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Unified Diff: src/preparser.cc

Issue 8688007: Statically check for assignments to const in harmony mode. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Addressed second round of comments. Created 9 years ago
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Index: src/preparser.cc
diff --git a/src/preparser.cc b/src/preparser.cc
index 95fde93f3efc7274bfd0d3b19faac594b2e56228..2bc3ab6910b06f11c2dcde837a28f8c0dd144892 100644
--- a/src/preparser.cc
+++ b/src/preparser.cc
@@ -199,6 +199,7 @@ PreParser::Statement PreParser::ParseStatement(bool* ok) {
return ParseBlock(ok);
case i::Token::CONST:
+ case i::Token::LET:
case i::Token::VAR:
return ParseVariableStatement(kStatement, ok);
@@ -349,6 +350,17 @@ PreParser::Statement PreParser::ParseVariableDeclarations(
if (peek() == i::Token::VAR) {
Consume(i::Token::VAR);
} else if (peek() == i::Token::CONST) {
+ // TODO(ES6): The ES6 Draft Rev4 section 12.2.2 reads:
+ //
+ // ConstDeclaration : const ConstBinding (',' ConstBinding)* ';'
+ //
+ // * It is a Syntax Error if the code that matches this production is not
+ // contained in extended code.
+ //
+ // However disallowing const in classic mode will break compatibility with
+ // existing pages. Therefore we keep allowing const with the old
+ // non-harmony semantics in classic mode.
+ Consume(i::Token::CONST);
switch (language_mode()) {
case i::CLASSIC_MODE:
break;
@@ -370,9 +382,21 @@ PreParser::Statement PreParser::ParseVariableDeclarations(
require_initializer = true;
break;
}
- Consume(i::Token::CONST);
} else if (peek() == i::Token::LET) {
- ASSERT(is_extended_mode());
+ // ES6 Draft Rev4 section 12.2.1:
+ //
+ // LetDeclaration : let LetBindingList ;
+ //
+ // * It is a Syntax Error if the code that matches this production is not
+ // contained in extended code.
+ if (!is_extended_mode()) {
+ i::Scanner::Location location = scanner_->peek_location();
+ ReportMessageAt(location.beg_pos, location.end_pos,
+ "illegal_let", NULL);
+ *ok = false;
+ return Statement::Default();
+ }
+ Consume(i::Token::LET);
if (var_context != kSourceElement &&
var_context != kForStatement) {
i::Scanner::Location location = scanner_->peek_location();
@@ -381,7 +405,6 @@ PreParser::Statement PreParser::ParseVariableDeclarations(
*ok = false;
return Statement::Default();
}
- Consume(i::Token::LET);
} else {
*ok = false;
return Statement::Default();
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