GoKawiilBlog post catalogs where GCC and Clang diverge from the C standard
A technical blog post lists concrete cases where GCC and Clang do not conform to the ISO C standard by default, including treatment of the asm keyword as a reserved extension and GCC's hardcoded FLT_ROUNDS macro that ignores runtime rounding-mode changes via fesetround. The author also flags unfinished coverage of the standard's five floating-point pragmas as an area of ongoing non-conformance.