golden hour

/usr/include/c++/4.8.2/bits

File/Folder	Size	Actions
algorithmfwd.h	20.66 KB
alloc_traits.h	17.66 KB
allocator.h	6.1 KB
atomic_base.h	24.99 KB
atomic_lockfree_defines.h	2.2 KB
basic_ios.h	14.76 KB
basic_ios.tcc	5.89 KB
basic_string.h	109.49 KB
basic_string.tcc	38.43 KB
boost_concept_check.h	26.41 KB
c++0x_warning.h	1.47 KB
char_traits.h	16.95 KB
codecvt.h	16.23 KB
concept_check.h	3.26 KB
cpp_type_traits.h	9.56 KB
cxxabi_forced.h	1.77 KB
deque.tcc	31.91 KB
exception_defines.h	1.6 KB
exception_ptr.h	5.29 KB
forward_list.h	46.72 KB
forward_list.tcc	15.17 KB
fstream.tcc	28.3 KB
functexcept.h	3.04 KB
functional_hash.h	6.05 KB
gslice.h	5.39 KB
gslice_array.h	7.59 KB
hash_bytes.h	2.1 KB
hashtable.h	61.05 KB
hashtable_policy.h	52.72 KB
indirect_array.h	7.68 KB
ios_base.h	27.85 KB
istream.tcc	30.36 KB
list.tcc	12.2 KB
locale_classes.h	22.45 KB
locale_classes.tcc	8.18 KB
locale_facets.h	88.84 KB
locale_facets.tcc	38.02 KB
locale_facets_nonio.h	63.51 KB
locale_facets_nonio.tcc	40.85 KB
localefwd.h	5.1 KB
mask_array.h	7.41 KB
memoryfwd.h	2.36 KB
move.h	5.67 KB
nested_exception.h	4.58 KB
ostream.tcc	12.03 KB
ostream_insert.h	3.91 KB
postypes.h	8.02 KB
ptr_traits.h	5.17 KB
random.h	173.19 KB
random.tcc	106.59 KB
range_access.h	3.06 KB
regex.h	83.49 KB
regex_compiler.h	27.68 KB
regex_constants.h	10.81 KB
regex_cursor.h	2.7 KB
regex_error.h	4.5 KB
regex_grep_matcher.h	4.23 KB
regex_grep_matcher.tcc	5.41 KB
regex_nfa.h	10.65 KB
regex_nfa.tcc	4.85 KB
shared_ptr.h	18.97 KB
shared_ptr_base.h	40.65 KB
slice_array.h	9.12 KB
sstream.tcc	9.27 KB
stl_algo.h	212.55 KB
stl_algobase.h	41.41 KB
stl_bvector.h	28.98 KB
stl_construct.h	5.05 KB
stl_deque.h	66.41 KB
stl_function.h	22.06 KB
stl_heap.h	19.99 KB
stl_iterator.h	35.77 KB
stl_iterator_base_funcs.h	6.8 KB
stl_iterator_base_types.h	8.19 KB
stl_list.h	52.83 KB
stl_map.h	36.78 KB
stl_multimap.h	33.94 KB
stl_multiset.h	28.37 KB
stl_numeric.h	13.5 KB
stl_pair.h	9.63 KB
stl_queue.h	18.21 KB
stl_raw_storage_iter.h	3.37 KB
stl_relops.h	4.49 KB
stl_set.h	28.61 KB
stl_stack.h	9.65 KB
stl_tempbuf.h	8.15 KB
stl_tree.h	53.56 KB
stl_uninitialized.h	19.95 KB
stl_vector.h	48.64 KB
stream_iterator.h	6.44 KB
streambuf.tcc	4.81 KB
streambuf_iterator.h	12.33 KB
stringfwd.h	2.37 KB
unique_ptr.h	17.19 KB
unordered_map.h	47.76 KB
unordered_set.h	43.25 KB
uses_allocator.h	3.49 KB
valarray_after.h	22.12 KB
valarray_array.h	21.23 KB
valarray_array.tcc	7.08 KB
valarray_before.h	18.08 KB
vector.tcc	25.55 KB

Edit: concept_check.h

// Concept-checking control -*- C++ -*-

// Copyright (C) 2001-2013 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file bits/concept_check.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{iterator}
 */

#ifndef _CONCEPT_CHECK_H
#define _CONCEPT_CHECK_H 1

#pragma GCC system_header

#include <bits/c++config.h>

// All places in libstdc++-v3 where these are used, or /might/ be used, or
// don't need to be used, or perhaps /should/ be used, are commented with
// "concept requirements" (and maybe some more text).  So grep like crazy
// if you're looking for additional places to use these.

// Concept-checking code is off by default unless users turn it on via
// configure options or editing c++config.h.

#ifndef _GLIBCXX_CONCEPT_CHECKS

#define __glibcxx_function_requires(...)
#define __glibcxx_class_requires(_a,_b)
#define __glibcxx_class_requires2(_a,_b,_c)
#define __glibcxx_class_requires3(_a,_b,_c,_d)
#define __glibcxx_class_requires4(_a,_b,_c,_d,_e)

#else // the checks are on

#include <bits/boost_concept_check.h>

// Note that the obvious and elegant approach of
//
//#define glibcxx_function_requires(C) debug::function_requires< debug::C >()
//
// won't work due to concept templates with more than one parameter, e.g.,
// BinaryPredicateConcept.  The preprocessor tries to split things up on
// the commas in the template argument list.  We can't use an inner pair of
// parenthesis to hide the commas, because "debug::(Temp<Foo,Bar>)" isn't
// a valid instantiation pattern.  Thus, we steal a feature from C99.

#define __glibcxx_function_requires(...)                                 \
            __gnu_cxx::__function_requires< __gnu_cxx::__VA_ARGS__ >();
#define __glibcxx_class_requires(_a,_C)                                  \
            _GLIBCXX_CLASS_REQUIRES(_a, __gnu_cxx, _C);
#define __glibcxx_class_requires2(_a,_b,_C)                              \
            _GLIBCXX_CLASS_REQUIRES2(_a, _b, __gnu_cxx, _C);
#define __glibcxx_class_requires3(_a,_b,_c,_C)                           \
            _GLIBCXX_CLASS_REQUIRES3(_a, _b, _c, __gnu_cxx, _C);
#define __glibcxx_class_requires4(_a,_b,_c,_d,_C)                        \
            _GLIBCXX_CLASS_REQUIRES4(_a, _b, _c, _d, __gnu_cxx, _C);

#endif // enable/disable

#endif // _GLIBCXX_CONCEPT_CHECK