages/babel-parser/benchmark/many-trailing-comments-nested/bench.mjs b/packages/babel-parser/benchmark/many-trailing-comments-nested/bench.mjs
index 44c61d88cbf0..ae9fc2b0a7ad 100644
--- a/packages/babel-parser/benchmark/many-trailing-comments-nested/bench.mjs
+++ b/packages/babel-parser/benchmark/many-trailing-comments-nested/bench.mjs
@@ -10,7 +10,7 @@ function createInput(length) {
 function benchCases(name, implementation, options) {
   for (const length of [128, 256, 512, 1024]) {
     const input = createInput(length);
-    suite.add(`${name} ${length} trailing comments`, () => {
+    suite.add(`${name} ${length} nested trailing comments`, () => {
       implementation.parse(input, options);
     });
   }
diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index e802c39c8d4a..38bb74144b49 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -3,33 +3,62 @@
 /*:: declare var invariant; */
 
 import BaseParser from "./base";
-import type { Comment, Node } from "../types";
+import type { Comment, Node, CommentWhitespace } from "../types";
 import * as charCodes from "charcodes";
 
+/**
+ * Merge comments with node's trailingComments or assign comments to be
+ * trailingComments.
+ *
+ * @param {Node} node
+ * @param {Array<Comment>} comments
+ */
+function setTrailingComments(node: Node, comments: Array<Comment>) {
+  if (node.trailingComments === undefined) {
+    node.trailingComments = comments;
+  } else {
+    node.trailingComments.unshift(...comments);
+  }
+}
+
+/**
+ * Merge comments with node's innerComments or assign comments to be
+ * innerComments.
+ *
+ * @param {Node} node
+ * @param {Array<Comment>} comments
+ */
 function setInnerComments(node: Node, comments: Array<Comment>) {
   if (node.innerComments === undefined) {
     node.innerComments = comments;
   } else {
-    node.innerComments.push(...comments);
+    node.innerComments.unshift(...comments);
   }
 }
 
+/**
+ * Given node and elements array, if elements has non-null element,
+ * merge comments to its trailingComments, otherwise merge comments
+ * to node's innerComments
+ *
+ * @param {Node} node
+ * @param {Array<Node>} elements
+ * @param {Array<Comment>} comments
+ */
 function adjustInnerComments(
   node: Node,
   elements: Array<Node>,
-  comments: Array<Comment>,
+  commentWS: CommentWhitespace,
 ) {
   let lastElement = null;
   let i = elements.length;
   while (lastElement === null && i > 0) {
     lastElement = elements[--i];
   }
-  if (lastElement === null) {
-    setInnerComments(node, comments);
-  } else if (lastElement.trailingComments === undefined) {
-    lastElement.trailingComments = comments;
+  if (lastElement === null || lastElement.start > commentWS.start) {
+    setInnerComments(node, commentWS.comments);
   } else {
-    lastElement.trailingComments.push(...comments);
+    setTrailingComments(lastElement, commentWS.comments);
   }
 }
 
@@ -39,21 +68,32 @@ export default class CommentsParser extends BaseParser {
     this.state.comments.push(comment);
   }
 
+  /**
+   * Given a newly created AST node _n_, attach _n_ to a comment whitespace _w_ if
+   * _n_ immediately precedes or follows _w_, or _n_ is the outermost AST node containing
+   * _w_ with minimal length (|end - start|)
+   *
+   * @param {Node} node
+   * @returns {void}
+   * @memberof CommentsParser
+   */
   processComment(node: Node): void {
-    const { unattachedCommentStack } = this.state;
-    const commentStackLength = unattachedCommentStack.length;
+    const { commentStack } = this.state;
+    const commentStackLength = commentStack.length;
     if (commentStackLength === 0) return;
     let i = commentStackLength - 1;
-    const lastComments = unattachedCommentStack[i];
+    const lastCommentWS = commentStack[i];
 
-    if (lastComments.start === node.end) {
-      lastComments.leadingNode = node;
+    const nodeEnd = node.end;
+    if (lastCommentWS.start === nodeEnd) {
+      lastCommentWS.leadingNode = node;
       i--;
     }
-    // invariant: for all 0 <= j <= i, c = commentStack[j] satisfies c.end < node.end
+
+    // invariant: for all 0 <= j <= i, let c = commentStack[j], c must satisfy c.end < node.end
     const nodeStart = node.start;
     for (; i >= 0; i--) {
-      const commentWS = unattachedCommentStack[i];
+      const commentWS = commentStack[i];
       const commentEnd = commentWS.end;
       if (commentEnd > nodeStart) {
         // by definition of commentWhiteSpace, this implies commentWS.start > nodeStart
@@ -62,8 +102,17 @@ export default class CommentsParser extends BaseParser {
         if (containerNode === null) {
           commentWS.containerNode = node;
         } else {
-          if (containerNode.end - containerNode.start < node.end - nodeStart) {
-            unattachedCommentStack.splice(i, 1);
+          if (containerNode.end - containerNode.start < nodeEnd - nodeStart) {
+            // a commentWhitespace is considered _attached_ if
+            // 1) its leadingNode or trailingNode, if exists, will not change
+            // 2) its containerNode have the minimum node length among all other
+            //    nodes containing the commentWhitespace
+            // In other words, an attached comment whitespace have fixed associated
+            // AST node and thus we can finalize the comment whitespace
+            // Note that there could be remaining commentWS after the Program node is finished,
+            // in this case they will be handled by {@link CommentParser#finalizeRemainingComments}
+            this.finalizeComment(commentWS);
+            commentStack.splice(i, 1);
           } else if (node.type !== "Program") {
             // we have a node with the same length of containerNode, but its finishNode is invoked later
             // than containerNode, so this node is the outer node and should replace the inner node.
@@ -71,57 +120,74 @@ export default class CommentsParser extends BaseParser {
             commentWS.containerNode = node;
           }
         }
-      } else if (commentEnd === nodeStart) {
-        commentWS.trailingNode = node;
+      } else {
+        if (commentEnd === nodeStart) {
+          commentWS.trailingNode = node;
+        }
         break;
       }
     }
   }
 
-  finalizeComment() {
-    const { commentStack } = this.state;
-    const commentStackLength = commentStack.length;
-    for (let i = 0; i < commentStackLength; i++) {
-      const commentWS = commentStack[i];
-      if (commentWS.leadingNode !== null || commentWS.trailingNode !== null) {
-        if (commentWS.leadingNode !== null) {
-          commentWS.leadingNode.trailingComments = commentWS.comments;
-        }
-        if (commentWS.trailingNode !== null) {
-          commentWS.trailingNode.leadingComments = commentWS.comments;
-        }
-      } else {
-        /*:: invariant(commentWS.containerNode !== null) */
-        const {
-          containerNode: node,
-          comments,
-          start: commentStart,
-        } = commentWS;
-        if (this.input.charCodeAt(commentStart - 1) === charCodes.comma) {
-          switch (node.type) {
-            case "ObjectExpression":
-            case "ObjectPattern":
-              adjustInnerComments(node, node.properties, comments);
-              break;
-            case "CallExpression":
-              adjustInnerComments(node, node.arguments, comments);
-              break;
-            case "ArrayExpression":
-            case "ArrayPattern":
-              adjustInnerComments(node, node.elements, comments);
-              break;
-            case "ExportNamedDeclaration":
-            case "ImportDeclaration":
-              adjustInnerComments(node, node.specifiers, comments);
-              break;
-            default: {
-              setInnerComments(node, comments);
-            }
+  /**
+   * Assign the comments of comment whitespaces to related AST nodes.
+   * Also adjust innerComments following trailing comma.
+   *
+   * @memberof CommentsParser
+   */
+  finalizeComment(commentWS: CommentWhitespace) {
+    const { comments } = commentWS;
+    if (commentWS.leadingNode !== null || commentWS.trailingNode !== null) {
+      if (commentWS.leadingNode !== null) {
+        setTrailingComments(commentWS.leadingNode, comments);
+      }
+      if (commentWS.trailingNode !== null) {
+        commentWS.trailingNode.leadingComments = comments;
+      }
+    } else {
+      /*:: invariant(commentWS.containerNode !== null) */
+      const { containerNode: node, start: commentStart } = commentWS;
+      if (this.input.charCodeAt(commentStart - 1) === charCodes.comma) {
+        // If a commentWhitespace follows a comma and the containerNode allows
+        // list structures with trailing comma, merge it to the trailingComment
+        // of the last non-null list element
+        switch (node.type) {
+          case "ObjectExpression":
+          case "ObjectPattern":
+            adjustInnerComments(node, node.properties, commentWS);
+            break;
+          case "CallExpression":
+            adjustInnerComments(node, node.arguments, commentWS);
+            break;
+          case "ArrayExpression":
+          case "ArrayPattern":
+            adjustInnerComments(node, node.elements, commentWS);
+            break;
+          case "ExportNamedDeclaration":
+          case "ImportDeclaration":
+            adjustInnerComments(node, node.specifiers, commentWS);
+            break;
+          default: {
+            setInnerComments(node, comments);
           }
-        } else {
-          setInnerComments(node, comments);
         }
+      } else {
+        setInnerComments(node, comments);
       }
     }
   }
+
+  /**
+   * Drains remaning commentStack and applies {@link CommentParser#finalizeComment}
+   * to each comment whitespace.
+   *
+   * @memberof CommentsParser
+   */
+  finalizeRemainingComments() {
+    const { commentStack } = this.state;
+    for (let i = commentStack.length - 1; i >= 0; i--) {
+      this.finalizeComment(commentStack[i]);
+    }
+    this.state.commentStack = [];
+  }
 }
diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 1d4d583fca4d..6c2aee761e86 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -161,7 +161,7 @@ export default class ExpressionParser extends LValParser {
     if (!this.match(tt.eof)) {
       this.unexpected();
     }
-    this.finalizeComment();
+    this.finalizeRemainingComments();
     expr.comments = this.state.comments;
     expr.errors = this.state.errors;
     if (this.options.tokens) {
diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
index 56a21f452abc..f19fa9a0f79a 100644
--- a/packages/babel-parser/src/parser/statement.js
+++ b/packages/babel-parser/src/parser/statement.js
@@ -99,7 +99,7 @@ export default class StatementParser extends ExpressionParser {
 
   parseTopLevel(file: N.File, program: N.Program): N.File {
     file.program = this.parseProgram(program);
-    this.finalizeComment();
+    this.finalizeRemainingComments();
     file.comments = this.state.comments;
 
     if (this.options.tokens) file.tokens = babel7CompatTokens(this.tokens);
diff --git a/packages/babel-parser/src/tokenizer/index.js b/packages/babel-parser/src/tokenizer/index.js
index c3b868939e15..bd2f059391f7 100644
--- a/packages/babel-parser/src/tokenizer/index.js
+++ b/packages/babel-parser/src/tokenizer/index.js
@@ -474,7 +474,6 @@ export default class Tokenizer extends ParserErrors {
         containerNode: null,
       };
       this.state.commentStack.push(CommentWhitespace);
-      this.state.unattachedCommentStack.push(CommentWhitespace);
     }
   }
 
diff --git a/packages/babel-parser/src/tokenizer/state.js b/packages/babel-parser/src/tokenizer/state.js
index 5c2b2979e93f..77e033b34a01 100644
--- a/packages/babel-parser/src/tokenizer/state.js
+++ b/packages/babel-parser/src/tokenizer/state.js
@@ -93,7 +93,6 @@ export default class State {
   comments: Array<N.Comment> = [];
 
   // Comment attachment store
-  unattachedCommentStack: Array<N.CommentWhitespace> = [];
   commentStack: Array<N.CommentWhitespace> = [];
 
   // The current position of the tokenizer in the input.
diff --git a/packages/babel-parser/test/fixtures/typescript/import/internal-comments/output.json b/packages/babel-parser/test/fixtures/typescript/import/internal-comments/output.json
index fbbb3ba324ab..cdec7ba32561 100644
--- a/packages/babel-parser/test/fixtures/typescript/import/internal-comments/output.json
+++ b/packages/babel-parser/test/fixtures/typescript/import/internal-comments/output.json
@@ -25,6 +25,11 @@
           }
         ],
         "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": "4",
+            "start":28,"end":33,"loc":{"start":{"line":1,"column":28},"end":{"line":1,"column":33}}
+          },
           {
             "type": "CommentBlock",
             "value": "11",
@@ -306,4 +311,4 @@
       "start":162,"end":167,"loc":{"start":{"line":2,"column":51},"end":{"line":2,"column":56}}
     }
   ]
-}
\ No newline at end of file
+}

From 54e7974c0e4dc34ce50c5d3f6239395db283ed95 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 18:24:57 -0400
Subject: [PATCH 08/35] fix: do not expose CommentWhitespace type

---
 packages/babel-parser/src/parser/comments.js | 11 ++++++++++-
 packages/babel-parser/src/tokenizer/state.js |  3 ++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 38bb74144b49..6c0437b7bcec 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -3,9 +3,18 @@
 /*:: declare var invariant; */
 
 import BaseParser from "./base";
-import type { Comment, Node, CommentWhitespace } from "../types";
+import type { Comment, Node } from "../types";
 import * as charCodes from "charcodes";
 
+// A whitespace containing comments
+export type CommentWhitespace = {
+  start: number,
+  end: number,
+  comments: Array<Comment>,
+  leadingNode: Node | null,
+  trailingNode: Node | null,
+  containerNode: Node | null,
+};
 /**
  * Merge comments with node's trailingComments or assign comments to be
  * trailingComments.
diff --git a/packages/babel-parser/src/tokenizer/state.js b/packages/babel-parser/src/tokenizer/state.js
index 77e033b34a01..b46819164f8d 100644
--- a/packages/babel-parser/src/tokenizer/state.js
+++ b/packages/babel-parser/src/tokenizer/state.js
@@ -2,6 +2,7 @@
 
 import type { Options } from "../options";
 import * as N from "../types";
+import type { CommentWhitespace } from "../parser/comments";
 import { Position } from "../util/location";
 
 import { types as ct, type TokContext } from "./context";
@@ -93,7 +94,7 @@ export default class State {
   comments: Array<N.Comment> = [];
 
   // Comment attachment store
-  commentStack: Array<N.CommentWhitespace> = [];
+  commentStack: Array<CommentWhitespace> = [];
 
   // The current position of the tokenizer in the input.
   pos: number = 0;

From 1366fc61d5869e29043e127db5e2b1ae688070b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 19:03:24 -0400
Subject: [PATCH 09/35] add comments on CommentWhitespace

---
 packages/babel-parser/src/parser/comments.js | 22 +++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 6c0437b7bcec..d33d90a3d896 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -6,7 +6,18 @@ import BaseParser from "./base";
 import type { Comment, Node } from "../types";
 import * as charCodes from "charcodes";
 
-// A whitespace containing comments
+/**
+ * A whitespace token containing comments
+ * @typedef CommentWhitespace
+ * @type {object}
+ * @property {number} start - the start of the whitespace token.
+ * @property {number} end - the end of the whitespace token.
+ * @property {Array<Comment>} comments - the containing comments
+ * @property {Node | null} leadingNode - the immediately preceding AST node of the whitespace token
+ * @property {Node | null} trailingNode - the immediately following AST node of the whitespace token
+ * @property {Node | null} containerNode - the outermost AST node containing the whitespace
+ *                                         with minimal size (|end - start|)
+ */
 export type CommentWhitespace = {
   start: number,
   end: number,
@@ -71,6 +82,7 @@ function adjustInnerComments(
   }
 }
 
+/** @class CommentsParser */
 export default class CommentsParser extends BaseParser {
   addComment(comment: Comment): void {
     if (this.filename) comment.loc.filename = this.filename;
@@ -78,9 +90,8 @@ export default class CommentsParser extends BaseParser {
   }
 
   /**
-   * Given a newly created AST node _n_, attach _n_ to a comment whitespace _w_ if
-   * _n_ immediately precedes or follows _w_, or _n_ is the outermost AST node containing
-   * _w_ with minimal length (|end - start|)
+   * Given a newly created AST node _n_, attach _n_ to a comment whitespace _w_ if applicable
+   * {@see {@link CommentWhitespace}}
    *
    * @param {Node} node
    * @returns {void}
@@ -187,8 +198,9 @@ export default class CommentsParser extends BaseParser {
   }
 
   /**
-   * Drains remaning commentStack and applies {@link CommentParser#finalizeComment}
+   * Drains remaning commentStack and applies finalizeComment
    * to each comment whitespace.
+   * {@see {@link CommentsParser#finalizeComment}}
    *
    * @memberof CommentsParser
    */

From ac59810fb2faec1709cbf11db21e3efd1295bf64 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 19:12:21 -0400
Subject: [PATCH 10/35] add test case for #11576

---
 .../call-expression-no-argument/input.js      |  1 +
 .../call-expression-no-argument/output.json   | 53 +++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/output.json

diff --git a/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/input.js b/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/input.js
new file mode 100644
index 000000000000..cf094ddddbeb
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/input.js
@@ -0,0 +1 @@
+foo /* 1 */ (/* 2 */)
diff --git a/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/output.json b/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/output.json
new file mode 100644
index 000000000000..1a52ab79278f
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/output.json
@@ -0,0 +1,53 @@
+{
+  "type": "File",
+  "start":0,"end":21,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":21}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":21,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":21}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":21,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":21}},
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 2 ",
+            "start":13,"end":20,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":20}}
+          }
+        ],
+        "expression": {
+          "type": "CallExpression",
+          "start":0,"end":21,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":21}},
+          "callee": {
+            "type": "Identifier",
+            "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+            "trailingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 1 ",
+                "start":4,"end":11,"loc":{"start":{"line":1,"column":4},"end":{"line":1,"column":11}}
+              }
+            ],
+            "name": "foo"
+          },
+          "arguments": []
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":4,"end":11,"loc":{"start":{"line":1,"column":4},"end":{"line":1,"column":11}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":13,"end":20,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":20}}
+    }
+  ]
+}

From 664af029d295fce1191632b9ed3a61c773c8d10f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 22:28:47 -0400
Subject: [PATCH 11/35] fix: mark containerNode be the innermost node
 containing commentWS

---
 packages/babel-parser/src/parser/comments.js  | 45 +++++--------------
 .../babel-parser/src/parser/expression.js     |  1 -
 packages/babel-parser/src/parser/statement.js |  1 -
 .../call-expression-no-argument/output.json   | 14 +++---
 4 files changed, 17 insertions(+), 44 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index d33d90a3d896..984f638a5112 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -15,7 +15,7 @@ import * as charCodes from "charcodes";
  * @property {Array<Comment>} comments - the containing comments
  * @property {Node | null} leadingNode - the immediately preceding AST node of the whitespace token
  * @property {Node | null} trailingNode - the immediately following AST node of the whitespace token
- * @property {Node | null} containerNode - the outermost AST node containing the whitespace
+ * @property {Node | null} containerNode - the innermost AST node containing the whitespace
  *                                         with minimal size (|end - start|)
  */
 export type CommentWhitespace = {
@@ -104,8 +104,7 @@ export default class CommentsParser extends BaseParser {
     let i = commentStackLength - 1;
     const lastCommentWS = commentStack[i];
 
-    const nodeEnd = node.end;
-    if (lastCommentWS.start === nodeEnd) {
+    if (lastCommentWS.start === node.end) {
       lastCommentWS.leadingNode = node;
       i--;
     }
@@ -122,23 +121,14 @@ export default class CommentsParser extends BaseParser {
         if (containerNode === null) {
           commentWS.containerNode = node;
         } else {
-          if (containerNode.end - containerNode.start < nodeEnd - nodeStart) {
-            // a commentWhitespace is considered _attached_ if
-            // 1) its leadingNode or trailingNode, if exists, will not change
-            // 2) its containerNode have the minimum node length among all other
-            //    nodes containing the commentWhitespace
-            // In other words, an attached comment whitespace have fixed associated
-            // AST node and thus we can finalize the comment whitespace
-            // Note that there could be remaining commentWS after the Program node is finished,
-            // in this case they will be handled by {@link CommentParser#finalizeRemainingComments}
-            this.finalizeComment(commentWS);
-            commentStack.splice(i, 1);
-          } else if (node.type !== "Program") {
-            // we have a node with the same length of containerNode, but its finishNode is invoked later
-            // than containerNode, so this node is the outer node and should replace the inner node.
-            // E.g. ExpressionStatement contains a VariableDeclaration
-            commentWS.containerNode = node;
-          }
+          // a commentWhitespace is considered _attached_ if
+          // 1) its leadingNode or trailingNode, if exists, will not change
+          // 2) its containerNode have the minimum node length among all other
+          //    nodes containing the commentWhitespace
+          // In other words, an attached comment whitespace have fixed associated
+          // AST node and thus we can finalize the comment whitespace
+          this.finalizeComment(commentWS);
+          commentStack.splice(i, 1);
         }
       } else {
         if (commentEnd === nodeStart) {
@@ -196,19 +186,4 @@ export default class CommentsParser extends BaseParser {
       }
     }
   }
-
-  /**
-   * Drains remaning commentStack and applies finalizeComment
-   * to each comment whitespace.
-   * {@see {@link CommentsParser#finalizeComment}}
-   *
-   * @memberof CommentsParser
-   */
-  finalizeRemainingComments() {
-    const { commentStack } = this.state;
-    for (let i = commentStack.length - 1; i >= 0; i--) {
-      this.finalizeComment(commentStack[i]);
-    }
-    this.state.commentStack = [];
-  }
 }
diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 6c2aee761e86..aaf4794f7724 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -161,7 +161,6 @@ export default class ExpressionParser extends LValParser {
     if (!this.match(tt.eof)) {
       this.unexpected();
     }
-    this.finalizeRemainingComments();
     expr.comments = this.state.comments;
     expr.errors = this.state.errors;
     if (this.options.tokens) {
diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
index f19fa9a0f79a..0f6ce71dcf31 100644
--- a/packages/babel-parser/src/parser/statement.js
+++ b/packages/babel-parser/src/parser/statement.js
@@ -99,7 +99,6 @@ export default class StatementParser extends ExpressionParser {
 
   parseTopLevel(file: N.File, program: N.Program): N.File {
     file.program = this.parseProgram(program);
-    this.finalizeRemainingComments();
     file.comments = this.state.comments;
 
     if (this.options.tokens) file.tokens = babel7CompatTokens(this.tokens);
diff --git a/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/output.json b/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/output.json
index 1a52ab79278f..97cde7e8ff11 100644
--- a/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/output.json
+++ b/packages/babel-parser/test/fixtures/comments/basic/call-expression-no-argument/output.json
@@ -10,16 +10,16 @@
       {
         "type": "ExpressionStatement",
         "start":0,"end":21,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":21}},
-        "innerComments": [
-          {
-            "type": "CommentBlock",
-            "value": " 2 ",
-            "start":13,"end":20,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":20}}
-          }
-        ],
         "expression": {
           "type": "CallExpression",
           "start":0,"end":21,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":21}},
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 2 ",
+              "start":13,"end":20,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":20}}
+            }
+          ],
           "callee": {
             "type": "Identifier",
             "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},

From 60bfe3900d15c65401412f95ef5ef7079a2dfdc1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 22:30:06 -0400
Subject: [PATCH 12/35] fix: adjust trailing comma comments for
 Record/Tuple/OptionalCall

---
 packages/babel-parser/src/parser/comments.js  |  3 +
 .../call-trailing-comma-comments/input.js     |  1 +
 .../call-trailing-comma-comments/output.json  | 60 +++++++++++++
 .../trailing-comma-comments/input.js          |  2 +
 .../trailing-comma-comments/options.json      |  3 +
 .../trailing-comma-comments/output.json       | 90 +++++++++++++++++++
 6 files changed, 159 insertions(+)
 create mode 100644 packages/babel-parser/test/fixtures/es2020/optional-chaining/call-trailing-comma-comments/input.js
 create mode 100644 packages/babel-parser/test/fixtures/es2020/optional-chaining/call-trailing-comma-comments/output.json
 create mode 100644 packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/input.js
 create mode 100644 packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/options.json
 create mode 100644 packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/output.json

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 984f638a5112..b8eacf170706 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -164,13 +164,16 @@ export default class CommentsParser extends BaseParser {
         switch (node.type) {
           case "ObjectExpression":
           case "ObjectPattern":
+          case "RecordExpression":
             adjustInnerComments(node, node.properties, commentWS);
             break;
           case "CallExpression":
+          case "OptionalCallExpression":
             adjustInnerComments(node, node.arguments, commentWS);
             break;
           case "ArrayExpression":
           case "ArrayPattern":
+          case "TupleExpression":
             adjustInnerComments(node, node.elements, commentWS);
             break;
           case "ExportNamedDeclaration":
diff --git a/packages/babel-parser/test/fixtures/es2020/optional-chaining/call-trailing-comma-comments/input.js b/packages/babel-parser/test/fixtures/es2020/optional-chaining/call-trailing-comma-comments/input.js
new file mode 100644
index 000000000000..5276e8e29ab9
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2020/optional-chaining/call-trailing-comma-comments/input.js
@@ -0,0 +1 @@
+foo?.(x, /* 1 */)/* 2 */
diff --git a/packages/babel-parser/test/fixtures/es2020/optional-chaining/call-trailing-comma-comments/output.json b/packages/babel-parser/test/fixtures/es2020/optional-chaining/call-trailing-comma-comments/output.json
new file mode 100644
index 000000000000..caad9020860a
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2020/optional-chaining/call-trailing-comma-comments/output.json
@@ -0,0 +1,60 @@
+{
+  "type": "File",
+  "start":0,"end":24,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":24}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":24,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":24}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 2 ",
+            "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+          }
+        ],
+        "expression": {
+          "type": "OptionalCallExpression",
+          "start":0,"end":17,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":17}},
+          "callee": {
+            "type": "Identifier",
+            "start":0,"end":3,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":3},"identifierName":"foo"},
+            "name": "foo"
+          },
+          "optional": true,
+          "arguments": [
+            {
+              "type": "Identifier",
+              "start":6,"end":7,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":7},"identifierName":"x"},
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 1 ",
+                  "start":9,"end":16,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":16}}
+                }
+              ],
+              "name": "x"
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":9,"end":16,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":16}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/input.js b/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/input.js
new file mode 100644
index 000000000000..48b103a6a95c
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/input.js
@@ -0,0 +1,2 @@
+#[ a,/* 1 */]
+#{ a,/* 1 */}
diff --git a/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/options.json b/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/options.json
new file mode 100644
index 000000000000..703c537be360
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["recordAndTuple", { "syntaxType": "hash" }]]
+}
diff --git a/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/output.json b/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/output.json
new file mode 100644
index 000000000000..e4a0c1abad3b
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/record-and-tuple/trailing-comma-comments/output.json
@@ -0,0 +1,90 @@
+{
+  "type": "File",
+  "start":0,"end":27,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":13}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":27,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":13}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+        "expression": {
+          "type": "TupleExpression",
+          "start":0,"end":13,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":13}},
+          "extra": {
+            "trailingComma": 4
+          },
+          "elements": [
+            {
+              "type": "Identifier",
+              "start":3,"end":4,"loc":{"start":{"line":1,"column":3},"end":{"line":1,"column":4},"identifierName":"a"},
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 1 ",
+                  "start":5,"end":12,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":12}}
+                }
+              ],
+              "name": "a"
+            }
+          ]
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":14,"end":27,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":13}},
+        "expression": {
+          "type": "RecordExpression",
+          "start":14,"end":27,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":13}},
+          "extra": {
+            "trailingComma": 18
+          },
+          "properties": [
+            {
+              "type": "ObjectProperty",
+              "start":17,"end":18,"loc":{"start":{"line":2,"column":3},"end":{"line":2,"column":4}},
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 1 ",
+                  "start":19,"end":26,"loc":{"start":{"line":2,"column":5},"end":{"line":2,"column":12}}
+                }
+              ],
+              "extra": {
+                "shorthand": true
+              },
+              "method": false,
+              "key": {
+                "type": "Identifier",
+                "start":17,"end":18,"loc":{"start":{"line":2,"column":3},"end":{"line":2,"column":4},"identifierName":"a"},
+                "name": "a"
+              },
+              "computed": false,
+              "shorthand": true,
+              "value": {
+                "type": "Identifier",
+                "start":17,"end":18,"loc":{"start":{"line":2,"column":3},"end":{"line":2,"column":4},"identifierName":"a"},
+                "name": "a"
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":5,"end":12,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":12}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":19,"end":26,"loc":{"start":{"line":2,"column":5},"end":{"line":2,"column":12}}
+    }
+  ]
+}
\ No newline at end of file

From 140f93cd7537e25eed88c14312958a8492bb9469 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 29 Jun 2021 22:54:11 -0400
Subject: [PATCH 13/35] fix: drain comment stacks in parseExpression

---
 packages/babel-parser/src/parser/comments.js   | 16 ++++++++++++++++
 packages/babel-parser/src/parser/expression.js |  3 +++
 2 files changed, 19 insertions(+)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index b8eacf170706..a94e2faec3fe 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -189,4 +189,20 @@ export default class CommentsParser extends BaseParser {
       }
     }
   }
+
+  /**
+   * Drains remaning commentStack and applies finalizeComment
+   * to each comment whitespace. Used only in parseExpression
+   * where the top level AST node is _not_ Program
+   * {@see {@link CommentsParser#finalizeComment}}
+   *
+   * @memberof CommentsParser
+   */
+  finalizeRemainingComments() {
+    const { commentStack } = this.state;
+    for (let i = commentStack.length - 1; i >= 0; i--) {
+      this.finalizeComment(commentStack[i]);
+    }
+    this.state.commentStack = [];
+  }
 }
diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index aaf4794f7724..3df50a4f25e0 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -161,6 +161,9 @@ export default class ExpressionParser extends LValParser {
     if (!this.match(tt.eof)) {
       this.unexpected();
     }
+    // Unlike parseTopLevel, we need to drain remaining commentStacks
+    // because the top level node is _not_ Program.
+    this.finalizeRemainingComments();
     expr.comments = this.state.comments;
     expr.errors = this.state.errors;
     if (this.options.tokens) {

From d0a8f4a6caf6ee23757024c0e9b4853bb45918cc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 30 Jun 2021 08:52:08 -0400
Subject: [PATCH 14/35] docs: update comments

---
 packages/babel-parser/src/parser/comments.js | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index a94e2faec3fe..3f3ee9fd3ffc 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -28,7 +28,8 @@ export type CommentWhitespace = {
 };
 /**
  * Merge comments with node's trailingComments or assign comments to be
- * trailingComments.
+ * trailingComments. New comments will be placed before old comments
+ * because the commentStack is enumerated reversely.
  *
  * @param {Node} node
  * @param {Array<Comment>} comments
@@ -43,7 +44,8 @@ function setTrailingComments(node: Node, comments: Array<Comment>) {
 
 /**
  * Merge comments with node's innerComments or assign comments to be
- * innerComments.
+ * innerComments. New comments will be placed before old comments
+ * because the commentStack is enumerated reversely.
  *
  * @param {Node} node
  * @param {Array<Comment>} comments
@@ -117,16 +119,14 @@ export default class CommentsParser extends BaseParser {
       if (commentEnd > nodeStart) {
         // by definition of commentWhiteSpace, this implies commentWS.start > nodeStart
         // so node can be a containerNode candidate
-        const { containerNode } = commentWS;
-        if (containerNode === null) {
+        if (commentWS.containerNode === null) {
+          // We can not finalize comment here, because at this time we have not set `trailingNode`
           commentWS.containerNode = node;
         } else {
-          // a commentWhitespace is considered _attached_ if
+          // At this time we can finalize the comment whitespace, because
           // 1) its leadingNode or trailingNode, if exists, will not change
-          // 2) its containerNode have the minimum node length among all other
-          //    nodes containing the commentWhitespace
-          // In other words, an attached comment whitespace have fixed associated
-          // AST node and thus we can finalize the comment whitespace
+          // 2) its containerNode have been assigned and will not change because it is the
+          //    innermost minimal-sized AST node
           this.finalizeComment(commentWS);
           commentStack.splice(i, 1);
         }
@@ -134,6 +134,7 @@ export default class CommentsParser extends BaseParser {
         if (commentEnd === nodeStart) {
           commentWS.trailingNode = node;
         }
+        // stop the loop when commentEnd <= nodeStart
         break;
       }
     }

From 1d401c6a219d99789a47e62f5f3f7539eddcad2a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 30 Jun 2021 09:05:27 -0400
Subject: [PATCH 15/35] add a new benchmark

---
 .../many-leading-trailing-comments/bench.mjs  | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 packages/babel-parser/benchmark/many-leading-trailing-comments/bench.mjs

diff --git a/packages/babel-parser/benchmark/many-leading-trailing-comments/bench.mjs b/packages/babel-parser/benchmark/many-leading-trailing-comments/bench.mjs
new file mode 100644
index 000000000000..fe613d4e5e6d
--- /dev/null
+++ b/packages/babel-parser/benchmark/many-leading-trailing-comments/bench.mjs
@@ -0,0 +1,27 @@
+import Benchmark from "benchmark";
+import baseline from "@babel-baseline/parser";
+import current from "../../lib/index.js";
+import { report } from "../util.mjs";
+
+const suite = new Benchmark.Suite();
+function createInput(length) {
+  return "\n// c\na".repeat(length);
+}
+current.parse(createInput(256), {});
+function benchCases(name, implementation, options) {
+  for (const length of [128, 256, 512, 1024]) {
+    const input = createInput(length);
+    const { parse } = implementation;
+    suite.add(
+      `${name} ${length} leading comments + ${length - 1} trailing comments`,
+      () => {
+        parse(input, options);
+      }
+    );
+  }
+}
+
+benchCases("baseline", baseline);
+benchCases("current", current);
+
+suite.on("cycle", report).run();

From b499b03c75ea654e339407b64153155e67038945 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 30 Jun 2021 15:58:53 -0400
Subject: [PATCH 16/35] chore: containerNode => containingNode

---
 packages/babel-parser/src/parser/comments.js | 18 +++++++++---------
 packages/babel-parser/src/tokenizer/index.js |  2 +-
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 3f3ee9fd3ffc..5dbbfa7b74fa 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -15,7 +15,7 @@ import * as charCodes from "charcodes";
  * @property {Array<Comment>} comments - the containing comments
  * @property {Node | null} leadingNode - the immediately preceding AST node of the whitespace token
  * @property {Node | null} trailingNode - the immediately following AST node of the whitespace token
- * @property {Node | null} containerNode - the innermost AST node containing the whitespace
+ * @property {Node | null} containingNode - the innermost AST node containing the whitespace
  *                                         with minimal size (|end - start|)
  */
 export type CommentWhitespace = {
@@ -24,7 +24,7 @@ export type CommentWhitespace = {
   comments: Array<Comment>,
   leadingNode: Node | null,
   trailingNode: Node | null,
-  containerNode: Node | null,
+  containingNode: Node | null,
 };
 /**
  * Merge comments with node's trailingComments or assign comments to be
@@ -118,14 +118,14 @@ export default class CommentsParser extends BaseParser {
       const commentEnd = commentWS.end;
       if (commentEnd > nodeStart) {
         // by definition of commentWhiteSpace, this implies commentWS.start > nodeStart
-        // so node can be a containerNode candidate
-        if (commentWS.containerNode === null) {
+        // so node can be a containingNode candidate
+        if (commentWS.containingNode === null) {
           // We can not finalize comment here, because at this time we have not set `trailingNode`
-          commentWS.containerNode = node;
+          commentWS.containingNode = node;
         } else {
           // At this time we can finalize the comment whitespace, because
           // 1) its leadingNode or trailingNode, if exists, will not change
-          // 2) its containerNode have been assigned and will not change because it is the
+          // 2) its containingNode have been assigned and will not change because it is the
           //    innermost minimal-sized AST node
           this.finalizeComment(commentWS);
           commentStack.splice(i, 1);
@@ -156,10 +156,10 @@ export default class CommentsParser extends BaseParser {
         commentWS.trailingNode.leadingComments = comments;
       }
     } else {
-      /*:: invariant(commentWS.containerNode !== null) */
-      const { containerNode: node, start: commentStart } = commentWS;
+      /*:: invariant(commentWS.containingNode !== null) */
+      const { containingNode: node, start: commentStart } = commentWS;
       if (this.input.charCodeAt(commentStart - 1) === charCodes.comma) {
-        // If a commentWhitespace follows a comma and the containerNode allows
+        // If a commentWhitespace follows a comma and the containingNode allows
         // list structures with trailing comma, merge it to the trailingComment
         // of the last non-null list element
         switch (node.type) {
diff --git a/packages/babel-parser/src/tokenizer/index.js b/packages/babel-parser/src/tokenizer/index.js
index bd2f059391f7..a11c91649971 100644
--- a/packages/babel-parser/src/tokenizer/index.js
+++ b/packages/babel-parser/src/tokenizer/index.js
@@ -471,7 +471,7 @@ export default class Tokenizer extends ParserErrors {
         comments,
         leadingNode: null,
         trailingNode: null,
-        containerNode: null,
+        containingNode: null,
       };
       this.state.commentStack.push(CommentWhitespace);
     }

From e0e5e110f8784d10258d9920df17b0f90c644085 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 30 Jun 2021 15:59:15 -0400
Subject: [PATCH 17/35] add more benchmark cases

---
 .../many-inner-comments-nested/bench.mjs      |  2 +-
 .../benchmark/many-inner-comments/bench.mjs   | 24 +++++++++++++++++++
 .../many-trailing-comments/bench.mjs          | 24 +++++++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 packages/babel-parser/benchmark/many-inner-comments/bench.mjs
 create mode 100644 packages/babel-parser/benchmark/many-trailing-comments/bench.mjs

diff --git a/packages/babel-parser/benchmark/many-inner-comments-nested/bench.mjs b/packages/babel-parser/benchmark/many-inner-comments-nested/bench.mjs
index 4159dc8125fb..38d80f1a8d40 100644
--- a/packages/babel-parser/benchmark/many-inner-comments-nested/bench.mjs
+++ b/packages/babel-parser/benchmark/many-inner-comments-nested/bench.mjs
@@ -5,7 +5,7 @@ import { report } from "../util.mjs";
 
 const suite = new Benchmark.Suite();
 function createInput(length) {
-  return "[".repeat(length) + "/* c */,]".repeat(length);
+  return "[,\n// c\n".repeat(length) + "\n]".repeat(length);
 }
 function benchCases(name, implementation, options) {
   for (const length of [128, 256, 512, 1024]) {
diff --git a/packages/babel-parser/benchmark/many-inner-comments/bench.mjs b/packages/babel-parser/benchmark/many-inner-comments/bench.mjs
new file mode 100644
index 000000000000..c0001e73ecd0
--- /dev/null
+++ b/packages/babel-parser/benchmark/many-inner-comments/bench.mjs
@@ -0,0 +1,24 @@
+import Benchmark from "benchmark";
+import baseline from "@babel-baseline/parser";
+import current from "../../lib/index.js";
+import { report } from "../util.mjs";
+
+const suite = new Benchmark.Suite();
+function createInput(length) {
+  return "[" + "// c\n".repeat(length) + "]";
+}
+current.parse(createInput(256), {});
+function benchCases(name, implementation, options) {
+  for (const length of [128, 256, 512, 1024]) {
+    const input = createInput(length);
+    const { parse } = implementation;
+    suite.add(`${name} ${length} inner comments`, () => {
+      parse(input, options);
+    });
+  }
+}
+
+benchCases("baseline", baseline);
+benchCases("current", current);
+
+suite.on("cycle", report).run();
diff --git a/packages/babel-parser/benchmark/many-trailing-comments/bench.mjs b/packages/babel-parser/benchmark/many-trailing-comments/bench.mjs
new file mode 100644
index 000000000000..1982485ee0ef
--- /dev/null
+++ b/packages/babel-parser/benchmark/many-trailing-comments/bench.mjs
@@ -0,0 +1,24 @@
+import Benchmark from "benchmark";
+import baseline from "@babel-baseline/parser";
+import current from "../../lib/index.js";
+import { report } from "../util.mjs";
+
+const suite = new Benchmark.Suite();
+function createInput(length) {
+  return "{}" + "// c\n".repeat(length);
+}
+current.parse(createInput(256), {});
+function benchCases(name, implementation, options) {
+  for (const length of [128, 256, 512, 1024]) {
+    const input = createInput(length);
+    const { parse } = implementation;
+    suite.add(`${name} ${length} trailing comments`, () => {
+      parse(input, options);
+    });
+  }
+}
+
+benchCases("baseline", baseline);
+benchCases("current", current);
+
+suite.on("cycle", report).run();

From 30a62e9b1284175fba6612617c597149ac7a7219 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 30 Jun 2021 18:03:23 -0400
Subject: [PATCH 18/35] fix: avoid finishNodeAt in stmtToDirective

---
 packages/babel-parser/src/parser/statement.js | 29 ++++++++++---------
 packages/babel-parser/src/plugins/estree.js   |  2 +-
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
index 0f6ce71dcf31..cff855036f19 100644
--- a/packages/babel-parser/src/parser/statement.js
+++ b/packages/babel-parser/src/parser/statement.js
@@ -130,26 +130,27 @@ export default class StatementParser extends ExpressionParser {
 
   // TODO
 
+  /**
+   * cast a Statement to a Directive. This method mutates input statement.
+   *
+   * @param {N.Statement} stmt
+   * @returns {N.Directive}
+   * @memberof StatementParser
+   */
   stmtToDirective(stmt: N.Statement): N.Directive {
-    const expr = stmt.expression;
+    const directive = (stmt: any);
+    directive.type = "Directive";
+    directive.value = directive.expression;
+    delete directive.expression;
 
-    const directiveLiteral = this.startNodeAt(expr.start, expr.loc.start);
-    const directive = this.startNodeAt(stmt.start, stmt.loc.start);
-
-    const raw = this.input.slice(expr.start, expr.end);
+    const directiveLiteral = directive.value;
+    const raw = this.input.slice(directiveLiteral.start, directiveLiteral.end);
     const val = (directiveLiteral.value = raw.slice(1, -1)); // remove quotes
 
     this.addExtra(directiveLiteral, "raw", raw);
     this.addExtra(directiveLiteral, "rawValue", val);
-
-    directive.value = this.finishNodeAt(
-      directiveLiteral,
-      "DirectiveLiteral",
-      expr.end,
-      expr.loc.end,
-    );
-
-    return this.finishNodeAt(directive, "Directive", stmt.end, stmt.loc.end);
+    directiveLiteral.type = "DirectiveLiteral";
+    return directive;
   }
 
   parseInterpreterDirective(): N.InterpreterDirective | null {
diff --git a/packages/babel-parser/src/plugins/estree.js b/packages/babel-parser/src/plugins/estree.js
index 8d566a1ddd3a..c4dad6e78f49 100644
--- a/packages/babel-parser/src/plugins/estree.js
+++ b/packages/babel-parser/src/plugins/estree.js
@@ -131,8 +131,8 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     stmtToDirective(stmt: N.Statement): N.Directive {
-      const directive = super.stmtToDirective(stmt);
       const value = stmt.expression.value;
+      const directive = super.stmtToDirective(stmt);
 
       // Record the expression value as in estree mode we want
       // the stmt to have the real value e.g. ("use strict") and

From 33502895b8a3871f8d210da2074a484163b72ffb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 30 Jun 2021 17:26:26 -0400
Subject: [PATCH 19/35] finalize comment right after containerNode is set

---
 packages/babel-parser/src/parser/comments.js | 22 ++++++++------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 5dbbfa7b74fa..9db2d15597f0 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -111,25 +111,21 @@ export default class CommentsParser extends BaseParser {
       i--;
     }
 
+    const { start: nodeStart } = node;
     // invariant: for all 0 <= j <= i, let c = commentStack[j], c must satisfy c.end < node.end
-    const nodeStart = node.start;
     for (; i >= 0; i--) {
       const commentWS = commentStack[i];
       const commentEnd = commentWS.end;
       if (commentEnd > nodeStart) {
         // by definition of commentWhiteSpace, this implies commentWS.start > nodeStart
-        // so node can be a containingNode candidate
-        if (commentWS.containingNode === null) {
-          // We can not finalize comment here, because at this time we have not set `trailingNode`
-          commentWS.containingNode = node;
-        } else {
-          // At this time we can finalize the comment whitespace, because
-          // 1) its leadingNode or trailingNode, if exists, will not change
-          // 2) its containingNode have been assigned and will not change because it is the
-          //    innermost minimal-sized AST node
-          this.finalizeComment(commentWS);
-          commentStack.splice(i, 1);
-        }
+        // so node can be a containingNode candidate. At this time we can finalize the comment
+        // whitespace, because
+        // 1) its leadingNode or trailingNode, if exists, will not change
+        // 2) its containingNode have been assigned and will not change because it is the
+        //    innermost minimal-sized AST node
+        commentWS.containingNode = node;
+        this.finalizeComment(commentWS);
+        commentStack.splice(i, 1);
       } else {
         if (commentEnd === nodeStart) {
           commentWS.trailingNode = node;

From b3c06de7db3395565332698b02fca3e8d088693d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 30 Jun 2021 18:08:44 -0400
Subject: [PATCH 20/35] add testcase about directive

---
 .../comments/basic/directive/input.js         |  1 +
 .../comments/basic/directive/output.json      | 64 +++++++++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/directive/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/directive/output.json

diff --git a/packages/babel-parser/test/fixtures/comments/basic/directive/input.js b/packages/babel-parser/test/fixtures/comments/basic/directive/input.js
new file mode 100644
index 000000000000..f8895a546d36
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/directive/input.js
@@ -0,0 +1 @@
+/* 1 */"use strict"/* 2 */;/* 3 */
diff --git a/packages/babel-parser/test/fixtures/comments/basic/directive/output.json b/packages/babel-parser/test/fixtures/comments/basic/directive/output.json
new file mode 100644
index 000000000000..752ac6c9153b
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/directive/output.json
@@ -0,0 +1,64 @@
+{
+  "type": "File",
+  "start":0,"end":34,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":34}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":34,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":34}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [],
+    "directives": [
+      {
+        "type": "Directive",
+        "start":7,"end":27,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":27}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 1 ",
+            "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+          }
+        ],
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 3 ",
+            "start":27,"end":34,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":34}}
+          }
+        ],
+        "value": {
+          "type": "DirectiveLiteral",
+          "start":7,"end":19,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":19}},
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 2 ",
+              "start":19,"end":26,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":26}}
+            }
+          ],
+          "extra": {
+            "rawValue": "use strict",
+            "raw": "\"use strict\""
+          },
+          "value": "use strict"
+        }
+      }
+    ]
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":19,"end":26,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":26}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":27,"end":34,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":34}}
+    }
+  ]
+}
\ No newline at end of file

From 1c65383db07a22ac43eff5ae806ce18ec7831447 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 30 Jun 2021 18:38:34 -0400
Subject: [PATCH 21/35] fix: finish SequenceExpression at current pos and
 adjust later

---
 .../babel-parser/src/parser/expression.js     |   5 +-
 .../basic/sequence-expression/input.js        |   1 +
 .../basic/sequence-expression/output.json     | 145 ++++++++++++++++++
 3 files changed, 150 insertions(+), 1 deletion(-)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/sequence-expression/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/sequence-expression/output.json

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 3df50a4f25e0..4300a69d0e35 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -1512,7 +1512,10 @@ export default class ExpressionParser extends LValParser {
     if (exprList.length > 1) {
       val = this.startNodeAt(innerStartPos, innerStartLoc);
       val.expressions = exprList;
-      this.finishNodeAt(val, "SequenceExpression", innerEndPos, innerEndLoc);
+      // finish node at current location so it can pick up comments after `)`
+      this.finishNode(val, "SequenceExpression");
+      val.end = innerEndPos;
+      val.loc.end = innerEndLoc;
     } else {
       val = exprList[0];
     }
diff --git a/packages/babel-parser/test/fixtures/comments/basic/sequence-expression/input.js b/packages/babel-parser/test/fixtures/comments/basic/sequence-expression/input.js
new file mode 100644
index 000000000000..ad3964a24326
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/sequence-expression/input.js
@@ -0,0 +1 @@
+/* 1 */ (/* 2 */ ( /* 3 */ a /* 4 */, /* 5 */ b /* 6 */ ) /* 7 */ ) /* 8 */; /* 9 */
diff --git a/packages/babel-parser/test/fixtures/comments/basic/sequence-expression/output.json b/packages/babel-parser/test/fixtures/comments/basic/sequence-expression/output.json
new file mode 100644
index 000000000000..4a3317680493
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/sequence-expression/output.json
@@ -0,0 +1,145 @@
+{
+  "type": "File",
+  "start":0,"end":84,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":84}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":84,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":84}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":8,"end":76,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":76}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 1 ",
+            "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+          }
+        ],
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 9 ",
+            "start":77,"end":84,"loc":{"start":{"line":1,"column":77},"end":{"line":1,"column":84}}
+          }
+        ],
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 2 ",
+            "start":9,"end":16,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":16}}
+          },
+          {
+            "type": "CommentBlock",
+            "value": " 8 ",
+            "start":68,"end":75,"loc":{"start":{"line":1,"column":68},"end":{"line":1,"column":75}}
+          }
+        ],
+        "expression": {
+          "type": "SequenceExpression",
+          "start":27,"end":47,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":47}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 3 ",
+              "start":19,"end":26,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":26}}
+            }
+          ],
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 7 ",
+              "start":58,"end":65,"loc":{"start":{"line":1,"column":58},"end":{"line":1,"column":65}}
+            }
+          ],
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 8
+          },
+          "expressions": [
+            {
+              "type": "Identifier",
+              "start":27,"end":28,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":28},"identifierName":"a"},
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 4 ",
+                  "start":29,"end":36,"loc":{"start":{"line":1,"column":29},"end":{"line":1,"column":36}}
+                }
+              ],
+              "name": "a"
+            },
+            {
+              "type": "Identifier",
+              "start":46,"end":47,"loc":{"start":{"line":1,"column":46},"end":{"line":1,"column":47},"identifierName":"b"},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 5 ",
+                  "start":38,"end":45,"loc":{"start":{"line":1,"column":38},"end":{"line":1,"column":45}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 6 ",
+                  "start":48,"end":55,"loc":{"start":{"line":1,"column":48},"end":{"line":1,"column":55}}
+                }
+              ],
+              "name": "b"
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":9,"end":16,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":16}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":19,"end":26,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":26}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":29,"end":36,"loc":{"start":{"line":1,"column":29},"end":{"line":1,"column":36}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":38,"end":45,"loc":{"start":{"line":1,"column":38},"end":{"line":1,"column":45}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":48,"end":55,"loc":{"start":{"line":1,"column":48},"end":{"line":1,"column":55}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":58,"end":65,"loc":{"start":{"line":1,"column":58},"end":{"line":1,"column":65}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":68,"end":75,"loc":{"start":{"line":1,"column":68},"end":{"line":1,"column":75}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":77,"end":84,"loc":{"start":{"line":1,"column":77},"end":{"line":1,"column":84}}
+    }
+  ]
+}

From a3188efc7e8b7bcd9df0c28b61e6ea0fba1ff5a5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Fri, 2 Jul 2021 09:56:44 -0400
Subject: [PATCH 22/35] chore: rename test cases

---
 .../input.js                                                      | 0
 .../output.json                                                   | 0
 .../input.js                                                      | 0
 .../output.json                                                   | 0
 4 files changed, 0 insertions(+), 0 deletions(-)
 rename packages/babel-parser/test/fixtures/comments/basic/{function-trailing-comma-shorthand => call-expression-trailing-comma-object-shorthand}/input.js (100%)
 rename packages/babel-parser/test/fixtures/comments/basic/{function-trailing-comma-shorthand => call-expression-trailing-comma-object-shorthand}/output.json (100%)
 rename packages/babel-parser/test/fixtures/comments/basic/{function-trailing-comma => call-expression-trailing-comma}/input.js (100%)
 rename packages/babel-parser/test/fixtures/comments/basic/{function-trailing-comma => call-expression-trailing-comma}/output.json (100%)

diff --git a/packages/babel-parser/test/fixtures/comments/basic/function-trailing-comma-shorthand/input.js b/packages/babel-parser/test/fixtures/comments/basic/call-expression-trailing-comma-object-shorthand/input.js
similarity index 100%
rename from packages/babel-parser/test/fixtures/comments/basic/function-trailing-comma-shorthand/input.js
rename to packages/babel-parser/test/fixtures/comments/basic/call-expression-trailing-comma-object-shorthand/input.js
diff --git a/packages/babel-parser/test/fixtures/comments/basic/function-trailing-comma-shorthand/output.json b/packages/babel-parser/test/fixtures/comments/basic/call-expression-trailing-comma-object-shorthand/output.json
similarity index 100%
rename from packages/babel-parser/test/fixtures/comments/basic/function-trailing-comma-shorthand/output.json
rename to packages/babel-parser/test/fixtures/comments/basic/call-expression-trailing-comma-object-shorthand/output.json
diff --git a/packages/babel-parser/test/fixtures/comments/basic/function-trailing-comma/input.js b/packages/babel-parser/test/fixtures/comments/basic/call-expression-trailing-comma/input.js
similarity index 100%
rename from packages/babel-parser/test/fixtures/comments/basic/function-trailing-comma/input.js
rename to packages/babel-parser/test/fixtures/comments/basic/call-expression-trailing-comma/input.js
diff --git a/packages/babel-parser/test/fixtures/comments/basic/function-trailing-comma/output.json b/packages/babel-parser/test/fixtures/comments/basic/call-expression-trailing-comma/output.json
similarity index 100%
rename from packages/babel-parser/test/fixtures/comments/basic/function-trailing-comma/output.json
rename to packages/babel-parser/test/fixtures/comments/basic/call-expression-trailing-comma/output.json

From 3ec0b2575c7c4886511c614369ed7a017e77c7c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Fri, 2 Jul 2021 09:57:11 -0400
Subject: [PATCH 23/35] add new test case on switch statement

---
 .../basic/switch-no-case-comment/input.js     |  1 +
 .../basic/switch-no-case-comment/output.json  | 59 +++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100755 packages/babel-parser/test/fixtures/comments/basic/switch-no-case-comment/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/switch-no-case-comment/output.json

diff --git a/packages/babel-parser/test/fixtures/comments/basic/switch-no-case-comment/input.js b/packages/babel-parser/test/fixtures/comments/basic/switch-no-case-comment/input.js
new file mode 100755
index 000000000000..44112e2dd05a
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/switch-no-case-comment/input.js
@@ -0,0 +1 @@
+switch (c)/*1*/ { /*2*/ } /*3*/
diff --git a/packages/babel-parser/test/fixtures/comments/basic/switch-no-case-comment/output.json b/packages/babel-parser/test/fixtures/comments/basic/switch-no-case-comment/output.json
new file mode 100644
index 000000000000..6a7bf50cc6f5
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/switch-no-case-comment/output.json
@@ -0,0 +1,59 @@
+{
+  "type": "File",
+  "start":0,"end":31,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":31}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":31,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":31}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "SwitchStatement",
+        "start":0,"end":25,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":25}},
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": "3",
+            "start":26,"end":31,"loc":{"start":{"line":1,"column":26},"end":{"line":1,"column":31}}
+          }
+        ],
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": "1",
+            "start":10,"end":15,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":15}}
+          },
+          {
+            "type": "CommentBlock",
+            "value": "2",
+            "start":18,"end":23,"loc":{"start":{"line":1,"column":18},"end":{"line":1,"column":23}}
+          }
+        ],
+        "discriminant": {
+          "type": "Identifier",
+          "start":8,"end":9,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":9},"identifierName":"c"},
+          "name": "c"
+        },
+        "cases": []
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": "1",
+      "start":10,"end":15,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":15}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "2",
+      "start":18,"end":23,"loc":{"start":{"line":1,"column":18},"end":{"line":1,"column":23}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "3",
+      "start":26,"end":31,"loc":{"start":{"line":1,"column":26},"end":{"line":1,"column":31}}
+    }
+  ]
+}
\ No newline at end of file

From 79cb03575983acf482254079a00751157ef58562 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Fri, 2 Jul 2021 09:57:37 -0400
Subject: [PATCH 24/35] fix: adjust comments after trailing comma of function
 params

---
 packages/babel-parser/src/parser/comments.js  |   8 +
 .../comments/basic/class-method/input.js      |   2 +
 .../comments/basic/class-method/output.json   | 362 ++++++++++++++++++
 .../basic/class-private-method/input.js       |   2 +
 .../basic/class-private-method/output.json    | 196 ++++++++++
 .../fixtures/comments/basic/function/input.js |   4 +
 .../comments/basic/function/output.json       | 290 ++++++++++++++
 .../comments/basic/object-method/input.js     |   1 +
 .../comments/basic/object-method/output.json  | 175 +++++++++
 9 files changed, 1040 insertions(+)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-method/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-method/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-private-method/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-private-method/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/function/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/function/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/object-method/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/object-method/output.json

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 9db2d15597f0..3ec4c14cef70 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -168,6 +168,14 @@ export default class CommentsParser extends BaseParser {
           case "OptionalCallExpression":
             adjustInnerComments(node, node.arguments, commentWS);
             break;
+          case "FunctionDeclaration":
+          case "FunctionExpression":
+          case "ArrowFunctionExpression":
+          case "ObjectMethod":
+          case "ClassMethod":
+          case "ClassPrivateMethod":
+            adjustInnerComments(node, node.params, commentWS);
+            break;
           case "ArrayExpression":
           case "ArrayPattern":
           case "TupleExpression":
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-method/input.js b/packages/babel-parser/test/fixtures/comments/basic/class-method/input.js
new file mode 100644
index 000000000000..be74e23344d9
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-method/input.js
@@ -0,0 +1,2 @@
+(/* 1 */ class /* 2 */ { /* 3 */ f /* 4 */ (/* 5 */ a /* 6 */, /* 7 */) /* 8 */ { /* 9 */ } /* 10 */ } /* 11 */);
+(class /* 1 */ { /* 2 */ #f /* 3 */ (/* 4 */ a /* 5 */, /* 6 */) /* 7 */ { /* 8 */ } /* 9 */ } /* 10 */);
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-method/output.json b/packages/babel-parser/test/fixtures/comments/basic/class-method/output.json
new file mode 100644
index 000000000000..8cbdd4dff91e
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-method/output.json
@@ -0,0 +1,362 @@
+{
+  "type": "File",
+  "start":0,"end":219,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":105}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":219,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":105}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":113,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":113}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":9,"end":102,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":102}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 1 ",
+              "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}}
+            }
+          ],
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 11 ",
+              "start":103,"end":111,"loc":{"start":{"line":1,"column":103},"end":{"line":1,"column":111}}
+            }
+          ],
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 0
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":23,"end":102,"loc":{"start":{"line":1,"column":23},"end":{"line":1,"column":102}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 2 ",
+                "start":15,"end":22,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":22}}
+              }
+            ],
+            "body": [
+              {
+                "type": "ClassMethod",
+                "start":33,"end":91,"loc":{"start":{"line":1,"column":33},"end":{"line":1,"column":91}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 3 ",
+                    "start":25,"end":32,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":32}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 10 ",
+                    "start":92,"end":100,"loc":{"start":{"line":1,"column":92},"end":{"line":1,"column":100}}
+                  }
+                ],
+                "static": false,
+                "key": {
+                  "type": "Identifier",
+                  "start":33,"end":34,"loc":{"start":{"line":1,"column":33},"end":{"line":1,"column":34},"identifierName":"f"},
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 4 ",
+                      "start":35,"end":42,"loc":{"start":{"line":1,"column":35},"end":{"line":1,"column":42}}
+                    }
+                  ],
+                  "name": "f"
+                },
+                "computed": false,
+                "kind": "method",
+                "id": null,
+                "generator": false,
+                "async": false,
+                "params": [
+                  {
+                    "type": "Identifier",
+                    "start":52,"end":53,"loc":{"start":{"line":1,"column":52},"end":{"line":1,"column":53},"identifierName":"a"},
+                    "leadingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 5 ",
+                        "start":44,"end":51,"loc":{"start":{"line":1,"column":44},"end":{"line":1,"column":51}}
+                      }
+                    ],
+                    "trailingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 6 ",
+                        "start":54,"end":61,"loc":{"start":{"line":1,"column":54},"end":{"line":1,"column":61}}
+                      },
+                      {
+                        "type": "CommentBlock",
+                        "value": " 7 ",
+                        "start":63,"end":70,"loc":{"start":{"line":1,"column":63},"end":{"line":1,"column":70}}
+                      }
+                    ],
+                    "name": "a"
+                  }
+                ],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":80,"end":91,"loc":{"start":{"line":1,"column":80},"end":{"line":1,"column":91}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 8 ",
+                      "start":72,"end":79,"loc":{"start":{"line":1,"column":72},"end":{"line":1,"column":79}}
+                    }
+                  ],
+                  "innerComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 9 ",
+                      "start":82,"end":89,"loc":{"start":{"line":1,"column":82},"end":{"line":1,"column":89}}
+                    }
+                  ],
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":114,"end":219,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":105}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":115,"end":208,"loc":{"start":{"line":2,"column":1},"end":{"line":2,"column":94}},
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 10 ",
+              "start":209,"end":217,"loc":{"start":{"line":2,"column":95},"end":{"line":2,"column":103}}
+            }
+          ],
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 114
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":129,"end":208,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":94}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 1 ",
+                "start":121,"end":128,"loc":{"start":{"line":2,"column":7},"end":{"line":2,"column":14}}
+              }
+            ],
+            "body": [
+              {
+                "type": "ClassPrivateMethod",
+                "start":139,"end":198,"loc":{"start":{"line":2,"column":25},"end":{"line":2,"column":84}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 2 ",
+                    "start":131,"end":138,"loc":{"start":{"line":2,"column":17},"end":{"line":2,"column":24}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 9 ",
+                    "start":199,"end":206,"loc":{"start":{"line":2,"column":85},"end":{"line":2,"column":92}}
+                  }
+                ],
+                "static": false,
+                "key": {
+                  "type": "PrivateName",
+                  "start":139,"end":141,"loc":{"start":{"line":2,"column":25},"end":{"line":2,"column":27}},
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 3 ",
+                      "start":142,"end":149,"loc":{"start":{"line":2,"column":28},"end":{"line":2,"column":35}}
+                    }
+                  ],
+                  "id": {
+                    "type": "Identifier",
+                    "start":140,"end":141,"loc":{"start":{"line":2,"column":26},"end":{"line":2,"column":27},"identifierName":"f"},
+                    "name": "f"
+                  }
+                },
+                "kind": "method",
+                "id": null,
+                "generator": false,
+                "async": false,
+                "params": [
+                  {
+                    "type": "Identifier",
+                    "start":159,"end":160,"loc":{"start":{"line":2,"column":45},"end":{"line":2,"column":46},"identifierName":"a"},
+                    "leadingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 4 ",
+                        "start":151,"end":158,"loc":{"start":{"line":2,"column":37},"end":{"line":2,"column":44}}
+                      }
+                    ],
+                    "trailingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 5 ",
+                        "start":161,"end":168,"loc":{"start":{"line":2,"column":47},"end":{"line":2,"column":54}}
+                      },
+                      {
+                        "type": "CommentBlock",
+                        "value": " 6 ",
+                        "start":170,"end":177,"loc":{"start":{"line":2,"column":56},"end":{"line":2,"column":63}}
+                      }
+                    ],
+                    "name": "a"
+                  }
+                ],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":187,"end":198,"loc":{"start":{"line":2,"column":73},"end":{"line":2,"column":84}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 7 ",
+                      "start":179,"end":186,"loc":{"start":{"line":2,"column":65},"end":{"line":2,"column":72}}
+                    }
+                  ],
+                  "innerComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 8 ",
+                      "start":189,"end":196,"loc":{"start":{"line":2,"column":75},"end":{"line":2,"column":82}}
+                    }
+                  ],
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":15,"end":22,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":22}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":25,"end":32,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":32}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":35,"end":42,"loc":{"start":{"line":1,"column":35},"end":{"line":1,"column":42}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":44,"end":51,"loc":{"start":{"line":1,"column":44},"end":{"line":1,"column":51}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":54,"end":61,"loc":{"start":{"line":1,"column":54},"end":{"line":1,"column":61}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":63,"end":70,"loc":{"start":{"line":1,"column":63},"end":{"line":1,"column":70}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":72,"end":79,"loc":{"start":{"line":1,"column":72},"end":{"line":1,"column":79}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":82,"end":89,"loc":{"start":{"line":1,"column":82},"end":{"line":1,"column":89}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 10 ",
+      "start":92,"end":100,"loc":{"start":{"line":1,"column":92},"end":{"line":1,"column":100}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 11 ",
+      "start":103,"end":111,"loc":{"start":{"line":1,"column":103},"end":{"line":1,"column":111}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":121,"end":128,"loc":{"start":{"line":2,"column":7},"end":{"line":2,"column":14}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":131,"end":138,"loc":{"start":{"line":2,"column":17},"end":{"line":2,"column":24}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":142,"end":149,"loc":{"start":{"line":2,"column":28},"end":{"line":2,"column":35}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":151,"end":158,"loc":{"start":{"line":2,"column":37},"end":{"line":2,"column":44}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":161,"end":168,"loc":{"start":{"line":2,"column":47},"end":{"line":2,"column":54}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":170,"end":177,"loc":{"start":{"line":2,"column":56},"end":{"line":2,"column":63}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":179,"end":186,"loc":{"start":{"line":2,"column":65},"end":{"line":2,"column":72}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":189,"end":196,"loc":{"start":{"line":2,"column":75},"end":{"line":2,"column":82}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":199,"end":206,"loc":{"start":{"line":2,"column":85},"end":{"line":2,"column":92}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 10 ",
+      "start":209,"end":217,"loc":{"start":{"line":2,"column":95},"end":{"line":2,"column":103}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-private-method/input.js b/packages/babel-parser/test/fixtures/comments/basic/class-private-method/input.js
new file mode 100644
index 000000000000..bf22324d0b8e
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-private-method/input.js
@@ -0,0 +1,2 @@
+(/* 1 */ class /* 2 */ { /* 3 */ #f /* 4 */ (/* 5 */ a /* 6 */, /* 7 */) /* 8 */ { /* 9 */ } /* 10 */ } /* 11 */);
+
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-private-method/output.json b/packages/babel-parser/test/fixtures/comments/basic/class-private-method/output.json
new file mode 100644
index 000000000000..231a18cc7844
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-private-method/output.json
@@ -0,0 +1,196 @@
+{
+  "type": "File",
+  "start":0,"end":114,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":114}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":114,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":114}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":114,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":114}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":9,"end":103,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":103}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 1 ",
+              "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}}
+            }
+          ],
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 11 ",
+              "start":104,"end":112,"loc":{"start":{"line":1,"column":104},"end":{"line":1,"column":112}}
+            }
+          ],
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 0
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":23,"end":103,"loc":{"start":{"line":1,"column":23},"end":{"line":1,"column":103}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 2 ",
+                "start":15,"end":22,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":22}}
+              }
+            ],
+            "body": [
+              {
+                "type": "ClassPrivateMethod",
+                "start":33,"end":92,"loc":{"start":{"line":1,"column":33},"end":{"line":1,"column":92}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 3 ",
+                    "start":25,"end":32,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":32}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 10 ",
+                    "start":93,"end":101,"loc":{"start":{"line":1,"column":93},"end":{"line":1,"column":101}}
+                  }
+                ],
+                "static": false,
+                "key": {
+                  "type": "PrivateName",
+                  "start":33,"end":35,"loc":{"start":{"line":1,"column":33},"end":{"line":1,"column":35}},
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 4 ",
+                      "start":36,"end":43,"loc":{"start":{"line":1,"column":36},"end":{"line":1,"column":43}}
+                    }
+                  ],
+                  "id": {
+                    "type": "Identifier",
+                    "start":34,"end":35,"loc":{"start":{"line":1,"column":34},"end":{"line":1,"column":35},"identifierName":"f"},
+                    "name": "f"
+                  }
+                },
+                "kind": "method",
+                "id": null,
+                "generator": false,
+                "async": false,
+                "params": [
+                  {
+                    "type": "Identifier",
+                    "start":53,"end":54,"loc":{"start":{"line":1,"column":53},"end":{"line":1,"column":54},"identifierName":"a"},
+                    "leadingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 5 ",
+                        "start":45,"end":52,"loc":{"start":{"line":1,"column":45},"end":{"line":1,"column":52}}
+                      }
+                    ],
+                    "trailingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 6 ",
+                        "start":55,"end":62,"loc":{"start":{"line":1,"column":55},"end":{"line":1,"column":62}}
+                      },
+                      {
+                        "type": "CommentBlock",
+                        "value": " 7 ",
+                        "start":64,"end":71,"loc":{"start":{"line":1,"column":64},"end":{"line":1,"column":71}}
+                      }
+                    ],
+                    "name": "a"
+                  }
+                ],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":81,"end":92,"loc":{"start":{"line":1,"column":81},"end":{"line":1,"column":92}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 8 ",
+                      "start":73,"end":80,"loc":{"start":{"line":1,"column":73},"end":{"line":1,"column":80}}
+                    }
+                  ],
+                  "innerComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 9 ",
+                      "start":83,"end":90,"loc":{"start":{"line":1,"column":83},"end":{"line":1,"column":90}}
+                    }
+                  ],
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":15,"end":22,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":22}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":25,"end":32,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":32}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":36,"end":43,"loc":{"start":{"line":1,"column":36},"end":{"line":1,"column":43}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":45,"end":52,"loc":{"start":{"line":1,"column":45},"end":{"line":1,"column":52}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":55,"end":62,"loc":{"start":{"line":1,"column":55},"end":{"line":1,"column":62}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":64,"end":71,"loc":{"start":{"line":1,"column":64},"end":{"line":1,"column":71}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":73,"end":80,"loc":{"start":{"line":1,"column":73},"end":{"line":1,"column":80}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":83,"end":90,"loc":{"start":{"line":1,"column":83},"end":{"line":1,"column":90}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 10 ",
+      "start":93,"end":101,"loc":{"start":{"line":1,"column":93},"end":{"line":1,"column":101}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 11 ",
+      "start":104,"end":112,"loc":{"start":{"line":1,"column":104},"end":{"line":1,"column":112}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/function/input.js b/packages/babel-parser/test/fixtures/comments/basic/function/input.js
new file mode 100644
index 000000000000..33244bdfd8c6
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/function/input.js
@@ -0,0 +1,4 @@
+/* 1 */ function /* 2 */ f /* 3 */ (/* 4 */ a /* 5 */, /* 6 */) /* 7 */ { /* 8 */ } /* 9 */
+(/* 1 */ function /* 2 */ f /* 3 */ (/* 4 */ a /* 5 */, /* 6 */) /* 7 */ { /* 8 */ } /* 9 */);
+
+
diff --git a/packages/babel-parser/test/fixtures/comments/basic/function/output.json b/packages/babel-parser/test/fixtures/comments/basic/function/output.json
new file mode 100644
index 000000000000..367b69f088c2
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/function/output.json
@@ -0,0 +1,290 @@
+{
+  "type": "File",
+  "start":0,"end":186,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":94}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":186,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":94}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start":8,"end":83,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":83}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 1 ",
+            "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+          }
+        ],
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 9 ",
+            "start":84,"end":91,"loc":{"start":{"line":1,"column":84},"end":{"line":1,"column":91}}
+          }
+        ],
+        "id": {
+          "type": "Identifier",
+          "start":25,"end":26,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":26},"identifierName":"f"},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 2 ",
+              "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+            }
+          ],
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 3 ",
+              "start":27,"end":34,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":34}}
+            }
+          ],
+          "name": "f"
+        },
+        "generator": false,
+        "async": false,
+        "params": [
+          {
+            "type": "Identifier",
+            "start":44,"end":45,"loc":{"start":{"line":1,"column":44},"end":{"line":1,"column":45},"identifierName":"a"},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 4 ",
+                "start":36,"end":43,"loc":{"start":{"line":1,"column":36},"end":{"line":1,"column":43}}
+              }
+            ],
+            "trailingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 5 ",
+                "start":46,"end":53,"loc":{"start":{"line":1,"column":46},"end":{"line":1,"column":53}}
+              },
+              {
+                "type": "CommentBlock",
+                "value": " 6 ",
+                "start":55,"end":62,"loc":{"start":{"line":1,"column":55},"end":{"line":1,"column":62}}
+              }
+            ],
+            "name": "a"
+          }
+        ],
+        "body": {
+          "type": "BlockStatement",
+          "start":72,"end":83,"loc":{"start":{"line":1,"column":72},"end":{"line":1,"column":83}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 7 ",
+              "start":64,"end":71,"loc":{"start":{"line":1,"column":64},"end":{"line":1,"column":71}}
+            }
+          ],
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 8 ",
+              "start":74,"end":81,"loc":{"start":{"line":1,"column":74},"end":{"line":1,"column":81}}
+            }
+          ],
+          "body": [],
+          "directives": []
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":92,"end":186,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":94}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 9 ",
+            "start":84,"end":91,"loc":{"start":{"line":1,"column":84},"end":{"line":1,"column":91}}
+          }
+        ],
+        "expression": {
+          "type": "FunctionExpression",
+          "start":101,"end":176,"loc":{"start":{"line":2,"column":9},"end":{"line":2,"column":84}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 1 ",
+              "start":93,"end":100,"loc":{"start":{"line":2,"column":1},"end":{"line":2,"column":8}}
+            }
+          ],
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 9 ",
+              "start":177,"end":184,"loc":{"start":{"line":2,"column":85},"end":{"line":2,"column":92}}
+            }
+          ],
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 92
+          },
+          "id": {
+            "type": "Identifier",
+            "start":118,"end":119,"loc":{"start":{"line":2,"column":26},"end":{"line":2,"column":27},"identifierName":"f"},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 2 ",
+                "start":110,"end":117,"loc":{"start":{"line":2,"column":18},"end":{"line":2,"column":25}}
+              }
+            ],
+            "trailingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 3 ",
+                "start":120,"end":127,"loc":{"start":{"line":2,"column":28},"end":{"line":2,"column":35}}
+              }
+            ],
+            "name": "f"
+          },
+          "generator": false,
+          "async": false,
+          "params": [
+            {
+              "type": "Identifier",
+              "start":137,"end":138,"loc":{"start":{"line":2,"column":45},"end":{"line":2,"column":46},"identifierName":"a"},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 4 ",
+                  "start":129,"end":136,"loc":{"start":{"line":2,"column":37},"end":{"line":2,"column":44}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 5 ",
+                  "start":139,"end":146,"loc":{"start":{"line":2,"column":47},"end":{"line":2,"column":54}}
+                },
+                {
+                  "type": "CommentBlock",
+                  "value": " 6 ",
+                  "start":148,"end":155,"loc":{"start":{"line":2,"column":56},"end":{"line":2,"column":63}}
+                }
+              ],
+              "name": "a"
+            }
+          ],
+          "body": {
+            "type": "BlockStatement",
+            "start":165,"end":176,"loc":{"start":{"line":2,"column":73},"end":{"line":2,"column":84}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 7 ",
+                "start":157,"end":164,"loc":{"start":{"line":2,"column":65},"end":{"line":2,"column":72}}
+              }
+            ],
+            "innerComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 8 ",
+                "start":167,"end":174,"loc":{"start":{"line":2,"column":75},"end":{"line":2,"column":82}}
+              }
+            ],
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":27,"end":34,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":34}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":36,"end":43,"loc":{"start":{"line":1,"column":36},"end":{"line":1,"column":43}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":46,"end":53,"loc":{"start":{"line":1,"column":46},"end":{"line":1,"column":53}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":55,"end":62,"loc":{"start":{"line":1,"column":55},"end":{"line":1,"column":62}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":64,"end":71,"loc":{"start":{"line":1,"column":64},"end":{"line":1,"column":71}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":74,"end":81,"loc":{"start":{"line":1,"column":74},"end":{"line":1,"column":81}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":84,"end":91,"loc":{"start":{"line":1,"column":84},"end":{"line":1,"column":91}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":93,"end":100,"loc":{"start":{"line":2,"column":1},"end":{"line":2,"column":8}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":110,"end":117,"loc":{"start":{"line":2,"column":18},"end":{"line":2,"column":25}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":120,"end":127,"loc":{"start":{"line":2,"column":28},"end":{"line":2,"column":35}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":129,"end":136,"loc":{"start":{"line":2,"column":37},"end":{"line":2,"column":44}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":139,"end":146,"loc":{"start":{"line":2,"column":47},"end":{"line":2,"column":54}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":148,"end":155,"loc":{"start":{"line":2,"column":56},"end":{"line":2,"column":63}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":157,"end":164,"loc":{"start":{"line":2,"column":65},"end":{"line":2,"column":72}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":167,"end":174,"loc":{"start":{"line":2,"column":75},"end":{"line":2,"column":82}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":177,"end":184,"loc":{"start":{"line":2,"column":85},"end":{"line":2,"column":92}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/object-method/input.js b/packages/babel-parser/test/fixtures/comments/basic/object-method/input.js
new file mode 100644
index 000000000000..f01543f7ffd5
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/object-method/input.js
@@ -0,0 +1 @@
+(/* 1 */ { /* 2 */ f /* 3 */ (/* 4 */ a /* 5 */, /* 6 */) /* 7 */ { /* 8 */ } /* 9 */ } /* 10 */);
diff --git a/packages/babel-parser/test/fixtures/comments/basic/object-method/output.json b/packages/babel-parser/test/fixtures/comments/basic/object-method/output.json
new file mode 100644
index 000000000000..f1604cd7dd61
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/object-method/output.json
@@ -0,0 +1,175 @@
+{
+  "type": "File",
+  "start":0,"end":98,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":98}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":98,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":98}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":98,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":98}},
+        "expression": {
+          "type": "ObjectExpression",
+          "start":9,"end":87,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":87}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 1 ",
+              "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}}
+            }
+          ],
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 10 ",
+              "start":88,"end":96,"loc":{"start":{"line":1,"column":88},"end":{"line":1,"column":96}}
+            }
+          ],
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 0
+          },
+          "properties": [
+            {
+              "type": "ObjectMethod",
+              "start":19,"end":77,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":77}},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 2 ",
+                  "start":11,"end":18,"loc":{"start":{"line":1,"column":11},"end":{"line":1,"column":18}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 9 ",
+                  "start":78,"end":85,"loc":{"start":{"line":1,"column":78},"end":{"line":1,"column":85}}
+                }
+              ],
+              "method": true,
+              "key": {
+                "type": "Identifier",
+                "start":19,"end":20,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":20},"identifierName":"f"},
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 3 ",
+                    "start":21,"end":28,"loc":{"start":{"line":1,"column":21},"end":{"line":1,"column":28}}
+                  }
+                ],
+                "name": "f"
+              },
+              "computed": false,
+              "kind": "method",
+              "id": null,
+              "generator": false,
+              "async": false,
+              "params": [
+                {
+                  "type": "Identifier",
+                  "start":38,"end":39,"loc":{"start":{"line":1,"column":38},"end":{"line":1,"column":39},"identifierName":"a"},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 4 ",
+                      "start":30,"end":37,"loc":{"start":{"line":1,"column":30},"end":{"line":1,"column":37}}
+                    }
+                  ],
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 5 ",
+                      "start":40,"end":47,"loc":{"start":{"line":1,"column":40},"end":{"line":1,"column":47}}
+                    },
+                    {
+                      "type": "CommentBlock",
+                      "value": " 6 ",
+                      "start":49,"end":56,"loc":{"start":{"line":1,"column":49},"end":{"line":1,"column":56}}
+                    }
+                  ],
+                  "name": "a"
+                }
+              ],
+              "body": {
+                "type": "BlockStatement",
+                "start":66,"end":77,"loc":{"start":{"line":1,"column":66},"end":{"line":1,"column":77}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 7 ",
+                    "start":58,"end":65,"loc":{"start":{"line":1,"column":58},"end":{"line":1,"column":65}}
+                  }
+                ],
+                "innerComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 8 ",
+                    "start":68,"end":75,"loc":{"start":{"line":1,"column":68},"end":{"line":1,"column":75}}
+                  }
+                ],
+                "body": [],
+                "directives": []
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":1,"end":8,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":8}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":11,"end":18,"loc":{"start":{"line":1,"column":11},"end":{"line":1,"column":18}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":21,"end":28,"loc":{"start":{"line":1,"column":21},"end":{"line":1,"column":28}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":30,"end":37,"loc":{"start":{"line":1,"column":30},"end":{"line":1,"column":37}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":40,"end":47,"loc":{"start":{"line":1,"column":40},"end":{"line":1,"column":47}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":49,"end":56,"loc":{"start":{"line":1,"column":49},"end":{"line":1,"column":56}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":58,"end":65,"loc":{"start":{"line":1,"column":58},"end":{"line":1,"column":65}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":68,"end":75,"loc":{"start":{"line":1,"column":68},"end":{"line":1,"column":75}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":78,"end":85,"loc":{"start":{"line":1,"column":78},"end":{"line":1,"column":85}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 10 ",
+      "start":88,"end":96,"loc":{"start":{"line":1,"column":88},"end":{"line":1,"column":96}}
+    }
+  ]
+}
\ No newline at end of file

From e02d6bd2d34f03bb850a65949762ab7d0f8f47f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Fri, 2 Jul 2021 10:25:27 -0400
Subject: [PATCH 25/35] add comment attachment design doc

---
 .../babel-parser/ast/comment-attachment.md    | 129 ++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 packages/babel-parser/ast/comment-attachment.md

diff --git a/packages/babel-parser/ast/comment-attachment.md b/packages/babel-parser/ast/comment-attachment.md
new file mode 100644
index 000000000000..a08ac8745bf5
--- /dev/null
+++ b/packages/babel-parser/ast/comment-attachment.md
@@ -0,0 +1,129 @@
+# Comment attachment
+
+When Babel is parsing JavaScript files, the comments will be attached to its adjacent AST nodes. If such neighbors do not exist, Babel will fallback to the innermost containing node.
+
+The [current implementation](https://github.com/babel/babel/pull/13521) is based on its converse problem: Instead of attaching comments directly to AST nodes, we attach nodes to a stack of applicable comment whitespaces (see below for definitions). After a comment whitespace has set up its node relationship including leading, trailing and container, we forward the comments to the AST nodes and perform adjustments such as merge innerComments after trailing comma to the last element's trailing comments.
+
+### Comment Whitespace
+
+A comment whitespace represents a sequence of whitespace characters and comments including `//` comment line, `/* */` comment block, `<!--` HTML Open comment and `-->` HTML close comment. For example, the following snippet
+
+```js
+a// 1
+/* 2 */
+ + <!-- 3
+-->
+2;
+```
+
+have two comment whitespaces
+
+```jsonc
+// for `// 1\n/* 2 */ `
+{
+  start: 1, // position of '/'
+  end: 15, // position of '+'
+  comments: [
+    CommentLine { start: 1, end: 5},
+    CommentBlock { start: 6, end: 13 }
+  ],
+  leadingNode: Identifier("a"),
+  trailingNode: null,
+  containerNode: BinaryExpression,
+}
+```
+
+and
+
+```jsonc
+// for ` <!-- 3\n-->\n`
+{
+  start: 16, // position of ' ' after '+'
+  end: 28, // position of '2'
+  comments: [
+    CommentLine { start: 17, end: 23},
+    CommentBlock { start: 24, end: 27 }
+  ],
+  leadingNode: null,
+  trailingNode: NumericLiteral(2),
+  containerNode: BinaryExpression,
+}
+```
+
+Given a program source, the set of all the comment whitespaces has the following properties:
+
+**Nonemptiness** (P1): For every `w` of comment whitespaces, `w` satisifies
+
+```
+w.start < w.end
+```
+
+**Isolation** (P2): There must not exist any pair of comment whitespaces `w1` and `w2` such that
+
+```
+w1.start ≤ w2.start ≤ w1.end
+```
+
+**Completeness** (P3): For every comment AST node `c`, there must exist a comment whitespace `w`, such that
+
+```
+w.start ≤ c.start < c.end ≤ w.end
+```
+
+We can also say `w` encompasses `c`.
+
+**Monotonicity** (Corollary from P1 and P2): Given a list of comment whitespaces orderred by `start`, denoted by `{ w1, w2, ... w_n }`, they must satisify
+
+```
+w1.start < w1.end < w2.start < w2.end < ... < w_n.start < w_n.end
+```
+
+For any given comment whitespace `w` and an AST node `n`, we can define the following relationships:
+
+1. `n` is the _leading node_ of `w` iff `n.end = w.start`
+2. `n` is the _trailing node_ of `w` iff `n.start = w.end`
+3. `n` is the _containing node_ of `w` iff for all AST nodes `N` satisfying `N.start < w.start < w.end < N.end`, the following proposition is true:
+
+```
+N.start ≤ n.start < w.start < w.end < n.end ≤ N.end
+```
+
+Note that the relationship from `w` to `n` is _not_ injective. In other words, a comment whitespace can have multiple leading nodes, trailing nodes, and/or containing nodes. To address this issue we can define the extrema of the set of related ast nodes.
+
+1. Outermost leading/trailing node: `n` is the _outermost leading/trailing node_ of `w` iff for every other leading/trailing node `N` of `w`, `N` is a descendant of `n`
+2. Innermost containing node: `n` is the _innermost containing node_ of `w` iff for every other containing node `N` of `w`, `n` is a descendant of `N`
+
+For any given comment `c` and AST node `n`, now we can (in)formally define leading comments, trailing comments and inner comments:
+
+**Leading Comment**: `c` is one of leading comments of `n` iff there exist a comment whitespace `w`, such that `n` is the outermost trailing node of `w` and `w` encompasses `c`
+
+**Trailing Comment**: `c` is one of trailing comments of `n` iff there exist a comment whitespace `w`, such that `n` is the outermost leading node of `w` and `w` encompasses `c`
+
+**Inner Comment**: `c` is one of inner comments of `n` iff
+
+1. there exist a comment whitespace `w`, such that `n` is the innermost containing node of `w` and `w` encompasses `c`.
+2. there does not exist a comment whitespace `w`, such that `n` is the outermost leading or trailing node of `w and `w`encompasses`c`.
+
+The Isolation (P2) of a comment whitespace gaurantees that if two comments `c1`, `c2` belongs to the leading/trailing comments of `n`, `c1` and `c2` must be encompassed by the same comment whitespace `w`. This property simplifies classification of leading/trailing because we can now mark a group of comments instead of checking every comments under the same comment whitespace.
+
+Note that Babel parser marks certain inner comments after a trailing comma of a list structures to be the trailing comments of the last element in that list. (https://github.com/babel/babel/pull/10369) This behaviour can be considered as conpensation due to lack of a `TrailingCommaElement` AST structure to which a comment can be attached. Although this PR implements such behaviour, we will not be discussing it in the design section.
+
+### Construct Comment Whitespace
+
+We construct the comment whitespace in `Tokenizer#skipSpace` of `packages/babel-parser/src/tokenizer/index.js`, after we exit from the skip loop, we collect the `comments`, mark the location info and push to `parser.state.commentStack`. In this PR we also merge the parsing of `HTMLOpenComment` and `HTMLCloseComment` to `skipSpace`.
+
+### Attaching Nodes to Comment Whitespace
+
+For every finished AST node invoked from `parser#finishNode`. Before an AST node is finished, the whitespace token have been read from `tokenizer#next()`, so if this node has trailing comments, it must be the `leadingNode` of the last element in `commentStack`.
+
+Note that the `leadingNode` will be updated by subsequent `finishNode()` calls invoked at the same position. The last `finishNode()` call is the winner, which is exactly the _outermost_ leading node that we are interested. Likewise for `trailingNode`.
+
+Then we iterate `state.commentStack` reversely. we mark `trailingNode` when `comment.end = node.start`, mark `containingNode` when it is not defined, so here the first `finishNode()` is the winner, which is exactly the _innermost_ containing node.
+
+After we set the containing node, we can assign comments to related node, since the nature of a recursive descending parser requires that when `containingNode` is finished, its `leadingNode` and `trailingNode` must have been parsed<sup>\*</sup>, so the related node stops being updated by `processComment`.
+
+<sub>\* Technically this is not always true because we have `estree` plugins invokes `finishNodeAt` at a different tokenizer location. However, since most `estree` users are using `@babel/eslint-parser`, which removes the attached comment. So we are good here.</sub>
+
+### Finalize comment whitespaces
+
+In this step we attach the comments and do the trailing comma adjustments. Note that an extra routine `finalizeRemainingComments` is provided for `parseExpression`, which may not have opportunity to finalize comments which is added to the leading/trailing of the top level Expression node.

From c3b2feaf4cdc2ee5d3955ad0a94d51a6a18fa672 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Fri, 2 Jul 2021 10:59:34 -0400
Subject: [PATCH 26/35] misc fix

---
 packages/babel-parser/ast/comment-attachment.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/babel-parser/ast/comment-attachment.md b/packages/babel-parser/ast/comment-attachment.md
index a08ac8745bf5..f5aafdf12355 100644
--- a/packages/babel-parser/ast/comment-attachment.md
+++ b/packages/babel-parser/ast/comment-attachment.md
@@ -42,7 +42,7 @@ and
   end: 28, // position of '2'
   comments: [
     CommentLine { start: 17, end: 23},
-    CommentBlock { start: 24, end: 27 }
+    CommentLine { start: 24, end: 27 }
   ],
   leadingNode: null,
   trailingNode: NumericLiteral(2),
@@ -72,7 +72,7 @@ w.start ≤ c.start < c.end ≤ w.end
 
 We can also say `w` encompasses `c`.
 
-**Monotonicity** (Corollary from P1 and P2): Given a list of comment whitespaces orderred by `start`, denoted by `{ w1, w2, ... w_n }`, they must satisify
+**Monotonicity** (Corollary from P1 and P2): Given a non-empty list of comment whitespaces orderred by `start`, denoted by `{ w1, w2, ... w_n }`, they must satisify
 
 ```
 w1.start < w1.end < w2.start < w2.end < ... < w_n.start < w_n.end

From 7ae3f42811e9a0afaa850a50ace44cb65f76e1f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Mon, 5 Jul 2021 15:26:03 -0400
Subject: [PATCH 27/35] fix: reset previous trailing comments when parsing
 async method/accessor

---
 packages/babel-parser/src/parser/comments.js  |  31 ++
 .../babel-parser/src/parser/expression.js     |   2 +
 packages/babel-parser/src/parser/statement.js |   2 +
 .../basic/class-accessor-computed/input.js    |   3 +
 .../basic/class-accessor-computed/output.json | 343 ++++++++++++++++++
 .../class-method-async-generator/input.js     |   2 +
 .../class-method-async-generator/output.json  | 207 +++++++++++
 .../basic/object-accessor-computed/input.js   |   3 +
 .../object-accessor-computed/output.json      | 325 +++++++++++++++++
 .../object-method-async-generator/input.js    |   2 +
 .../object-method-async-generator/output.json | 197 ++++++++++
 11 files changed, 1117 insertions(+)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-accessor-computed/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-accessor-computed/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-method-async-generator/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-method-async-generator/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/object-accessor-computed/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/object-accessor-computed/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/object-method-async-generator/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/object-method-async-generator/output.json

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 3ec4c14cef70..bab22ad79fa0 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -210,4 +210,35 @@ export default class CommentsParser extends BaseParser {
     }
     this.state.commentStack = [];
   }
+
+  /**
+   * Reset previous node trailing comments. Used in object / class
+   * property parsing. We parse `async`, `set` and `get` as an identifier
+   * but may reinterepret it into an async/accessor method later. In this case
+   * the identifier is not part of the AST and we should sync the knowledge
+   * to commentStacks
+   *
+   * For performance we do not check trailing node and we assume `node` is the
+   * last finished node before current token.
+   *
+   * @param {N.Node} node the last finished AST node _before_ current token
+   * @returns
+   * @memberof CommentsParser
+   */
+  resetPreviousNodeTrailingComments(node: N.Node) {
+    const { commentStack } = this.state;
+    let i = commentStack.length - 1;
+    if (i < 0) return;
+    let commentWS = commentStack[i];
+    if (commentWS.leadingNode === node) {
+      commentWS.leadingNode = null;
+      return;
+    }
+    i--;
+    if (i < 0) return;
+    commentWS = commentStack[i];
+    if (commentWS.leadingNode === node) {
+      commentWS.leadingNode = null;
+    }
+  }
 }
diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 4300a69d0e35..befb8e533ba6 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -1788,6 +1788,7 @@ export default class ExpressionParser extends LValParser {
       // https://tc39.es/ecma262/#prod-AsyncGeneratorMethod
       if (keyName === "async" && !this.hasPrecedingLineBreak()) {
         isAsync = true;
+        this.resetPreviousNodeTrailingComments(key);
         isGenerator = this.eat(tt.star);
         this.parsePropertyName(prop, /* isPrivateNameAllowed */ false);
       }
@@ -1795,6 +1796,7 @@ export default class ExpressionParser extends LValParser {
       // set PropertyName[?Yield, ?Await] ( PropertySetParameterList ) { FunctionBody[~Yield, ~Await] }
       if (keyName === "get" || keyName === "set") {
         isAccessor = true;
+        this.resetPreviousNodeTrailingComments(key);
         prop.kind = keyName;
         if (this.match(tt.star)) {
           isGenerator = true;
diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
index cff855036f19..1571dd1d3a1a 100644
--- a/packages/babel-parser/src/parser/statement.js
+++ b/packages/babel-parser/src/parser/statement.js
@@ -1495,6 +1495,7 @@ export default class StatementParser extends ExpressionParser {
       !this.isLineTerminator()
     ) {
       // an async method
+      this.resetPreviousNodeTrailingComments(key);
       const isGenerator = this.eat(tt.star);
 
       if (publicMember.optional) {
@@ -1536,6 +1537,7 @@ export default class StatementParser extends ExpressionParser {
     ) {
       // `get\n*` is an uninitialized property named 'get' followed by a generator.
       // a getter or setter
+      this.resetPreviousNodeTrailingComments(key);
       method.kind = key.name;
       // The so-called parsed name would have been "get/set": get the real name.
       const isPrivate = this.match(tt.privateName);
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-accessor-computed/input.js b/packages/babel-parser/test/fixtures/comments/basic/class-accessor-computed/input.js
new file mode 100644
index 000000000000..54d2e8c4768d
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-accessor-computed/input.js
@@ -0,0 +1,3 @@
+(class { /* 1 */ set /* 2 */ [ /* 3 */f/* 4 */] /* 5 */ (/* 6 */ a /* 7 */, /* 8 */) /* 9 */ {} });
+(class { /* 1 */ get /* 2 */ [ /* 3 */f/* 4 */] /* 5 */ (/* 6 */) /* 7 */ {} });
+(class { get /* 1 */ [f] () {} });
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-accessor-computed/output.json b/packages/babel-parser/test/fixtures/comments/basic/class-accessor-computed/output.json
new file mode 100644
index 000000000000..fdd022eeb802
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-accessor-computed/output.json
@@ -0,0 +1,343 @@
+{
+  "type": "File",
+  "start":0,"end":215,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":34}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":215,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":34}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":99,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":99}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":1,"end":97,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":97}},
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 0
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":7,"end":97,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":97}},
+            "body": [
+              {
+                "type": "ClassMethod",
+                "start":17,"end":95,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":95}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 1 ",
+                    "start":9,"end":16,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":16}}
+                  }
+                ],
+                "innerComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 2 ",
+                    "start":21,"end":28,"loc":{"start":{"line":1,"column":21},"end":{"line":1,"column":28}}
+                  },
+                  {
+                    "type": "CommentBlock",
+                    "value": " 5 ",
+                    "start":48,"end":55,"loc":{"start":{"line":1,"column":48},"end":{"line":1,"column":55}}
+                  }
+                ],
+                "static": false,
+                "key": {
+                  "type": "Identifier",
+                  "start":38,"end":39,"loc":{"start":{"line":1,"column":38},"end":{"line":1,"column":39},"identifierName":"f"},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 3 ",
+                      "start":31,"end":38,"loc":{"start":{"line":1,"column":31},"end":{"line":1,"column":38}}
+                    }
+                  ],
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 4 ",
+                      "start":39,"end":46,"loc":{"start":{"line":1,"column":39},"end":{"line":1,"column":46}}
+                    }
+                  ],
+                  "name": "f"
+                },
+                "computed": true,
+                "kind": "set",
+                "id": null,
+                "generator": false,
+                "async": false,
+                "params": [
+                  {
+                    "type": "Identifier",
+                    "start":65,"end":66,"loc":{"start":{"line":1,"column":65},"end":{"line":1,"column":66},"identifierName":"a"},
+                    "leadingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 6 ",
+                        "start":57,"end":64,"loc":{"start":{"line":1,"column":57},"end":{"line":1,"column":64}}
+                      }
+                    ],
+                    "trailingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 7 ",
+                        "start":67,"end":74,"loc":{"start":{"line":1,"column":67},"end":{"line":1,"column":74}}
+                      },
+                      {
+                        "type": "CommentBlock",
+                        "value": " 8 ",
+                        "start":76,"end":83,"loc":{"start":{"line":1,"column":76},"end":{"line":1,"column":83}}
+                      }
+                    ],
+                    "name": "a"
+                  }
+                ],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":93,"end":95,"loc":{"start":{"line":1,"column":93},"end":{"line":1,"column":95}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 9 ",
+                      "start":85,"end":92,"loc":{"start":{"line":1,"column":85},"end":{"line":1,"column":92}}
+                    }
+                  ],
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":100,"end":180,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":80}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":101,"end":178,"loc":{"start":{"line":2,"column":1},"end":{"line":2,"column":78}},
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 100
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":107,"end":178,"loc":{"start":{"line":2,"column":7},"end":{"line":2,"column":78}},
+            "body": [
+              {
+                "type": "ClassMethod",
+                "start":117,"end":176,"loc":{"start":{"line":2,"column":17},"end":{"line":2,"column":76}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 1 ",
+                    "start":109,"end":116,"loc":{"start":{"line":2,"column":9},"end":{"line":2,"column":16}}
+                  }
+                ],
+                "innerComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 2 ",
+                    "start":121,"end":128,"loc":{"start":{"line":2,"column":21},"end":{"line":2,"column":28}}
+                  },
+                  {
+                    "type": "CommentBlock",
+                    "value": " 5 ",
+                    "start":148,"end":155,"loc":{"start":{"line":2,"column":48},"end":{"line":2,"column":55}}
+                  },
+                  {
+                    "type": "CommentBlock",
+                    "value": " 6 ",
+                    "start":157,"end":164,"loc":{"start":{"line":2,"column":57},"end":{"line":2,"column":64}}
+                  }
+                ],
+                "static": false,
+                "key": {
+                  "type": "Identifier",
+                  "start":138,"end":139,"loc":{"start":{"line":2,"column":38},"end":{"line":2,"column":39},"identifierName":"f"},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 3 ",
+                      "start":131,"end":138,"loc":{"start":{"line":2,"column":31},"end":{"line":2,"column":38}}
+                    }
+                  ],
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 4 ",
+                      "start":139,"end":146,"loc":{"start":{"line":2,"column":39},"end":{"line":2,"column":46}}
+                    }
+                  ],
+                  "name": "f"
+                },
+                "computed": true,
+                "kind": "get",
+                "id": null,
+                "generator": false,
+                "async": false,
+                "params": [],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":174,"end":176,"loc":{"start":{"line":2,"column":74},"end":{"line":2,"column":76}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 7 ",
+                      "start":166,"end":173,"loc":{"start":{"line":2,"column":66},"end":{"line":2,"column":73}}
+                    }
+                  ],
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":181,"end":215,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":34}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":182,"end":213,"loc":{"start":{"line":3,"column":1},"end":{"line":3,"column":32}},
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 181
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":188,"end":213,"loc":{"start":{"line":3,"column":7},"end":{"line":3,"column":32}},
+            "body": [
+              {
+                "type": "ClassMethod",
+                "start":190,"end":211,"loc":{"start":{"line":3,"column":9},"end":{"line":3,"column":30}},
+                "innerComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 1 ",
+                    "start":194,"end":201,"loc":{"start":{"line":3,"column":13},"end":{"line":3,"column":20}}
+                  }
+                ],
+                "static": false,
+                "key": {
+                  "type": "Identifier",
+                  "start":203,"end":204,"loc":{"start":{"line":3,"column":22},"end":{"line":3,"column":23},"identifierName":"f"},
+                  "name": "f"
+                },
+                "computed": true,
+                "kind": "get",
+                "id": null,
+                "generator": false,
+                "async": false,
+                "params": [],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":209,"end":211,"loc":{"start":{"line":3,"column":28},"end":{"line":3,"column":30}},
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":9,"end":16,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":16}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":21,"end":28,"loc":{"start":{"line":1,"column":21},"end":{"line":1,"column":28}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":31,"end":38,"loc":{"start":{"line":1,"column":31},"end":{"line":1,"column":38}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":39,"end":46,"loc":{"start":{"line":1,"column":39},"end":{"line":1,"column":46}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":48,"end":55,"loc":{"start":{"line":1,"column":48},"end":{"line":1,"column":55}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":57,"end":64,"loc":{"start":{"line":1,"column":57},"end":{"line":1,"column":64}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":67,"end":74,"loc":{"start":{"line":1,"column":67},"end":{"line":1,"column":74}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":76,"end":83,"loc":{"start":{"line":1,"column":76},"end":{"line":1,"column":83}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":85,"end":92,"loc":{"start":{"line":1,"column":85},"end":{"line":1,"column":92}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":109,"end":116,"loc":{"start":{"line":2,"column":9},"end":{"line":2,"column":16}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":121,"end":128,"loc":{"start":{"line":2,"column":21},"end":{"line":2,"column":28}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":131,"end":138,"loc":{"start":{"line":2,"column":31},"end":{"line":2,"column":38}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":139,"end":146,"loc":{"start":{"line":2,"column":39},"end":{"line":2,"column":46}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":148,"end":155,"loc":{"start":{"line":2,"column":48},"end":{"line":2,"column":55}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":157,"end":164,"loc":{"start":{"line":2,"column":57},"end":{"line":2,"column":64}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":166,"end":173,"loc":{"start":{"line":2,"column":66},"end":{"line":2,"column":73}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":194,"end":201,"loc":{"start":{"line":3,"column":13},"end":{"line":3,"column":20}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-method-async-generator/input.js b/packages/babel-parser/test/fixtures/comments/basic/class-method-async-generator/input.js
new file mode 100644
index 000000000000..4b9c1f582cab
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-method-async-generator/input.js
@@ -0,0 +1,2 @@
+class C { /* 1 */ async /* 2 */ * /* 3 */ f /* 4 */ (/* 5 */ a /* 6 */, /* 7 */) /* 8 */ {} }
+(class { async /* 1 */ *f () {} });
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-method-async-generator/output.json b/packages/babel-parser/test/fixtures/comments/basic/class-method-async-generator/output.json
new file mode 100644
index 000000000000..b8b29273972e
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-method-async-generator/output.json
@@ -0,0 +1,207 @@
+{
+  "type": "File",
+  "start":0,"end":129,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":35}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":129,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":35}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ClassDeclaration",
+        "start":0,"end":93,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":93}},
+        "id": {
+          "type": "Identifier",
+          "start":6,"end":7,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":7},"identifierName":"C"},
+          "name": "C"
+        },
+        "superClass": null,
+        "body": {
+          "type": "ClassBody",
+          "start":8,"end":93,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":93}},
+          "body": [
+            {
+              "type": "ClassMethod",
+              "start":18,"end":91,"loc":{"start":{"line":1,"column":18},"end":{"line":1,"column":91}},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 1 ",
+                  "start":10,"end":17,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":17}}
+                }
+              ],
+              "innerComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 2 ",
+                  "start":24,"end":31,"loc":{"start":{"line":1,"column":24},"end":{"line":1,"column":31}}
+                }
+              ],
+              "static": false,
+              "key": {
+                "type": "Identifier",
+                "start":42,"end":43,"loc":{"start":{"line":1,"column":42},"end":{"line":1,"column":43},"identifierName":"f"},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 3 ",
+                    "start":34,"end":41,"loc":{"start":{"line":1,"column":34},"end":{"line":1,"column":41}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 4 ",
+                    "start":44,"end":51,"loc":{"start":{"line":1,"column":44},"end":{"line":1,"column":51}}
+                  }
+                ],
+                "name": "f"
+              },
+              "computed": false,
+              "kind": "method",
+              "id": null,
+              "generator": true,
+              "async": true,
+              "params": [
+                {
+                  "type": "Identifier",
+                  "start":61,"end":62,"loc":{"start":{"line":1,"column":61},"end":{"line":1,"column":62},"identifierName":"a"},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 5 ",
+                      "start":53,"end":60,"loc":{"start":{"line":1,"column":53},"end":{"line":1,"column":60}}
+                    }
+                  ],
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 6 ",
+                      "start":63,"end":70,"loc":{"start":{"line":1,"column":63},"end":{"line":1,"column":70}}
+                    },
+                    {
+                      "type": "CommentBlock",
+                      "value": " 7 ",
+                      "start":72,"end":79,"loc":{"start":{"line":1,"column":72},"end":{"line":1,"column":79}}
+                    }
+                  ],
+                  "name": "a"
+                }
+              ],
+              "body": {
+                "type": "BlockStatement",
+                "start":89,"end":91,"loc":{"start":{"line":1,"column":89},"end":{"line":1,"column":91}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 8 ",
+                    "start":81,"end":88,"loc":{"start":{"line":1,"column":81},"end":{"line":1,"column":88}}
+                  }
+                ],
+                "body": [],
+                "directives": []
+              }
+            }
+          ]
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":94,"end":129,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":35}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":95,"end":127,"loc":{"start":{"line":2,"column":1},"end":{"line":2,"column":33}},
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 94
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":101,"end":127,"loc":{"start":{"line":2,"column":7},"end":{"line":2,"column":33}},
+            "body": [
+              {
+                "type": "ClassMethod",
+                "start":103,"end":125,"loc":{"start":{"line":2,"column":9},"end":{"line":2,"column":31}},
+                "innerComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 1 ",
+                    "start":109,"end":116,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":22}}
+                  }
+                ],
+                "static": false,
+                "key": {
+                  "type": "Identifier",
+                  "start":118,"end":119,"loc":{"start":{"line":2,"column":24},"end":{"line":2,"column":25},"identifierName":"f"},
+                  "name": "f"
+                },
+                "computed": false,
+                "kind": "method",
+                "id": null,
+                "generator": true,
+                "async": true,
+                "params": [],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":123,"end":125,"loc":{"start":{"line":2,"column":29},"end":{"line":2,"column":31}},
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":10,"end":17,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":17}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":24,"end":31,"loc":{"start":{"line":1,"column":24},"end":{"line":1,"column":31}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":34,"end":41,"loc":{"start":{"line":1,"column":34},"end":{"line":1,"column":41}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":44,"end":51,"loc":{"start":{"line":1,"column":44},"end":{"line":1,"column":51}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":53,"end":60,"loc":{"start":{"line":1,"column":53},"end":{"line":1,"column":60}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":63,"end":70,"loc":{"start":{"line":1,"column":63},"end":{"line":1,"column":70}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":72,"end":79,"loc":{"start":{"line":1,"column":72},"end":{"line":1,"column":79}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":81,"end":88,"loc":{"start":{"line":1,"column":81},"end":{"line":1,"column":88}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":109,"end":116,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":22}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/object-accessor-computed/input.js b/packages/babel-parser/test/fixtures/comments/basic/object-accessor-computed/input.js
new file mode 100644
index 000000000000..b23bc2eb5c72
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/object-accessor-computed/input.js
@@ -0,0 +1,3 @@
+({ /* 1 */ set /* 2 */ [ /* 3 */f/* 4 */] /* 5 */ (/* 6 */ a /* 7 */, /* 8 */) /* 9 */ {} });
+({ /* 1 */ get /* 2 */ [ /* 3 */f/* 4 */] /* 5 */ (/* 6 */) /* 7 */ {} });
+({ get /* 1 */ [f] () {} });
diff --git a/packages/babel-parser/test/fixtures/comments/basic/object-accessor-computed/output.json b/packages/babel-parser/test/fixtures/comments/basic/object-accessor-computed/output.json
new file mode 100644
index 000000000000..fe999b322c9e
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/object-accessor-computed/output.json
@@ -0,0 +1,325 @@
+{
+  "type": "File",
+  "start":0,"end":197,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":28}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":197,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":28}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":93,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":93}},
+        "expression": {
+          "type": "ObjectExpression",
+          "start":1,"end":91,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":91}},
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 0
+          },
+          "properties": [
+            {
+              "type": "ObjectMethod",
+              "start":11,"end":89,"loc":{"start":{"line":1,"column":11},"end":{"line":1,"column":89}},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 1 ",
+                  "start":3,"end":10,"loc":{"start":{"line":1,"column":3},"end":{"line":1,"column":10}}
+                }
+              ],
+              "innerComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 2 ",
+                  "start":15,"end":22,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":22}}
+                },
+                {
+                  "type": "CommentBlock",
+                  "value": " 5 ",
+                  "start":42,"end":49,"loc":{"start":{"line":1,"column":42},"end":{"line":1,"column":49}}
+                }
+              ],
+              "method": false,
+              "key": {
+                "type": "Identifier",
+                "start":32,"end":33,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":33},"identifierName":"f"},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 3 ",
+                    "start":25,"end":32,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":32}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 4 ",
+                    "start":33,"end":40,"loc":{"start":{"line":1,"column":33},"end":{"line":1,"column":40}}
+                  }
+                ],
+                "name": "f"
+              },
+              "computed": true,
+              "kind": "set",
+              "id": null,
+              "generator": false,
+              "async": false,
+              "params": [
+                {
+                  "type": "Identifier",
+                  "start":59,"end":60,"loc":{"start":{"line":1,"column":59},"end":{"line":1,"column":60},"identifierName":"a"},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 6 ",
+                      "start":51,"end":58,"loc":{"start":{"line":1,"column":51},"end":{"line":1,"column":58}}
+                    }
+                  ],
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 7 ",
+                      "start":61,"end":68,"loc":{"start":{"line":1,"column":61},"end":{"line":1,"column":68}}
+                    },
+                    {
+                      "type": "CommentBlock",
+                      "value": " 8 ",
+                      "start":70,"end":77,"loc":{"start":{"line":1,"column":70},"end":{"line":1,"column":77}}
+                    }
+                  ],
+                  "name": "a"
+                }
+              ],
+              "body": {
+                "type": "BlockStatement",
+                "start":87,"end":89,"loc":{"start":{"line":1,"column":87},"end":{"line":1,"column":89}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 9 ",
+                    "start":79,"end":86,"loc":{"start":{"line":1,"column":79},"end":{"line":1,"column":86}}
+                  }
+                ],
+                "body": [],
+                "directives": []
+              }
+            }
+          ]
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":94,"end":168,"loc":{"start":{"line":2,"column":0},"end":{"line":2,"column":74}},
+        "expression": {
+          "type": "ObjectExpression",
+          "start":95,"end":166,"loc":{"start":{"line":2,"column":1},"end":{"line":2,"column":72}},
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 94
+          },
+          "properties": [
+            {
+              "type": "ObjectMethod",
+              "start":105,"end":164,"loc":{"start":{"line":2,"column":11},"end":{"line":2,"column":70}},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 1 ",
+                  "start":97,"end":104,"loc":{"start":{"line":2,"column":3},"end":{"line":2,"column":10}}
+                }
+              ],
+              "innerComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 2 ",
+                  "start":109,"end":116,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":22}}
+                },
+                {
+                  "type": "CommentBlock",
+                  "value": " 5 ",
+                  "start":136,"end":143,"loc":{"start":{"line":2,"column":42},"end":{"line":2,"column":49}}
+                },
+                {
+                  "type": "CommentBlock",
+                  "value": " 6 ",
+                  "start":145,"end":152,"loc":{"start":{"line":2,"column":51},"end":{"line":2,"column":58}}
+                }
+              ],
+              "method": false,
+              "key": {
+                "type": "Identifier",
+                "start":126,"end":127,"loc":{"start":{"line":2,"column":32},"end":{"line":2,"column":33},"identifierName":"f"},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 3 ",
+                    "start":119,"end":126,"loc":{"start":{"line":2,"column":25},"end":{"line":2,"column":32}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 4 ",
+                    "start":127,"end":134,"loc":{"start":{"line":2,"column":33},"end":{"line":2,"column":40}}
+                  }
+                ],
+                "name": "f"
+              },
+              "computed": true,
+              "kind": "get",
+              "id": null,
+              "generator": false,
+              "async": false,
+              "params": [],
+              "body": {
+                "type": "BlockStatement",
+                "start":162,"end":164,"loc":{"start":{"line":2,"column":68},"end":{"line":2,"column":70}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 7 ",
+                    "start":154,"end":161,"loc":{"start":{"line":2,"column":60},"end":{"line":2,"column":67}}
+                  }
+                ],
+                "body": [],
+                "directives": []
+              }
+            }
+          ]
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":169,"end":197,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":28}},
+        "expression": {
+          "type": "ObjectExpression",
+          "start":170,"end":195,"loc":{"start":{"line":3,"column":1},"end":{"line":3,"column":26}},
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 169
+          },
+          "properties": [
+            {
+              "type": "ObjectMethod",
+              "start":172,"end":193,"loc":{"start":{"line":3,"column":3},"end":{"line":3,"column":24}},
+              "innerComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 1 ",
+                  "start":176,"end":183,"loc":{"start":{"line":3,"column":7},"end":{"line":3,"column":14}}
+                }
+              ],
+              "method": false,
+              "key": {
+                "type": "Identifier",
+                "start":185,"end":186,"loc":{"start":{"line":3,"column":16},"end":{"line":3,"column":17},"identifierName":"f"},
+                "name": "f"
+              },
+              "computed": true,
+              "kind": "get",
+              "id": null,
+              "generator": false,
+              "async": false,
+              "params": [],
+              "body": {
+                "type": "BlockStatement",
+                "start":191,"end":193,"loc":{"start":{"line":3,"column":22},"end":{"line":3,"column":24}},
+                "body": [],
+                "directives": []
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":3,"end":10,"loc":{"start":{"line":1,"column":3},"end":{"line":1,"column":10}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":15,"end":22,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":22}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":25,"end":32,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":32}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":33,"end":40,"loc":{"start":{"line":1,"column":33},"end":{"line":1,"column":40}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":42,"end":49,"loc":{"start":{"line":1,"column":42},"end":{"line":1,"column":49}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":51,"end":58,"loc":{"start":{"line":1,"column":51},"end":{"line":1,"column":58}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":61,"end":68,"loc":{"start":{"line":1,"column":61},"end":{"line":1,"column":68}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":70,"end":77,"loc":{"start":{"line":1,"column":70},"end":{"line":1,"column":77}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":79,"end":86,"loc":{"start":{"line":1,"column":79},"end":{"line":1,"column":86}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":97,"end":104,"loc":{"start":{"line":2,"column":3},"end":{"line":2,"column":10}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":109,"end":116,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":22}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":119,"end":126,"loc":{"start":{"line":2,"column":25},"end":{"line":2,"column":32}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":127,"end":134,"loc":{"start":{"line":2,"column":33},"end":{"line":2,"column":40}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":136,"end":143,"loc":{"start":{"line":2,"column":42},"end":{"line":2,"column":49}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":145,"end":152,"loc":{"start":{"line":2,"column":51},"end":{"line":2,"column":58}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":154,"end":161,"loc":{"start":{"line":2,"column":60},"end":{"line":2,"column":67}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":176,"end":183,"loc":{"start":{"line":3,"column":7},"end":{"line":3,"column":14}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/object-method-async-generator/input.js b/packages/babel-parser/test/fixtures/comments/basic/object-method-async-generator/input.js
new file mode 100644
index 000000000000..4fec8e847cb2
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/object-method-async-generator/input.js
@@ -0,0 +1,2 @@
+({ /* 1 */ async /* 2 */ * /* 3 */ f /* 4 */ (/* 5 */ a /* 6 */, /* 7 */) /* 8 */ {} })
+({ async /* 1 */ *f () {} });
diff --git a/packages/babel-parser/test/fixtures/comments/basic/object-method-async-generator/output.json b/packages/babel-parser/test/fixtures/comments/basic/object-method-async-generator/output.json
new file mode 100644
index 000000000000..f7e58e7b502f
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/object-method-async-generator/output.json
@@ -0,0 +1,197 @@
+{
+  "type": "File",
+  "start":0,"end":117,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":29}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":117,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":29}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":117,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":29}},
+        "expression": {
+          "type": "CallExpression",
+          "start":0,"end":116,"loc":{"start":{"line":1,"column":0},"end":{"line":2,"column":28}},
+          "callee": {
+            "type": "ObjectExpression",
+            "start":1,"end":86,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":86}},
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 0
+            },
+            "properties": [
+              {
+                "type": "ObjectMethod",
+                "start":11,"end":84,"loc":{"start":{"line":1,"column":11},"end":{"line":1,"column":84}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 1 ",
+                    "start":3,"end":10,"loc":{"start":{"line":1,"column":3},"end":{"line":1,"column":10}}
+                  }
+                ],
+                "innerComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 2 ",
+                    "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+                  }
+                ],
+                "method": true,
+                "key": {
+                  "type": "Identifier",
+                  "start":35,"end":36,"loc":{"start":{"line":1,"column":35},"end":{"line":1,"column":36},"identifierName":"f"},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 3 ",
+                      "start":27,"end":34,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":34}}
+                    }
+                  ],
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 4 ",
+                      "start":37,"end":44,"loc":{"start":{"line":1,"column":37},"end":{"line":1,"column":44}}
+                    }
+                  ],
+                  "name": "f"
+                },
+                "computed": false,
+                "kind": "method",
+                "id": null,
+                "generator": true,
+                "async": true,
+                "params": [
+                  {
+                    "type": "Identifier",
+                    "start":54,"end":55,"loc":{"start":{"line":1,"column":54},"end":{"line":1,"column":55},"identifierName":"a"},
+                    "leadingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 5 ",
+                        "start":46,"end":53,"loc":{"start":{"line":1,"column":46},"end":{"line":1,"column":53}}
+                      }
+                    ],
+                    "trailingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": " 6 ",
+                        "start":56,"end":63,"loc":{"start":{"line":1,"column":56},"end":{"line":1,"column":63}}
+                      },
+                      {
+                        "type": "CommentBlock",
+                        "value": " 7 ",
+                        "start":65,"end":72,"loc":{"start":{"line":1,"column":65},"end":{"line":1,"column":72}}
+                      }
+                    ],
+                    "name": "a"
+                  }
+                ],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":82,"end":84,"loc":{"start":{"line":1,"column":82},"end":{"line":1,"column":84}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 8 ",
+                      "start":74,"end":81,"loc":{"start":{"line":1,"column":74},"end":{"line":1,"column":81}}
+                    }
+                  ],
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          },
+          "arguments": [
+            {
+              "type": "ObjectExpression",
+              "start":89,"end":115,"loc":{"start":{"line":2,"column":1},"end":{"line":2,"column":27}},
+              "properties": [
+                {
+                  "type": "ObjectMethod",
+                  "start":91,"end":113,"loc":{"start":{"line":2,"column":3},"end":{"line":2,"column":25}},
+                  "innerComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 1 ",
+                      "start":97,"end":104,"loc":{"start":{"line":2,"column":9},"end":{"line":2,"column":16}}
+                    }
+                  ],
+                  "method": true,
+                  "key": {
+                    "type": "Identifier",
+                    "start":106,"end":107,"loc":{"start":{"line":2,"column":18},"end":{"line":2,"column":19},"identifierName":"f"},
+                    "name": "f"
+                  },
+                  "computed": false,
+                  "kind": "method",
+                  "id": null,
+                  "generator": true,
+                  "async": true,
+                  "params": [],
+                  "body": {
+                    "type": "BlockStatement",
+                    "start":111,"end":113,"loc":{"start":{"line":2,"column":23},"end":{"line":2,"column":25}},
+                    "body": [],
+                    "directives": []
+                  }
+                }
+              ]
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":3,"end":10,"loc":{"start":{"line":1,"column":3},"end":{"line":1,"column":10}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":27,"end":34,"loc":{"start":{"line":1,"column":27},"end":{"line":1,"column":34}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":37,"end":44,"loc":{"start":{"line":1,"column":37},"end":{"line":1,"column":44}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":46,"end":53,"loc":{"start":{"line":1,"column":46},"end":{"line":1,"column":53}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":56,"end":63,"loc":{"start":{"line":1,"column":56},"end":{"line":1,"column":63}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":65,"end":72,"loc":{"start":{"line":1,"column":65},"end":{"line":1,"column":72}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":74,"end":81,"loc":{"start":{"line":1,"column":74},"end":{"line":1,"column":81}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":97,"end":104,"loc":{"start":{"line":2,"column":9},"end":{"line":2,"column":16}}
+    }
+  ]
+}
\ No newline at end of file

From 0981f2ef6e7cd6ead4d3975d522b5b185d9f25ba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Mon, 5 Jul 2021 15:26:23 -0400
Subject: [PATCH 28/35] chore: add more comment testcases

---
 .../comments/basic/arrow-function/input.js    |   3 +
 .../comments/basic/arrow-function/output.json | 126 +++++++
 .../comments/basic/switch-case/input.js       |   6 +
 .../comments/basic/switch-case/output.json    | 342 ++++++++++++++++++
 .../comments/basic/try-statement/input.js     |   4 +
 .../comments/basic/try-statement/output.json  | 259 +++++++++++++
 6 files changed, 740 insertions(+)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/arrow-function/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/arrow-function/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/switch-case/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/switch-case/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/try-statement/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/try-statement/output.json

diff --git a/packages/babel-parser/test/fixtures/comments/basic/arrow-function/input.js b/packages/babel-parser/test/fixtures/comments/basic/arrow-function/input.js
new file mode 100644
index 000000000000..f923f755c59c
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/arrow-function/input.js
@@ -0,0 +1,3 @@
+(/*1*/)=>x;
+
+(/*1*/x/*2*/,/*3*/) /*4*/ => /*5*/ {}
diff --git a/packages/babel-parser/test/fixtures/comments/basic/arrow-function/output.json b/packages/babel-parser/test/fixtures/comments/basic/arrow-function/output.json
new file mode 100644
index 000000000000..b0f4f03e995f
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/arrow-function/output.json
@@ -0,0 +1,126 @@
+{
+  "type": "File",
+  "start":0,"end":50,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":37}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":50,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":37}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":11,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":11}},
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start":0,"end":10,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":10}},
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": "1",
+              "start":1,"end":6,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":6}}
+            }
+          ],
+          "id": null,
+          "generator": false,
+          "async": false,
+          "params": [],
+          "body": {
+            "type": "Identifier",
+            "start":9,"end":10,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":10},"identifierName":"x"},
+            "name": "x"
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":13,"end":50,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":37}},
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start":13,"end":50,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":37}},
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": "4",
+              "start":33,"end":38,"loc":{"start":{"line":3,"column":20},"end":{"line":3,"column":25}}
+            }
+          ],
+          "id": null,
+          "generator": false,
+          "async": false,
+          "params": [
+            {
+              "type": "Identifier",
+              "start":19,"end":20,"loc":{"start":{"line":3,"column":6},"end":{"line":3,"column":7},"identifierName":"x"},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "1",
+                  "start":14,"end":19,"loc":{"start":{"line":3,"column":1},"end":{"line":3,"column":6}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "2",
+                  "start":20,"end":25,"loc":{"start":{"line":3,"column":7},"end":{"line":3,"column":12}}
+                },
+                {
+                  "type": "CommentBlock",
+                  "value": "3",
+                  "start":26,"end":31,"loc":{"start":{"line":3,"column":13},"end":{"line":3,"column":18}}
+                }
+              ],
+              "name": "x"
+            }
+          ],
+          "body": {
+            "type": "BlockStatement",
+            "start":48,"end":50,"loc":{"start":{"line":3,"column":35},"end":{"line":3,"column":37}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": "5",
+                "start":42,"end":47,"loc":{"start":{"line":3,"column":29},"end":{"line":3,"column":34}}
+              }
+            ],
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": "1",
+      "start":1,"end":6,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":6}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "1",
+      "start":14,"end":19,"loc":{"start":{"line":3,"column":1},"end":{"line":3,"column":6}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "2",
+      "start":20,"end":25,"loc":{"start":{"line":3,"column":7},"end":{"line":3,"column":12}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "3",
+      "start":26,"end":31,"loc":{"start":{"line":3,"column":13},"end":{"line":3,"column":18}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "4",
+      "start":33,"end":38,"loc":{"start":{"line":3,"column":20},"end":{"line":3,"column":25}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "5",
+      "start":42,"end":47,"loc":{"start":{"line":3,"column":29},"end":{"line":3,"column":34}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/switch-case/input.js b/packages/babel-parser/test/fixtures/comments/basic/switch-case/input.js
new file mode 100644
index 000000000000..bfca352a1b22
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/switch-case/input.js
@@ -0,0 +1,6 @@
+/*-1*/ foo /*0*/ : /*1*/ switch /*2*/ ( /*3*/ false /*4*/ ) /*5*/ {
+    /*6*/ case /*7*/ false /*8*/ : /*9*/
+    break /*10*/ foo /*11*/ ;
+    /*12*/ default /*13*/ : /*14*/
+    case /*15*/ false /*16*/ : /*17*/ { /*18*/ } /*19*/
+  }
diff --git a/packages/babel-parser/test/fixtures/comments/basic/switch-case/output.json b/packages/babel-parser/test/fixtures/comments/basic/switch-case/output.json
new file mode 100644
index 000000000000..cd2a5e6aefb8
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/switch-case/output.json
@@ -0,0 +1,342 @@
+{
+  "type": "File",
+  "start":0,"end":233,"loc":{"start":{"line":1,"column":0},"end":{"line":6,"column":3}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":233,"loc":{"start":{"line":1,"column":0},"end":{"line":6,"column":3}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "LabeledStatement",
+        "start":7,"end":233,"loc":{"start":{"line":1,"column":7},"end":{"line":6,"column":3}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": "-1",
+            "start":0,"end":6,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":6}}
+          }
+        ],
+        "body": {
+          "type": "SwitchStatement",
+          "start":25,"end":233,"loc":{"start":{"line":1,"column":25},"end":{"line":6,"column":3}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "1",
+              "start":19,"end":24,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":24}}
+            }
+          ],
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": "2",
+              "start":32,"end":37,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":37}}
+            },
+            {
+              "type": "CommentBlock",
+              "value": "5",
+              "start":60,"end":65,"loc":{"start":{"line":1,"column":60},"end":{"line":1,"column":65}}
+            }
+          ],
+          "discriminant": {
+            "type": "BooleanLiteral",
+            "start":46,"end":51,"loc":{"start":{"line":1,"column":46},"end":{"line":1,"column":51}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": "3",
+                "start":40,"end":45,"loc":{"start":{"line":1,"column":40},"end":{"line":1,"column":45}}
+              }
+            ],
+            "trailingComments": [
+              {
+                "type": "CommentBlock",
+                "value": "4",
+                "start":52,"end":57,"loc":{"start":{"line":1,"column":52},"end":{"line":1,"column":57}}
+              }
+            ],
+            "value": false
+          },
+          "cases": [
+            {
+              "type": "SwitchCase",
+              "start":78,"end":138,"loc":{"start":{"line":2,"column":10},"end":{"line":3,"column":29}},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "6",
+                  "start":72,"end":77,"loc":{"start":{"line":2,"column":4},"end":{"line":2,"column":9}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "12",
+                  "start":143,"end":149,"loc":{"start":{"line":4,"column":4},"end":{"line":4,"column":10}}
+                }
+              ],
+              "consequent": [
+                {
+                  "type": "BreakStatement",
+                  "start":113,"end":138,"loc":{"start":{"line":3,"column":4},"end":{"line":3,"column":29}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": "9",
+                      "start":103,"end":108,"loc":{"start":{"line":2,"column":35},"end":{"line":2,"column":40}}
+                    }
+                  ],
+                  "label": {
+                    "type": "Identifier",
+                    "start":126,"end":129,"loc":{"start":{"line":3,"column":17},"end":{"line":3,"column":20},"identifierName":"foo"},
+                    "leadingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": "10",
+                        "start":119,"end":125,"loc":{"start":{"line":3,"column":10},"end":{"line":3,"column":16}}
+                      }
+                    ],
+                    "trailingComments": [
+                      {
+                        "type": "CommentBlock",
+                        "value": "11",
+                        "start":130,"end":136,"loc":{"start":{"line":3,"column":21},"end":{"line":3,"column":27}}
+                      }
+                    ],
+                    "name": "foo"
+                  }
+                }
+              ],
+              "test": {
+                "type": "BooleanLiteral",
+                "start":89,"end":94,"loc":{"start":{"line":2,"column":21},"end":{"line":2,"column":26}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": "7",
+                    "start":83,"end":88,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":20}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": "8",
+                    "start":95,"end":100,"loc":{"start":{"line":2,"column":27},"end":{"line":2,"column":32}}
+                  }
+                ],
+                "value": false
+              }
+            },
+            {
+              "type": "SwitchCase",
+              "start":150,"end":166,"loc":{"start":{"line":4,"column":11},"end":{"line":4,"column":27}},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "12",
+                  "start":143,"end":149,"loc":{"start":{"line":4,"column":4},"end":{"line":4,"column":10}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "14",
+                  "start":167,"end":173,"loc":{"start":{"line":4,"column":28},"end":{"line":4,"column":34}}
+                }
+              ],
+              "innerComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "13",
+                  "start":158,"end":164,"loc":{"start":{"line":4,"column":19},"end":{"line":4,"column":25}}
+                }
+              ],
+              "consequent": [],
+              "test": null
+            },
+            {
+              "type": "SwitchCase",
+              "start":178,"end":222,"loc":{"start":{"line":5,"column":4},"end":{"line":5,"column":48}},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "14",
+                  "start":167,"end":173,"loc":{"start":{"line":4,"column":28},"end":{"line":4,"column":34}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "19",
+                  "start":223,"end":229,"loc":{"start":{"line":5,"column":49},"end":{"line":5,"column":55}}
+                }
+              ],
+              "consequent": [
+                {
+                  "type": "BlockStatement",
+                  "start":212,"end":222,"loc":{"start":{"line":5,"column":38},"end":{"line":5,"column":48}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": "17",
+                      "start":205,"end":211,"loc":{"start":{"line":5,"column":31},"end":{"line":5,"column":37}}
+                    }
+                  ],
+                  "innerComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": "18",
+                      "start":214,"end":220,"loc":{"start":{"line":5,"column":40},"end":{"line":5,"column":46}}
+                    }
+                  ],
+                  "body": [],
+                  "directives": []
+                }
+              ],
+              "test": {
+                "type": "BooleanLiteral",
+                "start":190,"end":195,"loc":{"start":{"line":5,"column":16},"end":{"line":5,"column":21}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": "15",
+                    "start":183,"end":189,"loc":{"start":{"line":5,"column":9},"end":{"line":5,"column":15}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": "16",
+                    "start":196,"end":202,"loc":{"start":{"line":5,"column":22},"end":{"line":5,"column":28}}
+                  }
+                ],
+                "value": false
+              }
+            }
+          ]
+        },
+        "label": {
+          "type": "Identifier",
+          "start":7,"end":10,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":10},"identifierName":"foo"},
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "0",
+              "start":11,"end":16,"loc":{"start":{"line":1,"column":11},"end":{"line":1,"column":16}}
+            }
+          ],
+          "name": "foo"
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": "-1",
+      "start":0,"end":6,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":6}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "0",
+      "start":11,"end":16,"loc":{"start":{"line":1,"column":11},"end":{"line":1,"column":16}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "1",
+      "start":19,"end":24,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":24}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "2",
+      "start":32,"end":37,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":37}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "3",
+      "start":40,"end":45,"loc":{"start":{"line":1,"column":40},"end":{"line":1,"column":45}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "4",
+      "start":52,"end":57,"loc":{"start":{"line":1,"column":52},"end":{"line":1,"column":57}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "5",
+      "start":60,"end":65,"loc":{"start":{"line":1,"column":60},"end":{"line":1,"column":65}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "6",
+      "start":72,"end":77,"loc":{"start":{"line":2,"column":4},"end":{"line":2,"column":9}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "7",
+      "start":83,"end":88,"loc":{"start":{"line":2,"column":15},"end":{"line":2,"column":20}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "8",
+      "start":95,"end":100,"loc":{"start":{"line":2,"column":27},"end":{"line":2,"column":32}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "9",
+      "start":103,"end":108,"loc":{"start":{"line":2,"column":35},"end":{"line":2,"column":40}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "10",
+      "start":119,"end":125,"loc":{"start":{"line":3,"column":10},"end":{"line":3,"column":16}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "11",
+      "start":130,"end":136,"loc":{"start":{"line":3,"column":21},"end":{"line":3,"column":27}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "12",
+      "start":143,"end":149,"loc":{"start":{"line":4,"column":4},"end":{"line":4,"column":10}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "13",
+      "start":158,"end":164,"loc":{"start":{"line":4,"column":19},"end":{"line":4,"column":25}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "14",
+      "start":167,"end":173,"loc":{"start":{"line":4,"column":28},"end":{"line":4,"column":34}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "15",
+      "start":183,"end":189,"loc":{"start":{"line":5,"column":9},"end":{"line":5,"column":15}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "16",
+      "start":196,"end":202,"loc":{"start":{"line":5,"column":22},"end":{"line":5,"column":28}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "17",
+      "start":205,"end":211,"loc":{"start":{"line":5,"column":31},"end":{"line":5,"column":37}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "18",
+      "start":214,"end":220,"loc":{"start":{"line":5,"column":40},"end":{"line":5,"column":46}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "19",
+      "start":223,"end":229,"loc":{"start":{"line":5,"column":49},"end":{"line":5,"column":55}}
+    }
+  ]
+}
diff --git a/packages/babel-parser/test/fixtures/comments/basic/try-statement/input.js b/packages/babel-parser/test/fixtures/comments/basic/try-statement/input.js
new file mode 100644
index 000000000000..b06c9f6c4176
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/try-statement/input.js
@@ -0,0 +1,4 @@
+/*1*/ try /*2*/ {
+    /*3*/ throw /*4*/ "no" /*5*/;
+/*6*/} /*7*/ catch /*8*/ ( /*9*/ e /*10*/ ) /*11*/ { /*12*/
+} /*13*/ finally /*14*/ { /*15*/ } /*16*/
diff --git a/packages/babel-parser/test/fixtures/comments/basic/try-statement/output.json b/packages/babel-parser/test/fixtures/comments/basic/try-statement/output.json
new file mode 100644
index 000000000000..fb3ba476e0a6
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/try-statement/output.json
@@ -0,0 +1,259 @@
+{
+  "type": "File",
+  "start":0,"end":153,"loc":{"start":{"line":1,"column":0},"end":{"line":4,"column":41}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":153,"loc":{"start":{"line":1,"column":0},"end":{"line":4,"column":41}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TryStatement",
+        "start":6,"end":146,"loc":{"start":{"line":1,"column":6},"end":{"line":4,"column":34}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": "1",
+            "start":0,"end":5,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":5}}
+          }
+        ],
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": "16",
+            "start":147,"end":153,"loc":{"start":{"line":4,"column":35},"end":{"line":4,"column":41}}
+          }
+        ],
+        "block": {
+          "type": "BlockStatement",
+          "start":16,"end":58,"loc":{"start":{"line":1,"column":16},"end":{"line":3,"column":6}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "2",
+              "start":10,"end":15,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":15}}
+            }
+          ],
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "7",
+              "start":59,"end":64,"loc":{"start":{"line":3,"column":7},"end":{"line":3,"column":12}}
+            }
+          ],
+          "body": [
+            {
+              "type": "ThrowStatement",
+              "start":28,"end":51,"loc":{"start":{"line":2,"column":10},"end":{"line":2,"column":33}},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "3",
+                  "start":22,"end":27,"loc":{"start":{"line":2,"column":4},"end":{"line":2,"column":9}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": "6",
+                  "start":52,"end":57,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":5}}
+                }
+              ],
+              "argument": {
+                "type": "StringLiteral",
+                "start":40,"end":44,"loc":{"start":{"line":2,"column":22},"end":{"line":2,"column":26}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": "4",
+                    "start":34,"end":39,"loc":{"start":{"line":2,"column":16},"end":{"line":2,"column":21}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": "5",
+                    "start":45,"end":50,"loc":{"start":{"line":2,"column":27},"end":{"line":2,"column":32}}
+                  }
+                ],
+                "extra": {
+                  "rawValue": "no",
+                  "raw": "\"no\""
+                },
+                "value": "no"
+              }
+            }
+          ],
+          "directives": []
+        },
+        "handler": {
+          "type": "CatchClause",
+          "start":65,"end":113,"loc":{"start":{"line":3,"column":13},"end":{"line":4,"column":1}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "7",
+              "start":59,"end":64,"loc":{"start":{"line":3,"column":7},"end":{"line":3,"column":12}}
+            }
+          ],
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "13",
+              "start":114,"end":120,"loc":{"start":{"line":4,"column":2},"end":{"line":4,"column":8}}
+            }
+          ],
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": "8",
+              "start":71,"end":76,"loc":{"start":{"line":3,"column":19},"end":{"line":3,"column":24}}
+            }
+          ],
+          "param": {
+            "type": "Identifier",
+            "start":85,"end":86,"loc":{"start":{"line":3,"column":33},"end":{"line":3,"column":34},"identifierName":"e"},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": "9",
+                "start":79,"end":84,"loc":{"start":{"line":3,"column":27},"end":{"line":3,"column":32}}
+              }
+            ],
+            "trailingComments": [
+              {
+                "type": "CommentBlock",
+                "value": "10",
+                "start":87,"end":93,"loc":{"start":{"line":3,"column":35},"end":{"line":3,"column":41}}
+              }
+            ],
+            "name": "e"
+          },
+          "body": {
+            "type": "BlockStatement",
+            "start":103,"end":113,"loc":{"start":{"line":3,"column":51},"end":{"line":4,"column":1}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": "11",
+                "start":96,"end":102,"loc":{"start":{"line":3,"column":44},"end":{"line":3,"column":50}}
+              }
+            ],
+            "innerComments": [
+              {
+                "type": "CommentBlock",
+                "value": "12",
+                "start":105,"end":111,"loc":{"start":{"line":3,"column":53},"end":{"line":3,"column":59}}
+              }
+            ],
+            "body": [],
+            "directives": []
+          }
+        },
+        "finalizer": {
+          "type": "BlockStatement",
+          "start":136,"end":146,"loc":{"start":{"line":4,"column":24},"end":{"line":4,"column":34}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": "14",
+              "start":129,"end":135,"loc":{"start":{"line":4,"column":17},"end":{"line":4,"column":23}}
+            }
+          ],
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": "15",
+              "start":138,"end":144,"loc":{"start":{"line":4,"column":26},"end":{"line":4,"column":32}}
+            }
+          ],
+          "body": [],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": "1",
+      "start":0,"end":5,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":5}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "2",
+      "start":10,"end":15,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":15}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "3",
+      "start":22,"end":27,"loc":{"start":{"line":2,"column":4},"end":{"line":2,"column":9}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "4",
+      "start":34,"end":39,"loc":{"start":{"line":2,"column":16},"end":{"line":2,"column":21}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "5",
+      "start":45,"end":50,"loc":{"start":{"line":2,"column":27},"end":{"line":2,"column":32}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "6",
+      "start":52,"end":57,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":5}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "7",
+      "start":59,"end":64,"loc":{"start":{"line":3,"column":7},"end":{"line":3,"column":12}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "8",
+      "start":71,"end":76,"loc":{"start":{"line":3,"column":19},"end":{"line":3,"column":24}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "9",
+      "start":79,"end":84,"loc":{"start":{"line":3,"column":27},"end":{"line":3,"column":32}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "10",
+      "start":87,"end":93,"loc":{"start":{"line":3,"column":35},"end":{"line":3,"column":41}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "11",
+      "start":96,"end":102,"loc":{"start":{"line":3,"column":44},"end":{"line":3,"column":50}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "12",
+      "start":105,"end":111,"loc":{"start":{"line":3,"column":53},"end":{"line":3,"column":59}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "13",
+      "start":114,"end":120,"loc":{"start":{"line":4,"column":2},"end":{"line":4,"column":8}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "14",
+      "start":129,"end":135,"loc":{"start":{"line":4,"column":17},"end":{"line":4,"column":23}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "15",
+      "start":138,"end":144,"loc":{"start":{"line":4,"column":26},"end":{"line":4,"column":32}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": "16",
+      "start":147,"end":153,"loc":{"start":{"line":4,"column":35},"end":{"line":4,"column":41}}
+    }
+  ]
+}
\ No newline at end of file

From 9e1b04bf7aa553f10b73f024195656a7ea481178 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Mon, 5 Jul 2021 15:44:51 -0400
Subject: [PATCH 29/35] fix flow errors

---
 packages/babel-parser/src/parser/comments.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index bab22ad79fa0..b8e03c84f32a 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -225,7 +225,7 @@ export default class CommentsParser extends BaseParser {
    * @returns
    * @memberof CommentsParser
    */
-  resetPreviousNodeTrailingComments(node: N.Node) {
+  resetPreviousNodeTrailingComments(node: Node) {
     const { commentStack } = this.state;
     let i = commentStack.length - 1;
     if (i < 0) return;

From b28aba127660808da357cd7f5fbb6a5a2d038261 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 6 Jul 2021 15:04:21 -0400
Subject: [PATCH 30/35] fix: handle comments when parsing async arrow

---
 packages/babel-parser/src/parser/comments.js  |   4 +-
 .../babel-parser/src/parser/expression.js     |   6 +
 .../basic/async-arrow-function/input.js       |   3 +
 .../basic/async-arrow-function/output.json    | 177 ++++++++++++++++++
 .../basic/async-call-expression/input.js      |   1 +
 .../basic/async-call-expression/output.json   |  65 +++++++
 6 files changed, 254 insertions(+), 2 deletions(-)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-arrow-function/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-arrow-function/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-call-expression/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-call-expression/output.json

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index b8e03c84f32a..04a40b35d87d 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -50,10 +50,10 @@ function setTrailingComments(node: Node, comments: Array<Comment>) {
  * @param {Node} node
  * @param {Array<Comment>} comments
  */
-function setInnerComments(node: Node, comments: Array<Comment>) {
+export function setInnerComments(node: Node, comments: Array<Comment>) {
   if (node.innerComments === undefined) {
     node.innerComments = comments;
-  } else {
+  } else if (comments !== undefined) {
     node.innerComments.unshift(...comments);
   }
 }
diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index befb8e533ba6..5bdd2c350951 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -56,6 +56,7 @@ import {
 } from "../util/expression-scope";
 import { Errors, SourceTypeModuleErrors } from "./error";
 import type { ParsingError } from "./error";
+import { setInnerComments } from "./comments";
 
 /*::
 import type { SourceType } from "../options";
@@ -941,6 +942,7 @@ export default class ExpressionParser extends LValParser {
     node: N.ArrowFunctionExpression,
     call: N.CallExpression,
   ): N.ArrowFunctionExpression {
+    this.resetPreviousNodeTrailingComments(call);
     this.expect(tt.arrow);
     this.parseArrowExpression(
       node,
@@ -948,6 +950,10 @@ export default class ExpressionParser extends LValParser {
       true,
       call.extra?.trailingComma,
     );
+    // mark inner comments of `async()` as inner comments of `async () =>`
+    setInnerComments(node, call.innerComments);
+    // mark trailing comments of `async` to be inner comments
+    setInnerComments(node, call.callee.trailingComments);
     return node;
   }
 
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-arrow-function/input.js b/packages/babel-parser/test/fixtures/comments/basic/async-arrow-function/input.js
new file mode 100644
index 000000000000..6e27c321e652
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-arrow-function/input.js
@@ -0,0 +1,3 @@
+/* 1 */ async /* 2 */ (/* 3 */) /* 4 */=>x;
+
+/* 1 */ async /* 2 */ (/* 3 */x/* 4 */) /* 5 */ => /* 6 */ {}
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-arrow-function/output.json b/packages/babel-parser/test/fixtures/comments/basic/async-arrow-function/output.json
new file mode 100644
index 000000000000..b75f51c4b8d9
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-arrow-function/output.json
@@ -0,0 +1,177 @@
+{
+  "type": "File",
+  "start":0,"end":106,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":61}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":106,"loc":{"start":{"line":1,"column":0},"end":{"line":3,"column":61}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":8,"end":43,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":43}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 1 ",
+            "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+          }
+        ],
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 1 ",
+            "start":45,"end":52,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":7}}
+          }
+        ],
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start":8,"end":42,"loc":{"start":{"line":1,"column":8},"end":{"line":1,"column":42}},
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 2 ",
+              "start":14,"end":21,"loc":{"start":{"line":1,"column":14},"end":{"line":1,"column":21}}
+            },
+            {
+              "type": "CommentBlock",
+              "value": " 3 ",
+              "start":23,"end":30,"loc":{"start":{"line":1,"column":23},"end":{"line":1,"column":30}}
+            },
+            {
+              "type": "CommentBlock",
+              "value": " 4 ",
+              "start":32,"end":39,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":39}}
+            }
+          ],
+          "id": null,
+          "generator": false,
+          "async": true,
+          "params": [],
+          "body": {
+            "type": "Identifier",
+            "start":41,"end":42,"loc":{"start":{"line":1,"column":41},"end":{"line":1,"column":42},"identifierName":"x"},
+            "name": "x"
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":53,"end":106,"loc":{"start":{"line":3,"column":8},"end":{"line":3,"column":61}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 1 ",
+            "start":45,"end":52,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":7}}
+          }
+        ],
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start":53,"end":106,"loc":{"start":{"line":3,"column":8},"end":{"line":3,"column":61}},
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 2 ",
+              "start":59,"end":66,"loc":{"start":{"line":3,"column":14},"end":{"line":3,"column":21}}
+            },
+            {
+              "type": "CommentBlock",
+              "value": " 5 ",
+              "start":85,"end":92,"loc":{"start":{"line":3,"column":40},"end":{"line":3,"column":47}}
+            }
+          ],
+          "id": null,
+          "generator": false,
+          "async": true,
+          "params": [
+            {
+              "type": "Identifier",
+              "start":75,"end":76,"loc":{"start":{"line":3,"column":30},"end":{"line":3,"column":31},"identifierName":"x"},
+              "leadingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 3 ",
+                  "start":68,"end":75,"loc":{"start":{"line":3,"column":23},"end":{"line":3,"column":30}}
+                }
+              ],
+              "trailingComments": [
+                {
+                  "type": "CommentBlock",
+                  "value": " 4 ",
+                  "start":76,"end":83,"loc":{"start":{"line":3,"column":31},"end":{"line":3,"column":38}}
+                }
+              ],
+              "name": "x"
+            }
+          ],
+          "body": {
+            "type": "BlockStatement",
+            "start":104,"end":106,"loc":{"start":{"line":3,"column":59},"end":{"line":3,"column":61}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 6 ",
+                "start":96,"end":103,"loc":{"start":{"line":3,"column":51},"end":{"line":3,"column":58}}
+              }
+            ],
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":14,"end":21,"loc":{"start":{"line":1,"column":14},"end":{"line":1,"column":21}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":23,"end":30,"loc":{"start":{"line":1,"column":23},"end":{"line":1,"column":30}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":32,"end":39,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":39}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":45,"end":52,"loc":{"start":{"line":3,"column":0},"end":{"line":3,"column":7}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":59,"end":66,"loc":{"start":{"line":3,"column":14},"end":{"line":3,"column":21}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":68,"end":75,"loc":{"start":{"line":3,"column":23},"end":{"line":3,"column":30}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":76,"end":83,"loc":{"start":{"line":3,"column":31},"end":{"line":3,"column":38}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":85,"end":92,"loc":{"start":{"line":3,"column":40},"end":{"line":3,"column":47}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":96,"end":103,"loc":{"start":{"line":3,"column":51},"end":{"line":3,"column":58}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-call-expression/input.js b/packages/babel-parser/test/fixtures/comments/basic/async-call-expression/input.js
new file mode 100644
index 000000000000..d50ac29542c6
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-call-expression/input.js
@@ -0,0 +1 @@
+async /* 1 */ (/* 2 */) /* 3 */
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-call-expression/output.json b/packages/babel-parser/test/fixtures/comments/basic/async-call-expression/output.json
new file mode 100644
index 000000000000..1abf750eb932
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-call-expression/output.json
@@ -0,0 +1,65 @@
+{
+  "type": "File",
+  "start":0,"end":31,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":31}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":31,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":31}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":23,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":23}},
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 3 ",
+            "start":24,"end":31,"loc":{"start":{"line":1,"column":24},"end":{"line":1,"column":31}}
+          }
+        ],
+        "expression": {
+          "type": "CallExpression",
+          "start":0,"end":23,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":23}},
+          "innerComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 2 ",
+              "start":15,"end":22,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":22}}
+            }
+          ],
+          "callee": {
+            "type": "Identifier",
+            "start":0,"end":5,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":5},"identifierName":"async"},
+            "trailingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 1 ",
+                "start":6,"end":13,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":13}}
+              }
+            ],
+            "name": "async"
+          },
+          "arguments": []
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":6,"end":13,"loc":{"start":{"line":1,"column":6},"end":{"line":1,"column":13}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":15,"end":22,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":22}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":24,"end":31,"loc":{"start":{"line":1,"column":24},"end":{"line":1,"column":31}}
+    }
+  ]
+}
\ No newline at end of file

From 6ac270c83485fe9ed2e268f4b5d8026bb6a427d6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 6 Jul 2021 15:29:02 -0400
Subject: [PATCH 31/35] fix: handle comments when "static" is a class modifier

---
 packages/babel-parser/src/parser/comments.js  |   8 +-
 packages/babel-parser/src/parser/statement.js |   1 +
 .../class-method-static-generator/input.js    |   2 +
 .../class-method-static-generator/output.json | 175 ++++++++++++++++++
 .../basic/class-static-block/input.js         |   1 +
 .../basic/class-static-block/options.json     |   3 +
 .../basic/class-static-block/output.json      | 110 +++++++++++
 7 files changed, 296 insertions(+), 4 deletions(-)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-method-static-generator/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-method-static-generator/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-static-block/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-static-block/options.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/class-static-block/output.json

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 04a40b35d87d..ee455fe2f432 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -213,10 +213,10 @@ export default class CommentsParser extends BaseParser {
 
   /**
    * Reset previous node trailing comments. Used in object / class
-   * property parsing. We parse `async`, `set` and `get` as an identifier
-   * but may reinterepret it into an async/accessor method later. In this case
-   * the identifier is not part of the AST and we should sync the knowledge
-   * to commentStacks
+   * property parsing. We parse `async`, `static`, `set` and `get`
+   * as an identifier but may reinterepret it into an async/static/accessor
+   * method later. In this case the identifier is not part of the AST and we
+   * should sync the knowledge to commentStacks
    *
    * For performance we do not check trailing node and we assume `node` is the
    * last finished node before current token.
diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
index 1571dd1d3a1a..fb51dd01587c 100644
--- a/packages/babel-parser/src/parser/statement.js
+++ b/packages/babel-parser/src/parser/statement.js
@@ -1375,6 +1375,7 @@ export default class StatementParser extends ExpressionParser {
       classBody.body.push(this.parseClassProperty(prop));
       return true;
     }
+    this.resetPreviousNodeTrailingComments(key);
     return false;
   }
 
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-method-static-generator/input.js b/packages/babel-parser/test/fixtures/comments/basic/class-method-static-generator/input.js
new file mode 100644
index 000000000000..11083698a225
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-method-static-generator/input.js
@@ -0,0 +1,2 @@
+(class /* 1 */ { /* 2 */ static /* 3 */ * /* 4 */ f /* 5 */ (/* 6 */) /* 7 */ { /* 8 */ } /* 9 */ } /* 10 */);
+
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-method-static-generator/output.json b/packages/babel-parser/test/fixtures/comments/basic/class-method-static-generator/output.json
new file mode 100644
index 000000000000..b6336d17844f
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-method-static-generator/output.json
@@ -0,0 +1,175 @@
+{
+  "type": "File",
+  "start":0,"end":110,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":110}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":110,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":110}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":110,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":110}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":1,"end":99,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":99}},
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 10 ",
+              "start":100,"end":108,"loc":{"start":{"line":1,"column":100},"end":{"line":1,"column":108}}
+            }
+          ],
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 0
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":15,"end":99,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":99}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 1 ",
+                "start":7,"end":14,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":14}}
+              }
+            ],
+            "body": [
+              {
+                "type": "ClassMethod",
+                "start":25,"end":89,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":89}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 2 ",
+                    "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 9 ",
+                    "start":90,"end":97,"loc":{"start":{"line":1,"column":90},"end":{"line":1,"column":97}}
+                  }
+                ],
+                "innerComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 3 ",
+                    "start":32,"end":39,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":39}}
+                  },
+                  {
+                    "type": "CommentBlock",
+                    "value": " 6 ",
+                    "start":61,"end":68,"loc":{"start":{"line":1,"column":61},"end":{"line":1,"column":68}}
+                  }
+                ],
+                "static": true,
+                "kind": "method",
+                "key": {
+                  "type": "Identifier",
+                  "start":50,"end":51,"loc":{"start":{"line":1,"column":50},"end":{"line":1,"column":51},"identifierName":"f"},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 4 ",
+                      "start":42,"end":49,"loc":{"start":{"line":1,"column":42},"end":{"line":1,"column":49}}
+                    }
+                  ],
+                  "trailingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 5 ",
+                      "start":52,"end":59,"loc":{"start":{"line":1,"column":52},"end":{"line":1,"column":59}}
+                    }
+                  ],
+                  "name": "f"
+                },
+                "computed": false,
+                "id": null,
+                "generator": true,
+                "async": false,
+                "params": [],
+                "body": {
+                  "type": "BlockStatement",
+                  "start":78,"end":89,"loc":{"start":{"line":1,"column":78},"end":{"line":1,"column":89}},
+                  "leadingComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 7 ",
+                      "start":70,"end":77,"loc":{"start":{"line":1,"column":70},"end":{"line":1,"column":77}}
+                    }
+                  ],
+                  "innerComments": [
+                    {
+                      "type": "CommentBlock",
+                      "value": " 8 ",
+                      "start":80,"end":87,"loc":{"start":{"line":1,"column":80},"end":{"line":1,"column":87}}
+                    }
+                  ],
+                  "body": [],
+                  "directives": []
+                }
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":7,"end":14,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":14}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":32,"end":39,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":39}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":42,"end":49,"loc":{"start":{"line":1,"column":42},"end":{"line":1,"column":49}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":52,"end":59,"loc":{"start":{"line":1,"column":52},"end":{"line":1,"column":59}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":61,"end":68,"loc":{"start":{"line":1,"column":61},"end":{"line":1,"column":68}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 7 ",
+      "start":70,"end":77,"loc":{"start":{"line":1,"column":70},"end":{"line":1,"column":77}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 8 ",
+      "start":80,"end":87,"loc":{"start":{"line":1,"column":80},"end":{"line":1,"column":87}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 9 ",
+      "start":90,"end":97,"loc":{"start":{"line":1,"column":90},"end":{"line":1,"column":97}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 10 ",
+      "start":100,"end":108,"loc":{"start":{"line":1,"column":100},"end":{"line":1,"column":108}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-static-block/input.js b/packages/babel-parser/test/fixtures/comments/basic/class-static-block/input.js
new file mode 100644
index 000000000000..00b068774ced
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-static-block/input.js
@@ -0,0 +1 @@
+(class /* 1 */ { /* 2 */ static /* 3 */ {/* 4 */} /* 5 */ } /* 6 */);
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-static-block/options.json b/packages/babel-parser/test/fixtures/comments/basic/class-static-block/options.json
new file mode 100644
index 000000000000..70adcb5e62d3
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-static-block/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["classStaticBlock"]
+}
diff --git a/packages/babel-parser/test/fixtures/comments/basic/class-static-block/output.json b/packages/babel-parser/test/fixtures/comments/basic/class-static-block/output.json
new file mode 100644
index 000000000000..e118bbb4f167
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/class-static-block/output.json
@@ -0,0 +1,110 @@
+{
+  "type": "File",
+  "start":0,"end":69,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":69}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":69,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":69}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":0,"end":69,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":69}},
+        "expression": {
+          "type": "ClassExpression",
+          "start":1,"end":59,"loc":{"start":{"line":1,"column":1},"end":{"line":1,"column":59}},
+          "trailingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 6 ",
+              "start":60,"end":67,"loc":{"start":{"line":1,"column":60},"end":{"line":1,"column":67}}
+            }
+          ],
+          "extra": {
+            "parenthesized": true,
+            "parenStart": 0
+          },
+          "id": null,
+          "superClass": null,
+          "body": {
+            "type": "ClassBody",
+            "start":15,"end":59,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":59}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 1 ",
+                "start":7,"end":14,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":14}}
+              }
+            ],
+            "body": [
+              {
+                "type": "StaticBlock",
+                "start":25,"end":49,"loc":{"start":{"line":1,"column":25},"end":{"line":1,"column":49}},
+                "leadingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 2 ",
+                    "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+                  }
+                ],
+                "trailingComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 5 ",
+                    "start":50,"end":57,"loc":{"start":{"line":1,"column":50},"end":{"line":1,"column":57}}
+                  }
+                ],
+                "innerComments": [
+                  {
+                    "type": "CommentBlock",
+                    "value": " 3 ",
+                    "start":32,"end":39,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":39}}
+                  },
+                  {
+                    "type": "CommentBlock",
+                    "value": " 4 ",
+                    "start":41,"end":48,"loc":{"start":{"line":1,"column":41},"end":{"line":1,"column":48}}
+                  }
+                ],
+                "body": []
+              }
+            ]
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":7,"end":14,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":14}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":17,"end":24,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":24}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":32,"end":39,"loc":{"start":{"line":1,"column":32},"end":{"line":1,"column":39}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":41,"end":48,"loc":{"start":{"line":1,"column":41},"end":{"line":1,"column":48}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":50,"end":57,"loc":{"start":{"line":1,"column":50},"end":{"line":1,"column":57}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 6 ",
+      "start":60,"end":67,"loc":{"start":{"line":1,"column":60},"end":{"line":1,"column":67}}
+    }
+  ]
+}
\ No newline at end of file

From cdf6b4f5403a9d585f827ba887c175a2591a1d9c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 6 Jul 2021 15:43:30 -0400
Subject: [PATCH 32/35] fix flow errors

---
 packages/babel-parser/src/parser/comments.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index ee455fe2f432..67d8db6fa04f 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -50,7 +50,7 @@ function setTrailingComments(node: Node, comments: Array<Comment>) {
  * @param {Node} node
  * @param {Array<Comment>} comments
  */
-export function setInnerComments(node: Node, comments: Array<Comment>) {
+export function setInnerComments(node: Node, comments: Array<Comment> | void) {
   if (node.innerComments === undefined) {
     node.innerComments = comments;
   } else if (comments !== undefined) {

From fb29d7577beaba1db511be2389a124dac961165a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 7 Jul 2021 10:17:30 -0400
Subject: [PATCH 33/35] fix: handle comments when parsing async function/do

---
 .../babel-parser/src/parser/expression.js     | 12 ++-
 .../basic/async-do-expression/input.js        |  1 +
 .../basic/async-do-expression/options.json    |  3 +
 .../basic/async-do-expression/output.json     | 90 +++++++++++++++++++
 .../comments/basic/async-function/input.js    |  1 +
 .../comments/basic/async-function/output.json | 57 ++++++++++++
 6 files changed, 161 insertions(+), 3 deletions(-)
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-do-expression/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-do-expression/options.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-do-expression/output.json
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-function/input.js
 create mode 100644 packages/babel-parser/test/fixtures/comments/basic/async-function/output.json

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 5bdd2c350951..82b531ff42a8 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -1008,6 +1008,7 @@ export default class ExpressionParser extends LValParser {
 
         if (!containsEsc && id.name === "async" && !this.canInsertSemicolon()) {
           if (this.match(tt._function)) {
+            this.resetPreviousNodeTrailingComments(id);
             this.next();
             return this.parseFunction(
               this.startNodeAtNode(id),
@@ -1019,13 +1020,19 @@ export default class ExpressionParser extends LValParser {
             // arrow function. (Peeking ahead for "=" lets us avoid a more
             // expensive full-token lookahead on this common path.)
             if (this.lookaheadCharCode() === charCodes.equalsTo) {
-              return this.parseAsyncArrowUnaryFunction(id);
+              // although `id` is not used in async arrow unary function,
+              // we don't need to reset `async`'s trailing comments because
+              // it will be attached to the upcoming async arrow binding identifier
+              return this.parseAsyncArrowUnaryFunction(
+                this.startNodeAtNode(id),
+              );
             } else {
               // Otherwise, treat "async" as an identifier and let calling code
               // deal with the current tt.name token.
               return id;
             }
           } else if (this.match(tt._do)) {
+            this.resetPreviousNodeTrailingComments(id);
             return this.parseDo(this.startNodeAtNode(id), true);
           }
         }
@@ -1198,8 +1205,7 @@ export default class ExpressionParser extends LValParser {
   }
 
   // async [no LineTerminator here] AsyncArrowBindingIdentifier[?Yield] [no LineTerminator here] => AsyncConciseBody[?In]
-  parseAsyncArrowUnaryFunction(id: N.Expression): N.ArrowFunctionExpression {
-    const node = this.startNodeAtNode(id);
+  parseAsyncArrowUnaryFunction(node: N.Node): N.ArrowFunctionExpression {
     // We don't need to push a new ParameterDeclarationScope here since we are sure
     // 1) it is an async arrow, 2) no biding pattern is allowed in params
     this.prodParam.enter(functionFlags(true, this.prodParam.hasYield));
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/input.js b/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/input.js
new file mode 100644
index 000000000000..b61e768397a7
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/input.js
@@ -0,0 +1 @@
+/* 1 */async/* 2 */do/* 3 */{/* 4 */}/* 5 */
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/options.json b/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/options.json
new file mode 100644
index 000000000000..94fd7ea36118
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["asyncDoExpressions", "doExpressions"]
+}
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/output.json b/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/output.json
new file mode 100644
index 000000000000..c82c2cfdbacc
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/output.json
@@ -0,0 +1,90 @@
+{
+  "type": "File",
+  "start":0,"end":44,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":44}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":44,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":44}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start":7,"end":37,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":37}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 1 ",
+            "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+          }
+        ],
+        "trailingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 5 ",
+            "start":37,"end":44,"loc":{"start":{"line":1,"column":37},"end":{"line":1,"column":44}}
+          }
+        ],
+        "expression": {
+          "type": "DoExpression",
+          "start":19,"end":37,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":37}},
+          "leadingComments": [
+            {
+              "type": "CommentBlock",
+              "value": " 2 ",
+              "start":12,"end":19,"loc":{"start":{"line":1,"column":12},"end":{"line":1,"column":19}}
+            }
+          ],
+          "async": true,
+          "body": {
+            "type": "BlockStatement",
+            "start":28,"end":37,"loc":{"start":{"line":1,"column":28},"end":{"line":1,"column":37}},
+            "leadingComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 3 ",
+                "start":21,"end":28,"loc":{"start":{"line":1,"column":21},"end":{"line":1,"column":28}}
+              }
+            ],
+            "innerComments": [
+              {
+                "type": "CommentBlock",
+                "value": " 4 ",
+                "start":29,"end":36,"loc":{"start":{"line":1,"column":29},"end":{"line":1,"column":36}}
+              }
+            ],
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":12,"end":19,"loc":{"start":{"line":1,"column":12},"end":{"line":1,"column":19}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 3 ",
+      "start":21,"end":28,"loc":{"start":{"line":1,"column":21},"end":{"line":1,"column":28}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 4 ",
+      "start":29,"end":36,"loc":{"start":{"line":1,"column":29},"end":{"line":1,"column":36}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 5 ",
+      "start":37,"end":44,"loc":{"start":{"line":1,"column":37},"end":{"line":1,"column":44}}
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-function/input.js b/packages/babel-parser/test/fixtures/comments/basic/async-function/input.js
new file mode 100644
index 000000000000..561c4d2562b1
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-function/input.js
@@ -0,0 +1 @@
+/* 1 */async/* 2 */function f () {}
diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-function/output.json b/packages/babel-parser/test/fixtures/comments/basic/async-function/output.json
new file mode 100644
index 000000000000..1cc9422626cb
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-function/output.json
@@ -0,0 +1,57 @@
+{
+  "type": "File",
+  "start":0,"end":35,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":35}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":35,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":35}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start":7,"end":35,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":35}},
+        "leadingComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 1 ",
+            "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+          }
+        ],
+        "innerComments": [
+          {
+            "type": "CommentBlock",
+            "value": " 2 ",
+            "start":12,"end":19,"loc":{"start":{"line":1,"column":12},"end":{"line":1,"column":19}}
+          }
+        ],
+        "id": {
+          "type": "Identifier",
+          "start":28,"end":29,"loc":{"start":{"line":1,"column":28},"end":{"line":1,"column":29},"identifierName":"f"},
+          "name": "f"
+        },
+        "generator": false,
+        "async": true,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start":33,"end":35,"loc":{"start":{"line":1,"column":33},"end":{"line":1,"column":35}},
+          "body": [],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  },
+  "comments": [
+    {
+      "type": "CommentBlock",
+      "value": " 1 ",
+      "start":0,"end":7,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":7}}
+    },
+    {
+      "type": "CommentBlock",
+      "value": " 2 ",
+      "start":12,"end":19,"loc":{"start":{"line":1,"column":12},"end":{"line":1,"column":19}}
+    }
+  ]
+}

From 430b3e0e3204b059c314a530dd708bcfbd078f79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Tue, 6 Jul 2021 21:12:26 -0400
Subject: [PATCH 34/35] refactor: simplify resetPreviousNodeTrailingComments

---
 packages/babel-parser/src/parser/comments.js | 21 +++++++++-----------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/packages/babel-parser/src/parser/comments.js b/packages/babel-parser/src/parser/comments.js
index 67d8db6fa04f..e6dc327e1f38 100644
--- a/packages/babel-parser/src/parser/comments.js
+++ b/packages/babel-parser/src/parser/comments.js
@@ -218,8 +218,12 @@ export default class CommentsParser extends BaseParser {
    * method later. In this case the identifier is not part of the AST and we
    * should sync the knowledge to commentStacks
    *
-   * For performance we do not check trailing node and we assume `node` is the
-   * last finished node before current token.
+   * For example, when parsing */
+  // async /* 1 */ function f() {}
+  /*
+   * the comment whitespace "* 1 *" has leading node Identifier(async). When
+   * we see the function token, we create a Function node and mark "* 1 *" as
+   * inner comments. So "* 1 *" should be detached from the Identifier node.
    *
    * @param {N.Node} node the last finished AST node _before_ current token
    * @returns
@@ -227,16 +231,9 @@ export default class CommentsParser extends BaseParser {
    */
   resetPreviousNodeTrailingComments(node: Node) {
     const { commentStack } = this.state;
-    let i = commentStack.length - 1;
-    if (i < 0) return;
-    let commentWS = commentStack[i];
-    if (commentWS.leadingNode === node) {
-      commentWS.leadingNode = null;
-      return;
-    }
-    i--;
-    if (i < 0) return;
-    commentWS = commentStack[i];
+    const { length } = commentStack;
+    if (length === 0) return;
+    const commentWS = commentStack[length - 1];
     if (commentWS.leadingNode === node) {
       commentWS.leadingNode = null;
     }

From 4f076f8f36c1c08972e2306dc9a66bc8aa3fc3ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 7 Jul 2021 10:24:56 -0400
Subject: [PATCH 35/35] update test fixtures

---
 .../fixtures/comments/basic/async-do-expression/output.json   | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/output.json b/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/output.json
index c82c2cfdbacc..481331445e28 100644
--- a/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/output.json
+++ b/packages/babel-parser/test/fixtures/comments/basic/async-do-expression/output.json
@@ -26,8 +26,8 @@
         ],
         "expression": {
           "type": "DoExpression",
-          "start":19,"end":37,"loc":{"start":{"line":1,"column":19},"end":{"line":1,"column":37}},
-          "leadingComments": [
+          "start":7,"end":37,"loc":{"start":{"line":1,"column":7},"end":{"line":1,"column":37}},
+          "innerComments": [
             {
               "type": "CommentBlock",
               "value": " 2 ",