pawosm-arm
commented
6 years ago My new findings: I couldn't find any traces in flang code for the behavior as described in my original bug report. Therefore I started to look at this problem from different angles. I found that the problem is not in the (abstract) interface definition itself, it's the things in the next defined interface that causes the havoc. In my proposed workaround, by adding fake interface definition (as it turned out, it does not need to be abstract and the subroutine in it does not need to accept any parameters at all), I have only hidden the real problem under the carpet. The real problem is that the next interface defines subroutine in which another interface is nested (it's unnamed, but adding it an explicit name does not help with anything). Somehow presence of interface nested into subroutine causing surprising interaction with the list of interfaces defined so far. Original plplot code causing the havoc:
abstract interface
subroutine pltransform_proc_data( x, y, tx, ty, data )
import :: wp, c_ptr
implicit none
real(kind=wp), intent(in) :: x, y
real(kind=wp), intent(out) :: tx, ty
type(c_ptr), intent(in) :: data
end subroutine pltransform_proc_data
end interface
procedure(pltransform_proc_data), pointer :: pltransform_data
private:: pltransform_proc_data, pltransform_data
interface
subroutine interface_plcont( z, nx, ny, kx, lx, ky, ly, clevel, nlevel, transform, data ) &
bind(c,name='c_plcont')
import :: c_funptr, c_ptr
import :: private_plint, private_plflt
implicit none
integer(kind=private_plint), value, intent(in) :: nx, ny, kx, lx, ky, ly, nlevel
type(c_ptr), dimension(*), intent(in) :: z
real(kind=private_plflt), dimension(*), intent(in) :: clevel
type(c_ptr), value, intent(in) :: data
interface
subroutine transform( x, y, tx, ty, data ) bind(c)
import :: private_plflt
import :: c_ptr
implicit none
real(kind=private_plflt), value, intent(in) :: x, y
real(kind=private_plflt), intent(out) :: tx, ty
type(c_ptr), value, intent(in) :: data
end subroutine transform
end interface
end subroutine interface_plcont
end interface
private :: interface_plcont
Following is the original report. Visit comments below for my latest findings.
Wile compiling plplot-5.13.0 I've encountered bizarre error:
The only common detail of those lines listed above is that they try to assign a pointer to procedure(pltransform_proc_data) which is defined in an abstract interface:
The strange thing about it is that all other abstract interfaces (some even more complicated than this one!) were fine. The only thing I could say about this one is that it's the last one defined. So I added some phony abstract interface, nowhere used in the program, right after this one and the whole thing compiled! This error does not occur when compiling with gfortran.