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From: "iains at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/94454] ICE 'canonical types differ for identical types'
Date: Thu, 02 Apr 2020 16:37:35 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94454

--- Comment #5 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Nathan Sidwell from comment #4)
> Oh, it is from the template specialization hash table.  I suggest making
> that very poor to increase collisions:
>=20
> pt.c:
> static hashval_t
> hash_tmpl_and_args (tree tmpl, tree args)
> {
>   hashval_t val =3D iterative_hash_object (DECL_UID (tmpl), 0);
>    return val; // INSERT THIS LINE
>   return iterative_hash_template_arg (args, val);
> }
>=20
> sorry for not realizing this earlier

[not wishing to disturb the c-reduce sessions already started]

On Darwin17 @r10-7488, which was always succeeding

I bootstrapped with this patch, and then built a --disable-bootstrap with t=
he
"spec_hasher::hash always returns 0" applied too.

Neither made any difference, the entire ranges-v3 suite built without issue.

Maybe that's informative in its own right.

Will hopefully have some kind of reduced test-case for x86-64-linux tomorro=
w.=