GDScript: Disallow strings as comments

modules/gdscript/gdscript_parser.cpp

@@ -763,14 +763,10 @@ void GDScriptParser::parse_program() {
 					break;
 				}
 			}
-		} else if (check(GDScriptTokenizer::Token::LITERAL) && current.literal.get_type() == Variant::STRING) {
-			// Allow strings in class body as multiline comments.
-			advance();
-			if (!match(GDScriptTokenizer::Token::NEWLINE)) {
-				push_error("Expected newline after comment string.");
-			}
 		} else {
-			break;
+			if (!parse_standalone_string()) {
+				break;
+			}
 		}
 	}
 
@@ -806,12 +802,7 @@ void GDScriptParser::parse_program() {
 				can_have_class_or_extends = false;
 				break;
 			case GDScriptTokenizer::Token::LITERAL:
-				if (current.literal.get_type() == Variant::STRING) {
-					// Allow strings in class body as multiline comments.
-					advance();
-					if (!match(GDScriptTokenizer::Token::NEWLINE)) {
-						push_error("Expected newline after comment string.");
-					}
+				if (parse_standalone_string()) {
 					break;
 				}
 				[[fallthrough]];
@@ -1201,12 +1192,7 @@ void GDScriptParser::parse_class_body(bool p_is_multiline) {
 				class_end = true;
 				break;
 			case GDScriptTokenizer::Token::LITERAL:
-				if (current.literal.get_type() == Variant::STRING) {
-					// Allow strings in class body as multiline comments.
-					advance();
-					if (!match(GDScriptTokenizer::Token::NEWLINE)) {
-						push_error("Expected newline after comment string.");
-					}
+				if (parse_standalone_string()) {
 					break;
 				}
 				[[fallthrough]];
@@ -2204,12 +2190,6 @@ GDScriptParser::Node *GDScriptParser::parse_statement() {
 						// Standalone lambdas can't be used, so make this an error.
 						push_error("Standalone lambdas cannot be accessed. Consider assigning it to a variable.", expression);
 						break;
-					case Node::LITERAL:
-						// Allow strings as multiline comments.
-						if (static_cast<GDScriptParser::LiteralNode *>(expression)->value.get_type() != Variant::STRING) {
-							push_warning(expression, GDScriptWarning::STANDALONE_EXPRESSION);
-						}
-						break;
 					case Node::TERNARY_OPERATOR:
 						push_warning(expression, GDScriptWarning::STANDALONE_TERNARY);
 						break;
@@ -3930,6 +3910,21 @@ GDScriptParser::TypeNode *GDScriptParser::parse_type(bool p_allow_void) {
 	return type;
 }
 
+bool GDScriptParser::parse_standalone_string() {
+	if (check(GDScriptTokenizer::Token::LITERAL) && current.literal.get_type() == Variant::STRING) {
+		// For compatibility we allow standalone strings without erroring.
+		advance();
+#ifdef DEBUG_ENABLED
+		push_warning(previous.start_line, previous.start_column, previous.end_line, previous.end_column, GDScriptWarning::STANDALONE_EXPRESSION);
+#endif
+		if (!match(GDScriptTokenizer::Token::NEWLINE)) {
+			push_error("Expected newline after comment string.");
+		}
+		return true;
+	}
+	return false;
+}
+
 #ifdef TOOLS_ENABLED
 enum DocLineState {
 	DOC_LINE_NORMAL,

modules/gdscript/gdscript_parser.h

@@ -1654,6 +1654,8 @@ class GDScriptParser {
 	ExpressionNode *parse_yield(ExpressionNode *p_previous_operand, bool p_can_assign);
 	ExpressionNode *parse_invalid_token(ExpressionNode *p_previous_operand, bool p_can_assign);
 	TypeNode *parse_type(bool p_allow_void = false);
+	// TODO: Remove in 5.x.
+	bool parse_standalone_string();
 
 #ifdef TOOLS_ENABLED
 	int max_script_doc_line = INT_MAX;

modules/gdscript/tests/scripts/parser/warnings/standalone_expression.gd

@@ -1,11 +1,29 @@
+"""
+This is not a comment.
+"""
+
+@tool
+
+"This also isn't a comment."
+
+extends RefCounted
+
+'''
+This one neither.
+'''
+
 func test():
 	# The following statements should all be reported as standalone expressions:
 	1234
 	0.0 + 0.0
-	Color(1, 1, 1)
+	Color(1, 1, 1) # TODO
 	Vector3.ZERO
 	[true, false]
-	float(125)
+	float(125) # TODO
+	"""
+	Python-like "comment".
+	"""
+	'single line string'
 	# The following statements should not produce `STANDALONE_EXPRESSION`:
 	var _a = 1
 	_a = 2 # Assignment is a local (or global) side effect.
@@ -14,8 +32,7 @@ func test():
 	absi(4) # A call (in general) can have side effects.
 	@warning_ignore("return_value_discarded")
 	preload("../../utils.notest.gd") # A static initializer may have side effects.
-	"""
-	Python-like "comment".
-	"""
 	@warning_ignore("standalone_ternary")
 	1 if 2 else 3 # Produces `STANDALONE_TERNARY` instead.
+
+'Still no comment...'

modules/gdscript/tests/scripts/parser/warnings/standalone_expression.out

@@ -1,5 +1,11 @@
 GDTEST_OK
-~~ WARNING at line 3: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
-~~ WARNING at line 4: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
-~~ WARNING at line 6: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 1: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
 ~~ WARNING at line 7: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 11: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 17: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 18: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 20: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 21: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 23: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 26: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).
+~~ WARNING at line 38: (STANDALONE_EXPRESSION) Standalone expression (the line may have no effect).