C++11 standard library features cross compilers support

I need to verify that some specific standard library feature is implemented and since which version.

For example: std::reference_wrapper

Compilers I need to verify: gcc, clang, msvc

MSVC

I am able to find http://ift.tt/2edIJiC so since version 10.0 the reference wrapper is implemented.

clang

On their webpage http://libcxx.llvm.org/ is written that the library is 100% completed. Is it possible to find in which version was what implemented?

gcc

I found: http://ift.tt/1slvKgE (language support)

Also: http://ift.tt/1JmvAMp - seems reference wrapper is implemented here

But for example 4.8.5 http://ift.tt/2dL1LAI There is:

This page describes the C++11 support in mainline GCC SVN, not in any particular release.

I'm confused. Can someone clarify that for me?