[es6] early error when Identifier is an escaped reserved word

src/scanner.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Features shared by parsing and pre-parsing scanners.
 
 #include "src/scanner.h"
 
 #include <stdint.h>
 
@@ skipping 1481 matching lines @@
 void Scanner::CopyTokenDesc(TokenDesc* to, TokenDesc* from) {
   DCHECK_NOT_NULL(to);
   DCHECK_NOT_NULL(from);
   to->token = from->token;
   to->location = from->location;
   to->literal_chars->CopyFrom(from->literal_chars);
   to->raw_literal_chars->CopyFrom(from->raw_literal_chars);
 }
 
 
+bool Scanner::IsNextEscapedReservedWord(LanguageMode language_mode,
+                                        bool is_generator, bool sloppy_let) {
+  if (next_.token == Token::IDENTIFIER) {
+    if (next_.literal_chars && next_.literal_chars->is_one_byte() &&

[adamk, 2015/11/03 23:00:57]

Please join this if() into the one on the line above

[caitp (gmail), 2015/11/04 04:49:24]

Done.

+        next_literal_contains_escapes(next_)) {

[adamk, 2015/11/03 23:00:57]

This won't compile, I'm guessing you can drop next_literal_contains_escapes and
just call (with my suggested renaming) LiteralContainsEscapes(next_).

[caitp (gmail), 2015/11/04 04:49:24]

It was a last minute fixup, which failed because of the parameter. I'll get rid
of the next_literal_.... helper if you want, but it's more consistent with other
functions in the Scanner, and a bit easier to read imo. 4 line difference, your
call.

+      Vector<const uint8_t> chars = next_.literal_chars->one_byte_literal();

[caitp (gmail), 2015/11/03 17:19:13]

I don't think this allocates a copy of the string, but if it does, let me know
so I can come up with a cheaper way

[adamk, 2015/11/03 23:00:57]

You're correct that there's no copy here.

[caitp (gmail), 2015/11/04 04:49:24]

Acknowledged.

+      switch (KeywordOrIdentifierToken(chars.start(), chars.length())) {
+        case Token::IDENTIFIER:
+          return false;
+        case Token::FUTURE_STRICT_RESERVED_WORD:
+          return is_strict(language_mode);
+        case Token::YIELD:
+          return is_generator;
+        case Token::LET:
+          return sloppy_let || is_strict(language_mode);

[adamk, 2015/11/03 23:00:57]

My reading of the spec you pointed to is that LET is allowed in sloppy mode in
this case:

It is a Syntax Error if this phrase is contained in strict mode code and the
StringValue of IdentifierName is: "implements", "interface", "let", "package",
"private", "protected", "public", "static", or "yield".

Is the sloppy_let branch here derived from some other piece of spec text?

[caitp (gmail), 2015/11/04 04:49:24]

It was meant for the block underneath, but I guess "let" was never a
ReservedWord, so the 2nd block doesn't really apply. I'll get rid of that stuff
then. Fixed this up

+        default:
+          return true;
+      }
+    }
+  }
+  return false;
+}
+
+
 int DuplicateFinder::AddOneByteSymbol(Vector<const uint8_t> key, int value) {
   return AddSymbol(key, true, value);
 }
 
 
 int DuplicateFinder::AddTwoByteSymbol(Vector<const uint16_t> key, int value) {
   return AddSymbol(Vector<const uint8_t>::cast(key), false, value);
 }
 
 
@@ skipping 121 matching lines @@
     backing_store_.Add(static_cast<uint8_t>((one_byte_length >> 7) | 0x80u));
   }
   backing_store_.Add(static_cast<uint8_t>(one_byte_length & 0x7f));
 
   backing_store_.AddBlock(bytes);
   return backing_store_.EndSequence().start();
 }
 
 }  // namespace internal
 }  // namespace v8