Changeset 266340 in webkit for trunk/Source/JavaScriptCore/parser/Parser.cpp

Timestamp:

Aug 30, 2020, 6:26:30 PM (5 years ago)

Author:

[email protected]

Message:

[JSC] async function cannot appear in single-statement context
​https://bugs.webkit.org/show_bug.cgi?id=215993

Reviewed by Darin Adler.

JSTests:

• stress/async-function-lookahead.js: Added.

(testSyntax):
(testSyntaxError):
(testSyntax.false.async t):
(testSyntaxError.false.async t):

• test262/expectations.yaml:

Source/JavaScriptCore:

The following code is syntax error[1] because ExpressionStatement has async [no LineTerminator here] function lookahead.

if (false)

async function t() { }

[1]: ​https://tc39.es/ecma262/#sec-expression-statement

• parser/Parser.cpp:

(JSC::Parser<LexerType>::parseStatement):
(JSC::Parser<LexerType>::maybeParseAsyncFunctionDeclarationStatement): Deleted.

• parser/Parser.h:

File:

• trunk/Source/JavaScriptCore/parser/Parser.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/parser/Parser.cpp

@@ -1983 +1983 @@
     case IDENT:
         if (UNLIKELY(*m_token.m_data.ident == m_vm.propertyNames->async && !m_token.m_data.escaped)) {
-            if (maybeParseAsyncFunctionDeclarationStatement(context, result, parentAllowsFunctionDeclarationAsStatement))
-                break;
+            SavePoint savePoint = createSavePoint(context);
+            next();
+            failIfTrue(match(FUNCTION) && !m_lexer->hasLineTerminatorBeforeToken(), "Cannot use async function declaration in single-statement context");
+            restoreSavePoint(context, savePoint);
         }
         FALLTHROUGH;
@@ -2066 +2068 @@
     popScope(blockScope, TreeBuilder::NeedsFreeVariableInfo);
     return result;
-}
-
-template <typename LexerType>
-template <class TreeBuilder> bool Parser<LexerType>::maybeParseAsyncFunctionDeclarationStatement(TreeBuilder& context, TreeStatement& result, bool parentAllowsFunctionDeclarationAsStatement)
-{
-    ASSERT(matchContextualKeyword(m_vm.propertyNames->async));
-    SavePoint savePoint = createSavePoint(context);
-    next();
-    if (match(FUNCTION) && !m_lexer->hasLineTerminatorBeforeToken()) {
-        const bool isAsync = true;
-        result = parseFunctionDeclarationStatement(context, isAsync, parentAllowsFunctionDeclarationAsStatement);
-        return true;
-    }
-    restoreSavePoint(context, savePoint);
-    return false;
 }