2 files changed, 44 insertions, 11 deletions
diff --git a/clang/lib/Sema/SemaCXXCast.cpp b/clang/lib/Sema/SemaCXXCast.cpp
index dda7f67d3f2..35b7f51df1c 100644
--- a/clang/lib/Sema/SemaCXXCast.cpp
+++ b/clang/lib/Sema/SemaCXXCast.cpp
@@ -981,12 +981,20 @@ TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType,
     return TC_Failed;
   }
 
-  if (!CStyle && Self.CheckBaseClassAccess(OpRange.getBegin(),
-                                           SrcType, DestType,
-                                           Paths.front(),
+  if (!CStyle) {
+    switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
+                                      SrcType, DestType,
+                                      Paths.front(),
                                 diag::err_downcast_from_inaccessible_base)) {
-    msg = 0;
-    return TC_Failed;
+    case Sema::AR_accessible:
+    case Sema::AR_delayed:     // be optimistic
+    case Sema::AR_dependent:   // be optimistic
+      break;
+
+    case Sema::AR_inaccessible:
+      msg = 0;
+      return TC_Failed;
+    }
   }
 
   Self.BuildBasePathArray(Paths, BasePath);
@@ -1065,12 +1073,22 @@ TryStaticMemberPointerUpcast(Sema &Self, Expr *&SrcExpr, QualType SrcType,
     return TC_Failed;
   }
 
-  if (!CStyle && Self.CheckBaseClassAccess(OpRange.getBegin(),
-                                           DestClass, SrcClass,
-                                           Paths.front(),
-                                     diag::err_upcast_to_inaccessible_base)) {
-    msg = 0;
-    return TC_Failed;
+  if (!CStyle) {
+    switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
+                                      DestClass, SrcClass,
+                                      Paths.front(),
+                                      diag::err_upcast_to_inaccessible_base)) {
+    case Sema::AR_accessible:
+    case Sema::AR_delayed:
+    case Sema::AR_dependent:
+      // Optimistically assume that the delayed and dependent cases
+      // will work out.
+      break;
+
+    case Sema::AR_inaccessible:
+      msg = 0;
+      return TC_Failed;
+    }
   }
 
   if (WasOverloadedFunction) {
diff --git a/clang/test/CXX/class.access/class.friend/p1.cpp b/clang/test/CXX/class.access/class.friend/p1.cpp
index af4df4c0f25..1668155c181 100644
--- a/clang/test/CXX/class.access/class.friend/p1.cpp
+++ b/clang/test/CXX/class.access/class.friend/p1.cpp
@@ -326,3 +326,18 @@ namespace test11 {
   void A::test2(B::private_type x) {} // expected-error {{'private_type' is a private member of 'test11::B'}}
   void A::test3(int x = B::private_type()) {} // expected-error {{'private_type' is a private member of 'test11::B'}}
 }
+
+
+// PR9221
+namespace test12 {
+  struct A {
+    void foo();
+  };
+  class B : private A {
+    friend void A::foo();
+    void *mem;
+  };
+  void A::foo() {
+    void *var = static_cast<B*>(this)->mem;
+  }
+}