[Bug fortran/91556] Problems with better interface checking

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91556

--- Comment #21 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Thu, Aug 29, 2019 at 09:38:09PM +0000, tkoenig at gcc dot gnu.org wrote:
> --- Comment #18 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
> (In reply to anlauf from comment #14)
> > The current solution is a bit annoying for implicitly-derived interfaces.
> > 
> > Consider a code like:
> > 
> > module foo
> >   implicit none
> >   type t1
> >      integer :: i = 1
> >   end type t1
> >   type t2
> >      integer :: j = 2
> >   end type t2
> > contains
> >   subroutine s1 (x)
> >     type(t1) :: x
> >     call my_mpi_bcast_wrapper (x, storage_size (x)/8)
> >   end subroutine s1
> >   subroutine s2 (y)
> >     type(t2) :: y
> >     call my_mpi_bcast_wrapper (y, storage_size (y)/8)
> >   end subroutine s2
> > end module foo
> > 
> > That's perfectly legal,
> 
> This is illegal, as far as I know. The type names are different,
> which makes them different types.
> 

Thomas,

I'll leave this to whatever you decide.  gfortran could
do -fallow-argument-mismatch=n. n=0 is an error, n=1
is for a warning, and n>1 silences the warning. n=0 would
be the default setting as I think the error messages 
will encourage people to fix their codes.

PS: the MPI argument is somewhat bogus.  At least, OpenMPI
has an Fortran 2008 interface for mpi_bcast() (ie., 
11 years ago).

USE mpi_f08
MPI_Bcast(buffer, count, datatype, root, comm, ierror)
    TYPE(*), DIMENSION(..) :: buffer
    INTEGER, INTENT(IN) :: count, root
    TYPE(MPI_Datatype), INTENT(IN) :: datatype
    TYPE(MPI_Comm), INTENT(IN) :: comm
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror