coreutils/lib/verify.h
Jim Meyering 8dbb507ee8 (verify_type__): Use `unsigned int' as the bitfield type
so we can once again use a positive bitfield width of 1 -- now we
don't have to explain why we were using a bitfield width of 2.
2005-09-23 23:05:39 +00:00

47 lines
1.7 KiB
C

/* 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. */
/* Written by Paul Eggert and Jim Meyering. */
#ifndef VERIFY_H
# define VERIFY_H 1
/* Each of these macros verifies that its argument R is a nonzero
constant expression. To be portable, R's type must be integer (or
boolean). Unlike assert, there is no run-time overhead. */
/* A type that is valid if and only if R is a nonzero constant expression.
The symbols verify_type__ and verify_error_if_negative_size__ are
private to this header file. */
# define verify_type__(R) \
struct { unsigned int verify_error_if_negative_size__ : (R) ? 1 : -1; }
/* Verify requirement R at compile-time, as a declaration. */
# define verify(R) \
extern int (* verify_function__ (void)) [sizeof (verify_type__ (R))]
/* Verify requirement R at compile-time, as an expression.
This macro can be used in some contexts where verify cannot, and vice versa.
Return void. */
# define verify_expr(R) ((void) ((verify_type__ (R) *) 0))
#endif