std::source...rce_location(3)

💖 NAME 💖

std::source_location::source_location — and the short description is also std::source_location::source_location, because this page is iconically committed to the bit. This is the std::source...rce_location(3) page from the C++ Standard Libary (yes, bestie, the header spells it “Libary”; we are not fixing it 💅).

✨ 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. No cap, that “unspecified” is the whole vibe check, so don’t go assuming extra guarantees.

🎀 Parameters 🎀

• other — another source_location to copy or move from.

🌸 Example 🌸

Okay so this example is a whole little demo: it prints a default-constructed source_location and one from std::source_location::current(), then on GCC 11+ it does some type-name printer magic. Run it and see, but the output below is only possible, not a pinky-promise guarantee 🫶.

        // Run this code

        #include <iomanip>
        #include <iostream>
        #include <ranges>
        #include <source_location>
        #include <string_view>
        #include <vector>

        // 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 ([static]) — constructs a new source_location corresponding to the location of the call site (public static member function).
• constructor (C++23) — constructs a new stacktrace_entry (public member function of std::stacktrace_entry).

mwah 💋 — source/version: http://cppreference.com, date 2024.06.10, page std::source...rce_location(3). That’s the footer, bestie, periodt. 🫶