https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91554
--- Comment #4 from Zack Weinberg <zackw at panix dot com> --- (In reply to Richard Biener from comment #3) > I guess you want to use > > __builtin_constant_p (b != 0) > > instead. That wouldn't do what I want. The goal is to warn for any argument _other than_ a compile-time null pointer. `!__builtin_constant_p(b) || b != 0` does just that (it might be easier to understand the De Morgan equivalent `!(__builtin_constant_p(b) && b == 0)`. This is in aid of deprecating the second argument to gettimeofday (see https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS;h=75453bbda865c7d51df39177caef40b16e086dcf#l53 and https://sourceware.org/git/?p=glibc.git;a=blob;f=manual/time.texi;h=cb234bd08fae1841034a2bdccf4e1d246be23034#l557 ). > The docs don't explain what a "constant at compile time" is > so whether for example the address of a global or the address of an > automatic var would be "constant". But I'd say the above incorrectly > disregards the NULL-pointer case. It seems like this code pre-dates tree optimizations, I would suggest removing these lines 8470 || AGGREGATE_TYPE_P (TREE_TYPE (arg)) 8471 || POINTER_TYPE_P (TREE_TYPE (arg)) (and fixing the comment above to match) and seeing if that breaks anything.
