Hacker News Reader

Clang has been able to build Linux since October of last year.

http://lists.cs.uiuc.edu/pipermail/cfe-dev/2010-October/0117...

Clang has support for a lot of gcc extensions: http://clang.llvm.org/docs/LanguageExtensions.html

And Linus's feelings about that relationship are...?

Pragmatic, I would guess.

"Quite frankly, I'd like there to be more competition in the open source compiler game, and that might cause some upheavals, but on the whole, gcc actually does a pretty damn good job."

http://kerneltrap.org/Linux/Volatile_Performance

But why would the kernel depend on gcc? Are there so many gcc-isms in there that would be hard to replicate on other compilers?

The biggest one is (was?) the use of GNU variable length arrays. The GNU extension has different syntax than C99's variable length arrays. There are also instances of __attributes__ on platform specific code.