On 24 Feb 2018, at 17:01, Alan Somers <asom...@freebsd.org> wrote: > > Author: asomers > Date: Sat Feb 24 16:01:21 2018 > New Revision: 329910 > URL: https://svnweb.freebsd.org/changeset/base/329910 > > Log: > Implement CTASSERT using _Static_assert > > Prevents warnings about "unused typedef" with GCC-6 > > Reported by: GCC-6 > MFC after: 18 days > X-MFC-With: 329722 > > Modified: > head/sys/cddl/contrib/opensolaris/uts/common/sys/debug.h > > Modified: head/sys/cddl/contrib/opensolaris/uts/common/sys/debug.h > ============================================================================== > --- head/sys/cddl/contrib/opensolaris/uts/common/sys/debug.h Sat Feb 24 > 15:13:20 2018 (r329909) > +++ head/sys/cddl/contrib/opensolaris/uts/common/sys/debug.h Sat Feb 24 > 16:01:21 2018 (r329910) > @@ -133,8 +133,8 @@ _NOTE(CONSTCOND) } while (0) > #ifndef CTASSERT > #define CTASSERT(x) _CTASSERT(x, __LINE__) > #define _CTASSERT(x, y) __CTASSERT(x, y) > -#define __CTASSERT(x, y) \ > - typedef char __compile_time_assertion__ ## y [(x) ? 1 : -1] > +#define __CTASSERT(x, y) \ > + _Static_assert((x), "Static assert failed at " #y) > #endif > > #ifdef _KERNEL
Note that the trick with the negatively indexed array is to support older versions of gcc, which did not yet recognize _Static_assert. It looks like this was added in gcc 4.6. -Dimitry
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