Bug 191220 – Assert JSValues can fit into a pointer when API casting

• Component: New Bugs
• Status: RESOLVED FIXED

[Keith Miller]

Assert JSValues can fit into a pointer when API casting

[Keith Miller]

Created attachment 353752 [details]
Patch

[Michael Saboff]

Comment on attachment 353752 [details]
Patch

r=me

[WebKit Commit Bot]

Comment on attachment 353752 [details]
Patch

Clearing flags on attachment: 353752

Committed r237764: <https://trac.webkit.org/changeset/237764>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/45779456>

[Mark Lam]

Comment on attachment 353752 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=353752&action=review

> Source/JavaScriptCore/API/APICast.h:83
> +    static_assert(sizeof(OpaqueJSValue*) == sizeof(JSC::JSValue), "JSValue needs to fit into a boxed pointer");
>      JSC::JSValue result = JSC::JSValue::decode(reinterpret_cast<JSC::EncodedJSValue>(const_cast<OpaqueJSValue*>(v)));

I believe this is what bitwise_cast does.  You should just use that instead.

[Saam Barati]

(In reply to Mark Lam from comment #6)
> Comment on attachment 353752 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=353752&action=review
> 
> > Source/JavaScriptCore/API/APICast.h:83
> > +    static_assert(sizeof(OpaqueJSValue*) == sizeof(JSC::JSValue), "JSValue needs to fit into a boxed pointer");
> >      JSC::JSValue result = JSC::JSValue::decode(reinterpret_cast<JSC::EncodedJSValue>(const_cast<OpaqueJSValue*>(v)));
> 
> I believe this is what bitwise_cast does.  You should just use that instead.

+1

[Keith Miller]

(In reply to Saam Barati from comment #7)
> (In reply to Mark Lam from comment #6)
> > Comment on attachment 353752 [details]
> > Patch
> > 
> > View in context:
> > https://bugs.webkit.org/attachment.cgi?id=353752&action=review
> > 
> > > Source/JavaScriptCore/API/APICast.h:83
> > > +    static_assert(sizeof(OpaqueJSValue*) == sizeof(JSC::JSValue), "JSValue needs to fit into a boxed pointer");
> > >      JSC::JSValue result = JSC::JSValue::decode(reinterpret_cast<JSC::EncodedJSValue>(const_cast<OpaqueJSValue*>(v)));
> > 
> > I believe this is what bitwise_cast does.  You should just use that instead.
> 
> +1

Good point! I filed https://bugs.webkit.org/show_bug.cgi?id=191272.