[Bug fortran/113997] New: Bogus 'Warning: Interface mismatch in global procedure' with C binding

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113997

            Bug ID: 113997
           Summary: Bogus 'Warning: Interface mismatch in global
                    procedure' with C binding
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

The following warning is bogus, unless
  -fno-leading-underscore
is used:

    8 |     subroutine foo_c(x) bind(C, name="foo")
      |                    1
Warning: Interface mismatch in global procedure 'foo_c' at (1): Type mismatch
in argument 'x' (TYPE(c_ptr)/TYPE(*))

* * *

Because for
  'subroutine acc_attach()'
  'subroutine acc_attach_c(x) bind(C, name="acc_attach"')

(A) the global Fortran name 'acc_attach' differs from the local name
'acc_attach_c'

(B) the actual name (DECL_ASSEMBLER_NAME) differs: 'acc_attach_c' is
'acc_attach' but 'acc_attach' is 'acc_attach_c'.

* * *

! The C and Fortran interfaces are part of OpenACC 3.3
! An alternative implementation would be a C implementation using
! ISO_Fortran_binding.h.

subroutine acc_attach(x)
  use iso_c_binding, only : c_loc
  implicit none (external, type)

  type(*), dimension(..), target :: x

  interface
    subroutine acc_attach_c(x) bind(C, name="acc_attach")
      use iso_c_binding
      type(c_ptr) :: x
    end subroutine
  end interface

  call acc_attach_c(c_loc(x))
end