(verify, verify_dcl): New file/macros.

This commit is contained in:
Jim Meyering 2005-07-04 16:05:41 +00:00
parent a54b48abe6
commit cfdfe3e318

43
lib/verify.h Normal file
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/* Compile-time assert-like macros.
Copyright (C) 2005 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#ifndef VERIFY_H
# define VERIFY_H 1
# ifndef verify_dcl
# define GL_CONCAT0(x, y) x##y
# define GL_CONCAT(x, y) GL_CONCAT0 (x, y)
/* Verify requirement, R, at compile-time, as a declaration.
The implementation uses a struct declaration whose name includes the
expansion of __LINE__, so there is a small chance that two uses of
verify_dcl from different files will end up colliding (for example,
f.c includes f.h and verify_dcl is used on the same line in each). */
# define verify_dcl(R) \
struct GL_CONCAT (ct_assert_, __LINE__) { char a[(R) ? 1 : -1]; }
# endif
/* Verify requirement, R, at compile-time, as an expression.
Unlike assert, there is no run-time overhead. Unlike verify_dcl,
above, there is no risk of collision, since there is no declared name.
This macro may be used in some contexts where the other may not, and
vice versa. Return void. */
# undef verify
# define verify(R) ((void) sizeof (struct { char a[(R) ? 1 : -1]; }))
#endif