[pclmulqdq]

Welcome to C! The guns are free, but you can only point them at your foot.

The C standard specifies so much less than everyone thinks.

[userbinator]

It specifies so much less, precisely to allow it to be usable on such weird architectures.

[detaro]

I wouldn't really qualify this as a foot gun, but rather appropriate flexibility. 98% of people never encounter it, and the 2% that do are happy that it is that way, and I don't think alternative approaches like having the compiler hide it are appropriate for C.