feat: error on 'for await' in non-async function

Added diagnostic when a 'for await' statement is in a non-async function, since this statement can only be used in contexts where 'await' can be used. closes #1137
quick-lint · Jan 5, 2024 · cae93d8 · cae93d8
1 parent 2343088
commit cae93d8
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Showing 3 changed files with 26 additions and 1 deletion.
diff --git a/src/quick-lint-js/fe/parse-statement.cpp b/src/quick-lint-js/fe/parse-statement.cpp
@@ -3998,6 +3998,12 @@ void Parser::parse_and_visit_for(Parse_Visitor_Base &v) {
 
   bool is_for_await = this->peek().type == Token_Type::kw_await;
   if (is_for_await) {
+    Source_Code_Span await_token_span = this->peek().span();
+    if (!this->in_async_function_) {
+      this->diag_reporter_->report(Diag_Await_Operator_Outside_Async{
+          await_token_span
+      });
+    }
     this->skip();
   }
 

diff --git a/test/test-parse-loop.cpp b/test/test-parse-loop.cpp
@@ -893,7 +893,8 @@ TEST_F(Test_Parse_Loop, for_of_loop) {
 
   {
     Spy_Visitor p = test_parse_and_visit_statement(
-        u8"for await (let x of xs) { body; }"_sv, no_diags, javascript_options);
+        u8"for await (let x of xs) { body; }"_sv,     //
+        u8"    ^^^^^ Diag_Await_Operator_Outside_Async"_diag);
     EXPECT_THAT(p.visits, ElementsAreArray({
                               "visit_enter_for_scope",       //
                               "visit_variable_use",          //

diff --git a/test/test-parse-statement.cpp b/test/test-parse-statement.cpp
@@ -1312,6 +1312,24 @@ TEST_F(Test_Parse_Statement, if_body_with_semicolon_typescript) {
     EXPECT_THAT(p.errors, IsEmpty());
   }
 }
+
+TEST_F(Test_Parse_Statement,
+       disallow_for_await_in_non_async_function) {
+  Spy_Visitor p = test_parse_and_visit_statement(
+      u8"function f() { for await (let x of []) {} }"_sv,  //
+             u8"                   ^^^^^ Diag_Await_Operator_Outside_Async"_diag);
+  EXPECT_THAT(p.visits, ElementsAreArray({
+                            "visit_enter_function_scope",       //
+                            "visit_enter_function_scope_body",  //
+                            "visit_enter_for_scope",            //
+                            "visit_variable_declaration",       // x
+                            "visit_enter_block_scope",          //
+                            "visit_exit_block_scope",           //
+                            "visit_exit_for_scope",             //
+                            "visit_exit_function_scope",        //
+                            "visit_variable_declaration",       //
+                        }));
+}
 }
 }