I've seen the bugs in Gentoo, so I am aware that this is annoying (and some of them I'm responsible to fix), but I think it's a good thing this is finally being

I've seen the bugs in Gentoo, so I am aware that this is annoying (and some of them I'm responsible to fix), but I think it's a good thing this is finally being cleaned up. The issue here is that functions are called without a function prototype, aka the proper headers included. The compiler basically guesses what the function prototype is. This is certainly error-prone, and the fact that autoconf relies on tons of test code pieces that aren't really correct C code is if anything worrying. It's also probably a good thing that this shows up first in clang, as most linux distros are built with gcc, so you have a testbed to fix all that stuff. gcc should eventually catch up and introduce the same default.