[Bug fortran/104630] New: module subroutine not accessible from submodule

["neil.n.carlson at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104630

            Bug ID: 104630
           Summary: module subroutine not accessible from submodule
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: neil.n.carlson at gmail dot com
  Target Milestone: ---

Consider this minimal example.

File module.f90:
  module modA
    private
    type, public :: typeA
    contains
      procedure :: foo
    end type
    interface
      module subroutine foo(this)
        class(typeA) :: this
      end subroutine
    end interface
  contains
    subroutine bar(this)
      type(typeA) :: this
    end subroutine
  end module

File submodule.f90:
  submodule(modA) foo_impl
  contains
    module subroutine foo(this)
      class(typeA) :: this
      call bar(this) ! a module subroutine in the host module
    end subroutine
  end submodule

File main.f90:
  use modA
  end

The implementation of subroutine foo in the submodule should have
access to subroutine bar defined in its host module but it apparently
does not judging from the link error:

$ gfortran module.f90 submodule.f90 main.f90
/usr/bin/ld: /tmp/ccEycu6t.o: in function `__moda_MOD_foo':
gfortran-20220221-submodule.f90:(.text+0x17): undefined reference to
`__moda_MOD_bar'
collect2: error: ld returned 1 exit status

If the 3 program units are combined into a single file, that will
compile and link without error.