svn commit: r329910 - head/sys/cddl/contrib/opensolaris/uts/common/sys

[Alan Somers]

On Sun, Feb 25, 2018 at 6:52 AM, Dimitry Andric <dim at freebsd.org> wrote:

> On 24 Feb 2018, at 17:01, Alan Somers <asomers at 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
>
>
sys/cdefs.h defines _Static_assert similarly on GCC 4.3-4.5, and defines it
to nothingness on GCC-4.2.  So we should be covered for all compilers that
we care about.

-Alan