[Bug c++/95657] Duplicate error messages for decltype(auto) with -std=c++11

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95657

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looks fixed in GCC 11:
<source>:1:1: error: 'decltype(auto)' type specifier only available with
'-std=c++14' or '-std=gnu++14'
    1 | decltype (auto) foo( decltype (auto) a ){   }
      | ^~~~~~~~
<source>:1:22: error: 'decltype(auto)' type specifier only available with
'-std=c++14' or '-std=gnu++14'
    1 | decltype (auto) foo( decltype (auto) a ){   }
      |                      ^~~~~~~~
<source>:1:38: error: expected initializer before 'a'
    1 | decltype (auto) foo( decltype (auto) a ){   }
      |                                      ^