External function passed to Interface function

[Jon Hurst <jhurst at ucar dot edu>]

Hello,

The attached piece of code is giving me the following errors with 
gfortran 4.3.3 and some earlier versions (4.1.2). 


gfortran -o test2 test2.f90
test2.f90:46.28:

      res = recSum( a, res, UserFunction, UserOp )
                          1
Error: Type/rank mismatch in argument 'userfunction' at (1)
test2.f90:25.20:

 rs = recSum( a, b, test1, sumInts )
                  1
Error: Type/rank mismatch in argument 'userfunction' at (1)



The code compiles and runs on pgf90 7.0-7  and gfortran 4.0.3.   
Removing the opfunc argument from the test1 function seems to fix the 
error, but removes the desired functionality.  I'm curious as to whether 
this code breaks some rules from the specification, or whether this is a 
gfortran issue.  I should emphasize that the earlier version of gfortran 
(4.0.3) handled this code successfully.

Thanks for the assistance,

Jonathan Hurst
Software Engineer
National Center for Atmospheric Research

MODULE  funcs

CONTAINS

  INTEGER FUNCTION test1(a,b,opfunc) 
    INTEGER :: a,b
    INTEGER, EXTERNAL :: opfunc
    test1 = opfunc( a, b ) 
  END FUNCTION test1

  INTEGER FUNCTION sumInts(a,b)
    INTEGER :: a,b
    sumInts = a + b
  END FUNCTION sumInts

END MODULE funcs

PROGRAM test
  
  USE funcs 

  INTEGER :: rs
  INTEGER, PARAMETER :: a = 2, b = 1

  rs = recSum( a, b, test1, sumInts )
  write(*,*) "Results", rs

CONTAINS

  RECURSIVE INTEGER FUNCTION recSum( a,b,UserFunction,UserOp ) RESULT( res )
     
    IMPLICIT NONE

    INTEGER :: a,b
    INTERFACE 
       INTEGER FUNCTION UserFunction(a,b,opfunc) 
         INTEGER :: a,b
         INTEGER, EXTERNAL :: opfunc
       END FUNCTION UserFunction
    END INTERFACE
    INTEGER, EXTERNAL :: UserOp 

    res = UserFunction( a,b, UserOp )

    if( res .lt. 10 ) then
       res = recSum( a, res, UserFunction, UserOp ) 
    end if

  END FUNCTION recSum

END PROGRAM test