[Bug fortran/45586] [4.6 Regression] ICE non-trivial conversion at assignment

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45586

--- Comment #31 from rguenther at suse dot de <rguenther at suse dot de> 2011-01-18 13:37:42 UTC ---
On Tue, 18 Jan 2011, mikael at gcc dot gnu.org wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45586
> 
> --- Comment #30 from Mikael Morin <mikael at gcc dot gnu.org> 2011-01-18 12:48:41 UTC ---
> (In reply to comment #28)
> > One way would be to keep for data types all the time the two versions around:
> > One with restrict and one without restrict;
> makes sense
> 
> > thus, if one does type extension,
> > one has always a fully restrictless data type.
> Why? From my point of view type extension is orthogonal to target. 
> If an entity of extended derived type has the target/pointer attribute, one
> uses the non-restrict variant for its base type, and if it hasn't one uses the
> restrict variant. Do I miss something?
> 
> > Unfortunately, that seems to
> > cause a missed-optimization for
> >   type t
> >     integer :: a
> >     integer, pointer :: b
> >   end type t
> >   type(t) :: x
> > as "x%a" cannot alias and only "x%b" can - but is seems that one cannot encode
> > this for the ME such that "t" as a whole has to be marked as unrestricted.
> 
> How about: 
> 
> struct t_restrict {
>   int a;
>   int * b;
> } * restrict
> 
> VS
> 
> struct t_norestrict {
>   int a;
>   int * b;
> } *
> 
> ?

Yes.  The restrict qualifier on t_restrict * does not apply
to members, so as long as int *b is not restrict qualified
the b's alias.

> > I think the easiest would be to create for derived types sym->backend_decl and
> > another backend_decl with "restrict" - and propagate both variants types
> > through, when extending the type or including it into another type. As soon as
> > it is used as POINTER component, one could drop propagating the
> > backend_decl_restricted.
> 
> Looks like a plan. :-)

I think Micha has started working on something.

Richard.