------- Comment #11 from rguenther at suse dot de 2008-04-15 08:58 ------- Subject: Re: [4.3/4.4 Regression] builtin isinf() mismatch to compile-time substitution
On Tue, 15 Apr 2008, ghazi at gcc dot gnu dot org wrote: > > > ------- Comment #10 from ghazi at gcc dot gnu dot org 2008-04-15 01:36 > ------- > (In reply to comment #8) > > I propose that we do the following: > > - add a warning to the C/C++ frontends that isinf (x) CMP isinf (y) is > > only well-defined for !isinf (x) && !isinf (y). > > this doesn't result in a runtime penalty and informs people about the > > possible > > problem in their code (it is non-portable). > > IMHO the above warning would have limited coverage because there are other > ways > users can test the results of isinf that would run into the sign problem. Well, of course. > > A different workaround would be to canonicalize the return value of isinf to > > bool. > > Doesn't this change the interface defined by c99? Yes, we would need to hide that fact and always add promotion code to int via isinf() != 0. Richard. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35509
