[Webkit-unassigned] [Bug 30526] Supporting multiple OS X versions in one binary

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=30526





--- Comment #4 from Mark Rowe (bdash) <mrowe at apple.com>  2009-10-19 14:55:42 PDT ---
(In reply to comment #3)
> (In reply to comment #2)
> > (From update of attachment 41439 [details] [details])
> > It may appear to work but it will have subtle bugs as *all* of the code wrapped
> > with these macros was written with the assumption that the code within these
> > blocks was targeted for the specific OS version.  When building in the manner
> > you mention it will be running on a different version of the OS and may not
> > behave as expected.  A number of aspects of the code would likely need to be
> > updated to determine the underlying OS version at runtime and to react
> > accordingly.
> > 
> > It also doesn’t make sense to switch a single use of BUILDING_ON_TIGER and
> > BUILDING_ON_LEOPARD to using availability macros.  If we’re going to make this
> > change it needs to be done in a more consistent manner.
> 
> Okay, after doing a grep what I'm seeing is that a vast majority of the use of
> these macros are in Mac port sources or code blocks, which won't use this
> support anyway, at least not in the short term. Perhaps that somewhat explains
> why the change didn't seem so problematic for the wx port.

Many of them are Mac-only, yes.  ICU is a significant case that is not specific
to the Mac version of WebKit, but where the behavior can differ significantly
from Tiger’s version to SnowLeopard.  We handle this with compile-time checks.

> So, how about this? We create a SUPPORTS_<CAT> or <CAT>_COMPATIBLE (where CAT
> is release name) type of define that corresponds to MIN_REQUIRED for non-Mac
> ports but for Mac (or any port that wants to keep the existing behavior) will
> simply be defined to  BUILDING_ON_<CAT> for compatibility. The only other thing
> this would probably require is to add weakly defined symbol checks to allow to
> use the newer API when running on a newer release, but since wx doesn't use
> much of the Mac port's Cocoa, CF or CG code,  nor presumably would Qt or GTK, I
> suspect this would actually only need to be done in a few spots.

I can’t easily follow what you’re suggesting here.

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