From 3755a3ec8ae801a112d0a4bae6879dc7a9bc3df8 Mon Sep 17 00:00:00 2001
From: David Michon <dmichon@microsoft.com>
Date: Wed, 26 Feb 2025 04:03:47 -0800
Subject: [PATCH] fix: forward semicolons from meta.webpackAST (#19252)

---
 lib/javascript/JavascriptParser.js              | 7 +++++++
 test/cases/parsing/precreated-ast/ast-loader.js | 6 +++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/javascript/JavascriptParser.js b/lib/javascript/JavascriptParser.js
index 084292385..0ccf0a069 100644
--- a/lib/javascript/JavascriptParser.js
+++ b/lib/javascript/JavascriptParser.js
@@ -4379,6 +4379,13 @@ class JavascriptParser extends Parser {
 		if (typeof source === "object") {
 			ast = /** @type {Program} */ (source);
 			comments = source.comments;
+			if (source.semicolons) {
+				// Forward semicolon information from the preparsed AST if present
+				// This ensures the output is consistent with that of a fresh AST
+				for (const pos of source.semicolons) {
+					semicolons.add(pos);
+				}
+			}
 		} else {
 			comments = [];
 			ast = JavascriptParser._parse(source, {
diff --git a/test/cases/parsing/precreated-ast/ast-loader.js b/test/cases/parsing/precreated-ast/ast-loader.js
index e15037726..52ba5cc6e 100644
--- a/test/cases/parsing/precreated-ast/ast-loader.js
+++ b/test/cases/parsing/precreated-ast/ast-loader.js
@@ -7,12 +7,14 @@ const acornParser = acorn.Parser;
 module.exports = function (source) {
 	const comments = [];
 
+	const semicolons = new Set();
 	const ast = acornParser.parse(source, {
 		ranges: true,
 		locations: true,
 		ecmaVersion: 11,
 		sourceType: "module",
-		onComment: comments
+		onComment: comments,
+		onInsertedSemicolon: (pos) => semicolons.add(pos)
 	});
 
 	// change something to test if it's really used
@@ -23,6 +25,8 @@ module.exports = function (source) {
 
 	//@ts-ignore
 	ast.comments = comments;
+	//@ts-ignore
+	ast.semicolons = semicolons;
 	this.callback(null, source, null, {
 		webpackAST: ast
 	});