How has it been a huge boon to the GNU ecosystem? Clang is slow, the code generated is not consistently better than GCC for most of the software I personally run benchmarks for, and it's not like GCC has ever been worse for feature support than a Microsoft compiler.
> How has it been a huge boon to the GNU ecosystem?
It would seem that you never used GCC in the pre-llvm era. The GCC project has had a couple of notable periods of stagnation, in each case being "rescued" by the emergence of meaningful competition. First EGCS, and then later llvm.
Clang brought new developers to the space, it disproved the assertion that error messages had to be cryptic and unhelpful, and it has been a peer competitor for an extended period of time now. The two projects compete and cross-pollinate to their mutual benefit.
It's better to point out WebKit.