fixes #69655

src/vs/base/browser/ui/menu/menu.ts

@@ -20,22 +20,8 @@ import { Event, Emitter } from 'vs/base/common/event';
 import { AnchorAlignment } from 'vs/base/browser/ui/contextview/contextview';
 import { isLinux, isMacintosh } from 'vs/base/common/platform';
 
-function createMenuMnemonicRegExp() {
-	try {
-		return new RegExp('\\(&([^\\s&])\\)|(?<!&)&([^\\s&])');
-	} catch (err) {
-		return new RegExp('\uFFFF'); // never match please
-	}
-}
-export const MENU_MNEMONIC_REGEX = createMenuMnemonicRegExp();
-function createMenuEscapedMnemonicRegExp() {
-	try {
-		return new RegExp('(?<!&amp;)(?:&amp;)([^\\s&])');
-	} catch (err) {
-		return new RegExp('\uFFFF'); // never match please
-	}
-}
-export const MENU_ESCAPED_MNEMONIC_REGEX: RegExp = createMenuEscapedMnemonicRegExp();
+export const MENU_MNEMONIC_REGEX = /\(&([^\s&])\)|(^|[^&])&([^\s&])/;
+export const MENU_ESCAPED_MNEMONIC_REGEX = /(&amp;)?(&amp;)([^\s&])/g;
 
 export interface IMenuOptions {
 	context?: any;
@@ -391,7 +377,7 @@ class BaseMenuActionViewItem extends BaseActionViewItem {
 			if (label) {
 				let matches = MENU_MNEMONIC_REGEX.exec(label);
 				if (matches) {
-					this.mnemonic = (!!matches[1] ? matches[1] : matches[2]).toLocaleLowerCase();
+					this.mnemonic = (!!matches[1] ? matches[1] : matches[3]).toLocaleLowerCase();
 				}
 			}
 		}
@@ -480,9 +466,23 @@ class BaseMenuActionViewItem extends BaseActionViewItem {
 				const matches = MENU_MNEMONIC_REGEX.exec(label);
 
 				if (matches) {
-					label = strings.escape(label).replace(MENU_ESCAPED_MNEMONIC_REGEX, '<u aria-hidden="true">$1</u>');
+					label = strings.escape(label);
+
+					// This is global, reset it
+					MENU_ESCAPED_MNEMONIC_REGEX.lastIndex = 0;
+					let escMatch = MENU_ESCAPED_MNEMONIC_REGEX.exec(label);
+
+					// We can't use negative lookbehind so if we match our negative and skip
+					while (escMatch && escMatch[1]) {
+						escMatch = MENU_ESCAPED_MNEMONIC_REGEX.exec(label);
+					}
+
+					if (escMatch) {
+						label = `${label.substr(0, escMatch.index)}<u aria-hidden="true">${escMatch[3]}</u>${label.substr(escMatch.index + escMatch[0].length)}`;
+					}
+
 					label = label.replace(/&amp;&amp;/g, '&amp;');
-					this.item.setAttribute('aria-keyshortcuts', (!!matches[1] ? matches[1] : matches[2]).toLocaleLowerCase());
+					this.item.setAttribute('aria-keyshortcuts', (!!matches[1] ? matches[1] : matches[3]).toLocaleLowerCase());
 				} else {
 					label = label.replace(/&&/g, '&');
 				}
@@ -815,7 +815,7 @@ export function cleanMnemonic(label: string): string {
 		return label;
 	}
 
-	const mnemonicInText = matches[0].charAt(0) === '&';
+	const mnemonicInText = !matches[1];
 
-	return label.replace(regex, mnemonicInText ? '$2' : '').trim();
+	return label.replace(regex, mnemonicInText ? '$2$3' : '').trim();
 }

src/vs/base/browser/ui/menu/menubar.ts

@@ -209,7 +209,7 @@ export class MenuBar extends Disposable {
 
 			// Register mnemonics
 			if (mnemonicMatches) {
-				let mnemonic = !!mnemonicMatches[1] ? mnemonicMatches[1] : mnemonicMatches[2];
+				let mnemonic = !!mnemonicMatches[1] ? mnemonicMatches[1] : mnemonicMatches[3];
 
 				this.registerMnemonic(this.menuCache.length, mnemonic);
 			}
@@ -472,15 +472,34 @@ export class MenuBar extends Disposable {
 		const cleanMenuLabel = cleanMnemonic(label);
 
 		// Update the button label to reflect mnemonics
-		titleElement.innerHTML = this.options.enableMnemonics ?
-			strings.escape(label).replace(MENU_ESCAPED_MNEMONIC_REGEX, '<mnemonic aria-hidden="true">$1</mnemonic>').replace(/&amp;&amp;/g, '&amp;') :
-			cleanMenuLabel.replace(/&&/g, '&');
+
+		if (this.options.enableMnemonics) {
+			let innerHtml = strings.escape(label);
+
+			// This is global so reset it
+			MENU_ESCAPED_MNEMONIC_REGEX.lastIndex = 0;
+			let escMatch = MENU_ESCAPED_MNEMONIC_REGEX.exec(innerHtml);
+
+			// We can't use negative lookbehind so we match our negative and skip
+			while (escMatch && escMatch[1]) {
+				escMatch = MENU_ESCAPED_MNEMONIC_REGEX.exec(innerHtml);
+			}
+
+			if (escMatch) {
+				innerHtml = `${innerHtml.substr(0, escMatch.index)}<mnemonic aria-hidden="true">${escMatch[3]}</mnemonic>${innerHtml.substr(escMatch.index + escMatch[0].length)}`;
+			}
+
+			innerHtml = innerHtml.replace(/&amp;&amp;/g, '&amp;');
+			titleElement.innerHTML = innerHtml;
+		} else {
+			titleElement.innerHTML = cleanMenuLabel.replace(/&&/g, '&');
+		}
 
 		let mnemonicMatches = MENU_MNEMONIC_REGEX.exec(label);
 
 		// Register mnemonics
 		if (mnemonicMatches) {
-			let mnemonic = !!mnemonicMatches[1] ? mnemonicMatches[1] : mnemonicMatches[2];
+			let mnemonic = !!mnemonicMatches[1] ? mnemonicMatches[1] : mnemonicMatches[3];
 
 			if (this.options.enableMnemonics) {
 				buttonElement.setAttribute('aria-keyshortcuts', 'Alt+' + mnemonic.toLocaleLowerCase());
@@ -1012,4 +1031,4 @@ class ModifierKeyEmitter extends Emitter<IModifierKeyStatus> {
 		super.dispose();
 		this._subscriptions.dispose();
 	}
-}
\ No newline at end of file
+}