Implement initialization of a reference (C++ [dcl.init.ref]) as part
of copy initialization. Other pieces of the puzzle:

  - Try/Perform-ImplicitConversion now handles implicit conversions
    that don't involve references.
  - Try/Perform-CopyInitialization uses
    CheckSingleAssignmentConstraints for C. PerformCopyInitialization
    is now used for all argument passing and returning values from a
    function.
  - Diagnose errors with declaring references and const values without
    an initializer. (Uses a new Action callback, ActOnUninitializedDecl).
  
We do not yet have implicit conversion sequences for reference
binding, which means that we don't have any overloading support for
reference parameters yet.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@58353 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index a4fae91..8317653 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1174,14 +1174,11 @@
         Arg = new CXXDefaultArgExpr(FDecl->getParamDecl(i));
       QualType ArgType = Arg->getType();
 
-      // Compute implicit casts from the operand to the formal argument type.
-      AssignConvertType ConvTy =
-        CheckSingleAssignmentConstraints(ProtoArgType, Arg);
-      TheCall->setArg(i, Arg);
-
-      if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), ProtoArgType,
-                                   ArgType, Arg, "passing"))
+      // Pass the argument.
+      if (PerformCopyInitialization(Arg, ProtoArgType, "passing"))
         return true;
+
+      TheCall->setArg(i, Arg);
     }
     
     // If this is a variadic call, handle args passed through "...".