[supar]

GCC speedup is actually quite substantial in math/numerical code (which, in turn, is not as fast as Intel's ICC). Moreover, GCC supports OpenMP, whereas Clang does not. This alone make building several scientific software packages not possible with Clang.

It's important to note though that it has only been recently (starting with GCC 4.4) that I've started to see some _improvement_ over previous GCC versions. GCC 3.x was known to be bloated, buggy and emit poor code for almost every architecture. Open64 was superior in _all_ regargs up to GCC 4.2/4.3 in my opinion.

Clearly, the whole project greatly benefited from Clang's competition.

[gillianseed]

Agreed. Competition is GREAT, and seeing these two excellent open source compiler offerings engaging in friendly competition means we as end users all benefit, no matter which solution we prefer (or use both, as I assume I'm not the only one doing).

[pmr_]

Starting with gcc 4.7 and 4.8 the error message for C++ are also improved [1] and start to get close to clang. The competitions seems to be good for gcc and I like to have the choice between two compilers.

[1] : http://gcc.gnu.org/wiki/ClangDiagnosticsComparison