[Bug c/97154] gcc/c/c-decl.c:5729:38: error: Dereference of an invalid iterator

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97154

--- Comment #1 from David Binderman <dcb314 at hotmail dot com> ---
Source code is

              if (spec.empty () || spec.end ()[-1] != ' ')

Looks suspicious to me. Is this allowed ?