------- Comment #2 from joseph at codesourcery dot com 2009-12-20 01:16 ------- Subject: Re: New: Linux kernel BUILD_BUG_ON() broke
This is a different sort of not-an-integer-constant-expression from the previous cases the kernel was found to use with invalid unevaluated operands (I asked in <http://gcc.gnu.org/ml/gcc/2009-04/msg00678.html> if it was being used for bit-field widths). const int max = [valid expression]; ((void)(sizeof(struct { int:-!!(max >= (1 << 16)); }))); Here, you are using a const variable in what's meant to be an integer constant expression, which is only valid for C++ not C. Much the same workaround as applied for enums in <http://gcc.gnu.org/ml/gcc-patches/2009-04/msg02022.html> would probably work for this, but it's clearly a different undocumented extension being used. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42439
