Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -990,6 +990,12 @@
       RHS = S.ImpCastExprToType(RHS.get(), ResultType, CK_FloatingComplexCast);
     else
       RHS = S.ImpCastExprToType(RHS.get(), LHSElementType, CK_FloatingCast);
+  } else {
+    // Convert either RHS or LHS from real to complex.
+    if (LHSComplexType)
+      RHS = S.ImpCastExprToType(RHS.get(), ResultType, CK_FloatingRealToComplex);
+    else
+      LHS = S.ImpCastExprToType(LHS.get(), ResultType, CK_FloatingRealToComplex);
   }
   return ResultType;
 }