[Bug c++/84798] [6/7/8 Regression] ICE (Segmentation fault) if `auto` appears in a template argument

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84798

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Outside of lambdas the patch essentially changed an error diagnostic to
                else if (cxx_dialect < cxx1y)
                  pedwarn (location_of (type), 0,
                      "use of %<auto%> in parameter declaration "
                      "only available with "
                      "-std=c++1y or -std=gnu++1y");
                   else
                     pedwarn (location_of (type), OPT_Wpedantic,
                              "ISO C++ forbids use of %<auto%> in parameter "
                              "declaration");
Do we really want that extension and what uses it?