[Bug fortran/66973] New: Incorrect resolution of generic interface with TYPE(C_PTR)

[Bug fortran/66973] New: Incorrect resolution of generic interface with TYPE(C_PTR)

[brtnfld at hdfgroup dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

            Bug ID: 66973
           Summary: Incorrect resolution of generic interface with
                    TYPE(C_PTR)
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: brtnfld at hdfgroup dot org
  Target Milestone: ---

Created attachment 36035
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36035&action=edit
H5Tff.F90 -- contains the module

The following sequence picks the f90 interface, when it should pick the

[Bug fortran/66973] Incorrect resolution of generic interface with TYPE(C_PTR)

[brtnfld at hdfgroup dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

--- Comment #1 from Scot Breitenfeld <brtnfld at hdfgroup dot org> ---
Created attachment 36036
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36036&action=edit
fortranlib_test_F03, main program

[Bug fortran/66973] Incorrect resolution of generic interface with TYPE(C_PTR)

[brtnfld at hdfgroup dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

--- Comment #2 from Scot Breitenfeld <brtnfld at hdfgroup dot org> ---
The following sequence picks the f90 interface, when it should pick the f03
(TYPE(C_PTR)) interface.

gfortran -c H5Tff.F90
gfortran fortranlib_test_F03.f90 -o H5Tff.o

The program prints: 

PRINT*,'Inside pick_f90'

[Bug fortran/66973] Incorrect resolution of generic interface with TYPE(C_PTR)

[brtnfld at hdfgroup dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

--- Comment #3 from Scot Breitenfeld <brtnfld at hdfgroup dot org> ---
(In reply to Scot Breitenfeld from comment #2)
> The following sequence picks the f90 interface, when it should pick the f03
> (TYPE(C_PTR)) interface.
> 
> gfortran -c H5Tff.F90
> gfortran fortranlib_test_F03.f90 -o H5Tff.o
> 
> The program prints: 
> 
> PRINT*,'Inside pick_f90'

I meant gfortran fortranlib_test_F03.f90 H5Tff.o

[Bug fortran/66973] Incorrect resolution of generic interface with TYPE(C_PTR)

[brtnfld at hdfgroup dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

--- Comment #4 from Scot Breitenfeld <brtnfld at hdfgroup dot org> ---
The work around is instead to do:

PROGRAM main
  USE H5T
  IMPLICIT NONE
  REAL, TARGET :: val
  TYPE(C_PTR) :: f_ptr
  f_ptr = C_LOC(val)
  CALL pickone(f_ptr)
END PROGRAM main

[Bug fortran/66973] Incorrect resolution of generic interface with TYPE(C_PTR)

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-07-22
     Ever confirmed|0                           |1

--- Comment #5 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Confirmed when the test is made of two files. If I merge the two files in one,
I get

 Inside pick_f03

Tested with 4.9 to trunk (6.0).

[Bug fortran/66973] Incorrect resolution of generic interface with TYPE(C_PTR)

[brtnfld at hdfgroup dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

--- Comment #6 from Scot Breitenfeld <brtnfld at hdfgroup dot org> ---
it also works if you add USE ISO_C_BINDING to the main program:

PROGRAM main
  USE ISO_C_BINDING
  USE H5T
  IMPLICIT NONE
  REAL, TARGET :: val
  CALL pickone(C_LOC(val))
END PROGRAM main

[Bug fortran/66973] Incorrect resolution of generic interface with TYPE(C_PTR)

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2015-07-22 00:00:00         |2023-4-12
                 CC|                            |anlauf at gcc dot gnu.org

--- Comment #7 from anlauf at gcc dot gnu.org ---
This issue still persists at r13-7146 when using separate files for the
module and the main program.

gfortran's behavior is fragile: using e.g.

  USE ISO_C_BINDING, only: C_PTR

in the module makes the code work as desired (needs USE ISO_C_BINDING in the
main).

However, using

  USE ISO_C_BINDING, only: C_PTR, C_LOC

in the module breaks it again.

The behavior also depends on the order of USE statements in the main:

  USE H5T
  USE ISO_C_BINDING

differs from

  USE ISO_C_BINDING
  USE H5T

which should not happen...

[Bug fortran/66973] Incorrect resolution of generic interface with TYPE(C_PTR)

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66973

--- Comment #8 from anlauf at gcc dot gnu.org ---
(In reply to anlauf from comment #7)
> The behavior also depends on the order of USE statements in the main:
> 
>   USE H5T
>   USE ISO_C_BINDING
> 
> differs from
> 
>   USE ISO_C_BINDING
>   USE H5T
> 
> which should not happen...

A workaround is to use a temporary of type(c_ptr) for the actual argument:

  type(c_ptr) :: ptr
  CALL pickone(ptr)

This works for me.

Possibly the issue is with the resolution of (the type of?) C_LOC ...