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The C and C++ Include Header Files

cat -n /usr/include/c++/15/source_location

     1	// <source_location> -*- C++ -*-
     2	
     3	// Copyright (C) 2020-2025 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 include/source_location
    26	 *  This is a Standard C++ Library header.
    27	 */
    28	
    29	#ifndef _GLIBCXX_SRCLOC
    30	#define _GLIBCXX_SRCLOC 1
    31	
    32	#define __glibcxx_want_source_location
    33	#include <bits/version.h>
    34	
    35	#if __cpp_lib_source_location // C++ >= 20 && builtin_source_location
    36	#include <bits/c++config.h>
    37	
    38	namespace std
    39	{
    40	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    41	
    42	  /// A class that describes a location in source code.
    43	  struct source_location
    44	  {
    45	  private:
    46	    using uint_least32_t = __UINT_LEAST32_TYPE__;
    47	    struct __impl
    48	    {
    49	      const char* _M_file_name;
    50	      const char* _M_function_name;
    51	      unsigned _M_line;
    52	      unsigned _M_column;
    53	    };
    54	    using __builtin_ret_type = decltype(__builtin_source_location());
    55	
    56	  public:
    57	
    58	    // [support.srcloc.cons], creation
    59	    static consteval source_location
    60	    current(__builtin_ret_type __p = __builtin_source_location()) noexcept
    61	    {
    62	      source_location __ret;
    63	      __ret._M_impl = static_cast <const __impl*>(__p);
    64	      return __ret;
    65	    }
    66	
    67	    constexpr source_location() noexcept { }
    68	
    69	    // [support.srcloc.obs], observers
    70	    constexpr uint_least32_t
    71	    line() const noexcept
    72	    { return _M_impl ? _M_impl->_M_line : 0u; }
    73	
    74	    constexpr uint_least32_t
    75	    column() const noexcept
    76	    { return _M_impl ? _M_impl->_M_column : 0u; }
    77	
    78	    constexpr const char*
    79	    file_name() const noexcept
    80	    { return _M_impl ? _M_impl->_M_file_name : ""; }
    81	
    82	    constexpr const char*
    83	    function_name() const noexcept
    84	    { return _M_impl ? _M_impl->_M_function_name : ""; }
    85	
    86	  private:
    87	    const __impl* _M_impl = nullptr;
    88	  };
    89	
    90	_GLIBCXX_END_NAMESPACE_VERSION
    91	} // namespace std
    92	#endif // __cpp_lib_source_location
    93	#endif // _GLIBCXX_SRCLOC