Fix the __interface inheritence rules to work better with IUnknown and IDispatch

__interface objects in MSVC are permitted to inherit from __interface types, 
and interface-like types.

Additionally, there are two default interface-like types 
(IUnknown and IDispatch) that all interface-like
types must inherit from.

Differential Revision: https://reviews.llvm.org/D37308

llvm-svn: 313364

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/ms-iunknown-outofline-def.cpp b/clang/test/SemaCXX/ms-iunknown-outofline-def.cpp
new file mode 100644
index 00000000000..b6e74d0eb60
--- /dev/null
+++ b/clang/test/SemaCXX/ms-iunknown-outofline-def.cpp
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -fms-extensions %s 
+
+struct __declspec(uuid("00000000-0000-0000-C000-000000000046")) IUnknown {
+  void foo();
+};
+
+__interface NoError : public IUnknown {};
+void IUnknown::foo() {}
+// expected-error@+1{{interface type cannot inherit from}}
+__interface HasError : public IUnknown {};