static consteval source_location current() noexcept;
A presumed line number ([cpp.predefined]).
Line numbers are presumed to be 1-indexed; however, an implementation is encouraged to use 0 when the line number is unknown.
A presumed name of the current source file ([cpp.predefined]) as an ntbs.
A name of the current function such as in __func__ ([dcl.fct.def.general]) if any, an empty string otherwise.
constexpr source_location() noexcept;