[Bug fortran/60777] New: Fortran 2003: RECURSIVE function rejected in specification expression

[Bug fortran/60777] New: Fortran 2003: RECURSIVE function rejected in specification expression

[vladimir.fuka at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60777

            Bug ID: 60777
           Summary: Fortran 2003: RECURSIVE function rejected in
                    specification expression
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vladimir.fuka at gmail dot com

John Harper reports on comp.lang.fortran:

! A recursive function in a specification expression
  module recur 
    implicit none
  contains

    pure recursive function f(n) result(answer)
      integer,intent(in) ::   n
      integer            ::             answer
      if (n<2) then
         answer = 1
      else
         answer = f(n-1)*n
      end if
    end function f ! factorial of max(n,0)

    pure function usef(    n)
      integer,intent(in):: n
      character(f(n))   :: usef
      usef = repeat('*',f(n))
    end function usef
  end module recur

  program testspecexpr
    use recur
    implicit none
    integer :: n
    do n = 1,3
       print *,usef(n)
    end do
  end program testspecexpr



Which gives gfortran-4.9 resspec.f90 
resspec.f90:18.16:

      character(f(n))   :: usef
                1
Error: Specification function 'f' at (1) cannot be RECURSIVE



but Fortran 2003 and 2008 just require:

7.1.11.6 (F2008): Evaluation of a specification expression shall not directly
or indirectly cause a procedure defined by the subprogram in which it appears
to be invoked.

[Bug fortran/60777] Fortran 2003: RECURSIVE function rejected in specification expression

[kargl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60777

--- Comment #1 from kargl at gcc dot gnu.org ---
Index: expr.c
===================================================================
--- expr.c      (revision 208947)
+++ expr.c      (working copy)
@@ -2733,12 +2733,10 @@ external_spec_function (gfc_expr *e)
       return false;
     }

-  if (f->attr.recursive)
-    {
-      gfc_error ("Specification function '%s' at %L cannot be RECURSIVE",
-                f->name, &e->where);
+  if (f->attr.recursive
+      && !gfc_notify_std (GFC_STD_F2003, "Specification function '%s' "
+                         "at %L cannot be RECURSIVE",  f->name, &e->where));
       return false;
-    }

   return restricted_args (e->value.function.actual);
 }

[Bug fortran/60777] Fortran 2003: RECURSIVE function rejected in specification expression

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60777

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-04-09
     Ever confirmed|0                           |1

--- Comment #2 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Confirmed.