https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107968
Bug ID: 107968
Summary: array slicing gives wrong result for an array pointer
defined in a subroutine
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: dreier at dkrz dot de
Target Milestone: ---
Created attachment 54010
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54010&action=edit
source code
The following code show some weird behavior to me:
```
PROGRAM foo
implicit none
TYPE t_geographical_coordinates
REAL :: lon
REAL :: lat
END TYPE t_geographical_coordinates
TYPE t_vertices
REAL, POINTER :: vlon(:) => null()
REAL, POINTER :: vlat(:) => null()
END TYPE t_vertices
TYPE(t_vertices), POINTER :: vertices_pointer
TYPE(t_vertices), TARGET :: vertices_target
TYPE(t_geographical_coordinates), ALLOCATABLE, TARGET :: vertex(:)
! initialization
ALLOCATE(vertex(2))
vertex%lon = 1
vertex%lat = 2
! obtain pointer to (non-contiguous) field
vertices_target%vlon => vertex%lon
! set pointer in a subroutine
CALL set_vertices_pointer(vertices_target)
WRITE (0,*) vertices_pointer%vlon
WRITE (0,*) vertices_pointer%vlon(1:)
! It seems that setting the pointer in a subroutine does something else
than
! setting it directly. Furthermore uncommenting the following line fixes
the
! issue but changes the output of the lines above ?!
! vertices_pointer => vertices_target
CONTAINS
SUBROUTINE set_vertices_pointer(vertices)
TYPE(t_vertices), POINTER, INTENT(IN) :: vertices
vertices_pointer => vertices
END SUBROUTINE set_vertices_pointer
END PROGRAM foo
```
I expect the output to be:
```
1.00000000 1.00000000
1.00000000 1.00000000
```
Instead, the compiled program gives me
```
1.00000000 1.00000000
1.00000000 2.00000000
```
Compiled with gfortran 12.2 on Ubuntu 22.10.
No warnings with `-Wall -Wextra`. Same behavior with `-fno-strict-aliasing
-fwrapv`.
