http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-03-28 08:53:54 UTC --- Created attachment 29742 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29742 gcc49-pr19449.patch Untested patch. There is another case where we'd better fold __builtin_constant_p right away, for static/extern function-local array dimensions: int y; static char a[__builtin_constant_p (y) ? -1 : 1]; extern char b[__builtin_constant_p (y) ? -1 : 1]; char d[__builtin_constant_p (y) ? -1 : 1]; void foo (int x) { static char e[__builtin_constant_p (x) ? -1 : 1]; extern char f[__builtin_constant_p (x) ? -1 : 1]; auto char g[__builtin_constant_p (x) ? -1 : 1]; char h[__builtin_constant_p (x) ? -1 : 1]; } Right now this compiles fine for -O0, but for -O1 and above it errors on e and f (twice on the latter actually). When cfun == NULL, we always fold __builtin_constant_p right away, but when cfun is NULL, we don't consider static/extern. Not sure how to fix this issue though, because I think the declspecs aren't passed down to declarator parsing.
