Clang has been a viable compiler for only about a decade--a third of Linux's existence--and could itself build Linux only a few years ago. Prior to clang's exis

Clang has been a viable compiler for only about a decade--a third of Linux's existence--and could itself build Linux only a few years ago. Prior to clang's existence, Linus is on record as saying that he didn't care about compatibility with other compilers, which at the time would have been something like Sun's C compiler. So it's very much against the historical policy of the Linux kernel to not be tied into a single compiler, even if it is a welcome change in policy.