[Bug fortran/49331] Accepts invalid specification expressions

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49331

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-06-09 08:17:30 UTC ---
The examples of the IR 11-101 do not work for me as the examples do not involve
constant expressions when defining the kind value (unless I am seriously
mistaken).

Better/shorter example:

module m
  type t
    integer :: i
  end type t

  interface LEN
    module procedure my_len
  end interface LEN

contains

  function one(x)
    type(t),intent(in) :: x
    character(len=LEN(x)) :: one
    one = ''
  end function one

  integer pure function my_len(x)
    type(t), intent(in) :: x
    my_len  = x%i
  end function my_len
end module m


The suggested wording for specification expressions - but also for constant
expressions (cf. 11-101 for the latter) is:

  Replace F08/7.1.11p9 [10-007:151:13-15] by

  "A generic entity referenced in a specification expression in the
   <specification-part> of a scoping unit shall have no specific
   procedures defined in that scoping unit, or its host scoping unit,
   subsequent to the specification expression."

Thus, the example would also be invalid if instead of
  LEN(x)   ! Calls specific which is later defined
one had used
  LEN(x%i) ! Call intrinsic LEN
(and, indeed, crayftn also rejects that example).


I wonder whether there is a better method than:

  if (generic_sym->ns == current_ns->parent && !generic_sym->attr.use_assoc)
    {
    LOOP through all specific_sym:
      if (current_ns->parent == specific_sym->ns->parent)
          && LOCATION_LINE (current_loc->location)
             < LOCATION_LINE (specific_sym->declared_at->location))
        gfc_error (...)
    }

(In case the specific function is referenced for a specific function which is
an internal function, gfortran already prints: "Error: Generic function 'len'
at (1) is not consistent with a specific intrinsic interface".)


 * * *

Example for a constant expression:

module m
  type t
    integer :: i
  end type t
  interface LEN
    module procedure my_len
  end interface LEN
contains
  function one(x)
    type(t),intent(in) :: x
    character(kind=kind(LEN())) :: one
    one = ''
  end function one
  integer pure function my_len()
    my_len  = 1
  end function my_len
end module m