[Bug c++/94775] [8/9/10 Regression] ICE in strip_typedefs, at cp/tree.c:1734 since r8-4668-g8a5ee94a082b3d48

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94775

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #7)
> So a fix could be this, but maybe it would make us create a lot more
> variants (?):
> 
> --- a/gcc/tree.c
> +++ b/gcc/tree.c
> @@ -6493,7 +6493,8 @@ check_base_type (const_tree cand, const_tree base)
>                     TYPE_ATTRIBUTES (base)))
>      return false;
>    /* Check alignment.  */
> -  if (TYPE_ALIGN (cand) == TYPE_ALIGN (base))
> +  if (TYPE_ALIGN (cand) == TYPE_ALIGN (base)
> +      && TYPE_USER_ALIGN (cand) == TYPE_USER_ALIGN (base))
>      return true;
>    /* Atomic types increase minimal alignment.  We must to do so as well
>       or we get duplicated canonical types. See PR88686.  */
> @@ -6528,6 +6529,7 @@ check_aligned_type (const_tree cand, const_tree base,
> unsigned int align)
>       && TYPE_CONTEXT (cand) == TYPE_CONTEXT (base)
>       /* Check alignment.  */
>       && TYPE_ALIGN (cand) == align
> +     && TYPE_USER_ALIGN (cand) == TYPE_USER_ALIGN (base)
>       && attribute_list_equal (TYPE_ATTRIBUTES (cand),
>                    TYPE_ATTRIBUTES (base))
>       && check_lang_type (cand, base));

It looks like the right thing to me.  I guess if we really wanted, we could
instrument the compiler to see how common this was (though best in a separate
build from just the above patch), i.e. when we would create a new type only
with this patch and not without.