It's just that on Linux open source development tools [and libraries] work out of the box. Sudo apt-get, and you are in business. Not the case on Macs. Apple tend to break things with every xcode/clang release. And things tend to stay broken.
I'd love to see citations on clang bugs that persist without good reason (e.g. clang's adhering more closely to a standard, or refuses to implement a rarely used gcc extension).
Well, aside from clang + boost + mac monstrosity [there is always something wrong with boost + clang + mac], I haven't seen any persistent problems with clang itself.
It's just that configure+build on mac is often a time sink... You try a default ./configure - it picks up legacy gcc4.2. Fail. You try forcing it to clang - there is something wrong with the switches/defines/gcc exts/etc. Easy to fix. But still sinks time :(
