Array's toString() is incorrect if join() is non-callable

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Alexey Shvayka]

Array's toString() is incorrect if join() is non-callable

[Alexey Shvayka]

Created attachment 425225 [details]
Patch

[Yusuke Suzuki]

Comment on attachment 425225 [details]
Patch

r=me

[Alexey Shvayka]

Committed r275544 (236200@main): <https://commits.webkit.org/236200@main>

[Radar WebKit Bug Importer]

<rdar://problem/76281426>

[Darin Adler]

Comment on attachment 425225 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=425225&action=review

> Source/JavaScriptCore/runtime/ObjectPrototype.cpp:322
> +    if (thisValue.isUndefined())
> +        return vm.smallStrings.undefinedObjectString();
> +    if (thisValue.isNull())
> +        return vm.smallStrings.nullObjectString();

Isn’t it an error to return after invoking DECLARE_THROW_SCOPE without using RELEASE_AND_RETURN? Must admit I am confused about the ThrowScope idioms.

[Mark Lam]

Comment on attachment 425225 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=425225&action=review

>> Source/JavaScriptCore/runtime/ObjectPrototype.cpp:322
>> +        return vm.smallStrings.nullObjectString();
> 
> Isn’t it an error to return after invoking DECLARE_THROW_SCOPE without using RELEASE_AND_RETURN? Must admit I am confused about the ThrowScope idioms.

It's not if the statement you evaluate here cannot throw.  The "release" in RELEASE_AND_RETURN means that this ThrowScope is releasing the responsibility to check for any exceptions from this point on till the return, and letting the caller handle it.  This makes sense if the last statement we evaluate can throw.  If you don't release the responsibility, and you don't check for an exception, but the statement can throw, then that's an unhandled exception because you still have the responsibility and you didn't do the check when one is needed.

But if the statement cannot throw, then all is well because no check is needed after all before we return though we still have the responsibility.