[Bug fortran/57778] New: Missing warning for -Wimplicit-procedure for dummy arguments

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57778

            Bug ID: 57778
           Summary: Missing warning for -Wimplicit-procedure for dummy
                    arguments
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org

Based on https://groups.google.com/forum/#!topic/comp.lang.fortran/3idUN6kMjjo

The following program should give a warning with -Wimplicit-procedure - but it
doesn't.


Expected:

* Intel (no special options):
z.f90(14): warning #6717: This name has not been given an explicit type.  
[FUN]
subroutine l1(inp,fun,outp)
------------------^

* gfortran (for non dummy arguments):
  Warning: Procedure 'fun' called at (1) is not explicitly declared

Note: -Wimplicit-procedure does not warn when one uses EXTERNAL.

Seemingly, the using it as dummy argument someone creates an EXTERNAL attribute
- at least there is no warning in the following case.


module subs
implicit none

!! The following is in the original code, but not relevant for this PR
!! However, the warning is also required with this code.
! interface
!  subroutine fun(inp,outp)
!   real,intent(in) :: inp
!   real,intent(out) :: outp
!  end subroutine fun
! end interface

contains

  subroutine l1(inp,fun,outp)
    implicit none
    real,intent(in) :: inp
    real,intent(out) :: outp
    call fun(inp,outp)
   end subroutine l1
end module subs