[Bug c++/109621] [10/11/12/13/14 Regression] GCC accepts invalid program with multiple using declarations

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109621

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Which makes it a regression in 4.3.0 and later.