FM / bits

/usr/include/c++/8/bits

Name	Size	Mode	Actions
algorithmfwd.h	21736	0644	edit dl rm
allocated_ptr.h	3293	0644	edit dl rm
allocator.h	7569	0644	edit dl rm
alloc_traits.h	20066	0644	edit dl rm
atomic_base.h	23842	0644	edit dl rm
atomic_futex.h	9576	0644	edit dl rm
atomic_lockfree_defines.h	2253	0644	edit dl rm
basic_ios.h	16074	0644	edit dl rm
basic_ios.tcc	6083	0644	edit dl rm
basic_string.h	242697	0644	edit dl rm
basic_string.tcc	53755	0644	edit dl rm
boost_concept_check.h	27161	0644	edit dl rm
c++0x_warning.h	1474	0644	edit dl rm
char_traits.h	20915	0644	edit dl rm
codecvt.h	21289	0644	edit dl rm
concept_check.h	3423	0644	edit dl rm
cpp_type_traits.h	9789	0644	edit dl rm
cxxabi_forced.h	1811	0644	edit dl rm
cxxabi_init_exception.h	2220	0644	edit dl rm
deque.tcc	34122	0644	edit dl rm
enable_special_members.h	12387	0644	edit dl rm
exception.h	2280	0644	edit dl rm
exception_defines.h	1645	0644	edit dl rm
exception_ptr.h	5981	0644	edit dl rm
forward_list.h	48919	0644	edit dl rm
forward_list.tcc	13169	0644	edit dl rm
fstream.tcc	32799	0644	edit dl rm
fs_dir.h	14724	0644	edit dl rm
fs_fwd.h	10279	0644	edit dl rm
fs_ops.h	9730	0644	edit dl rm
fs_path.h	32894	0644	edit dl rm
functexcept.h	3254	0644	edit dl rm
functional_hash.h	8238	0644	edit dl rm
gslice.h	5518	0644	edit dl rm
gslice_array.h	7769	0644	edit dl rm
hashtable.h	73785	0644	edit dl rm
hashtable_policy.h	67971	0644	edit dl rm
hash_bytes.h	2146	0644	edit dl rm
indirect_array.h	7861	0644	edit dl rm
invoke.h	3657	0644	edit dl rm
ios_base.h	31023	0644	edit dl rm
istream.tcc	31093	0644	edit dl rm
list.tcc	15976	0644	edit dl rm
localefwd.h	5646	0644	edit dl rm
locale_classes.h	24897	0644	edit dl rm
locale_classes.tcc	8375	0644	edit dl rm
locale_conv.h	16097	0644	edit dl rm
locale_facets.h	92328	0644	edit dl rm
locale_facets.tcc	39548	0644	edit dl rm
locale_facets_nonio.h	68980	0644	edit dl rm
locale_facets_nonio.tcc	45280	0644	edit dl rm
mask_array.h	7595	0644	edit dl rm
memoryfwd.h	2453	0644	edit dl rm
move.h	6529	0644	edit dl rm
nested_exception.h	4802	0644	edit dl rm
node_handle.h	8216	0644	edit dl rm
ostream.tcc	12315	0644	edit dl rm
ostream_insert.h	4002	0644	edit dl rm
parse_numbers.h	7944	0644	edit dl rm
postypes.h	8208	0644	edit dl rm
predefined_ops.h	9083	0644	edit dl rm
ptr_traits.h	6626	0644	edit dl rm
quoted_string.h	5053	0644	edit dl rm
random.h	175250	0644	edit dl rm
random.tcc	105590	0644	edit dl rm
range_access.h	10030	0644	edit dl rm
refwrap.h	11884	0644	edit dl rm
regex.h	97402	0644	edit dl rm
regex.tcc	16565	0644	edit dl rm
regex_automaton.h	10722	0644	edit dl rm
regex_automaton.tcc	7838	0644	edit dl rm
regex_compiler.h	18050	0644	edit dl rm
regex_compiler.tcc	19288	0644	edit dl rm
regex_constants.h	14708	0644	edit dl rm
regex_error.h	4904	0644	edit dl rm
regex_executor.h	7488	0644	edit dl rm
regex_executor.tcc	18841	0644	edit dl rm
regex_scanner.h	7088	0644	edit dl rm
regex_scanner.tcc	15009	0644	edit dl rm
shared_ptr.h	23433	0644	edit dl rm
shared_ptr_atomic.h	9769	0644	edit dl rm
shared_ptr_base.h	54286	0644	edit dl rm
slice_array.h	9348	0644	edit dl rm
specfun.h	47051	0644	edit dl rm
sstream.tcc	10142	0644	edit dl rm
std_abs.h	3266	0644	edit dl rm
std_function.h	23260	0644	edit dl rm
std_mutex.h	9298	0644	edit dl rm
stl_algo.h	214294	0644	edit dl rm
stl_algobase.h	50494	0644	edit dl rm
stl_bvector.h	33728	0644	edit dl rm
stl_construct.h	7397	0644	edit dl rm
stl_deque.h	78575	0644	edit dl rm
stl_function.h	41745	0644	edit dl rm
stl_heap.h	20206	0644	edit dl rm
stl_iterator.h	42291	0644	edit dl rm
stl_iterator_base_funcs.h	8178	0644	edit dl rm
stl_iterator_base_types.h	8680	0644	edit dl rm
stl_list.h	67558	0644	edit dl rm
stl_map.h	52791	0644	edit dl rm
stl_multimap.h	41557	0644	edit dl rm
stl_multiset.h	35809	0644	edit dl rm
stl_numeric.h	13832	0644	edit dl rm
stl_pair.h	18642	0644	edit dl rm
stl_queue.h	24073	0644	edit dl rm
stl_raw_storage_iter.h	3830	0644	edit dl rm
stl_relops.h	4594	0644	edit dl rm
stl_set.h	36125	0644	edit dl rm
stl_stack.h	11938	0644	edit dl rm
stl_tempbuf.h	8344	0644	edit dl rm
stl_tree.h	74904	0644	edit dl rm
stl_uninitialized.h	27709	0644	edit dl rm
stl_vector.h	60534	0644	edit dl rm
streambuf.tcc	4929	0644	edit dl rm
streambuf_iterator.h	13758	0644	edit dl rm
stream_iterator.h	6654	0644	edit dl rm
stringfwd.h	2607	0644	edit dl rm
string_view.tcc	6698	0644	edit dl rm
uniform_int_dist.h	10081	0644	edit dl rm
unique_ptr.h	25984	0644	edit dl rm
unordered_map.h	75341	0644	edit dl rm
unordered_set.h	59148	0644	edit dl rm
uses_allocator.h	6525	0644	edit dl rm
valarray_after.h	22655	0644	edit dl rm
valarray_array.h	21807	0644	edit dl rm
valarray_array.tcc	7254	0644	edit dl rm
valarray_before.h	18513	0644	edit dl rm
vector.tcc	29644	0644	edit dl rm

Edit: /usr/include/c++/8/bits/functional_hash.h (8238B)

// functional_hash.h header -*- C++ -*-

// Copyright (C) 2007-2018 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/functional_hash.h
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{functional}
 */

#ifndef _FUNCTIONAL_HASH_H
#define _FUNCTIONAL_HASH_H 1

#pragma GCC system_header

#include <bits/hash_bytes.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

/** @defgroup hashes Hashes
   *  @ingroup functors
   *
   *   Hashing functors taking a variable type and returning a @c std::size_t.
   *
   *  @{
   */

template<typename _Result, typename _Arg>
    struct __hash_base
    {
      typedef _Result     result_type _GLIBCXX17_DEPRECATED;
      typedef _Arg      argument_type _GLIBCXX17_DEPRECATED;
    };

/// Primary class template hash.
  template<typename _Tp>
    struct hash;

template<typename _Tp, typename = void>
    struct __poison_hash
    {
      static constexpr bool __enable_hash_call = false;
    private:
      // Private rather than deleted to be non-trivially-copyable.
      __poison_hash(__poison_hash&&);
      ~__poison_hash();
    };

template<typename _Tp>
    struct __poison_hash<_Tp, __void_t<decltype(hash<_Tp>()(declval<_Tp>()))>>
    {
      static constexpr bool __enable_hash_call = true;
    };

// Helper struct for SFINAE-poisoning non-enum types.
  template<typename _Tp, bool = is_enum<_Tp>::value>
    struct __hash_enum
    {
    private:
      // Private rather than deleted to be non-trivially-copyable.
      __hash_enum(__hash_enum&&);
      ~__hash_enum();
    };

// Helper struct for hash with enum types.
  template<typename _Tp>
    struct __hash_enum<_Tp, true> : public __hash_base<size_t, _Tp>
    {
      size_t
      operator()(_Tp __val) const noexcept
      {
       using __type = typename underlying_type<_Tp>::type;
       return hash<__type>{}(static_cast<__type>(__val));
      }
    };

/// Primary class template hash, usable for enum types only.
  // Use with non-enum types still SFINAES.
  template<typename _Tp>
    struct hash : __hash_enum<_Tp>
    { };

/// Partial specializations for pointer types.
  template<typename _Tp>
    struct hash<_Tp*> : public __hash_base<size_t, _Tp*>
    {
      size_t
      operator()(_Tp* __p) const noexcept
      { return reinterpret_cast<size_t>(__p); }
    };

// Explicit specializations for integer types.
#define _Cxx_hashtable_define_trivial_hash(_Tp) 	\
  template<>						\
    struct hash<_Tp> : public __hash_base<size_t, _Tp>  \
    {                                                   \
      size_t                                            \
      operator()(_Tp __val) const noexcept              \
      { return static_cast<size_t>(__val); }            \
    };

/// Explicit specialization for bool.
  _Cxx_hashtable_define_trivial_hash(bool)

/// Explicit specialization for char.
  _Cxx_hashtable_define_trivial_hash(char)

/// Explicit specialization for signed char.
  _Cxx_hashtable_define_trivial_hash(signed char)

/// Explicit specialization for unsigned char.
  _Cxx_hashtable_define_trivial_hash(unsigned char)

/// Explicit specialization for wchar_t.
  _Cxx_hashtable_define_trivial_hash(wchar_t)

/// Explicit specialization for char16_t.
  _Cxx_hashtable_define_trivial_hash(char16_t)

/// Explicit specialization for char32_t.
  _Cxx_hashtable_define_trivial_hash(char32_t)

/// Explicit specialization for short.
  _Cxx_hashtable_define_trivial_hash(short)

/// Explicit specialization for int.
  _Cxx_hashtable_define_trivial_hash(int)

/// Explicit specialization for long.
  _Cxx_hashtable_define_trivial_hash(long)

/// Explicit specialization for long long.
  _Cxx_hashtable_define_trivial_hash(long long)

/// Explicit specialization for unsigned short.
  _Cxx_hashtable_define_trivial_hash(unsigned short)

/// Explicit specialization for unsigned int.
  _Cxx_hashtable_define_trivial_hash(unsigned int)

/// Explicit specialization for unsigned long.
  _Cxx_hashtable_define_trivial_hash(unsigned long)

/// Explicit specialization for unsigned long long.
  _Cxx_hashtable_define_trivial_hash(unsigned long long)

#ifdef __GLIBCXX_TYPE_INT_N_0
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_0)
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_0 unsigned)
#endif
#ifdef __GLIBCXX_TYPE_INT_N_1
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_1)
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_1 unsigned)
#endif
#ifdef __GLIBCXX_TYPE_INT_N_2
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_2)
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_2 unsigned)
#endif
#ifdef __GLIBCXX_TYPE_INT_N_3
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_3)
  _Cxx_hashtable_define_trivial_hash(__GLIBCXX_TYPE_INT_N_3 unsigned)
#endif

#undef _Cxx_hashtable_define_trivial_hash

struct _Hash_impl
  {
    static size_t
    hash(const void* __ptr, size_t __clength,
	 size_t __seed = static_cast<size_t>(0xc70f6907UL))
    { return _Hash_bytes(__ptr, __clength, __seed); }

template<typename _Tp>
      static size_t
      hash(const _Tp& __val)
      { return hash(&__val, sizeof(__val)); }

template<typename _Tp>
      static size_t
      __hash_combine(const _Tp& __val, size_t __hash)
      { return hash(&__val, sizeof(__val), __hash); }
  };

// A hash function similar to FNV-1a (see PR59406 for how it differs).
  struct _Fnv_hash_impl
  {
    static size_t
    hash(const void* __ptr, size_t __clength,
	 size_t __seed = static_cast<size_t>(2166136261UL))
    { return _Fnv_hash_bytes(__ptr, __clength, __seed); }

template<typename _Tp>
      static size_t
      hash(const _Tp& __val)
      { return hash(&__val, sizeof(__val)); }

template<typename _Tp>
      static size_t
      __hash_combine(const _Tp& __val, size_t __hash)
      { return hash(&__val, sizeof(__val), __hash); }
  };

/// Specialization for float.
  template<>
    struct hash<float> : public __hash_base<size_t, float>
    {
      size_t
      operator()(float __val) const noexcept
      {
	// 0 and -0 both hash to zero.
	return __val != 0.0f ? std::_Hash_impl::hash(__val) : 0;
      }
    };

/// Specialization for double.
  template<>
    struct hash<double> : public __hash_base<size_t, double>
    {
      size_t
      operator()(double __val) const noexcept
      {
	// 0 and -0 both hash to zero.
	return __val != 0.0 ? std::_Hash_impl::hash(__val) : 0;
      }
    };

/// Specialization for long double.
  template<>
    struct hash<long double>
    : public __hash_base<size_t, long double>
    {
      _GLIBCXX_PURE size_t
      operator()(long double __val) const noexcept;
    };

// @} group hashes

// Hint about performance of hash functor. If not fast the hash-based
  // containers will cache the hash code.
  // Default behavior is to consider that hashers are fast unless specified
  // otherwise.
  template<typename _Hash>
    struct __is_fast_hash : public std::true_type
    { };

template<>
    struct __is_fast_hash<hash<long double>> : public std::false_type
    { };

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif // _FUNCTIONAL_HASH_H

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