[Bug c++/51213] [C++11][DR 1170] Access control checking has to be done under SFINAE conditions

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51213

--- Comment #20 from Paolo Carlini <paolo.carlini at oracle dot com> ---
This is already fixed in mainline, though. I'm adding the testcase.