[Bug c++/37016] [4.3/4.4 Regression] member function pointer failure with optimization

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #13 from rguenther at suse dot de  2008-08-04 21:11 -------
Subject: Re:  [4.3/4.4 Regression] member function pointer
 failure with optimization

On Mon, 4 Aug 2008, jason at gcc dot gnu dot org wrote:

> ------- Comment #12 from jason at gcc dot gnu dot org  2008-08-04 21:03 -------
> Well, that's the problem then: we have two POINTER_TYPE to METHOD_TYPE which
> are considered equivalent in the front end, but not equivalent in the tree-ssa
> types_compatible_p.
> 
> The specific bug seems to be that useless_type_conversion_1 doesn't expect to
> need to do structural comparison of non-aggregate types.  That's an invalid
> assumption; it should check TYPE_STRUCTURAL_EQUALITY_P.  Does the attached
> patch seem appropriate to you?  It fixes the bug for me, though I haven't
> regression tested it.

Duh, if TYPE_STRUCTURAL_EQUALITY_P is used on non-aggregates then yes,
this is a correct patch (the code currently makes FUNCTION_TYPEs and
METHOD_TYPEs distinct if they are not pointer-equivalent or linked
via TYPE_CANONICAL / TYPE_MAIN_VARIANT).  So I would prefer if
you add those to the AGGREGATE_TYPE_P case instead of letting
it fall-through to the "default" case - we should probably add
some gcc_unreachable () to make sure we handled all cases.

Thanks,
Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37016