[Bug fortran/106576] New: Finalization of temporaries from functions not occuring

[Bug fortran/106576] New: Finalization of temporaries from functions not occuring

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

            Bug ID: 106576
           Summary: Finalization of temporaries from functions not
                    occuring
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tkoenig at gcc dot gnu.org
  Target Milestone: ---

Test case:

$ cat g2.f90
module y
  implicit none
  type foo
     integer :: n
   contains
     final :: cleanup
  end type foo
  interface assignment (=)
     module procedure assign
  end interface assignment (=)
contains

  subroutine assign (rop, op)
    type(foo), intent(inout) :: rop
    type(foo), intent(in) :: op
    rop%n = op%n + 1
    print '(A12,I3)',"assign", rop%n
  end subroutine assign

  function to_foo(n) result(res)
    integer, intent(in) :: n
    type (foo) :: res
    res%n = n
    print '(A12,I3)', "to_foo", res%n
  end function to_foo

  subroutine cleanup (self)
    type (foo), intent(inout) :: self
    print '(A12,I3)', "cleanup", self%n
  end subroutine cleanup
end module y

program memain
  use y
  implicit none
  call chk
contains
  subroutine chk
    type (foo) :: a
    a = to_foo(3)
  end subroutine chk
end program memain
$ gfortran g2.f90 && ./a.out
      to_foo  3
      assign  4
     cleanup  4
$ nagfor g2.f90 && ./a.out
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7101
[NAG Fortran Compiler normal termination]
      to_foo  3
      assign  4
     cleanup  3
     cleanup  4

NAG is in fact correct, the temporary from the function results should also
be finalized.

This actually blocks my little FMPFR library, so I might have a stab
at this myself.

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

--- Comment #1 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
There currently is a c.l.f. thread on this, with this test case.
Although what nagfor and xlf are doing makes sense, it does
not (to me) follow from the language of the standard.

https://groups.google.com/g/comp.lang.fortran/c/7bB13FEa10w is
the link to the thread.

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
           Assignee|unassigned at gcc dot gnu.org      |tkoenig at gcc dot gnu.org
   Last reconfirmed|                            |2022-08-13
             Status|UNCONFIRMED                 |ASSIGNED

--- Comment #2 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Created attachment 53451
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53451&action=edit
Concept  patch to show where stuff can be added (finding the cases only)

Here's a raw concept patch which shows (via fprintf) where the work could
be done.  The idea is to look at the statement (and nothing else) and
then create a finalization block around it if there is something to
finalize. When creating the temporary with gfc_create_var, it probably would
make sense to add it to the symbols of the block as well and add it to
the routines to be finalized.

How does that sound?

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW

--- Comment #3 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
No time to work on this at the moment.

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

--- Comment #4 from Paul Thomas <pault at gcc dot gnu.org> ---
Created attachment 53977
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53977&action=edit
Ongoing patch for PR37336

Fixes this PR, so testcase will be added to the collection.

Paul

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

--- Comment #5 from Paul Thomas <pault at gcc dot gnu.org> ---
Hi Thomas,

I hope that you are well and that the lack of time is for a good cause?

I have just returned to my finalizer patch. With it applied, your testcase
produces the same output as NAG.

I will attach the present version of the patch to this PR.

Cheers

Paul

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

--- Comment #6 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---

> I hope that you are well and that the lack of time is for a good cause?

Hi Paul,

yes, I'm well, and the lack of time is indeed for a good cause :-)

> I have just returned to my finalizer patch. With it applied, your testcase
> produces the same output as NAG.

That's great!

> I will attach the present version of the patch to this PR.

Is there a chance that we will see this patch in gcc13?  Even if it
does not fix every last bug in finalizers in gfortran, it would still
be a very large improvement compared to the current condition.

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

--- Comment #7 from Paul Thomas <pault at gcc dot gnu.org> ---
(In reply to Thomas Koenig from comment #6)
>  
> > I hope that you are well and that the lack of time is for a good cause?
> 
> Hi Paul,
> 
> yes, I'm well, and the lack of time is indeed for a good cause :-)
> 
> > I have just returned to my finalizer patch. With it applied, your testcase
> > produces the same output as NAG.
> 
> That's great!
>  
> > I will attach the present version of the patch to this PR.
> 
> Is there a chance that we will see this patch in gcc13?  Even if it
> does not fix every last bug in finalizers in gfortran, it would still
> be a very large improvement compared to the current condition.

Hi Thomas,

It's good to hear from you. I hope to submit the patches before Christmas. I am
working on some final wrinkles and testcases. I am still intensely busy on the
daytime job, which is something of a blocker.

Regards

Paul

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Paul Thomas <pault@gcc.gnu.org>:

https://gcc.gnu.org/g:d7caf313525a46f200d7f5db1ba893f853774aee

commit r13-6747-gd7caf313525a46f200d7f5db1ba893f853774aee
Author: Paul Thomas <pault@gcc.gnu.org>
Date:   Sat Mar 18 07:56:23 2023 +0000

    Fortran: Fix bugs and missing features in finalization [PR37336]

    2023-03-18  Paul Thomas  <pault@gcc.gnu.org>

    gcc/fortran
            PR fortran/103854
            PR fortran/96122
            PR fortran/37336
            * class.cc (finalize_component): Include the missing arguments
            in the call to the component's finalizer wrapper.
            (has_finalizer_component): Do not return true for procedure
            pointer components.
            (finalizer_insert_packed_call): Remove the redundant argument
            in the call to the final subroutine.
            (generate_finalization_wrapper): Add support for assumed rank
            finalizers.
            (gfc_may_be_finalized): New helper function.
            * dump-parse-tree.cc (write_proc): Whitespace.
            * gfortran.h : Add prototype for gfc_may_be_finalized.
            * resolve.cc (resolve_function): Correct derived types that
            have an incomplete namespace.
            (resolve_where, gfc_resolve_where_code_in_forall,
            gfc_resolve_forall_body, gfc_resolve_code): Check that the op
            code is still EXEC_ASSIGN. If it is set lhs to must finalize.
            (is_finalizable_type): New function.
            (generate_component_assignments): Set must_finalize if needed.
            (gfc_resolve_finalizers): Error if assumed rank finalizer is
            not the only one. Warning on lack of scalar finalizer modified
            to account for assumed rank finalizers.
            (generate_final_call): New function.
            (generate_component_assignments): Enclose the outermost call in
            a block to capture automatic deallocation and final calls.
            Set must_finalize as required to satisfy the standards. Use an
            explicit pointer assignment for pointer components to capture
            finalization of the target. Likewise use explicit assignment
            for allocatable components. Do not use the temporary copy of
            the lhs in defined assignment if the component is allocatable.
            Put the temporary in the same namespace as the lhs symbol if
            the component may be finalized. Remove the leading assignment
            from the expansion of assignment of components that have their
            own defined assignment components. Suppress finalization of
            assignment of temporary components to the lhs. Make an explicit
            final call for the rhs function temporary if it exists.
            (gfc_resolve_code): Set must_finalize for assignments with an
            array constructor on the rhs.
            (gfc_resolve_finalizers): Ensure that an assumed rank finalizer
            is the only finalizer for that type and correct the surprising
            warning for the lack of a scalar finalizer.
            (check_defined_assignments): Handle allocatable components.
            (resolve_fl_derived): Set referenced the vtab for use
            associated symbols.
            (resolve_symbol): Set referenced an unreferenced symbol that
            will be finalized.
            * trans-array.cc (gfc_trans_array_constructor_value): Add code
            to finalize the constructor result. Warn that this feature was
            removed in F2018 and that it is suppressed by -std=2018.
            (trans_array_constructor): Add finalblock, pass to previous
            and apply to loop->post if filled.
            (gfc_add_loop_ss_code): Add se finalblock to outer loop post.
            (gfc_trans_array_cobounds, gfc_trans_array_bounds): Add any
            generated finalization code to the main block.
            (structure_alloc_comps): Add boolean argument to suppress
            finalization and use it for calls from
            gfc_deallocate_alloc_comp_no_caf. Otherwise it defaults to
            false.
            (gfc_copy_alloc_comp_no_fini): New wrapper for
            structure_alloc_comps.
            (gfc_alloc_allocatable_for_assignment): Suppress finalization
            by setting new arg in call to gfc_deallocate_alloc_comp_no_caf.
            (gfc_trans_deferred_array): Use gfc_may_be_finalized and do not
            deallocate the components of entities with a leading '_' in the
            name that are also marked as artificial.
            * trans-array.h : Add the new boolean argument to the prototype
            of gfc_deallocate_alloc_comp_no_caf with a default of false.
            Add prototype for gfc_copy_alloc_comp_no_fini.
            * trans-decl.cc(init_intent_out_dt): Tidy up the code.
            * trans-expr.cc (gfc_init_se): Initialize finalblock.
            (gfc_conv_procedure_call): Use gfc_finalize_tree_expr to
            finalize function results. Replace in-line block for class
            results with call to new function.
            (gfc_conv_expr): Finalize structure constructors for F2003 and
            F2008. Warn that this feature was deleted in F2018 and, unlike
            array constructors, is not default. Add array constructor
            finalblock to the post block.
            (gfc_trans_scalar_assign): Suppress finalization by setting new
            argument in call to gfc_deallocate_alloc_comp_no_caf. Add the
            finalization blocks to the main block.
            (gfc_trans_arrayfunc_assign): Use gfc_assignment_finalizer_call
            and ensure that finalization occurs after the evaluation of the
            rhs but using the initial value for the lhs. Finalize rhs
            function results using gfc_finalize_tree_expr.
            (trans_class_assignment, gfc_trans_assignment_1): As previous
            function, taking care to order evaluation, assignment and
            finalization correctly.
            * trans-io.cc (gfc_trans_transfer): Add the final block.
            * trans-stmt.cc (gfc_trans_call, gfc_trans_allocate): likewise.
            (trans_associate_var): Nullify derived allocatable components
            and finalize function targets with defined assignment
            components on leaving the block scope.
            (trans_allocate): Finalize source expressions, if required,
            and set init_expr artificial temporarily to suppress the
            finalization in gfc_trans_assignment.
            * trans.cc (gfc_add_finalizer_call): Do not finalize the
            temporaries generated in type assignment with defined
            assignment components.
            (gfc_assignment_finalizer_call): New function.
            (gfc_finalize_tree_expr): New function.
            * trans.h: Add finalblock to gfc_se. Add the prototypes for
            gfc_finalize_tree_expr and gfc_assignment_finalizer_call.

    gcc/testsuite/
            PR fortran/64290
            * gfortran.dg/finalize_38.f90 : New test.
            * gfortran.dg/finalize_38a.f90 : New test.
            * gfortran.dg/allocate_with_source_25.f90 : The number of final
            calls goes down from 6 to 4.
            * gfortran.dg/associate_25.f90 : Remove the incorrect comment.
            * gfortran.dg/auto_dealloc_2.f90 : Change the tree dump expr
            but the final count remains the same.
            * gfortran.dg/unlimited_polymorphic_8.f90 : Tree dump reveals
            foo.1.x rather than foo.0.x

            PR fortran/67444
            * gfortran.dg/finalize_39.f90 : New test.

            PR fortran/67471
            * gfortran.dg/finalize_40.f90 : New test.

            PR fortran/69298
            PR fortran/70863
            * gfortran.dg/finalize_41.f90 : New test.

            PR fortran/71798
            * gfortran.dg/finalize_42.f90 : New test.

            PR fortran/80524
            * gfortran.dg/finalize_43.f90 : New test.

            PR fortran/82996
            * gfortran.dg/finalize_44.f90 : New test.

            PR fortran/84472
            * gfortran.dg/finalize_45.f90 : New test.

            PR fortran/88735
            PR fortran/93691
            * gfortran.dg/finalize_46.f90 : New test.

            PR fortran/91316
            * gfortran.dg/finalize_47.f90 : New test.

            PR fortran/106576
            * gfortran.dg/finalize_48.f90 : New test.

            PR fortran/37336
            * gfortran.dg/finalize_49.f90 : New test.
            * gfortran.dg/finalize_50.f90 : New test.
            * gfortran.dg/finalize_51.f90 : New test.

[Bug fortran/106576] Finalization of temporaries from functions not occuring

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106576

Paul Thomas <pault at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #9 from Paul Thomas <pault at gcc dot gnu.org> ---
Thanks for the report Thomas.

I'll be bugging you in a few weeks to backport to 12-branch.

Tschuess

Paul