The C and C++ Include Header Files

/usr/include/c++/11/bits/concept_check.h


$ cat -n /usr/include/c++/11/bits/concept_check.h

     1	// Concept-checking control -*- C++ -*-
     2	
     3	// Copyright (C) 2001-2021 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	#pragma GCC system_header
    34	
    35	#include <bits/c++config.h>
    36	
    37	// All places in libstdc++-v3 where these are used, or /might/ be used, or
    38	// don't need to be used, or perhaps /should/ be used, are commented with
    39	// "concept requirements" (and maybe some more text).  So grep like crazy
    40	// if you're looking for additional places to use these.
    41	
    42	// Concept-checking code is off by default unless users turn it on via
    43	// configure options or editing c++config.h.
    44	// It is not supported for freestanding implementations.
    45	
    46	#if !defined(_GLIBCXX_CONCEPT_CHECKS) || !_GLIBCXX_HOSTED
    47	
    48	#define __glibcxx_function_requires(...)
    49	#define __glibcxx_class_requires(_a,_b)
    50	#define __glibcxx_class_requires2(_a,_b,_c)
    51	#define __glibcxx_class_requires3(_a,_b,_c,_d)
    52	#define __glibcxx_class_requires4(_a,_b,_c,_d,_e)
    53	
    54	#else // the checks are on
    55	
    56	#include <bits/boost_concept_check.h>
    57	
    58	// Note that the obvious and elegant approach of
    59	//
    60	//#define glibcxx_function_requires(C) debug::function_requires< debug::C >()
    61	//
    62	// won't work due to concept templates with more than one parameter, e.g.,
    63	// BinaryPredicateConcept.  The preprocessor tries to split things up on
    64	// the commas in the template argument list.  We can't use an inner pair of
    65	// parenthesis to hide the commas, because "debug::(Temp<Foo,Bar>)" isn't
    66	// a valid instantiation pattern.  Thus, we steal a feature from C99.
    67	
    68	#define __glibcxx_function_requires(...)                                 \
    69	            __gnu_cxx::__function_requires< __gnu_cxx::__VA_ARGS__ >();
    70	#define __glibcxx_class_requires(_a,_C)                                  \
    71	            _GLIBCXX_CLASS_REQUIRES(_a, __gnu_cxx, _C);
    72	#define __glibcxx_class_requires2(_a,_b,_C)                              \
    73	            _GLIBCXX_CLASS_REQUIRES2(_a, _b, __gnu_cxx, _C);
    74	#define __glibcxx_class_requires3(_a,_b,_c,_C)                           \
    75	            _GLIBCXX_CLASS_REQUIRES3(_a, _b, _c, __gnu_cxx, _C);
    76	#define __glibcxx_class_requires4(_a,_b,_c,_d,_C)                        \
    77	            _GLIBCXX_CLASS_REQUIRES4(_a, _b, _c, _d, __gnu_cxx, _C);
    78	
    79	#endif // enable/disable
    80	
    81	#endif // _GLIBCXX_CONCEPT_CHECK