From 523633872ac859b97c453f3c7356201f934e3478 Mon Sep 17 00:00:00 2001
From: Mark Mitchell <mark@markmitchell.com>
Date: Fri, 7 Aug 1998 09:56:06 +0000
Subject: [PATCH] cvt.c (cp_convert_to_pointer): Handle NULL pointer
 conversions, even in complex virtual base class hierarchies.

	* cvt.c (cp_convert_to_pointer): Handle NULL pointer
	conversions, even in complex virtual base class hierarchies.

From-SVN: r21626
---
 gcc/cp/ChangeLog                             |  5 +++++
 gcc/cp/cvt.c                                 | 10 +++++++++-
 gcc/testsuite/g++.old-deja/g++.other/cast1.C | 16 ++++++++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.old-deja/g++.other/cast1.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index f6bc1b67b19..f1957d80cd3 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+1998-08-07  Mark Mitchell  <mark@markmitchell.com>
+
+	* cvt.c (cp_convert_to_pointer): Handle a NULL pointer
+	conversions, even in complex virtual base class hierarchies.
+
 1998-08-06  Mark Mitchell  <mark@markmitchell.com>
 
 	* cp-tree.h (ENUM_TEMPLATE_INFO): New macro.
diff --git a/gcc/cp/cvt.c b/gcc/cp/cvt.c
index 18b7d8be482..1078488c293 100644
--- a/gcc/cp/cvt.c
+++ b/gcc/cp/cvt.c
@@ -154,7 +154,15 @@ cp_convert_to_pointer (type, expr)
 	  && TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
 	  && IS_AGGR_TYPE (TREE_TYPE (type))
 	  && IS_AGGR_TYPE (TREE_TYPE (intype))
-	  && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
+	  && TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE
+	  /* If EXPR is NULL, then we don't need to do any arithmetic
+	     to convert it:
+
+	       [conv.ptr]
+
+	       The null pointer value is converted to the null pointer
+	       value of the destination type.  */
+	  && !integer_zerop (expr))
 	{
 	  enum tree_code code = PLUS_EXPR;
 	  tree binfo = get_binfo (TREE_TYPE (type), TREE_TYPE (intype), 1);
diff --git a/gcc/testsuite/g++.old-deja/g++.other/cast1.C b/gcc/testsuite/g++.old-deja/g++.other/cast1.C
new file mode 100644
index 00000000000..7cd805975aa
--- /dev/null
+++ b/gcc/testsuite/g++.old-deja/g++.other/cast1.C
@@ -0,0 +1,16 @@
+// Build don't link:
+
+struct S0 { };
+struct S1 : virtual public S0 { };
+struct S2 : virtual public S0 { };
+
+struct S3 : public S1, public S2, virtual public S0
+{
+};
+
+void f(const S0*) {}
+
+void g()
+{
+  f(static_cast<S3*>(0));
+}