Rename CodeGenFunction::EmitMemSetToZero to EmitNullInitialization. Handle setting null data member pointers correctly. Fixes PR7139.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@104387 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGenCXX/pointers-to-data-members.cpp b/test/CodeGenCXX/pointers-to-data-members.cpp
index cab06db..ac238fb 100644
--- a/test/CodeGenCXX/pointers-to-data-members.cpp
+++ b/test/CodeGenCXX/pointers-to-data-members.cpp
@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=x86_64-apple-darwin10 | FileCheck %s
-
+// RUN: %clang_cc1 %s -emit-llvm -o - -triple=x86_64-apple-darwin10 -O3 | FileCheck --check-prefix=CHECK-O3 %s
 struct A { int a; int b; };
 struct B { int b; };
 struct C : B, A { };
@@ -118,3 +118,30 @@
 
 }
 
+namespace PR7139 {
+
+struct pair {
+  int first;
+  int second;
+};
+
+typedef int pair::*ptr_to_member_type;
+
+struct ptr_to_member_struct { 
+  ptr_to_member_type data;
+  int i;
+};
+
+struct A {
+  ptr_to_member_struct a;
+
+  A() : a() {}
+};
+
+// CHECK-O3: define zeroext i1 @_ZN6PR71395checkEv() nounwind readnone
+bool check() {
+  // CHECK-O3: ret i1 true
+  return A().a.data == 0;
+}
+
+}