Create valid LValue to represent null pointers in constant exprs

We were leaving the SubobjectDesignator in a surprising situation, where
it was allegedly valid but didn't actually refer to a type. This caused
a crash later on.

This patch fills out the SubobjectDesignator with the pointee type (as
happens in other evaluations of constant pointers) so that we don't
crash later.

llvm-svn: 303957

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/null-cast.cpp b/clang/test/SemaCXX/null-cast.cpp
new file mode 100644
index 00000000000..c80ab8fced1
--- /dev/null
+++ b/clang/test/SemaCXX/null-cast.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+struct A {};
+struct B : virtual A {};
+
+void foo() {
+  (void)static_cast<A&>(*(B *)0); // expected-warning {{binding dereferenced null pointer to reference has undefined behavior}}
+}