[flang] Compilation error of explicit declaration of dummy argument

[ohno-fj]

Version of flang-new : 16.0.0(77f2f34d696b77fe5bf05afbe7386966b6bcc8ba)

flang-new points out that there is no explicit type declaration of dummy argument.

The following are the test program, flang-new, gfortran and ifort compilation result.

snggm004_2.f90:

PROGRAM main
  IMPLICIT NONE
  EXTERNAL    sub1
  INTEGER  :: i1 = 1
  integer  :: j
  CALL sub (sub1, i1)
  print *,'OK'
END PROGRAM main

SUBROUTINE sub (routine, i)
  IMPLICIT NONE
  INTEGER, INTENT(IN   ) :: i
  CALL routine (i)
END SUBROUTINE sub

SUBROUTINE sub1 (ii)
  IMPLICIT NONE
  INTEGER, INTENT(IN   ) :: ii
  WRITE (6,*)  ii
END SUBROUTINE sub1

$ flang-new -flang-experimental-exec snggm004_2.f90
error: Semantic errors in snggm004_2.f90
./snggm004_2.f90:10:17: error: No explicit type declared for 'routine'
  SUBROUTINE sub (routine, i)
                  ^^^^^^^
$

$ gfortran snggm004_2.f90
$

$ ifort snggm004_2.f90
$

[llvmbot]

@llvm/issue-subscribers-flang-frontend

[klausler]

Bug remains in current sources, and would be a good first project for somebody in the "community" to fix.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

[shourya5]

I'd like to take this

[s-pratik]

Hii, I want to contribute can anyone help me how can I get started?

[omjavaid]

Hi s-pratik and shourya5 kindly assign this bug to you if you are interested in fixing it.

[s-pratik]

Hi s-pratik and shourya5 kindly assign this bug to you if you are interested in fixing it.

Ya sure I am interested but I need some help to understand the issue properly

[luporl]

It seems the issue is that routine's type not being explicitly declared should not be an error in this case, because of the call statement using it.
However, I'm having a hard time to find this in F2018 spec. If someone could point out where this is described it would help.

[kiranchandramohan]

In the standard (https://j3-fortran.org/doc/year/18/18-007r1.pdf), there is a section on Dummy procedure.

15.2.2.3 Dummy procedures
32 1 A dummy argument that is specified to be a procedure or appears as the procedure designator in a procedure
33 reference is a dummy procedure. A dummy procedure with the POINTER attribute is a dummy procedure
34 pointer.

There is some discussion about this in https://groups.google.com/g/comp.lang.fortran/c/X8SEt0Mx_X8/m/OeK7F0kJAgAJ.

[sscalpone]

Try with and without the IMPLICIT NONE in subroutine sub. That might give a clue to why the error is raised.