[Bug fortran/104908] New: gfortran 11/trunk regression: incorrect Fortran out-of-bound runtime error.

[Bug fortran/104908] New: gfortran 11/trunk regression: incorrect Fortran out-of-bound runtime error.

[a.shahmoradi at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

            Bug ID: 104908
           Summary: gfortran 11/trunk regression: incorrect Fortran
                    out-of-bound runtime error.
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: a.shahmoradi at gmail dot com
  Target Milestone: ---

The following code appears to be standard-conforming, but gfortran throws a
runtime error with the flag `-check=bounds`,

```
program test

    type vec
        integer :: x(3)
    end type

    type(vec) :: v(2)

    call sub(v)

contains

    subroutine sub (v)

        class(vec), intent(in) :: v(:)

        integer :: k, q(3)

        q = [ (v(1)%x(k), k = 1, 3) ]   ! <-- fails here

   end subroutine

end program
```

Here is the error message,

```
At line 19 of file /app/example.f90
Fortran runtime error: Index '3' of dimension 1 of array 'v%_data%x' above
upper bound of 2
```

This is a gfortran-11 regression since the code is functional with gfortran-10
with the same compile flags. It can be tested here with different versions of
gfortran: https://godbolt.org/z/K6chcYE5e

This issue was raised in a StackOverflow question:
https://stackoverflow.com/questions/71441100/class-dummy-argument-for-array-of-custom-types-stuck-on-fcheck-bounds

I am only reporting it to the GNU Bugzilla.

[Bug fortran/104908] [11/12 Regression] incorrect Fortran out-of-bound runtime error.

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|gfortran 11/trunk           |[11/12 Regression]
                   |regression: incorrect       |incorrect Fortran
                   |Fortran out-of-bound        |out-of-bound runtime error.
                   |runtime error.              |
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-03-15
           Priority|P3                          |P4

--- Comment #1 from anlauf at gcc dot gnu.org ---
Likely caused by the fix for PR95331 (r11-1235).  Class-related.
Applying

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index cfb6eac11c7..3a14600101f 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -3864,8 +3864,8 @@ gfc_conv_array_ref (gfc_se * se, gfc_array_ref * ar,
gfc_expr *expr,
     }

   decl = se->expr;
-  if (IS_CLASS_ARRAY (sym) && sym->attr.dummy && ar->as->type != AS_DEFERRED)
-    decl = sym->backend_decl;
+  // if (IS_CLASS_ARRAY (sym) && sym->attr.dummy && ar->as->type !=
AS_DEFERRED)
+  //   decl = sym->backend_decl;

   cst_offset = offset = gfc_index_zero_node;
   add_to_offset (&cst_offset, &offset, gfc_conv_array_offset (decl));

apparently "fixes" the wrong bounds check.

[Bug fortran/104908] [11/12 Regression] incorrect Fortran out-of-bound runtime error.

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |albandil at atlas dot cz

--- Comment #2 from anlauf at gcc dot gnu.org ---
*** Bug 104972 has been marked as a duplicate of this bug. ***

[Bug fortran/104908] [11/12 Regression] incorrect Fortran out-of-bound runtime error.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.3

[Bug fortran/104908] [11/12 Regression] incorrect Fortran out-of-bound runtime error.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.3                        |11.4

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 11.3 is being released, retargeting bugs to GCC 11.4.

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.4                        |11.5

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 11.4 is being released, retargeting bugs to GCC 11.5.

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |anlauf at gcc dot gnu.org
           Keywords|                            |ice-on-valid-code

--- Comment #5 from anlauf at gcc dot gnu.org ---
The following code generates an ICE:

subroutine sub (v)
  implicit none
  type vec
     integer :: x(2,1)
  end type vec
! type(vec),  intent(in) :: v(:)   ! works with type
  class(vec), intent(in) :: v(:)   ! ICE with class
  integer :: k
  k = v(1)%x(2,1)
end

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

--- Comment #6 from anlauf at gcc dot gnu.org ---
Studying the cases that ICE (CLASS array dummy) and testcase PR95331.f90
which fixes an unlimited polymorphic problem, I tried the following change:

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index f6ddce2d023..be7d42ff847 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -4097,7 +4097,10 @@ gfc_conv_array_ref (gfc_se * se, gfc_array_ref * ar,
gfc_expr *expr,
     }

   decl = se->expr;
-  if (IS_CLASS_ARRAY (sym) && sym->attr.dummy && ar->as->type != AS_DEFERRED)
+  if (UNLIMITED_POLY(sym)
+      && IS_CLASS_ARRAY (sym)
+      && sym->attr.dummy
+      && ar->as->type != AS_DEFERRED)
     decl = sym->backend_decl;

   cst_offset = offset = gfc_index_zero_node;


This is currently regtesting.

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

--- Comment #7 from anlauf at gcc dot gnu.org ---
(In reply to anlauf from comment #6)
> This is currently regtesting.

Regtesting succeeded.

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[jvdelisle at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

Jerry DeLisle <jvdelisle at gcc dot gnu.org> changed:

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

--- Comment #8 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> ---
(In reply to anlauf from comment #7)
> (In reply to anlauf from comment #6)
> > This is currently regtesting.
> 
> Regtesting succeeded.

Simple enough to just commit.

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

--- Comment #9 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:ce61de1b8a1bb3a22118e900376f380768f2ba59

commit r14-8471-gce61de1b8a1bb3a22118e900376f380768f2ba59
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sat Jan 27 17:41:43 2024 +0100

    Fortran: fix bounds-checking errors for CLASS array dummies [PR104908]

    Commit r11-1235 addressed issues with bounds of unlimited polymorphic array
    dummies.  However, using the descriptor from sym->backend_decl does break
    the case of CLASS array dummies.  The obvious solution is to restrict the
    fix to the unlimited polymorphic case, thus keeping the original descriptor
    in the ordinary case.

    gcc/fortran/ChangeLog:

            PR fortran/104908
            * trans-array.cc (gfc_conv_array_ref): Restrict use of transformed
            descriptor (sym->backend_decl) to the unlimited polymorphic case.

    gcc/testsuite/ChangeLog:

            PR fortran/104908
            * gfortran.dg/pr104908.f90: New test.

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Harald Anlauf
<anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:5741e5fc53161ccf2056e0670334ea528431feb7

commit r13-8266-g5741e5fc53161ccf2056e0670334ea528431feb7
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sat Jan 27 17:41:43 2024 +0100

    Fortran: fix bounds-checking errors for CLASS array dummies [PR104908]

    Commit r11-1235 addressed issues with bounds of unlimited polymorphic array
    dummies.  However, using the descriptor from sym->backend_decl does break
    the case of CLASS array dummies.  The obvious solution is to restrict the
    fix to the unlimited polymorphic case, thus keeping the original descriptor
    in the ordinary case.

    gcc/fortran/ChangeLog:

            PR fortran/104908
            * trans-array.cc (gfc_conv_array_ref): Restrict use of transformed
            descriptor (sym->backend_decl) to the unlimited polymorphic case.

    gcc/testsuite/ChangeLog:

            PR fortran/104908
            * gfortran.dg/pr104908.f90: New test.

    (cherry picked from commit ce61de1b8a1bb3a22118e900376f380768f2ba59)

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

--- Comment #11 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Harald Anlauf
<anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:f7b3a82be2f4e9f43524185226c0df686c7b0154

commit r12-10148-gf7b3a82be2f4e9f43524185226c0df686c7b0154
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sat Jan 27 17:41:43 2024 +0100

    Fortran: fix bounds-checking errors for CLASS array dummies [PR104908]

    Commit r11-1235 addressed issues with bounds of unlimited polymorphic array
    dummies.  However, using the descriptor from sym->backend_decl does break
    the case of CLASS array dummies.  The obvious solution is to restrict the
    fix to the unlimited polymorphic case, thus keeping the original descriptor
    in the ordinary case.

    gcc/fortran/ChangeLog:

            PR fortran/104908
            * trans-array.cc (gfc_conv_array_ref): Restrict use of transformed
            descriptor (sym->backend_decl) to the unlimited polymorphic case.

    gcc/testsuite/ChangeLog:

            PR fortran/104908
            * gfortran.dg/pr104908.f90: New test.

    (cherry picked from commit ce61de1b8a1bb3a22118e900376f380768f2ba59)

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Harald Anlauf
<anlauf@gcc.gnu.org>:

https://gcc.gnu.org/g:07b575d5860dbc8791dbb9d10af9f918f34d7ff0

commit r11-11231-g07b575d5860dbc8791dbb9d10af9f918f34d7ff0
Author: Harald Anlauf <anlauf@gmx.de>
Date:   Sat Jan 27 17:41:43 2024 +0100

    Fortran: fix bounds-checking errors for CLASS array dummies [PR104908]

    Commit r11-1235 addressed issues with bounds of unlimited polymorphic array
    dummies.  However, using the descriptor from sym->backend_decl does break
    the case of CLASS array dummies.  The obvious solution is to restrict the
    fix to the unlimited polymorphic case, thus keeping the original descriptor
    in the ordinary case.

    gcc/fortran/ChangeLog:

            PR fortran/104908
            * trans-array.c (gfc_conv_array_ref): Restrict use of transformed
            descriptor (sym->backend_decl) to the unlimited polymorphic case.

    gcc/testsuite/ChangeLog:

            PR fortran/104908
            * gfortran.dg/pr104908.f90: New test.

    (cherry picked from commit ce61de1b8a1bb3a22118e900376f380768f2ba59)

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

anlauf at gcc dot gnu.org changed:

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

--- Comment #13 from anlauf at gcc dot gnu.org ---
Fixed on mainline for gcc-14, and backported to all open branches.

Thanks for the report, and sorry that it took so long.

[Bug fortran/104908] [11/12/13/14 Regression] incorrect Fortran out-of-bound runtime error.

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104908

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |philippe.wautelet at aero dot obs-
                   |                            |mip.fr

--- Comment #14 from anlauf at gcc dot gnu.org ---
*** Bug 109157 has been marked as a duplicate of this bug. ***