std::source_location::source_location(3)

NAME
std::source_location::source_location - std::source_location::source_location

Synopsis
   constexpr source_location() noexcept; (1) (since C++20)
   source_location( const source_location& other ); (2) (since C++20)
   source_location( source_location&& other ) noexcept; (3) (since C++20)
   1) Constructs a source_location object of unspecified value.
   2-3) Copy and move constructors. It is unspecified whether they are trivial and/or
   constexpr.

Parameters
   other - another source_location to copy or move from

Example
// Run this code
 #include <iomanip>
 #include <iostream>
 #include <ranges>
 #include <vector>
 #include <source_location>
 #include <string_view>
 // GCC specific type name printer
 #if (__GNUG__ >= 11)
 template <typename T>
 auto type_name_helper(const std::source_location s = std::source_location::current()) {
     using std::operator""sv;
     const std::string_view fun_name{s.function_name()};
     constexpr auto prefix {"[with T = "sv};
     const auto type_name_begin {fun_name.find(prefix)};
     if (""sv.npos == type_name_begin) return ""sv;
     const std::size_t first {type_name_begin + prefix.length()};
     return std::string_view{fun_name.cbegin() + first, fun_name.cend() - 1};
 }
 template <typename T>
 auto type_name() { return type_name_helper<T>(); }
 #endif
 void print(std::string_view const comment, std::source_location const l) {
     std::cout
         << comment << ":\n"
         << " file_name : " << std::quoted(l.file_name()) << '\n'
         << " function_name : " << std::quoted(l.function_name()) << '\n'
         << " line : " << l.line() << '\n'
         << " column : " << l.column() << '\n';
 }
 int main()
 {
     constexpr std::source_location default_constructed;
     print("default constructed", default_constructed);
     constexpr std::source_location current = std::source_location::current();
     print("current", current);
 # if (__GNUG__ >= 11)
     const std::vector<std::vector<int>> v{ {1,2}, {3,4,5}, {6} };
     auto jv = std::ranges::join_view(v);
     std::cout
         << '\n'
         << '[' << type_name<int>() << "]\n"
         << '[' << type_name<double*>() << "]\n"
         << '[' << type_name<decltype([](){})>() << "]\n"
         << '[' << type_name<decltype(type_name<int>())>() << "]\n"
         << '[' << type_name<decltype(jv)>() << "]\n"
         ;
 # endif
 }

Possible output:
 default constructed:
   file_name : ""
   function_name : ""
   line : 0
   column : 0
 current:
   file_name : "main.cpp"
   function_name : "int main()"
   line : 39
   column : 75
 [int]
 [double*]
 [main()::<lambda()>]
 [std::basic_string_view<char>]
 [std::ranges::join_view<std::ranges::ref_view<const std::vector<std::vector<int> > > >]

See also
   current constructs a new source_location corresponding to the location of the
   [static] call site
                 (public static member function)
   constructor constructs a new stacktrace_entry
   (C++23) (public member function of std::stacktrace_entry)