[GTK][OSX] JavaScriptCore fails to build on older versions of OS X due to CF_AVAILABLE usage

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Jeremy Huddleston Sequoia]

Building webkit-gtk 2.11.2 on the MacPorts Mavericks buildbot failed due CF_AVAILABLE macro usage.  These macros should only be used by the OS X system frameworks and not local builds.  

/opt/local/var/macports/build/_opt_mports_dports_www_webkit2-gtk/webkit2-gtk/work/webkitgtk-2.11.2/Source/JavaScriptCore/API/JSContextRef.h:144:71: error: expected '=' after '__NSi_10_10'
JS_EXPORT JSStringRef JSGlobalContextCopyName(JSGlobalContextRef ctx) CF_AVAILABLE(10_10, 8_0);
                                                                      ^
/System/Library/Frameworks/CoreFoundation.framework/Headers/CFAvailability.h:95:81: note: expanded from macro 'CF_AVAILABLE'
#define CF_AVAILABLE(_mac, _ios) __attribute__((availability(macosx,__NSi_##_mac)))
                                                                                ^
---

Elsewhere, I see these warnings, which seem to attempt to do that:

/opt/local/var/macports/build/_opt_mports_dports_www_webkit2-gtk/webkit2-gtk/work/webkitgtk-2.11.2/Source/JavaScriptCore/API/WebKitAvailability.h:68:9: warning: 'CF_AVAILABLE' macro redefined
#define CF_AVAILABLE(_mac, _ios)
        ^
/System/Library/Frameworks/CoreFoundation.framework/Headers/CFAvailability.h:95:9: note: previous definition is here
#define CF_AVAILABLE(_mac, _ios) __attribute__((availability(macosx,__NSi_##_mac)))
        ^

---

Thus, it looks like WebKitAvailability.h needs to be included in JSContextRef.h before that CF_AVAILABLE usage.

Also, please add an #undef before the #define in WebKitAvailability.h to silence that warning.

[Jeremy Huddleston Sequoia]

Actually, the issue seems to be that WebKitAvailability.h is guarded by:

#if defined(__APPLE__) && !defined(BUILDING_GTK__)

And thus has no effect when building webkit-gtk for some reason.  Why was that done?

[Jeremy Huddleston Sequoia]

This regression was caused by:

commit e47eb45c6bcb88b853858eb0a3aaecbbdcc3aa38
Author: [e-mail] <[e-mail]@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Date:   Mon Oct 12 17:59:45 2015 +0000

    webkit-gtk 2.3.3 fails to build on OS X - Conflicting type "Fixed"
    https://bugs.webkit.org/show_bug.cgi?id=126433
    
    Patch by Philip Chimento <[e-mail]> on 2015-10-12
    Reviewed by Philippe Normand
    
    Don't include CoreFoundation.h when building the GTK port.
    
    * Source/JavaScriptCore/API/WebKitAvailability.h: Add !defined(BUILDING_GTK__) to defined(__APPLE__).
    
    git-svn-id: http://svn.webkit.org/repository/webkit/trunk@190862 268f45cc-cd09-0410-ab3c-d52691b4dbfc

[Jeremy Huddleston Sequoia]

Odd, that change looks fine to my eyes, and we should be getting:

#define CF_AVAILABLE(_mac, _ios)

out of WebKitAvailability.h.  Something isn't adding up.  I need to take a closer look at this.

[Philip Chimento]

The idea was that we wouldn't include CoreFoundation.h even if it was available, when building WebKitGTK, because some types included from CF conflicted with other types in WebKitGTK. I don't quite understand what's going wrong with that change.

[Jeremy Huddleston Sequoia]

Based on the other build warnings (redefinition of the macro), CF is getting included elsewhere as well.  In some cases, the ordering works out, but in this case, it doesn't.

I think a better approach might be to include it and then redefine the macro.  Gonna give that a test tomorrow.

[Jeremy Huddleston Sequoia]

Created attachment 269059 [details]
patch

Yep, that did the trick.  Patch attached.

[Jeremy Huddleston Sequoia]

Created attachment 269158 [details]
Updated patch with ChangeLog entry

[WebKit Commit Bot]

Comment on attachment 269158 [details]
Updated patch with ChangeLog entry

Clearing flags on attachment: 269158

Committed r195184: <http://trac.webkit.org/changeset/195184>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.