From cc23d15e2c02fad3a6a76a4d7412a888cd2a46c9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Wed, 4 May 2022 16:38:34 -0400
Subject: [PATCH 1/2] fix: perserve () of lhs id with rhs unamed fn

---
 packages/babel-generator/src/node/parentheses.ts      | 11 +++++++++++
 .../test/fixtures/parentheses/identifier-lhs/input.js |  4 ++++
 .../fixtures/parentheses/identifier-lhs/output.js     |  7 +++++++
 3 files changed, 22 insertions(+)
 create mode 100644 packages/babel-generator/test/fixtures/parentheses/identifier-lhs/input.js
 create mode 100644 packages/babel-generator/test/fixtures/parentheses/identifier-lhs/output.js

diff --git a/packages/babel-generator/src/node/parentheses.ts b/packages/babel-generator/src/node/parentheses.ts
index bb651b6d2287..873deb203f3a 100644
--- a/packages/babel-generator/src/node/parentheses.ts
+++ b/packages/babel-generator/src/node/parentheses.ts
@@ -17,6 +17,7 @@ import {
   isForInStatement,
   isForOfStatement,
   isForStatement,
+  isFunctionExpression,
   isIfStatement,
   isIndexedAccessType,
   isIntersectionTypeAnnotation,
@@ -344,6 +345,16 @@ export function Identifier(
   parent: t.Node,
   printStack: Array<t.Node>,
 ): boolean {
+  // 13.15.2 AssignmentExpression RS: Evaluation
+  // (fn) = function () {};
+  if (
+    node.extra?.parenthesized &&
+    isAssignmentExpression(parent, { left: node }) &&
+    isFunctionExpression(parent.right) &&
+    parent.right.id == null
+  ) {
+    return true;
+  }
   // Non-strict code allows the identifier `let`, but it cannot occur as-is in
   // certain contexts to avoid ambiguity with contextual keyword `let`.
   if (node.name === "let") {
diff --git a/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/input.js b/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/input.js
new file mode 100644
index 000000000000..173c0b81819e
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/input.js
@@ -0,0 +1,4 @@
+var f, g, h;
+(f) = function () {};
+g = function () {};
+(h) = function noParen() {}
diff --git a/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/output.js b/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/output.js
new file mode 100644
index 000000000000..b718a3d40c4d
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/output.js
@@ -0,0 +1,7 @@
+var f, g, h;
+
+(f) = function () {};
+
+g = function () {};
+
+h = function noParen() {};
\ No newline at end of file

From e26b420ea682d601902c6133ee0cb419778d4e90 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hu=C3=A1ng=20J=C3=B9nli=C3=A0ng?= <jlhwung@gmail.com>
Date: Thu, 5 May 2022 13:49:11 -0400
Subject: [PATCH 2/2] review comments

---
 packages/babel-generator/src/node/parentheses.ts          | 2 +-
 .../test/fixtures/parentheses/identifier-lhs/input.js     | 5 ++++-
 .../test/fixtures/parentheses/identifier-lhs/output.js    | 8 +++++++-
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/packages/babel-generator/src/node/parentheses.ts b/packages/babel-generator/src/node/parentheses.ts
index 873deb203f3a..2570a5c451b3 100644
--- a/packages/babel-generator/src/node/parentheses.ts
+++ b/packages/babel-generator/src/node/parentheses.ts
@@ -350,7 +350,7 @@ export function Identifier(
   if (
     node.extra?.parenthesized &&
     isAssignmentExpression(parent, { left: node }) &&
-    isFunctionExpression(parent.right) &&
+    (isFunctionExpression(parent.right) || isClassExpression(parent.right)) &&
     parent.right.id == null
   ) {
     return true;
diff --git a/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/input.js b/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/input.js
index 173c0b81819e..b1c118d215b6 100644
--- a/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/input.js
+++ b/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/input.js
@@ -1,4 +1,7 @@
 var f, g, h;
 (f) = function () {};
+(f) = class {};
 g = function () {};
-(h) = function noParen() {}
+g = class {};
+(h) = function noParen() {};
+(h) = class noParen {}
diff --git a/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/output.js b/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/output.js
index b718a3d40c4d..164de06f999a 100644
--- a/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/output.js
+++ b/packages/babel-generator/test/fixtures/parentheses/identifier-lhs/output.js
@@ -2,6 +2,12 @@ var f, g, h;
 
 (f) = function () {};
 
+(f) = class {};
+
 g = function () {};
 
-h = function noParen() {};
\ No newline at end of file
+g = class {};
+
+h = function noParen() {};
+
+h = class noParen {};
\ No newline at end of file