Fix moving comments of removed nodes (#15427)

packages/babel-helper-create-class-features-plugin/src/fields.ts

@@ -1283,6 +1283,12 @@ export function buildFieldsInitNodes(
     pureStaticNodes: pureStaticNodes.filter(Boolean),
     wrapClass(path: NodePath<t.Class>) {
       for (const prop of props) {
+        // Delete leading comments so that they don't get attached as
+        // trailing comments of the previous sibling.
+        // When transforming props, we explicitly attach their leading
+        // comments to the transformed node with `inheritPropComments`
+        // above.
+        prop.node.leadingComments = null;
         prop.remove();
       }
 

packages/babel-plugin-proposal-class-properties/test/fixtures/compile-to-class/constructor-collision-ignores-types-babel-7/output.js

@@ -1,7 +1,6 @@
 class C {
-  // Output should not use `_initialiseProps`
-
   constructor(T) {
+    // Output should not use `_initialiseProps`
     babelHelpers.defineProperty(this, "y", 0);
   }
 }

packages/babel-plugin-proposal-class-properties/test/fixtures/compile-to-class/constructor-collision-ignores-types-loose-babel-7/output.js

@@ -1,7 +1,6 @@
 class C {
-  // Output should not use `_initialiseProps`
-
   constructor(T) {
+    // Output should not use `_initialiseProps`
     this.y = 0;
   }
 }

packages/babel-plugin-proposal-class-properties/test/fixtures/compile-to-class/constructor-collision-ignores-types-loose/output.js

@@ -1,7 +1,6 @@
 class C {
-  // Output should not use `_initialiseProps`
-
   constructor(T) {
+    // Output should not use `_initialiseProps`
     this.x = void 0;
     this.y = 0;
   }

packages/babel-plugin-proposal-class-properties/test/fixtures/compile-to-class/constructor-collision-ignores-types/output.js

@@ -1,7 +1,6 @@
 class C {
-  // Output should not use `_initialiseProps`
-
   constructor(T) {
+    // Output should not use `_initialiseProps`
     babelHelpers.defineProperty(this, "x", void 0);
     babelHelpers.defineProperty(this, "y", 0);
   }

packages/babel-plugin-transform-typescript/test/fixtures/exports/declared-types/output.mjs

@@ -1,4 +1,7 @@
 export class C2 {}
+
+// Not-even E
+
 // everything removed
 export { C2 as C3 }; // only C2->C3
 var BB = /*#__PURE__*/function (BB) {
@@ -20,6 +23,5 @@ function foo() {}
 export { BB2 as BB3, foo }; // only BB2->BB3 and foo
 
 // export an interface before declaration
-
 // everything removed
 export { C2 as C4 }; // only C2->C4

packages/babel-plugin-transform-typescript/test/fixtures/exports/issue-9916-1/input.ts

@@ -0,0 +1,17 @@
+/**
+ * @module
+ */
+
+import '../message-bus';
+
+/**
+ * @typedef {Function} PromiseResolveCb
+ */
+export type PromiseResolveCb<T> = (value?: T | PromiseLike<T>) => void;
+
+/**
+ * @typedef {Function} PromiseRejectCb
+ */
+export type PromiseRejectCb = (reason?: any) => void;
+
+var a;

packages/babel-plugin-transform-typescript/test/fixtures/exports/issue-9916-1/output.mjs

@@ -0,0 +1,15 @@
+/**
+ * @module
+ */
+
+import '../message-bus';
+
+/**
+ * @typedef {Function} PromiseResolveCb
+ */
+
+/**
+ * @typedef {Function} PromiseRejectCb
+ */
+
+var a;

packages/babel-plugin-transform-typescript/test/fixtures/exports/issue-9916-2/input.ts

@@ -0,0 +1,15 @@
+/**
+ * @module
+ */
+
+import '../message-bus';
+
+/**
+ * @typedef {Function} PromiseResolveCb
+ */
+export type PromiseResolveCb<T> = (value?: T | PromiseLike<T>) => void;
+
+/**
+ * @typedef {Function} PromiseRejectCb
+ */
+export type PromiseRejectCb = (reason?: any) => void;

packages/babel-plugin-transform-typescript/test/fixtures/exports/issue-9916-2/output.mjs

@@ -0,0 +1,13 @@
+/**
+ * @module
+ */
+
+import '../message-bus';
+
+/**
+ * @typedef {Function} PromiseResolveCb
+ */
+
+/**
+ * @typedef {Function} PromiseRejectCb
+ */

packages/babel-plugin-transform-typescript/test/fixtures/exports/issue-9916-3/input.ts

@@ -0,0 +1,15 @@
+/**
+ * @module
+ */
+
+/**
+ * @typedef {Function} PromiseResolveCb
+ */
+export type PromiseResolveCb<T> = (value?: T | PromiseLike<T>) => void;
+
+/**
+ * @typedef {Function} PromiseRejectCb
+ */
+export type PromiseRejectCb = (reason?: any) => void;
+
+var a;

packages/babel-plugin-transform-typescript/test/fixtures/exports/issue-9916-3/output.mjs

@@ -0,0 +1,14 @@
+/**
+ * @module
+ */
+
+/**
+ * @typedef {Function} PromiseResolveCb
+ */
+
+/**
+ * @typedef {Function} PromiseRejectCb
+ */
+
+var a;
+export {};

packages/babel-traverse/src/path/comments.ts

@@ -25,13 +25,37 @@ export function shareCommentsWithSiblings(this: NodePath) {
   const next = this.getSibling(this.key + 1);
   const hasPrev = Boolean(prev.node);
   const hasNext = Boolean(next.node);
-  if (hasPrev && !hasNext) {
-    prev.addComments("trailing", trailing);
-  } else if (hasNext && !hasPrev) {
-    next.addComments("leading", leading);
+
+  if (hasPrev) {
+    if (leading) {
+      prev.addComments(
+        "trailing",
+        removeIfExisting(leading, prev.node.trailingComments),
+      );
+    }
+    if (trailing && !hasNext) prev.addComments("trailing", trailing);
+  }
+  if (hasNext) {
+    if (trailing) {
+      next.addComments(
+        "leading",
+        removeIfExisting(trailing, next.node.leadingComments),
+      );
+    }
+    if (leading && !hasPrev) next.addComments("leading", leading);
   }
 }
 
+function removeIfExisting<T>(list: T[], toRemove?: T[]): T[] {
+  if (!toRemove) return list;
+  let lastFoundIndex = -1;
+  return list.filter(el => {
+    const i = toRemove.indexOf(el, lastFoundIndex);
+    if (i === -1) return true;
+    lastFoundIndex = i;
+  });
+}
+
 export function addComment(
   this: NodePath,
   type: t.CommentTypeShorthand,

packages/babel-traverse/test/fixtures/comments/attachment/output.js

@@ -2,10 +2,10 @@
 {
   hasPrev;
   /* top */
-  /* left */ /* right */
+  /* left */
+  /* right */
   /* bottom */
 }
-
 {
   /* top */
   /* left */ /* right */
@@ -16,7 +16,6 @@
   hasPrev;
   /* top */
   /* left */
-
   /* right */
   /* bottom */
   hasNext;