[Bug fortran/61527] New: class/extends, multiple generic assignment, accept invalid

[Bug fortran/61527] New: class/extends, multiple generic assignment, accept invalid

[mrestelli at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

            Bug ID: 61527
           Summary: class/extends, multiple generic assignment, accept
                    invalid
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mrestelli at gmail dot com

Hi,
   I see that gfortran accepts the following code (even with strict
debug flags) which is ambiguous in the resolution of the generic. The
code is correctly rejected if disp2 uses CLASS(t2) instead of
TYPE(t2), while with TYPE(T2) the code compiles and DISP2 is called,
which I think should not be allowed.


$ gfortran --version
GNU Fortran (GCC) 4.10.0 20140613 (experimental)



module m
 implicit none

 private
 public :: t1, t2, disp

 type :: t1
  integer :: i = 1
 end type t1

 type, extends(t1) :: t2
  real :: r = 2.0
 end type t2

 interface disp
  module procedure disp1, disp2
 end interface

contains

 subroutine disp1(x)
  class(t1), intent(in) :: x
   write(*,*) "Disp 1: ",x%i
 end subroutine disp1

 subroutine disp2(x)
  type(t2), intent(in) :: x ! <- accepted
  !class(t2), intent(in) :: x ! <- rejected
   write(*,*) "Disp 2: ",x%r
 end subroutine disp2

end module m


program p
 use m
 implicit none

 type(t1) :: a
 type(t2) :: b

 call disp(a)
 call disp(b)

end program p

[Bug fortran/61527] class/extends, multiple generic assignment, accept invalid

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Up to r200946 (2013-07-14, 4.9) gfortran gives an error

Error: Ambiguous interfaces 'disp2' and 'disp1' in generic interface 'disp' at
(1)

>From at least r201266 (2013-07-26) gfortran accepts the code. I did not find
any obvious culprit in this range for the change in behavior. I also don't know
what is the correct behavior.

[Bug fortran/61527] class/extends, multiple generic assignment, accept invalid

[mrestelli at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

--- Comment #2 from mrestelli <mrestelli at gmail dot com> ---
I am no expert, but I think that the correct behaviour is that of the
older version: the two interfaces indeed are ambiguous, since a call
like

 type(t2) :: b
 call disp(b)

could call both disp1 and disp2.

[Bug fortran/61527] [4.9/4.10 Regression] class/extends, multiple generic assignment, accept invalid

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid
                 CC|                            |burnus at gcc dot gnu.org
   Target Milestone|---                         |4.9.2
            Summary|class/extends, multiple     |[4.9/4.10 Regression]
                   |generic assignment, accept  |class/extends, multiple
                   |invalid                     |generic assignment, accept
                   |                            |invalid

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> ---
It seems to be due to the following code in interface.c, which was added for
PR57530 in r201329:

compare_type (gfc_symbol *s1, gfc_symbol *s2)
{
  if (s2->attr.ext_attr & (1 << EXT_ATTR_NO_ARG_CHECK))
    return 1;

  /* TYPE and CLASS of the same declared type are type compatible,
     but have different characteristics.  */
  if ((s1->ts.type == BT_CLASS && s2->ts.type == BT_DERIVED)
      || (s1->ts.type == BT_DERIVED && s2->ts.type == BT_CLASS))
    return 0;

[Bug fortran/61527] [4.9/4.10 Regression] class/extends, multiple generic assignment, accept invalid

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-07-12
     Ever confirmed|0                           |1

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Confirmed per comment 3.

[Bug fortran/61527] [4.9/5 Regression] class/extends, multiple generic assignment, accept invalid

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.9.2                       |4.9.3

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.9.2 has been released.

[Bug fortran/61527] [4.9/5 Regression] class/extends, multiple generic assignment, accept invalid

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P5

[Bug fortran/61527] [4.9/5 Regression] class/extends, multiple generic assignment, accept invalid

[janus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |janus at gcc dot gnu.org

--- Comment #6 from janus at gcc dot gnu.org ---
(In reply to Tobias Burnus from comment #3)
> It seems to be due to the following code in interface.c, which was added for
> PR57530 in r201329:

Reverting this part of the patch ...


Index: gcc/fortran/interface.c
===================================================================
--- gcc/fortran/interface.c    (Revision 219753)
+++ gcc/fortran/interface.c    (Arbeitskopie)
@@ -515,12 +515,6 @@
   if (s2->attr.ext_attr & (1 << EXT_ATTR_NO_ARG_CHECK))
     return 1;

-  /* TYPE and CLASS of the same declared type are type compatible,
-     but have different characteristics.  */
-  if ((s1->ts.type == BT_CLASS && s2->ts.type == BT_DERIVED)
-      || (s1->ts.type == BT_DERIVED && s2->ts.type == BT_CLASS))
-    return 0;
-
   return gfc_compare_types (&s1->ts, &s2->ts) || s2->ts.type == BT_ASSUMED;
 }


... indeed brings back the expected error message for comment 0. However, it
causes a few testsuite regressions:

FAIL: gfortran.dg/dummy_procedure_4.f90   -O   (test for errors, line 28)
FAIL: gfortran.dg/proc_ptr_30.f90   -O   (test for errors, line 25)
FAIL: gfortran.dg/proc_ptr_comp_32.f90   -O   (test for errors, line 34)
FAIL: gfortran.dg/proc_ptr_comp_33.f90   -O   (test for errors, line 14)
FAIL: gfortran.dg/proc_ptr_comp_33.f90   -O   (test for errors, line 54)

[Bug fortran/61527] [4.9/5 Regression] class/extends, multiple generic assignment, accept invalid

[janus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

--- Comment #7 from janus at gcc dot gnu.org ---
Reverting the whole commit of r201329 does not work either, but produces a
different set of failures:

FAIL: gfortran.dg/class_to_type_3.f03   -O0  (test for excess errors)
FAIL: gfortran.dg/pointer_assign_8.f90   -O0  (test for excess errors)
FAIL: gfortran.dg/pointer_assign_9.f90   -O0  (test for excess errors)

[Bug fortran/61527] [4.9/5/6 Regression] class/extends, multiple generic assignment, accept invalid

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.9.3 has been released.

[Bug fortran/61527] [4.9/5/6 Regression] class/extends, multiple generic assignment, accept invalid

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.9.3                       |4.9.4

[Bug fortran/61527] [9/10/11/12 Regression] [OOP] class/extends, multiple generic assignment, accept invalid

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|8.5                         |9.4

--- Comment #13 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 8 branch is being closed.

[Bug fortran/61527] [9/10/11/12 Regression] [OOP] class/extends, multiple generic assignment, accept invalid

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.4                         |9.5

--- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9.4 is being released, retargeting bugs to GCC 9.5.

[Bug fortran/61527] [10/11/12/13 Regression] [OOP] class/extends, multiple generic assignment, accept invalid

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.5                         |10.4

--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed

[Bug fortran/61527] [10/11/12/13 Regression] [OOP] class/extends, multiple generic assignment, accept invalid

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.4                        |10.5

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.

[Bug fortran/61527] [11/12/13/14 Regression] [OOP] class/extends, multiple generic assignment, accept invalid

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.5                        |11.5

--- Comment #17 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.

[Bug fortran/61527] [11/12/13/14 Regression] [OOP] class/extends, multiple generic assignment, accept invalid

[pault at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61527

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
                 CC|                            |pault at gcc dot gnu.org

--- Comment #18 from Paul Thomas <pault at gcc dot gnu.org> ---
From at least 7.4.1 20191027 on, gfortran gives the correct result and detects
ambiguity for both cases. NAG and Intel agree.

Closing as resolved.

Paul