How do I test the version of libstdc++, not GCC, at compile time?

Question

I am trying to test the version of libstdc++ because std::regex is implemented, but largely broken, in the versions of libstdc++ distributed with GCC before version 4.9.0.

Note that:

• I need to test the version of libstdc++ , not GCC because Clang also supports using libstdc++ as the standard library. This rules out testing the __GNUC_PATCHLEVEL__ , __GNUC__ , and __GNUC_MINOR__ macros .

• The __GLIBCXX__ macro is a date, not a version number and does not increase monotonically . For example, GCC 4.8.4 ships with #define __GLIBCXX__ 20150426 , which is newer than the release date of GCC 4.9.0.

Is there any portable way to test the version of libstdc++ that does not depend on using GCC my compiler?

Answer 1

In my opinion the problem is sufficiently small to be solved by brute force.

In a header file called machine.hpp or similar I would test that the version of the C++ Standard is at least what I need it to be (the __cplusplus macro). Then I would add the various macro checks to reject any library that I know to be flawed.

In other words, I would take a black-list approach instead of a white-list approach.

For example:

#pragma once
#ifndef MACHINE_HPP_HEADER_GUARDS
#define MACHINE_HPP_HEADER_GUARDS

#if __cplusplus < 201103L
// Library is incompatible if it does not implement at least the C++11
// standard.
#error "I need a library that supports at least C++11."
#else
// Load an arbitrary header to ensure that the pre-processor macro is
// defined. Otherwise you will need to load this header AFTER you
// #include the header you care about.
#include <iosfwd>
#endif

#if __GLIBCXX__ == 20150422
#error "This version of GLIBCXX (20150422) has flaws in it"
#endif

// ...repeat for other versions of GLIBCXX that you know to be flawed

#endif // MACHINE_HPP_HEADER_GUARDS