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The C and C++ Include Header Files

cat -n /usr/include/c++/15/bits/concept_check.h

     1	// Concept-checking control -*- C++ -*-
     2	
     3	// Copyright (C) 2001-2025 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