fix #55627

src/vs/editor/contrib/snippet/snippetParser.ts

@@ -346,7 +346,7 @@ export class Transform extends Marker {
 	}
 
 	toTextmateString(): string {
-		return `/${Text.escape(this.regexp.source)}/${this.children.map(c => c.toTextmateString())}/${(this.regexp.ignoreCase ? 'i' : '') + (this.regexp.global ? 'g' : '')}`;
+		return `/${this.regexp.source}/${this.children.map(c => c.toTextmateString())}/${(this.regexp.ignoreCase ? 'i' : '') + (this.regexp.global ? 'g' : '')}`;
 	}
 
 	clone(): Transform {

src/vs/editor/contrib/snippet/test/snippetParser.test.ts

@@ -673,6 +673,11 @@ suite('SnippetParser', () => {
 		assert.equal(new FormatString(1, undefined, 'bar', 'foo').resolve('baz'), 'bar');
 	});
 
+	test('Snippet variable transformation doesn\'t work if regex is complicated and snippet body contains \'$$\' #55627', function () {
+		const snippet = new SnippetParser().parse('const fileName = "${TM_FILENAME/(.*)\\..+$/$1/}"');
+		assert.equal(snippet.toTextmateString(), 'const fileName = "${TM_FILENAME/(.*)\\..+$/${1}/}"');
+	});
+
 	test('[BUG] HTML attribute suggestions: Snippet session does not have end-position set, #33147', function () {
 
 		const { placeholders } = new SnippetParser().parse('src="$1"', true);