Just to address the other compiler issue
No, they will work on other compilers, since 'configure' won't use -O2 with those other compilers.
icc defaults to -O2 without any options, so unless you are passing -O0, it will enable this.
Unless you know of some real-world C compiler that breaks wrapv semantics even compiling without optimization? If so, I'd like to hear the details.
Sure. All of them,AFAIK, because they make the assumptions during constant folding, and they all still constant fold at -O0. It just so happens that it tends to affect a lot smaller number of programs, because it essentially ends up being a very very local optimization. But it's still going to break some programs, even at -O0.
