1 /* Compile-time assert-like macros.
3 Copyright (C) 2005 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
19 /* Written by Paul Eggert and Jim Meyering. */
24 /* Each of these macros verifies that its argument R is a nonzero
25 constant expression. To be portable, R's type must be integer (or
26 boolean). Unlike assert, there is no run-time overhead. */
28 /* A type that is valid if and only if R is a nonzero constant expression.
29 The symbols verify_type__ and verify_error_if_negative_size__ are
30 private to this header file. */
32 # define verify_type__(R) \
33 struct { int verify_error_if_negative_size__ : (R) ? 2 : -1; }
35 /* Verify requirement R at compile-time, as a declaration. */
38 extern int (* verify_function__ (void)) [sizeof (verify_type__ (R))]
40 /* Verify requirement R at compile-time, as an expression.
41 This macro can be used in some contexts where verify cannot, and vice versa.
44 # define verify_expr(R) ((void) ((verify_type__ (R) *) 0))