1 files changed, 33 insertions, 0 deletions
diff --git a/gcc/testsuite/gfortran.dg/func_assign.f90 b/gcc/testsuite/gfortran.dg/func_assign.f90
new file mode 100644
index 000000000..7ecf32941
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/func_assign.f90
@@ -0,0 +1,33 @@
+! { dg-do compile }
+!
+! PR fortran/31559
+! Do not allow assigning to external functions
+!
+! Contributed by Steve Kargl <sgk@troutmask.apl.washington.edu>
+!
+module mod
+  implicit none
+contains
+  integer function bar()
+    bar = 4
+  end function bar
+
+  subroutine a() 
+   implicit none
+   real :: fun
+   external fun
+   interface
+     function funget(a)
+       integer :: a
+     end function
+     subroutine sub()
+     end subroutine sub
+   end interface
+   sub = 'a'  ! { dg-error "is not a variable" }
+   fun = 4.4  ! { dg-error "is not a variable" }
+   funget = 4 ! { dg-error "is not a variable" }
+   bar = 5    ! { dg-error "is not a variable" }
+  end subroutine a
+end module mod
+
+end