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Files
coreutils/lib/verify.h
Paul Eggert 7c97d643b9 (verify_expr): Use ((verify_type__ (R) *) 0), not
sizeof (verify_type__ (R)), to pacify C++ compilers.
2005-07-11 23:28:09 +00:00

58 lines
2.2 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
# define GL_CONCAT0(x, y) x##y
# define GL_CONCAT(x, y) GL_CONCAT0 (x, y)
/* A type that is valid if and only if R is nonzero.
R should be an integer constant expression.
verify_type__ and verify_error_if_negative_size__ are symbols that
are private to this header file. */
# define verify_type__(R) \
struct { int verify_error_if_negative_size__[(R) ? 1 : -1]; }
/* Verify requirement R at compile-time, as a declaration.
R should be an integer constant expression.
Unlike assert, there is no run-time overhead.
The implementation uses __LINE__ to lessen the probability of
generating a warning that verify_function_NNN is multiply declared.
However, even if two declarations in different files have the same
__LINE__, the multiple declarations are still valid C89 and C99
code because they simply redeclare the same external function, so
no conforming compiler will reject them outright. */
# define verify(R) \
extern verify_type__ (R) GL_CONCAT (verify_function_, __LINE__) (void)
/* Verify requirement R at compile-time, as an expression.
R should be an integer constant expression.
Unlike assert, there is no run-time overhead.
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