libstdc++: concept_check.h Source File

libstdc++

concept_check.h
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1// Concept-checking control -*- C++ -*-
2
3// Copyright (C) 2001-2026 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file bits/concept_check.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{iterator}
28 */
29
30#ifndef _CONCEPT_CHECK_H
31#define _CONCEPT_CHECK_H 1
32
33#ifdef _GLIBCXX_SYSHDR
34#pragma GCC system_header
35#endif
36
37#include <bits/c++config.h>
38
39#pragma GCC diagnostic push
40#pragma GCC diagnostic ignored "-Wvariadic-macros"
41
42// All places in libstdc++-v3 where these are used, or /might/ be used, or
43// don't need to be used, or perhaps /should/ be used, are commented with
44// "concept requirements" (and maybe some more text). So grep like crazy
45// if you're looking for additional places to use these.
46
47// Concept-checking code is off by default unless users turn it on via
48// configure options or editing c++config.h.
49// It is not supported for freestanding implementations.
50
51#if !defined(_GLIBCXX_CONCEPT_CHECKS)
52
53#define __glibcxx_function_requires(...)
54#define __glibcxx_class_requires(_a,_b)
55#define __glibcxx_class_requires2(_a,_b,_c)
56#define __glibcxx_class_requires3(_a,_b,_c,_d)
57#define __glibcxx_class_requires4(_a,_b,_c,_d,_e)
58
59#else // the checks are on
60
61#include <bits/boost_concept_check.h>
62
63// Note that the obvious and elegant approach of
64//
65//#define glibcxx_function_requires(C) debug::function_requires< debug::C >()
66//
67// won't work due to concept templates with more than one parameter, e.g.,
68// BinaryPredicateConcept. The preprocessor tries to split things up on
69// the commas in the template argument list. We can't use an inner pair of
70// parenthesis to hide the commas, because "debug::(Temp<Foo,Bar>)" isn't
71// a valid instantiation pattern. Thus, we steal a feature from C99.
72
73#define __glibcxx_function_requires(...) \
74 __gnu_cxx::__function_requires< __gnu_cxx::__VA_ARGS__ >();
75#define __glibcxx_class_requires(_a,_C) \
76 _GLIBCXX_CLASS_REQUIRES(_a, __gnu_cxx, _C);
77#define __glibcxx_class_requires2(_a,_b,_C) \
78 _GLIBCXX_CLASS_REQUIRES2(_a, _b, __gnu_cxx, _C);
79#define __glibcxx_class_requires3(_a,_b,_c,_C) \
80 _GLIBCXX_CLASS_REQUIRES3(_a, _b, _c, __gnu_cxx, _C);
81#define __glibcxx_class_requires4(_a,_b,_c,_d,_C) \
82 _GLIBCXX_CLASS_REQUIRES4(_a, _b, _c, _d, __gnu_cxx, _C);
83
84#endif // enable/disable
85
86#pragma GCC diagnostic pop
87#endif // _GLIBCXX_CONCEPT_CHECK
boost_concept_check.h
c++config.h