[parser] Disallow for (async of expr)

Implements tc39/ecma262#2034 Currently the token sequence `for (async of` is ambiguous. It can be the prefix for either `(async of => {};;);` or `for (async of foo);`. This CL disallows the token sequence. Note that `for await (async of` is still allowed, since there is no C-style `for await (;;)`, and thus no ambiguity. Bug: v8:11412 Change-Id: I3fede83a69420996baa2bc8b6c1cff000535d990 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2683221 Commit-Queue: Shu-yu Guo <syg@chromium.org> Reviewed-by: Marja Hölttä <marja@chromium.org> Cr-Commit-Position: refs/heads/master@{#72607}
ashu8912 · Feb 9, 2021 · bd82cdb · bd82cdb
1 parent 36dedea
commit bd82cdb
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Showing 7 changed files with 26 additions and 22 deletions.
diff --git a/src/common/message-template.h b/src/common/message-template.h
@@ -391,6 +391,7 @@ namespace internal {
   T(ForInOfLoopInitializer,                                                    \
     "% loop variable declaration may not have an initializer.")                \
   T(ForOfLet, "The left-hand side of a for-of loop may not start with 'let'.") \
+  T(ForOfAsync, "The left-hand side of a for-of loop may not be 'async'.")     \
   T(ForInOfLoopMultiBindings,                                                  \
     "Invalid left-hand side in % loop: Must have a single binding.")           \
   T(GeneratorInSingleStatementContext,                                         \

diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
@@ -5928,12 +5928,18 @@ typename ParserBase<Impl>::StatementT ParserBase<Impl>::ParseForStatement(
       ExpressionParsingScope parsing_scope(impl());
       AcceptINScope scope(this, false);
       expression = ParseExpressionCoverGrammar();
+      // `for (async of` is disallowed but `for (async.x of` is allowed, so
+      // check if the token is ASYNC after parsing the expression.
+      bool expression_is_async = scanner()->current_token() == Token::ASYNC;
       // Initializer is reference followed by in/of.
       lhs_end_pos = end_position();
       is_for_each = CheckInOrOf(&for_info.mode);
       if (is_for_each) {
-        if (starts_with_let && for_info.mode == ForEachStatement::ITERATE) {
-          impl()->ReportMessageAt(next_loc, MessageTemplate::kForOfLet);
+        if ((starts_with_let || expression_is_async) &&
+            for_info.mode == ForEachStatement::ITERATE) {
+          impl()->ReportMessageAt(next_loc, starts_with_let
+                                                ? MessageTemplate::kForOfLet
+                                                : MessageTemplate::kForOfAsync);
           return impl()->NullStatement();
         }
         if (expression->IsPattern()) {

diff --git a/src/parsing/parser.h b/src/parsing/parser.h
@@ -557,7 +557,7 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
     return property != nullptr && property->IsPrivateReference();
   }
 
-  // This returns true if the expression is an indentifier (wrapped
+  // This returns true if the expression is an identifier (wrapped
   // inside a variable proxy).  We exclude the case of 'this', which
   // has been converted to a variable proxy.
   V8_INLINE static bool IsIdentifier(Expression* expression) {

diff --git a/test/cctest/interpreter/bytecode_expectations/PrivateAccessorAccess.golden b/test/cctest/interpreter/bytecode_expectations/PrivateAccessorAccess.golden
@@ -83,7 +83,7 @@ bytecodes: [
                 B(Mov), R(this), R(0),
                 B(Mov), R(context), R(2),
   /*   48 E> */ B(CallRuntime), U16(Runtime::kAddPrivateBrand), R(0), U8(3),
-  /*   53 S> */ B(Wide), B(LdaSmi), I16(275),
+  /*   53 S> */ B(Wide), B(LdaSmi), I16(276),
                 B(Star), R(3),
                 B(LdaConstant), U8(0),
                 B(Star), R(4),
@@ -114,7 +114,7 @@ bytecodes: [
                 B(Mov), R(this), R(0),
                 B(Mov), R(context), R(2),
   /*   41 E> */ B(CallRuntime), U16(Runtime::kAddPrivateBrand), R(0), U8(3),
-  /*   46 S> */ B(Wide), B(LdaSmi), I16(274),
+  /*   46 S> */ B(Wide), B(LdaSmi), I16(275),
                 B(Star), R(3),
                 B(LdaConstant), U8(0),
                 B(Star), R(4),
@@ -145,7 +145,7 @@ bytecodes: [
                 B(Mov), R(this), R(0),
                 B(Mov), R(context), R(2),
   /*   48 E> */ B(CallRuntime), U16(Runtime::kAddPrivateBrand), R(0), U8(3),
-  /*   53 S> */ B(Wide), B(LdaSmi), I16(275),
+  /*   53 S> */ B(Wide), B(LdaSmi), I16(276),
                 B(Star), R(3),
                 B(LdaConstant), U8(0),
                 B(Star), R(4),
@@ -176,7 +176,7 @@ bytecodes: [
                 B(Mov), R(this), R(0),
                 B(Mov), R(context), R(2),
   /*   41 E> */ B(CallRuntime), U16(Runtime::kAddPrivateBrand), R(0), U8(3),
-  /*   46 S> */ B(Wide), B(LdaSmi), I16(274),
+  /*   46 S> */ B(Wide), B(LdaSmi), I16(275),
                 B(Star), R(4),
                 B(LdaConstant), U8(0),
                 B(Star), R(5),

diff --git a/test/cctest/interpreter/bytecode_expectations/PrivateMethodAccess.golden b/test/cctest/interpreter/bytecode_expectations/PrivateMethodAccess.golden
@@ -56,7 +56,7 @@ bytecodes: [
                 B(Mov), R(this), R(0),
                 B(Mov), R(context), R(2),
   /*   44 E> */ B(CallRuntime), U16(Runtime::kAddPrivateBrand), R(0), U8(3),
-  /*   49 S> */ B(Wide), B(LdaSmi), I16(273),
+  /*   49 S> */ B(Wide), B(LdaSmi), I16(274),
                 B(Star), R(3),
                 B(LdaConstant), U8(0),
                 B(Star), R(4),
@@ -88,7 +88,7 @@ bytecodes: [
                 B(Mov), R(this), R(0),
                 B(Mov), R(context), R(2),
   /*   44 E> */ B(CallRuntime), U16(Runtime::kAddPrivateBrand), R(0), U8(3),
-  /*   49 S> */ B(Wide), B(LdaSmi), I16(273),
+  /*   49 S> */ B(Wide), B(LdaSmi), I16(274),
                 B(Star), R(3),
                 B(LdaConstant), U8(0),
                 B(Star), R(4),

diff --git a/test/cctest/interpreter/bytecode_expectations/StaticPrivateMethodAccess.golden b/test/cctest/interpreter/bytecode_expectations/StaticPrivateMethodAccess.golden
@@ -24,7 +24,7 @@ bytecodes: [
                 B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(1),
                 B(JumpIfTrue), U8(18),
-                B(Wide), B(LdaSmi), I16(271),
+                B(Wide), B(LdaSmi), I16(272),
                 B(Star), R(2),
                 B(LdaConstant), U8(0),
                 B(Star), R(3),
@@ -55,7 +55,7 @@ frame size: 2
 parameter count: 1
 bytecode array length: 16
 bytecodes: [
-  /*   56 S> */ B(Wide), B(LdaSmi), I16(273),
+  /*   56 S> */ B(Wide), B(LdaSmi), I16(274),
                 B(Star), R(0),
                 B(LdaConstant), U8(0),
                 B(Star), R(1),
@@ -82,7 +82,7 @@ frame size: 2
 parameter count: 1
 bytecode array length: 16
 bytecodes: [
-  /*   56 S> */ B(Wide), B(LdaSmi), I16(273),
+  /*   56 S> */ B(Wide), B(LdaSmi), I16(274),
                 B(Star), R(0),
                 B(LdaConstant), U8(0),
                 B(Star), R(1),
@@ -121,7 +121,7 @@ bytecodes: [
   /*   94 E> */ B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(18),
-                B(Wide), B(LdaSmi), I16(271),
+                B(Wide), B(LdaSmi), I16(272),
                 B(Star), R(2),
                 B(LdaConstant), U8(0),
                 B(Star), R(3),
@@ -143,7 +143,7 @@ bytecodes: [
   /*  109 E> */ B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(1),
                 B(JumpIfTrue), U8(18),
-                B(Wide), B(LdaSmi), I16(272),
+                B(Wide), B(LdaSmi), I16(273),
                 B(Star), R(3),
                 B(LdaConstant), U8(0),
                 B(Star), R(4),
@@ -158,7 +158,7 @@ bytecodes: [
   /*  133 E> */ B(TestReferenceEqual), R(this),
                 B(Mov), R(this), R(0),
                 B(JumpIfTrue), U8(18),
-                B(Wide), B(LdaSmi), I16(271),
+                B(Wide), B(LdaSmi), I16(272),
                 B(Star), R(2),
                 B(LdaConstant), U8(0),
                 B(Star), R(3),
@@ -188,7 +188,7 @@ frame size: 2
 parameter count: 1
 bytecode array length: 16
 bytecodes: [
-  /*   60 S> */ B(Wide), B(LdaSmi), I16(275),
+  /*   60 S> */ B(Wide), B(LdaSmi), I16(276),
                 B(Star), R(0),
                 B(LdaConstant), U8(0),
                 B(Star), R(1),
@@ -214,7 +214,7 @@ frame size: 2
 parameter count: 1
 bytecode array length: 16
 bytecodes: [
-  /*   53 S> */ B(Wide), B(LdaSmi), I16(274),
+  /*   53 S> */ B(Wide), B(LdaSmi), I16(275),
                 B(Star), R(0),
                 B(LdaConstant), U8(0),
                 B(Star), R(1),
@@ -240,7 +240,7 @@ frame size: 2
 parameter count: 1
 bytecode array length: 16
 bytecodes: [
-  /*   60 S> */ B(Wide), B(LdaSmi), I16(275),
+  /*   60 S> */ B(Wide), B(LdaSmi), I16(276),
                 B(Star), R(0),
                 B(LdaConstant), U8(0),
                 B(Star), R(1),
@@ -266,7 +266,7 @@ frame size: 3
 parameter count: 1
 bytecode array length: 16
 bytecodes: [
-  /*   46 S> */ B(Wide), B(LdaSmi), I16(274),
+  /*   46 S> */ B(Wide), B(LdaSmi), I16(275),
                 B(Star), R(1),
                 B(LdaConstant), U8(0),
                 B(Star), R(2),

diff --git a/test/test262/test262.status b/test/test262/test262.status
@@ -587,9 +587,6 @@
   'intl402/DateTimeFormat/prototype/formatRange/date-same-returns-single-date': [FAIL],
   'intl402/DateTimeFormat/prototype/formatRangeToParts/date-same-returns-single-date': [FAIL],
 
-  # https://bugs.chromium.org/p/v8/issues/detail?id=11412
-  'language/statements/for-of/head-lhs-async-invalid': [FAIL],
-
   ######################## NEEDS INVESTIGATION ###########################
 
   # https://bugs.chromium.org/p/v8/issues/detail?id=7833