[Bug fortran/56939] New: [4.8/4.9 Regression] [OOP] Derived type is being used before it is defined

[janus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56939

             Bug #: 56939
           Summary: [4.8/4.9 Regression] [OOP] Derived type is being used
                    before it is defined
    Classification: Unclassified
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: janus@gcc.gnu.org


The following is a reduction of PR 55959 comment 0, which is valid code AFAICS:


module pdfs
  type, abstract :: pdf
    integer dims
  contains
    procedure(getx), deferred :: getx
  end type

  abstract interface
    function getx(this)
      import pdf
      class(pdf), intent(in) :: this
      real getx(this%dims)
    end function
  end interface

  type point
    real x, y
  end type

  type, extends(pdf) :: pdf_point
    type(point) p
  contains
    procedure :: getx => pdf_point_getx
  end type

contains

  function pdf_point_getx(this)
    class(pdf_point), intent(in) :: this
    real pdf_point_getx(this%dims)
  end function

end module pdfs


program abstract
  use pdfs
end program


With 4.8 and trunk it gives the nonsensical error message:

  use pdfs
      1
Error: Derived type 'pdf' at (1) is being used before it is defined

(while 4.7 accepts it without a problem.)