[Bug bootstrap/78817] stage2 bootstrap failure in vec.h:1613:5: error: argument 1 null where non-null expected after r243661

["msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78817

--- Comment #13 from Martin Sebor <msebor at gcc dot gnu.org> ---
(In reply to Franz Sirl from comment #7)
> And on x86_64 a profiledbootstrap with --enable-checking=yes fails like this:

I have just confirmed this by doing the same.  My profiledbootstrap shows the
following warnings:

Diagnostic                        Count   Unique    Files
-Wformat-length=                      3        2        1
-Wimplicit-fallthrough=              58       11        4
-Wmaybe-uninitialized                10        6        5
-Wnonnull                            17        6        4

With the following unique -Wnonnull instances: 
  cc1plus: warning: argument 1 null where non-null expected [-Wnonnull]
  /opt/notnfs/msebor/src/gcc/trunk/gcc/gengtype.c:1760
  /opt/notnfs/msebor/src/gcc/trunk/gcc/gengtype.c:1762
  /opt/notnfs/msebor/src/gcc/trunk/gcc/gengtype-parse.c:951
  /opt/notnfs/msebor/src/gcc/trunk/gcc/gengtype-parse.c:952
  /opt/notnfs/msebor/src/gcc/trunk/gcc/vec.h:1613

The -Wnonnull warnings all look justified to me (as best I can tell), but also
easily avoidable.