[Win32 ABI] Defer operator delete checks until vtable is marked used

We were previously checking at every destructor declaration, but that was a bit
excessive. Since the deleting destructor is emitted with the vtable, do the
check when the vtable is marked used.

Differential Revision: http://llvm-reviews.chandlerc.com/D2851

llvm-svn: 202046
diff --git a/clang/test/SemaCXX/microsoft-dtor-lookup.cpp b/clang/test/SemaCXX/microsoft-dtor-lookup.cpp
index a9f6f65..51129ae 100644
--- a/clang/test/SemaCXX/microsoft-dtor-lookup.cpp
+++ b/clang/test/SemaCXX/microsoft-dtor-lookup.cpp
@@ -1,12 +1,11 @@
 // RUN: %clang_cc1 -triple %itanium_abi_triple -fsyntax-only %s
-// RUN: %clang_cc1 -triple %ms_abi_triple -verify -DMSVC_ABI %s
+// RUN: %clang_cc1 -triple %ms_abi_triple -verify %s
 
 namespace Test1 {
 
 // Should be accepted under the Itanium ABI (first RUN line) but rejected
 // under the Microsoft ABI (second RUN line), as Microsoft ABI requires
-// operator delete() lookups to be done at all virtual destructor declaration
-// points.
+// operator delete() lookups to be done when vtables are marked used.
 
 struct A {
   void operator delete(void *); // expected-note {{member found by ambiguous name lookup}}
@@ -24,6 +23,10 @@
   virtual ~VC(); // expected-error {{member 'operator delete' found in multiple base classes of different types}}
 };
 
+void f(VC vc) {
+  // This marks VC's vtable used.
+}
+
 }
 
 namespace Test2 {