[Bug libstdc++/79702] AX_CXX_COMPILE_STDCXX([17]) does not work with GCC=7.0.1

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79702

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
this is already known

*** This bug has been marked as a duplicate of bug 78939 ***