When determining whether the two types involved in reference binding

are reference-compatible, reference-related, etc., do not complete the
type of the reference itself because it is not necessary to determine
well-formedness of the program. Complete the type that we are binding
to, since that can affect whether we know about a derived-to-base
conversion. 

Fixes PR7080.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@103220 91177308-0d34-0410-b5e6-96231b3b80d8

Author: DougGregor

lib/Sema/SemaOverload.cpp

@@ -2289,8 +2289,7 @@ Sema::CompareReferenceRelationship(SourceLocation Loc,
   //   T1 is a base class of T2.
   if (UnqualT1 == UnqualT2)
     DerivedToBase = false;
-  else if (!RequireCompleteType(Loc, OrigT1, PDiag()) &&
-           !RequireCompleteType(Loc, OrigT2, PDiag()) &&
+  else if (!RequireCompleteType(Loc, OrigT2, PDiag()) &&
            IsDerivedFrom(UnqualT2, UnqualT1))
     DerivedToBase = true;
   else

test/SemaTemplate/instantiate-complete.cpp

@@ -99,3 +99,23 @@ namespace TemporaryObjectCopy {
 
   template void f(int);
 }
+
+namespace PR7080 {
+  template <class T, class U>
+  class X
+  {
+    typedef char true_t;
+    class false_t { char dummy[2]; };
+    static true_t dispatch(U);
+    static false_t dispatch(...);
+    static T trigger();
+  public:
+    enum { value = sizeof(dispatch(trigger())) == sizeof(true_t) };
+  };
+
+  template <class T>
+  class rv : public T
+  { };
+
+  bool x = X<int, rv<int>&>::value;
+}