From e7c55831de4c7903b63ca3efe413087984823457 Mon Sep 17 00:00:00 2001
From: Sean Larkin <selarkin@microsoft.com>
Date: Tue, 26 Apr 2022 09:34:51 -0700
Subject: [PATCH 1/2] hoist regexp literals in SourceMapDerToolPlugin

---
 lib/SourceMapDevToolPlugin.js | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/lib/SourceMapDevToolPlugin.js b/lib/SourceMapDevToolPlugin.js
index fc5a3dcf287..ce67713d6a4 100644
--- a/lib/SourceMapDevToolPlugin.js
+++ b/lib/SourceMapDevToolPlugin.js
@@ -47,13 +47,21 @@ const validate = createSchemaValidation(
  * @property {ItemCacheFacade} cacheItem cache item
  */
 
+const METACHARACTERS_REGEXP = /[-[\]\\/{}()*+?.^$|]/g;
+const CONTENT_HASH_DETECT_REGEXP = /\[contenthash(:\w+)?\]/;
+const CSS_AND_JS_MODULE_EXTENSIONS_REGEXP = /\.((c|m)?js|css)($|\?)/i;
+const CSS_EXTENSION_DETECT_REGEXP = /\.css($|\?)/i;
+const MAP_URL_COMMENT_REGEXP = /\[map\]/g;
+const URL_COMMENT_REGEXP = /\[url\]/g;
+const URL_FORMATTING_REGEXP = /^\n\/\/(.*)$/;
+
 /**
  * Escapes regular expression metacharacters
  * @param {string} str String to quote
  * @returns {string} Escaped string
  */
 const quoteMeta = str => {
-	return str.replace(/[-[\]\\/{}()*+?.^$|]/g, "\\$&");
+	return str.replace(METACHARACTERS_REGEXP, "\\$&");
 };
 
 /**
@@ -152,7 +160,7 @@ class SourceMapDevToolPlugin {
 		const fallbackModuleFilenameTemplate = this.fallbackModuleFilenameTemplate;
 		const requestShortener = compiler.requestShortener;
 		const options = this.options;
-		options.test = options.test || /\.((c|m)?js|css)($|\?)/i;
+		options.test = options.test || CSS_AND_JS_MODULE_EXTENSIONS_REGEXP;
 
 		const matchObject = ModuleFilenameHelpers.matchObject.bind(
 			undefined,
@@ -409,7 +417,7 @@ class SourceMapDevToolPlugin {
 									sourceMap.file = file;
 									const usesContentHash =
 										sourceMapFilename &&
-										/\[contenthash(:\w+)?\]/.test(sourceMapFilename);
+										CONTENT_HASH_DETECT_REGEXP.test(sourceMapFilename);
 
 									// If SourceMap and asset uses contenthash, avoid a circular dependency by hiding hash in `file`
 									if (usesContentHash && task.assetInfo.contenthash) {
@@ -430,11 +438,11 @@ class SourceMapDevToolPlugin {
 									let currentSourceMappingURLComment = sourceMappingURLComment;
 									if (
 										currentSourceMappingURLComment !== false &&
-										/\.css($|\?)/i.test(file)
+										CSS_EXTENSION_DETECT_REGEXP.test(file)
 									) {
 										currentSourceMappingURLComment =
 											currentSourceMappingURLComment.replace(
-												/^\n\/\/(.*)$/,
+												URL_FORMATTING_REGEXP,
 												"\n/*$1*/"
 											);
 									}
@@ -516,9 +524,9 @@ class SourceMapDevToolPlugin {
 										const asset = new ConcatSource(
 											new RawSource(source),
 											currentSourceMappingURLComment
-												.replace(/\[map\]/g, () => sourceMapString)
+												.replace(MAP_URL_COMMENT_REGEXP, () => sourceMapString)
 												.replace(
-													/\[url\]/g,
+													URL_COMMENT_REGEXP,
 													() =>
 														`data:application/json;charset=utf-8;base64,${Buffer.from(
 															sourceMapString,

From 5e31761419bf9c1c4080d375da0ef4d85f684bcf Mon Sep 17 00:00:00 2001
From: Sean Larkin <selarkin@microsoft.com>
Date: Tue, 26 Apr 2022 13:46:26 -0700
Subject: [PATCH 2/2] reset state for stateful regexp

---
 lib/SourceMapDevToolPlugin.js | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/lib/SourceMapDevToolPlugin.js b/lib/SourceMapDevToolPlugin.js
index ce67713d6a4..49ebabc9b30 100644
--- a/lib/SourceMapDevToolPlugin.js
+++ b/lib/SourceMapDevToolPlugin.js
@@ -55,6 +55,17 @@ const MAP_URL_COMMENT_REGEXP = /\[map\]/g;
 const URL_COMMENT_REGEXP = /\[url\]/g;
 const URL_FORMATTING_REGEXP = /^\n\/\/(.*)$/;
 
+/**
+ * Reset's .lastIndex of stateful Regular Expressions
+ * For when `test` or `exec` is called on them
+ * @param {RegExp} regexp Stateful Regular Expression to be reset
+ * @returns {void}
+ *
+ */
+const resetRegexpState = regexp => {
+	regexp.lastIndex = -1;
+};
+
 /**
  * Escapes regular expression metacharacters
  * @param {string} str String to quote
@@ -419,6 +430,8 @@ class SourceMapDevToolPlugin {
 										sourceMapFilename &&
 										CONTENT_HASH_DETECT_REGEXP.test(sourceMapFilename);
 
+									resetRegexpState(CONTENT_HASH_DETECT_REGEXP);
+
 									// If SourceMap and asset uses contenthash, avoid a circular dependency by hiding hash in `file`
 									if (usesContentHash && task.assetInfo.contenthash) {
 										const contenthash = task.assetInfo.contenthash;
@@ -436,9 +449,12 @@ class SourceMapDevToolPlugin {
 
 									/** @type {string | false} */
 									let currentSourceMappingURLComment = sourceMappingURLComment;
+									let cssExtensionDetected =
+										CSS_EXTENSION_DETECT_REGEXP.test(file);
+									resetRegexpState(CSS_EXTENSION_DETECT_REGEXP);
 									if (
 										currentSourceMappingURLComment !== false &&
-										CSS_EXTENSION_DETECT_REGEXP.test(file)
+										cssExtensionDetected
 									) {
 										currentSourceMappingURLComment =
 											currentSourceMappingURLComment.replace(