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 # define GL_CONCAT0(x, y) x##y
25 # define GL_CONCAT(x, y) GL_CONCAT0 (x, y)
27 /* A type that is valid if and only if R is nonzero.
28 R should be an integer constant expression.
29 verify_type__ and verify_error_if_negative_size__ are symbols that
30 are private to this header file. */
32 # define verify_type__(R) \
33 struct { int verify_error_if_negative_size__ : (R) ? 1 : -1; }
35 /* Verify requirement R at compile-time, as a declaration.
36 R should be an integer constant expression.
37 Unlike assert, there is no run-time overhead.
39 The implementation uses __LINE__ to lessen the probability of
40 generating a warning that verify_function_NNN is multiply declared.
41 However, even if two declarations in different files have the same
42 __LINE__, the multiple declarations are still valid C89 and C99
43 code because they simply redeclare the same external function, so
44 no conforming compiler will reject them outright. */
47 extern verify_type__ (R) GL_CONCAT (verify_function_, __LINE__) (void)
49 /* Verify requirement R at compile-time, as an expression.
50 R should be an integer constant expression.
51 Unlike assert, there is no run-time overhead.
52 This macro can be used in some contexts where verify cannot, and vice versa.
55 # define verify_expr(R) ((void) ((verify_type__ (R) *) 0))