re PR fortran/15754 (Accepts assignment of the form P = NULL())

fortran/
PR fortran/15754
* expr.c (gfc_check_assign): Print ranks if incompatible. Issue
warning if assigning NULL().

testsuite/
PR fortran/17574
* gfortran.dg/pr15754.f90: New test.
the changes to expr.c were accidentally committed previously

From-SVN: r84521

gcc/fortran/ChangeLog

@@ -17,6 +17,10 @@
 	* primary.c (match_boz_constant): Call gfc_notify_std only if
 	we actually have a non-standard boz-literal-constant.
 
+	PR fortran/15754
+	* expr.c (gfc_check_assign): Print ranks if incompatible. Issue
+	warning if assigning NULL().
+
 2004-07-11  Joseph S. Myers  <jsm@polyomino.org.uk>
 
 	* f95-lang.c (set_block): Remove.

gcc/testsuite/gfortran.dg/pr15754.f90

+! we didn't give a warning if the RHS of an assignment was NULL
+! { dg-do-compile }
+INTEGER, POINTER :: P
+I = NULL() ! { dg-warning "NULL appears" "Assignment non-pointer = NULL" }
+P = NULL() ! { dg-warning "NULL appears" "Assignment pointer = NULL" }
+P => NULL()
+END