Fix -Woverloaded-virtual when the using statement refers to a base declaration of a virtual function.

GCC and Clang both do not warn on:

  struct a { virtual void func(); };
  struct b: a { virtual void func(); void func(int); };
  struct c: b { void func(int); using b::func; };

but if the "using" was using a::func GCC would still remain silent where Clang
would warn. This change makes Clang consistent with GCC's existing behavior.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@166154 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 22 insertions, 1 deletions

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 8d891a37e7..357f338f11 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -4770,7 +4770,12 @@ static bool FindHiddenVirtualMethod(const CXXBaseSpecifier *Specifier,
       if (!Data.S->IsOverload(Data.Method, MD, false))
         return true;
       // Collect the overload only if its hidden.
-      if (!Data.OverridenAndUsingBaseMethods.count(MD))
+      bool Using = Data.OverridenAndUsingBaseMethods.count(MD);
+      for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(),
+                                          E = MD->end_overridden_methods();
+           I != E && !Using; ++I)
+        Using = Data.OverridenAndUsingBaseMethods.count(*I);
+      if (!Using)
         overloadedMethods.push_back(MD);
     }
   }
diff --git a/test/SemaCXX/warn-overloaded-virtual.cpp b/test/SemaCXX/warn-overloaded-virtual.cpp
index 8e2b671bf4..79635a62f8 100644
--- a/test/SemaCXX/warn-overloaded-virtual.cpp
+++ b/test/SemaCXX/warn-overloaded-virtual.cpp
@@ -64,3 +64,19 @@ public:
   static void f() {}
 };
 }
+
+namespace ThreeLayer {
+struct A {
+  virtual void f();
+};
+
+struct B: A {
+  void f();
+  void f(int);
+};
+
+struct C: B {
+  void f(int);
+  using A::f;
+};
+}