Re: [Patch, fortran] PR49213 - [OOP] gfortran rejects structure constructor expression

[Paul Richard Thomas <paul.richard.thomas@gmail.com>]

Hi Harald,

I feel very foolish! You are absolutely right about gfc_is_ptr_fcn
(gfc_expr *e). I never checked what gfc_expr_attr did here.

I have fixed character (kind=4) but have now run into trouble with
expressions such as cont = tContainer(sqrt (2.0_8)). I think that
simplification is being missed somewhere.

I'm onto it.

Paul

On Sat, 24 Jun 2023 at 20:50, Harald Anlauf <anlauf@gmx.de> wrote:
>
> Hi Paul!
>
> On 6/24/23 15:18, Paul Richard Thomas via Gcc-patches wrote:
> > I have included the adjustment to 'gfc_is_ptr_fcn' and eliminating the
> > extra blank line, introduced by my last patch. I played safe and went
> > exclusively for class functions with attr.class_pointer set on the
> > grounds that these have had all the accoutrements checked and built
> > (ie. class_ok). I am still not sure if this is necessary or not.
>
> maybe it is my fault, but I find the version in the patch confusing:
>
> @@ -816,7 +816,7 @@ bool
>   gfc_is_ptr_fcn (gfc_expr *e)
>   {
>     return e != NULL && e->expr_type == EXPR_FUNCTION
> -             && (gfc_expr_attr (e).pointer
> +             && ((e->ts.type != BT_CLASS && gfc_expr_attr (e).pointer)
>                    || (e->ts.type == BT_CLASS
>                        && CLASS_DATA (e)->attr.class_pointer));
>   }
>
> The caller 'gfc_is_ptr_fcn' has e->expr_type == EXPR_FUNCTION, so
> gfc_expr_attr (e) boils down to:
>
>        if (e->value.function.esym && e->value.function.esym->result)
>         {
>           gfc_symbol *sym = e->value.function.esym->result;
>           attr = sym->attr;
>           if (sym->ts.type == BT_CLASS && sym->attr.class_ok)
>             {
>               attr.dimension = CLASS_DATA (sym)->attr.dimension;
>               attr.pointer = CLASS_DATA (sym)->attr.class_pointer;
>               attr.allocatable = CLASS_DATA (sym)->attr.allocatable;
>             }
>         }
> ...
>        else if (e->symtree)
>         attr = gfc_variable_attr (e, NULL);
>
> So I thought this should already do what you want if you do
>
> gfc_is_ptr_fcn (gfc_expr *e)
> {
>    return e != NULL && e->expr_type == EXPR_FUNCTION && gfc_expr_attr
> (e).pointer;
> }
>
> or what am I missing?  The additional checks in gfc_expr_attr are
> there to avoid ICEs in case CLASS_DATA (sym) has issues, and we all
> know Gerhard who showed that he is an expert in exploiting this.
>
> To sum up, I'd prefer to use the safer form if it works.  If it
> doesn't, I would expect a latent issue.
>
> The rest of the code looked good to me, but I was suspicious about
> the handling of CHARACTER.
>
> Nasty as I am, I modified the testcase to use character(kind=4)
> instead of kind=1 (see attached).  This either fails here (stop 10),
> or if I activate the marked line
>
> !    cont = tContainer('hello!')       ! ### ICE! ###
>
> I get an ICE.
>
> Can you have another look?
>
> Thanks,
> Harald
>
> >
>
> > OK for trunk?
> >
> > Paul
> >
> > Fortran: Enable class expressions in structure constructors [PR49213]
> >
> > 2023-06-24  Paul Thomas  <pault@gcc.gnu.org>
> >
> > gcc/fortran
> > PR fortran/49213
> > * expr.cc (gfc_is_ptr_fcn): Guard pointer attribute to exclude
> > class expressions.
> > * resolve.cc (resolve_assoc_var): Call gfc_is_ptr_fcn to allow
> > associate names with pointer function targets to be used in
> > variable definition context.
> > * trans-decl.cc (get_symbol_decl): Remove extraneous line.
> > * trans-expr.cc (alloc_scalar_allocatable_subcomponent): Obtain
> > size of intrinsic and character expressions.
> > (gfc_trans_subcomponent_assign): Expand assignment to class
> > components to include intrinsic and character expressions.
> >
> > gcc/testsuite/
> > PR fortran/49213
> > * gfortran.dg/pr49213.f90 : New test



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- Albert Einstein