Support more inner comments (#15008)

Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com>

packages/babel-generator/src/generators/expressions.ts

@@ -28,7 +28,10 @@ export function UnaryExpression(this: Printer, node: t.UnaryExpression) {
 export function DoExpression(this: Printer, node: t.DoExpression) {
   if (node.async) {
     this.word("async");
-    this.space();
+    this.ensureNoLineTerminator(() => {
+      this.printInnerComments(node);
+      this.space();
+    });
   }
   this.word("do");
   this.space();
@@ -230,12 +233,20 @@ export function YieldExpression(this: Printer, node: t.YieldExpression) {
   this.word("yield");
 
   if (node.delegate) {
+    this.ensureNoLineTerminator(() => {
+      this.printInnerComments(node);
+    });
     this.token("*");
-  }
-
-  if (node.argument) {
-    this.space();
-    this.printTerminatorless(node.argument, node, false);
+    if (node.argument) {
+      this.space();
+      // line terminators are allowed after yield*
+      this.print(node.argument, node);
+    }
+  } else {
+    if (node.argument) {
+      this.space();
+      this.printTerminatorless(node.argument, node, false);
+    }
   }
 }
 

packages/babel-generator/src/generators/methods.ts

@@ -25,14 +25,18 @@ export function _parameters(
     | t.TSFunctionType
     | t.TSConstructorType,
 ) {
-  for (let i = 0; i < parameters.length; i++) {
+  const paramLength = parameters.length;
+  for (let i = 0; i < paramLength; i++) {
     this._param(parameters[i], parent);
 
     if (i < parameters.length - 1) {
       this.token(",");
       this.space();
     }
   }
+  if (paramLength === 0) {
+    this.printInnerComments(parent);
+  }
 }
 
 export function _param(
@@ -71,9 +75,10 @@ export function _methodHead(this: Printer, node: t.Method | t.TSDeclareMethod) {
     this.space();
   }
 
+  const { _noLineTerminator } = this;
   if (node.async) {
-    // ensure `async` is in the same line with property name
-    this._catchUp("start", key.loc);
+    // ensure no line terminator between async and class element name / *
+    this._noLineTerminator = true;
     this.word("async");
     this.space();
   }
@@ -84,16 +89,23 @@ export function _methodHead(this: Printer, node: t.Method | t.TSDeclareMethod) {
     kind === "init"
   ) {
     if (node.generator) {
+      if (node.async) {
+        this.printInnerComments(node);
+      }
       this.token("*");
+      this._noLineTerminator = _noLineTerminator;
     }
   }
 
   if (node.computed) {
     this.token("[");
+    this._noLineTerminator = _noLineTerminator;
     this.print(key, node);
     this.token("]");
+    this.printInnerComments(node);
   } else {
     this.print(key, node);
+    this._noLineTerminator = _noLineTerminator;
   }
 
   if (
@@ -158,33 +170,36 @@ export function ArrowFunctionExpression(
   this: Printer,
   node: t.ArrowFunctionExpression,
 ) {
+  const { _noLineTerminator } = this;
   if (node.async) {
+    this._noLineTerminator = true;
     this.word("async");
     this.space();
   }
 
-  const firstParam = node.params[0];
-
   // Try to avoid printing parens in simple cases, but only if we're pretty
   // sure that they aren't needed by type annotations or potential newlines.
+  let firstParam;
   if (
     !this.format.retainLines &&
-    // Auxiliary comments can introduce unexpected newlines
-    !this.format.auxiliaryCommentBefore &&
-    !this.format.auxiliaryCommentAfter &&
     node.params.length === 1 &&
-    isIdentifier(firstParam) &&
+    isIdentifier((firstParam = node.params[0])) &&
     !hasTypesOrComments(node, firstParam)
   ) {
     this.print(firstParam, node);
+    this._noLineTerminator = _noLineTerminator;
   } else {
+    this._noLineTerminator = _noLineTerminator;
     this._params(node);
   }
 
   this._predicate(node);
+  this.ensureNoLineTerminator(() => {
+    this.space();
+    this.printInnerComments(node);
+    this.token("=>");
+  });
 
-  this.space();
-  this.token("=>");
   this.space();
 
   this.print(node.body, node);
@@ -200,6 +215,7 @@ function hasTypesOrComments(
     node.predicate ||
     param.typeAnnotation ||
     param.optional ||
+    // Flow does not support `foo /*: string*/ => {};`
     param.leadingComments?.length ||
     param.trailingComments?.length
   );

packages/babel-generator/src/generators/modules.ts

@@ -80,9 +80,19 @@ export function ExportAllDeclaration(
   this.space();
   this.word("from");
   this.space();
-  this.print(node.source, node);
   // @ts-expect-error Fixme: assertions is not defined in DeclareExportAllDeclaration
-  this.printAssertions(node);
+  if (node.assertions?.length) {
+    this.ensureNoLineTerminator(() => {
+      this.print(node.source, node);
+      this.space();
+      this.word("assert");
+    });
+    // @ts-expect-error Fixme: assertions is not defined in DeclareExportAllDeclaration
+    this.printAssertions(node);
+  } else {
+    this.print(node.source, node);
+  }
+
   this.semicolon();
 }
 
@@ -146,8 +156,16 @@ export function ExportNamedDeclaration(
       this.space();
       this.word("from");
       this.space();
-      this.print(node.source, node);
-      this.printAssertions(node);
+      if (node.assertions?.length) {
+        this.ensureNoLineTerminator(() => {
+          this.print(node.source, node);
+          this.space();
+          this.word("assert");
+        });
+        this.printAssertions(node);
+      } else {
+        this.print(node.source, node);
+      }
     }
 
     this.semicolon();
@@ -220,9 +238,16 @@ export function ImportDeclaration(this: Printer, node: t.ImportDeclaration) {
     this.space();
   }
 
-  this.print(node.source, node);
-
-  this.printAssertions(node);
+  if (node.assertions?.length) {
+    this.print(node.source, node, true);
+    this.ensureNoLineTerminator(() => {
+      this.space();
+      this.word("assert");
+    });
+    this.printAssertions(node);
+  } else {
+    this.print(node.source, node);
+  }
   if (!process.env.BABEL_8_BREAKING) {
     // @ts-ignore(Babel 7 vs Babel 8) Babel 7 supports module attributes
     if (node.attributes?.length) {

packages/babel-generator/src/printer.ts

@@ -1070,18 +1070,14 @@ class Printer {
       }
     }
   }
-  // todo(flow->ts): was Node
   printAssertions(node: Extract<t.Node, { assertions?: t.ImportAttribute[] }>) {
-    if (node.assertions?.length) {
-      this.space();
-      this.word("assert");
-      this.space();
-      this.token("{");
-      this.space();
-      this.printList(node.assertions, node);
-      this.space();
-      this.token("}");
-    }
+    this.space();
+    this.printInnerComments(node);
+    this.token("{");
+    this.space();
+    this.printList(node.assertions, node);
+    this.space();
+    this.token("}");
   }
 }
 

packages/babel-generator/test/arrow-functions.js

@@ -28,18 +28,15 @@ describe("parameter parentheses", () => {
     const output = generate(ast, { auxiliaryCommentBefore: "BEFORE" }).code;
     expect(output).toMatchInlineSnapshot(`
       "() => {};
-      (
       /*BEFORE*/
-      a) => {};
+      a => {};
       (
       /*BEFORE*/
       a,
       /*BEFORE*/
       b) => {};
       async () => {};
-      async (
-      /*BEFORE*/
-      a) => {};
+      async /*BEFORE*/a => {};
       async (
       /*BEFORE*/
       a,
@@ -53,18 +50,14 @@ describe("parameter parentheses", () => {
     const output = generate(ast, { auxiliaryCommentAfter: "AFTER" }).code;
     expect(output).toMatchInlineSnapshot(`
       "() => {};
-      (a
-      /*AFTER*/
-      ) => {};
+      a /*AFTER*/=> {};
       (a
       /*AFTER*/
       , b
       /*AFTER*/
       ) => {};
       async () => {};
-      async (a
-      /*AFTER*/
-      ) => {};
+      async a /*AFTER*/=> {};
       async (a
       /*AFTER*/
       , b

packages/babel-generator/test/fixtures/async-do-expressions/inner-comments/input.js

@@ -0,0 +1 @@
+async /* 1 */ do /* 2 */ { /* 3 */ }

packages/babel-generator/test/fixtures/async-do-expressions/inner-comments/output.js

@@ -0,0 +1 @@
+async /* 1 */ do /* 2 */{/* 3 */};

packages/babel-generator/test/fixtures/comments/arrow-single-param-comment/input.js

@@ -0,0 +1 @@
+(x)/* 1 */=>{}

packages/babel-generator/test/fixtures/comments/arrow-single-param-comment/output.js

@@ -0,0 +1 @@
+x /* 1 */=> {};

packages/babel-generator/test/fixtures/comments/async-class-method-comment/input.js

@@ -0,0 +1,3 @@
+class C {
+  async /* 1 */ foo(/* 2 */) /* 3 */ {}
+}

packages/babel-generator/test/fixtures/comments/async-class-method-comment/output.js

@@ -0,0 +1,3 @@
+class C {
+  async /* 1 */foo( /* 2 */) /* 3 */{}
+}

packages/babel-generator/test/fixtures/comments/async-class-method-computed-key-comment/input.js

@@ -0,0 +1,3 @@
+class C {
+  async /* 1 */ [ /* 2 */ foo /* 3 */] /* 4 */ (/* 5 */) {}
+}

packages/babel-generator/test/fixtures/comments/async-class-method-computed-key-comment/output.js

@@ -0,0 +1,3 @@
+class C {
+  async [/* 2 */foo /* 3 */] /* 1 */ /* 4 */ /* 5 */() {}
+}

packages/babel-generator/test/fixtures/comments/async-generator-class-method-comment/input.js

@@ -0,0 +1,3 @@
+class C {
+  async /* 1 */ * /* 2 */ foo /* 3 */ (/* 4 */) /* 5 */ {}
+}

packages/babel-generator/test/fixtures/comments/async-generator-class-method-comment/output.js

@@ -0,0 +1,3 @@
+class C {
+  async /* 1 */ /* 4 */* /* 2 */foo /* 3 */() /* 5 */{}
+}

packages/babel-generator/test/fixtures/comments/async-generator-class-method-computed-key-comment/input.js

@@ -0,0 +1,3 @@
+class C {
+  async /* 1 */ * /* 2 */ [ /* 3 */ foo /* 4 */] /* 5 */ (/* 6 */) {}
+}

packages/babel-generator/test/fixtures/comments/async-generator-class-method-computed-key-comment/output.js

@@ -0,0 +1,3 @@
+class C {
+  async /* 1 */ /* 2 */ /* 5 */ /* 6 */*[/* 3 */foo /* 4 */]() {}
+}

packages/babel-generator/test/fixtures/comments/import-assertion-inner-comment/input.js

@@ -0,0 +1 @@
+import "foo" /* 1 */ assert /* 2 */ { type: "json" }

packages/babel-generator/test/fixtures/comments/import-assertion-inner-comment/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["importAssertions"]
+}

packages/babel-generator/test/fixtures/comments/import-assertion-inner-comment/output.js

@@ -0,0 +1 @@
+import "foo" /* 1 */ assert /* 2 */{ type: "json" };

packages/babel-generator/test/fixtures/comments/yield-star-inner-comment/input.js

@@ -0,0 +1,3 @@
+function * loop() {
+  yield /* 1 */ * /* 2 */ loop();
+}

packages/babel-generator/test/fixtures/comments/yield-star-inner-comment/output.js

@@ -0,0 +1,3 @@
+function* loop() {
+  yield /* 1 */* /* 2 */loop();
+}