From 77a8508e6d8011a8d9f058f0e7ea2fdff7a56fe3 Mon Sep 17 00:00:00 2001
From: Max <135263966+verifizieren@users.noreply.github.com>
Date: Sat, 16 May 2026 02:40:43 +0200
Subject: [PATCH] Trim surrounding whitespace from line comment token

A line comment token configured with leading or trailing whitespace
(e.g. " #") broke Toggle Line Comment: the inserted comment could
never be detected again, so each toggle stacked another comment
instead of removing it.

Whitespace around the marker is not semantically meaningful - spacing
on insertion is controlled by `editor.comments.insertSpace` - so the
token is now trimmed when the comment configuration is resolved. This
also keeps the `${LINE_COMMENT}` snippet variable and notebook inline
variable detection consistent. No built-in language is affected.

Fixes #249958
---
 .../languageConfigurationRegistry.ts          |  7 +-
 .../test/browser/lineCommentCommand.test.ts   | 66 +++++++++++++++++++
 2 files changed, 71 insertions(+), 2 deletions(-)

diff --git a/src/vs/editor/common/languages/languageConfigurationRegistry.ts b/src/vs/editor/common/languages/languageConfigurationRegistry.ts
index 0dffed073d4c2..09397ccdd98d4 100644
--- a/src/vs/editor/common/languages/languageConfigurationRegistry.ts
+++ b/src/vs/editor/common/languages/languageConfigurationRegistry.ts
@@ -457,10 +457,13 @@ export class ResolvedLanguageConfiguration {
 		const comments: ICommentsConfiguration = {};
 
 		if (commentRule.lineComment) {
+			// Surrounding whitespace is not part of the comment marker; spacing on
+			// insertion is controlled by the `editor.comments.insertSpace` setting.
+			// Keeping it would break comment toggling, see #249958.
 			if (typeof commentRule.lineComment === 'string') {
-				comments.lineCommentToken = commentRule.lineComment;
+				comments.lineCommentToken = commentRule.lineComment.trim();
 			} else {
-				comments.lineCommentToken = commentRule.lineComment.comment;
+				comments.lineCommentToken = commentRule.lineComment.comment.trim();
 				comments.lineCommentNoIndent = commentRule.lineComment.noIndent;
 			}
 		}
diff --git a/src/vs/editor/contrib/comment/test/browser/lineCommentCommand.test.ts b/src/vs/editor/contrib/comment/test/browser/lineCommentCommand.test.ts
index 8c4e0b6dce244..e733835de19da 100644
--- a/src/vs/editor/contrib/comment/test/browser/lineCommentCommand.test.ts
+++ b/src/vs/editor/contrib/comment/test/browser/lineCommentCommand.test.ts
@@ -101,6 +101,72 @@ suite('Editor Contrib - Line Comment Command', () => {
 		);
 	});
 
+	test('toggle line comment when the comment token has surrounding whitespace (#249958)', function () {
+		const testLineCommentCommand = createTestCommandHelper(
+			{ lineComment: ' !@# ' },
+			(accessor, sel) => new LineCommentCommand(accessor.get(ILanguageConfigurationService), sel, 4, Type.Toggle, true, true)
+		);
+
+		// Adds the trimmed comment token
+		testLineCommentCommand(
+			[
+				'some text'
+			],
+			new Selection(1, 1, 1, 1),
+			[
+				'!@# some text'
+			],
+			new Selection(1, 5, 1, 5)
+		);
+
+		// Toggling again removes it instead of stacking another comment
+		testLineCommentCommand(
+			[
+				'!@# some text'
+			],
+			new Selection(1, 1, 1, 1),
+			[
+				'some text'
+			],
+			new Selection(1, 1, 1, 1)
+		);
+	});
+
+	test('toggle line comment when the object-form comment token has surrounding whitespace (#249958)', function () {
+		const testLineCommentCommand = createTestCommandHelper(
+			{ lineComment: { comment: ' !@# ', noIndent: true } },
+			(accessor, sel) => new LineCommentCommand(accessor.get(ILanguageConfigurationService), sel, 4, Type.Toggle, true, true)
+		);
+
+		// Adds the trimmed comment token at the first column (noIndent)
+		testLineCommentCommand(
+			[
+				'some text',
+				'\tsome more text'
+			],
+			new Selection(2, 1, 2, 1),
+			[
+				'some text',
+				'!@# \tsome more text'
+			],
+			new Selection(2, 5, 2, 5)
+		);
+
+		// Toggling again removes it instead of stacking another comment
+		testLineCommentCommand(
+			[
+				'some text',
+				'!@# \tsome more text'
+			],
+			new Selection(2, 1, 2, 1),
+			[
+				'some text',
+				'\tsome more text'
+			],
+			new Selection(2, 1, 2, 1)
+		);
+	});
+
 	function createSimpleModel(lines: string[]): ISimpleModel {
 		return {
 			getLineContent: (lineNumber: number) => {