[Bug c++/54130] Recognize builtins with bool return type

[joseph at codesourcery dot com]

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.