1! { dg-do compile }
2! { dg-options "-fwhole-file -Wno-unused-dummy-argument" }
3!
4! PR fortran/34260
5!
6      PROGRAM MAIN
7      REAL A
8      CALL SUB(A)             ! { dg-error "Explicit interface required" }
9      END PROGRAM
10
11      SUBROUTINE SUB(A,I)
12      REAL :: A
13      INTEGER, OPTIONAL :: I
14      END SUBROUTINE
15