[webkit-changes] [WebKit/WebKit] 36f50a: [JSC] Disallow yield/await expressions in class fi...

[Dan Hecht]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 36f50aab423c74d3b9b941e41a49b7ca2d581668
      https://github.com/WebKit/WebKit/commit/36f50aab423c74d3b9b941e41a49b7ca2d581668
  Author: Dan Hecht <dan.hecht at apple.com>
  Date:   2024-07-10 (Wed, 10 Jul 2024)

  Changed paths:
    A JSTests/stress/yield-await-class-field-initializer-expr.js
    M Source/JavaScriptCore/parser/Parser.cpp

  Log Message:
  -----------
  [JSC] Disallow yield/await expressions in class field initializers
https://bugs.webkit.org/show_bug.cgi?id=276438
rdar://119044881

Reviewed by Yusuke Suzuki.

The language spec doesn't explictly disallow yield and await expressions
in class field initializers, however it implicitly does given that
the expression is effectively evaluated as if it's inside a method.
Additionally, the consensus seems to be that these expressions
should not be allowed, see:

https://github.com/tc39/ecma262/issues/3333

The yield and await expressions are now handled differently, but
similar to how they are each handled in other contexts. This also
seems to be the least disruptive way to handle existing scripts,
as well as consistent with other engines:

yield: raise syntax error
await: parse as an identifier

Also adding a new test that generates and verifies scripts containing
a class with a field initializer containing yield and await, where the
class is either not nested or nested inside generator or async functions
to verify the behavior of various combinations.

* Source/JavaScriptCore/parser/Parser.cpp:
(JSC::Parser<LexerType>::parseYieldExpression):
(JSC::Parser<LexerType>::parseAwaitExpression):
(JSC::Parser<LexerType>::parsePrimaryExpression):
(JSC::Parser<LexerType>::parseUnaryExpression):

Canonical link: https://commits.webkit.org/280837@main



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