[Bug fortran/105543] New: Function returning a class array with contiguous attribute rejected

[Bug fortran/105543] New: Function returning a class array with contiguous attribute rejected

[mscfd at gmx dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105543

            Bug ID: 105543
           Summary: Function returning a class array with contiguous
                    attribute rejected
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mscfd at gmx dot net
  Target Milestone: ---

Created attachment 52947
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52947&action=edit
func_contiguous.f90

The attached code, compiled with "gfortran func_contiguous.f90 -c", fails with
the error message

func_contiguous.f90:8:0:

    8 | function create() result(x)
      | 
Error: ‘create’ at (1) has the CONTIGUOUS attribute but is not an array pointer
or an assumed-shape or assumed-rank array.

[Bug fortran/105543] Function returning a class array with contiguous attribute rejected

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105543

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-05-10
     Ever confirmed|0                           |1

--- Comment #1 from anlauf at gcc dot gnu.org ---
Confirmed.

The code is accepted if you *don't* use the result clause, as in:

function create()
  class(a), dimension(:), contiguous, pointer :: create
end function create

There are a couple PRs about declarations involving CLASS where attributes
are specified separately.  There could be a relation.

[Bug fortran/105543] Function returning a class array with contiguous attribute rejected

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105543

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
                 CC|                            |anlauf at gcc dot gnu.org

--- Comment #2 from anlauf at gcc dot gnu.org ---
The following hack makes the code compile:

diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index 166b702cd9a..16813853b30 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -16102,6 +16116,10 @@ resolve_symbol (gfc_symbol *sym)
       specification_expr = saved_specification_expr;
     }

+  // Hackish fix-up for a CLASS result variable
+  if (sym->ts.type == BT_CLASS && sym->result && sym->result->attr.class_ok)
+    sym->attr.class_ok = sym->result->attr.class_ok;
+
   if (sym->ts.type == BT_CLASS && sym->attr.class_ok && sym->ts.u.derived
       && CLASS_DATA (sym))
     {


Not sure yet where this should have been properly set in the first place...

[Bug fortran/105543] Function returning a class array with contiguous attribute rejected

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105543

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |anlauf at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #3 from anlauf at gcc dot gnu.org ---
Submitted: https://gcc.gnu.org/pipermail/fortran/2023-December/059999.html

[Bug fortran/105543] Function returning a class array with contiguous attribute rejected

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105543

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Harald Anlauf <anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:1e462fb480d38de5f9a4578bbe5c5bc66a01a9ed

commit r14-6381-g1e462fb480d38de5f9a4578bbe5c5bc66a01a9ed
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Wed Dec 6 20:42:27 2023 +0100

    Fortran: function returning contiguous class array [PR105543]

    gcc/fortran/ChangeLog:

            PR fortran/105543
            * resolve.cc (resolve_symbol): For a CLASS-valued function having a
            RESULT clause, ensure that attr.class_ok is set for its symbol as
            well as for its resolved result variable.

    gcc/testsuite/ChangeLog:

            PR fortran/105543
            * gfortran.dg/contiguous_13.f90: New test.

[Bug fortran/105543] Function returning a class array with contiguous attribute rejected

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105543

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |14.0
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from anlauf at gcc dot gnu.org ---
Fixed on mainline for gcc-14.  Thanks for the report!

The fix seems backportable.  If needed, please inquire.