Bug 220809 – REGRESSION (r270874): Some React Native apps are reported broken on iOS

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Alexey Shvayka]

REGRESSION (r270874): Some React Native apps are reported broken on iOS

[Alexey Shvayka]

Created attachment 418061 [details]
Patch

[Alexey Shvayka]

Comment on attachment 418061 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=418061&action=review

> Source/JavaScriptCore/runtime/JSObject.cpp:2001
> +    bool reportAsEnumerable = !(slot.attributes() & PropertyAttribute::DontEnum) || structure(vm)->typeInfo().getOwnPropertySlotIsWrongAboutDontEnum();

The flag should probably be queried from slotBase() rather than |this|.

[Alexey Shvayka]

Created attachment 418064 [details]
Patch

Query GetOwnPropertySlotIsWrongAboutDontEnum from the slotBase().

[Radar WebKit Bug Importer]

<rdar://problem/73475533>

[Saam Barati]

I'm going to test this soon and can review too

[Saam Barati]

Comment on attachment 418064 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=418064&action=review

Confirmed this fixes the React native crashes we were seeing

> Source/JavaScriptCore/runtime/JSTypeInfo.h:62
> +static constexpr unsigned GetOwnPropertySlotIsWrongAboutDontEnum = 1 << 20;

nit, I think I'd call this:
GetOwnPropertySlotMayBeWrongAboutDontEnum

since we don't know definitively, but the runtime must be conservative.

> Source/WebCore/bridge/runtime_array.h:38
> +    static constexpr unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | OverridesGetOwnPropertyNames | InterceptsGetOwnPropertySlotByIndexEvenWhenLengthIsNotZero | GetOwnPropertySlotIsWrongAboutDontEnum;

is it worth reverting these back to how they used to be and provide this flag? Or should we make them truthful? I don't think we have evidence that this part of the patch broke stuff

[Alexey Shvayka]

Created attachment 418359 [details]
Patch for landing

[EWS]

Committed r271873: <https://trac.webkit.org/changeset/271873>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 418359 [details].