Re: CVS commit: src/sys/sys

[Alan Barrett <apb%cequrux.com@localhost>]

On Fri, 14 Mar 2014, Joerg Sonnenberger wrote:
> > Modified Files:
> >         src/sys/sys: cdefs.h
> >
> > Log Message:
> > For compilers without __COUNTER__, make the ctassert name contain
> > __INCLUDE_LEVEL__ ## _ ## __LINE__.  It's not perfect, but at least it's
> > better than just __LINE__ since it avoids collisions between .c's and .h's.
>
> This is wrong, __INCLUDE_LEVEL__ does not exist unconditionally.

You could define a special token in each include file, and then use
that token if it is defined.  You could also use __INCLUDE_LEVEL__ only
if it's defined.  Something like this (untested):

/* in foo/bar.h: */
#ifndef _FOO_BAR_H
#define _FOO_BAR_H
#undef __HEADER_NAME_TOKEN
#define __HEADER_NAME_TOKEN _FOO_BAR_H
/* insert real content here */
#endif /* _FOO_BAR_H */

/* in sys/cdefs.h: */
#define __CTASSERT0(x, y, z1, z2, z3)    __CTASSERT1(x, y, z1, z2, z3)
#define __CTASSERT1(x, y, z) \
        typedef char y ## z1 ## z2 ## z3[/*CONSTCOND*/(x) ? 1 : -1] __unused

#if defined(__COUNTER__)
# define __CTASSERT(x)          __CTASSERT0(x, __ctassert, __COUNTER__,,)
#else
# if defined(__INCLUDE_LEVEL__)
#  define __tmp_z1 __INCLUDE_LEVEL__
# else
#  define __tmp_z1 /* Empty */
# endif
# if defined(__HEADER_NAME_TOKEN)
#  define __tmp_z2 __HEADER_NAME_TOKEN
# else
#  define __tmp_z2 /* Empty */
# endif
# define __CTASSERT(x) _CTASSERT0(x, __ctassert, __tmp_z1, __tmp_z2, __LINE__)
# undef __tmp_z1
# undef __tmp_z2
#endif

--apb (Alan Barrett)