Disallow generator declarations in certain locations

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 7124 matching lines @@
     "for (var i = 0; i < 1; i++) label: function f() { };",
     "for (var x in {a: 1}) label: function f() { };",
     "for (var x in {}) label: function f() { };",
     "for (var x in {}) label: function foo() {}",
     "for (x in {a: 1}) label: function f() { };",
     "for (x in {}) label: function f() { };",
     "var x; for (x in {}) label: function foo() {}",
     "with ({}) label: function f() { };",
     "if (true) label: function f() {}",
     "if (true) {} else label: function f() {}",
+    "if (true) function* f() { }",
+    "label: function* f() { }",
+    // TODO(littledan, v8:4806): Ban duplicate generator declarations in
+    // a block, maybe by tracking whether a Variable is a generator declaration
+    // "{ function* f() {} function* f() {} }",
+    // "{ function f() {} function* f() {} }",
+    // "{ function* f() {} function f() {} }",
     NULL
   };
   // Valid only in sloppy mode, with or without
   // --harmony-restrictive-declarations
   const char* sloppy_data[] = {
     "if (true) function foo() {}",
     "if (false) {} else function f() { };",
     "label: function f() { }",
     "label: if (true) function f() { }",
     "label: if (true) {} else function f() { }",
@@ skipping 131 matching lines @@
     "for (const x = 0 in {});",
     "for (let x = 0 in {});",
     NULL
   };
   // clang-format on
 
   static const ParserFlag always_flags[] = {kAllowHarmonyForIn};
   RunParserSyncTest(context_data, error_data, kError, nullptr, 0, always_flags,
                     arraysize(always_flags));
 }