First non-embarrassing cut at checking for ambiguous derived-to-base 
conversions.

Added PerformImplicitConversion, which follows an implicit conversion sequence
computed by TryCopyInitialization and actually performs the implicit
conversions, including the extra check for ambiguity mentioned above.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@58071 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 9f27f8d..ecc8e24 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1774,17 +1774,10 @@
       // C++ 5.17p3: If the left operand is not of class type, the
       // expression is implicitly converted (C++ 4) to the
       // cv-unqualified type of the left operand.
-      ImplicitConversionSequence ICS 
-        = TryCopyInitialization(rExpr, lhsType.getUnqualifiedType());
-      if (ICS.ConversionKind == ImplicitConversionSequence::BadConversion) {
-        // No implicit conversion available; we cannot perform this
-        // assignment.
+      if (PerformImplicitConversion(rExpr, lhsType.getUnqualifiedType()))
         return Incompatible;
-      } else {
-        // Perform the appropriate cast to the right-handle side.
-        ImpCastExprToType(rExpr, lhsType.getUnqualifiedType());
+      else
         return Compatible;
-      }
     }
 
     // FIXME: Currently, we fall through and treat C++ classes like C