http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54130
--- Comment #5 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2012-07-31 19:59:50 UTC --- On Tue, 31 Jul 2012, glisse at gcc dot gnu.org wrote: > I understand your comments, but I don't know what conclusion to take from them > about whether gcc should recognize int/bool isnan(double) as a builtin... Even for C, declaring library functions yourself is very much a legacy possibility, not good coding practice. GCC matches builtins to declared functions primarily to optimize code using the standard headers, not code declaring them directly, and the cases where the type matching is fuzzy are for the sake of some old system headers. If your system headers declare isnan with bool return type I advise making fixincludes fix them. If the declaration doesn't come from system headers I don't think it's worth GCC optimizing for it.
