[Pixman] clang 3.0: Unsupported asm: input constraint with a matching output constraint of incompatible type!

[Ryan Schmidt]

Hi, I'm the maintainer of pixman in MacPorts. I just updated our pixman port to 0.26.0. Unfortunately I now find that it does not build with clang 3.0:

http://build.macports.org/builders/buildports-lion-x86_64/builds/1324/steps/compile/logs/stdio

fatal error: error in backend: Unsupported asm: input constraint with a matching output constraint of incompatible type!

It appears this problem was known to the developers of pixman in February:

http://lists.freedesktop.org/archives/pixman/2012-February/001765.html

I see that various fixes were committed, then reverted when it was reported that clang 3.1 would no longer have this problem.

That's nice, but Apple has not yet released a version of Xcode containing clang 3.1, and even once they do, I would want to continue to support the use of older Xcode versions for the foreseeable future.

What patch should we apply to make pixman 0.26.0 compile with clang 3.0?