re PR fortran/20888 (dereferencing NULL still accepted)

2007-07-03  Tobias Burnus  <burnus@net-b.de>

	PR fortran/20888
	* resolve.c (resolve_operator): Check for NULL as operand.

2007-07-03  Tobias Burnus  <burnus@net-b.de>

	PR fortran/20888
	* gfortran.dg/null_2.f90: New.

From-SVN: r126247

gcc/fortran/ChangeLog

+2007-07-03  Tobias Burnus  <burnus@net-b.de>
+
+	PR fortran/20888
+	* resolve.c (resolve_operator): Check for NULL as operand.
+
 2007-07-02  Tobias Burnus  <burnus@net-b.de>
 
 	* gfortran.texi (Fortran 2003): Add ISO Bind C.

gcc/fortran/resolve.c

@@ -2583,6 +2583,13 @@ resolve_operator (gfc_expr *e)
   op2 = e->value.op.op2;
   dual_locus_error = false;
 
+  if ((op1 && op1->expr_type == EXPR_NULL)
+      || (op2 && op2->expr_type == EXPR_NULL))
+    {
+      sprintf (msg, _("Invalid context for NULL() pointer at %%L"));
+      goto bad_op;
+    }
+
   switch (e->value.op.operator)
     {
     case INTRINSIC_UPLUS:

gcc/testsuite/ChangeLog

+2007-07-03  Tobias Burnus  <burnus@net-b.de>
+
+	PR fortran/20888
+	* gfortran.dg/null_2.f90: New.
+
 2007-07-03  Uros Bizjak  <ubizjak@gmail.com>
 	    Francois-Xavier Coudert <fxcoudert@gcc.gnu.org>
 

gcc/testsuite/gfortran.dg/null_2.f90

+! { dg-do compile }
+!
+! NULL(...) pointer is not allowed as operand
+! PR fortran/20888
+!
+! Contributed by Joost VandeVondele
+!
+PROGRAM main
+  IMPLICIT NONE
+  REAL, POINTER :: TEST
+  NULLIFY(TEST)
+  TEST => -NULL(TEST) ! { dg-error "Invalid context for NULL" }
+  IF (TEST .EQ. NULL(TEST)) TEST=>NULL() ! { dg-error "Invalid context for NULL" }
+  IF (NULL(TEST) .EQ. TEST) TEST=>NULL() ! { dg-error "Invalid context for NULL" }
+END PROGRAM main