Fix bug for completing function name parameters if function name contained special snippet syntax

extensions/typescript-language-features/src/test/functionCallSnippet.test.ts

@@ -107,4 +107,14 @@ suite('typescript function call snippets', () => {
 			).snippet.value,
 			'methoda(${1:x})$0');
 	});
+
+	test('Should escape snippet syntax in method name', async () => {
+		assert.strictEqual(
+			snippetForFunctionCall(
+				{ label: '$abc', },
+				[]
+			).snippet.value,
+			'\\$abc()$0');
+	});
+
 });

extensions/typescript-language-features/src/utils/snippetForFunctionCall.ts

@@ -16,7 +16,8 @@ export function snippetForFunctionCall(
 	}
 
 	const parameterListParts = getParameterListParts(displayParts);
-	const snippet = new vscode.SnippetString(`${item.insertText || item.label}(`);
+	const snippet = new vscode.SnippetString();
+	snippet.appendText(`${item.insertText || item.label}(`);
 	appendJoinedPlaceholders(snippet, parameterListParts.parts, ', ');
 	if (parameterListParts.hasOptionalParameters) {
 		snippet.appendTabstop();