[Bug c++/85011] GCC complains that 2 identical function prototypes are different

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85011

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
EDG and MSVC reject it too. They all accept it if the definition says
decltype(x), matching the declaration.

I think the bug is in GCC's diagnostic printing, which doesn't show the
signature as it was written in the source.