C++ linux demangler for clang ang gcc

linux_demangler_for_clang_and_gcc.h

/* 
 (c) 2018-2021 by [email protected] -- https://dbj.org/license_dbj
        usage:
    auto demangled_name = dbj::demang< int (&) [42] >() ;
        This is both windows and linux code.
        
    https://godbolt.org/z/7bTxazhTv
*/

#ifndef _WIN32
#include <cxxabi.h>
#endif
namespace dbj {
#ifdef _WIN32
template <typename T>
const char* demang() noexcept {
  static auto demangled_name = []() { return {typeid(T).name()}; }();
  return demangled_name.data();
}
#else   // __linux__
template <typename T>
const char* demang() noexcept {
  // once per one type
  static auto demangled_name = []() {
    int error = 0;
    std::string retval;
    char* name = abi::__cxa_demangle(typeid(T).name(), 0, 0, &error);

    switch (error) {
      case 0:
        retval = name;
        break;
      case -1:
        retval = "memory allocation failed";
        break;
      case -2:
        retval = "not a valid mangled name";
        break;
      default:
        retval = "__cxa_demangle failed";
        break;
    }
    std::free(name);
    return retval;
  }();
  // std::free(name) ;
  return demangled_name.data();
}
#endif  // __linux__
// calling with instances
template <typename T>
const char* demang(T const&) noexcept {
  return demang<T>();
}
}  // namespace dbj

Note the optimization vs the previous version. Since one type has one name for the lifetime of a program above we do that only once and not before requested.

Current version demo