[Bug fortran/69834] Collision in derived type hashes

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69834

--- Comment #6 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> Created attachment 37791
>   --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37791&action=edit
> Better Patch

Withe patch applied to my working tree (many patches) fixes the PR but I see
several regressions at run time

FAIL: gfortran.dg/allocate_with_source_(7|8).f08   *  execution test
FAIL: gfortran.dg/unlimited_polymorphic_zzz.f03   *  execution test

with zzz in (1, 5, 6, 14, 17, 18, 20, 22). AFAICT it "fixes"

FAIL: gfortran.dg/finalize_21.f90   -O   scan-tree-dump original "static struct
__vtype__STAR __vtab__STAR = {._hash=0, ._size=., ._extends=0B, ._def_init=0B,
._copy=0B, ._final=0B};"