current-location.cpp

#include <boost/assert/source_location.hpp>
#include <algorithm>
#include <source_location>

#if not _MSC_VER
template<unsigned M, unsigned N>
#endif
struct sloc_literal {
#if _MSC_VER
    char const* file = nullptr;
    char const* function = nullptr;
#else
    char file[M] = {};
    char function[N] = {};
#endif
    unsigned line;
    unsigned column;
    constexpr sloc_literal(std::source_location loc) {
#if _MSC_VER
        file = loc.file_name();
        function = loc.function_name();
#else
        std::copy_n(loc.file_name(), M, file);
        std::copy_n(loc.function_name(), N, function);
#endif
        line = loc.line();
        column = loc.column();
    }
};
#if _MSC_VER
template<sloc_literal loc>
static boost::source_location sloc(loc.file, loc.line, loc.function, loc.column);
#define PCURRENT_LOCATION &::sloc< \
    std::source_location::current()>
#elif 0
#define PCURRENT_LOCATION ([](auto l) { \
    static boost::source_location const loc = l; \
    return &loc; \
}(std::source_location::current()))
#elif 1 and __GNUC__
#define PCURRENT_LOCATION reinterpret_cast<boost::source_location const*>( \
    __builtin_source_location())
#else
template<unsigned M, unsigned N, sloc_literal<M, N> loc>
static boost::source_location sloc(loc.file, loc.line, loc.function, loc.column);
#define PCURRENT_LOCATION &::sloc< \
    std::strlen(std::source_location::current().file_name()), \
    std::strlen(std::source_location::current().function_name()), \
    std::source_location::current()>
#endif

auto f() { return PCURRENT_LOCATION; }
#if 0
#include <boost/system/error_code.hpp>
#include <iostream>
int main() {
    auto const ec = boost::system::error_code(
        make_error_code(boost::system::errc::io_error,
        PCURRENT_LOCATION));
    std::cout << ec.what();
}
#endif