cp-tree.h (ansi_null_node): New variable.

* cp-tree.h (ansi_null_node): New variable.
	* decl.c (ansi_null_node): New variable.
	(init_decl_processing): Initialize its type.
	* lex.c (init_parse): Initialize its value.  Use ansi_null_node
	for null_node in non-ANSI mode.
	* typeck.c (build_binary_op_nodefault): Use ansi_null_node in
	place of null_node to avoid spurious errors.

From-SVN: r21858

gcc/cp/ChangeLog

@@ -1,3 +1,13 @@
+1998-08-19  Mark Mitchell  <mark@markmitchell.com>
+
+	* cp-tree.h (ansi_null_node): New variable.
+	* decl.c (ansi_null_node): New variable.
+	(init_decl_processing): Initialize its type.
+	* lex.c (init_parse): Initialize its value.  Use ansi_null_node
+	for null_node in non-ANSI mode.
+	* typeck.c (build_binary_op_nodefault): Use ansi_null_node in
+	place of null_node to avoid spurious errors.
+	
 1998-08-17  Mark Mitchell  <mark@markmitchell.com>
 
 	* cp-tree.h (enter_scope_of): New function.

gcc/cp/cp-tree.h

@@ -1918,6 +1918,7 @@ extern tree long_long_integer_type_node, long_long_unsigned_type_node;
 extern tree integer_two_node, integer_three_node;
 extern tree boolean_type_node, boolean_true_node, boolean_false_node;
 
+extern tree ansi_null_node;
 extern tree null_node;
 
 /* in pt.c  */

gcc/cp/decl.c

@@ -429,9 +429,13 @@ tree static_aggregates;
 tree integer_zero_node;
 tree null_pointer_node;
 
-/* The value for __null (NULL), either of type `void *' or, with -ansi,
-   an integer type of the same size.  */
+/* The value for __null (NULL), when -ansi is specified.  As per the
+   standard, this is an implementation-defined null pointer constant.  */
+tree ansi_null_node;
 
+/* The value for __null (NULL).  With -ansi, this is just
+   ansi_null_node.  Without -ansi, this is a zero-valued pointer
+   constant of type `{unknown type}*'.  */
 tree null_node;
 
 /* A node for the integer constants 1, 2, and 3.  */
@@ -6030,9 +6034,8 @@ init_decl_processing ()
   /* Indirecting an UNKNOWN_TYPE node yields an UNKNOWN_TYPE node.  */
   TREE_TYPE (unknown_type_node) = unknown_type_node;
 
-  if (flag_ansi)
-    TREE_TYPE (null_node) = type_for_size (POINTER_SIZE, 0);
-  else
+  TREE_TYPE (ansi_null_node) = type_for_size (POINTER_SIZE, 0);
+  if (!flag_ansi)
     TREE_TYPE (null_node) = build_pointer_type (unknown_type_node);
 
   /* Looking up TYPE_POINTER_TO and TYPE_REFERENCE_TO yield the same

gcc/cp/lex.c

@@ -777,7 +777,15 @@ init_parse (filename)
   TREE_TYPE (signature_type_node) = signature_type_node;
   ridpointers[(int) RID_SIGNATURE] = signature_type_node;
 
-  null_node = build_int_2 (0, 0);
+  /* Create the built-in __null node.  Note that we can't yet call for
+     type_for_size here because integer_type_node and so forth are not
+     set up.  Therefore, we don't set the type of these nodes until
+     init_decl_processing.  */
+  ansi_null_node = build_int_2 (0, 0);
+  if (flag_ansi)
+    null_node = ansi_null_node;
+  else
+    null_node = build_int_2 (0, 0);
   ridpointers[RID_NULL] = null_node;
 
   opname_tab[(int) COMPONENT_REF] = "->";

gcc/cp/typeck.c

@@ -3244,6 +3244,15 @@ build_binary_op_nodefault (code, orig_op0, orig_op1, error_code)
   /* Nonzero means set RESULT_TYPE to the common type of the args.  */
   int common = 0;
 
+  /* Unless -ansi is specified, __null has pointer type.  But, then,
+     things like `7 != NULL' result in errors about comparisons
+     between pointers and integers.  So, here, we replace __null with
+     an appropriate null pointer constant.  */
+  if (orig_op0 == null_node)
+    orig_op0 = ansi_null_node;
+  if (orig_op1 == null_node)
+    orig_op1 = ansi_null_node;
+
   /* Apply default conversions.  */
   if (code == TRUTH_AND_EXPR || code == TRUTH_ANDIF_EXPR
       || code == TRUTH_OR_EXPR || code == TRUTH_ORIF_EXPR

gcc/testsuite/g++.old-deja/g++.other/null1.C

@@ -0,0 +1,12 @@
+// Build don't link:
+
+#include <cstddef>
+
+void f()
+{
+  int i;
+  float f;
+
+  i != NULL;
+  f != NULL;
+}