The C standard covers a lot of details and cases that the kernel doesn't need to worry about. That makes the C standard a lot more restricted and constrained. G

The C standard covers a lot of details and cases that the kernel doesn't need to worry about. That makes the C standard a lot more restricted and constrained. GNUC has some convenient features and extensions because it makes assumptions not guaranteed by the C standard that happen to work for all the platforms that Linux cares about, and also, not beeing driven by a comittee, it can generally iterate and improve the language in a more agressive and fast way.