Eli Zaretskii <eliz@gnu.org> writes:

> > It might be worth configuring with --enable-checking: you could get an
> > assertion failure closer to where the actual problem is.
>
> Right.  And if you are reconfiguring anyway, also use
>
>   CFLAGS='-O0 -gdwarf-4 -g3'

Ok, compiler is running.  And I made a hard reset to the most recent
emacs-25 commit, too.

I attach two other gdb sessions with backtraces.  Maybe they look
different, or they don't, I'm not good at reading this stuff.