unexpected 'await' keyword on function declaration

docs/errors/E0719.md

@@ -0,0 +1,15 @@
+# E0719: unexpected 'await' keyword on function declaration
+
+If you meant to define an asynchronous function, you need to explicitly annotate
+the function with `async` keyword, not `await`.
+
+```javascript
+await function f() {}
+```
+
+To fix this warning, simply replace `await` by `async`. Now, you have an
+asynchronous function and you're able to use `await` inside it.
+
+```javascript
+async function f() {}
+```

po/messages.pot

@@ -2417,6 +2417,10 @@ msgstr ""
 msgid "using a '.' after a '?.' might fail, since '?.' might return 'undefined'."
 msgstr ""
 
+#: src/quick-lint-js/diag/diagnostic-metadata-generated.cpp
+msgid "Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?"
+msgstr ""
+
 #: test/test-diagnostic-formatter.cpp
 #: test/test-vim-qflist-json-diag-reporter.cpp
 msgid "something happened"

src/quick-lint-js/diag/diagnostic-metadata-generated.cpp

@@ -6927,6 +6927,20 @@ const QLJS_CONSTINIT Diagnostic_Info all_diagnostic_infos[] = {
         },
       },
     },
+
+    // Diag_Unexpected_Await_On_Function_Declaration
+    {
+      .code = 719,
+      .severity = Diagnostic_Severity::warning,
+      .message_formats = {
+        QLJS_TRANSLATABLE("Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?"),
+      },
+      .message_args = {
+        {
+          Diagnostic_Message_Arg_Info(offsetof(Diag_Unexpected_Await_On_Function_Declaration, await_keyword), Diagnostic_Arg_Type::source_code_span),
+        },
+      },
+    },
 };
 }
 

src/quick-lint-js/diag/diagnostic-metadata-generated.h

@@ -473,10 +473,11 @@ namespace quick_lint_js {
   QLJS_DIAG_TYPE_NAME(Diag_Unintuitive_Bitshift_Precedence) \
   QLJS_DIAG_TYPE_NAME(Diag_TypeScript_Namespace_Alias_Cannot_Use_Import_Type) \
   QLJS_DIAG_TYPE_NAME(Diag_Using_Dot_After_Optional_Chaining) \
+  QLJS_DIAG_TYPE_NAME(Diag_Unexpected_Await_On_Function_Declaration) \
   /* END */
 // clang-format on
 
-inline constexpr int Diag_Type_Count = 462;
+inline constexpr int Diag_Type_Count = 463;
 
 extern const Diagnostic_Info all_diagnostic_infos[Diag_Type_Count];
 }

src/quick-lint-js/diag/diagnostic-types-2.h

@@ -3599,6 +3599,15 @@ struct Diag_Using_Dot_After_Optional_Chaining {
   Source_Code_Span dot_op;
   Source_Code_Span optional_chain_op;
 };
+
+struct Diag_Unexpected_Await_On_Function_Declaration {
+  [[qljs::diag("E0719", Diagnostic_Severity::warning)]]  //
+  // clang-format off
+  [[qljs::message("Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?",
+                  ARG(await_keyword))]]  //
+  // clang-format on
+  Source_Code_Span await_keyword;
+};
 }
 QLJS_WARNING_POP
 

src/quick-lint-js/fe/parse-statement.cpp

@@ -1,6 +1,7 @@
 // Copyright (C) 2020  Matthew "strager" Glazar
 // See end of file for extended copyright information.
 
+#include <cstdio>
 #include <cstdlib>
 #include <optional>
 #include <quick-lint-js/assert.h>
@@ -417,6 +418,20 @@ bool Parser::parse_and_visit_statement(Parse_Visitor_Base &v,
       this->skip();
       this->check_body_after_label();
       goto parse_statement;
+    } else if (this->peek().type == Token_Type::kw_function) {
+      this->parse_and_visit_function_declaration(
+          v, Function_Declaration_Options{
+                 .attributes = Function_Attributes::normal,
+                 .begin = this->peek().begin,
+                 .require_name = Name_Requirement::required_for_statement,
+                 .async_keyword = std::nullopt,
+                 .declare_keyword = std::nullopt,
+             });
+      if (this->peek().type != Token_Type::left_paren) {
+        this->diag_reporter_->report(
+            Diag_Unexpected_Await_On_Function_Declaration{
+                .await_keyword = await_token.span()});
+      }
     } else {
       Expression *ast =
           this->parse_await_expression(v, await_token, Precedence{});

src/quick-lint-js/i18n/translation-table-generated.cpp

@@ -164,7 +164,8 @@ const Translation_Table translation_data = {
         {0, 0, 0, 55, 0, 47},                //
         {0, 36, 0, 53, 0, 57},               //
         {0, 0, 0, 66, 0, 67},                //
-        {56, 22, 0, 65, 0, 66},              //
+        {0, 0, 0, 0, 0, 66},                 //
+        {56, 22, 0, 65, 0, 77},              //
         {23, 15, 0, 19, 0, 18},              //
         {0, 0, 0, 0, 0, 13},                 //
         {18, 18, 0, 14, 0, 16},              //
@@ -2036,6 +2037,7 @@ const Translation_Table translation_data = {
         u8"TypeScript's 'enum' feature is not allowed in JavaScript\0"
         u8"TypeScript's 'interface' feature is not allowed in JavaScript code\0"
         u8"TypeScript's 'readonly' feature is not allowed in JavaScript code\0"
+        u8"Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?\0"
         u8"a 'do-while' loop\0"
         u8"a 'for' loop\0"
         u8"a 'typeof' type\0"

src/quick-lint-js/i18n/translation-table-generated.h

@@ -18,8 +18,8 @@ namespace quick_lint_js {
 using namespace std::literals::string_view_literals;
 
 constexpr std::uint32_t translation_table_locale_count = 5;
-constexpr std::uint16_t translation_table_mapping_table_size = 606;
-constexpr std::size_t translation_table_string_table_size = 82482;
+constexpr std::uint16_t translation_table_mapping_table_size = 607;
+constexpr std::size_t translation_table_string_table_size = 82559;
 constexpr std::size_t translation_table_locale_table_size = 35;
 
 QLJS_CONSTEVAL std::uint16_t translation_table_const_look_up(
@@ -179,6 +179,7 @@ QLJS_CONSTEVAL std::uint16_t translation_table_const_look_up(
           "TypeScript's 'enum' feature is not allowed in JavaScript"sv,
           "TypeScript's 'interface' feature is not allowed in JavaScript code"sv,
           "TypeScript's 'readonly' feature is not allowed in JavaScript code"sv,
+          "Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?"sv,
           "a 'do-while' loop"sv,
           "a 'for' loop"sv,
           "a 'typeof' type"sv,

src/quick-lint-js/i18n/translation-table-test-generated.h

@@ -27,7 +27,7 @@ struct Translated_String {
 };
 
 // clang-format off
-inline const Translated_String test_translation_table[605] = {
+inline const Translated_String test_translation_table[606] = {
     {
         "\"global-groups\" entries must be strings"_translatable,
         u8"\"global-groups\" entries must be strings",
@@ -1711,6 +1711,17 @@ inline const Translated_String test_translation_table[605] = {
             u8"TypeScript's 'readonly' feature is not allowed in JavaScript code",
         },
     },
+    {
+        "Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?"_translatable,
+        u8"Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?",
+        {
+            u8"Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?",
+            u8"Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?",
+            u8"Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?",
+            u8"Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?",
+            u8"Unexpected 'await' keyword on function declaration. Maybe you meant 'async'?",
+        },
+    },
     {
         "a 'do-while' loop"_translatable,
         u8"a 'do-while' loop",

test/test-parse-function.cpp

@@ -1799,6 +1799,21 @@ TEST_F(Test_Parse_Function, return_with_comma_operator_missing_arguments) {
       u8"                      ^ Diag_Missing_Operand_For_Operator"_diag);
 }
 }
+
+TEST_F(Test_Parse_Function, unexpected_await_on_function_declaration) {
+  test_parse_and_visit_statement(
+      u8"await function f() { }"_sv,  //
+      u8"^^^^^ Diag_Unexpected_Await_On_Function_Declaration"_diag);
+
+  test_parse_and_visit_statement(u8"async function f() { }"_sv,  //
+                                 no_diags);
+
+  test_parse_and_visit_statement(u8"await function foo() {}();"_sv,  //
+                                 no_diags);
+
+  test_parse_and_visit_statement(u8"await (function foo() {});"_sv,  //
+                                 no_diags);
+}
 }
 
 // quick-lint-js finds bugs in JavaScript programs.