Don't omit `this' from expression args if it couldn't be read, but warn loudly.

<rdar://problem/26935520>

llvm-svn: 273445
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
index 53b6fe1..a756e2b 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
@@ -26,6 +26,7 @@
 #include "ClangDiagnostic.h"
 
 #include "lldb/Core/ConstString.h"
+#include "lldb/Core/Debugger.h"
 #include "lldb/Core/Log.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/StreamFile.h"
@@ -641,9 +642,7 @@
 
         if (!object_ptr_error.Success())
         {
-            diagnostic_manager.Printf(eDiagnosticSeverityWarning,
-                                      "couldn't get required object pointer (substituting NULL): %s",
-                                      object_ptr_error.AsCString());
+            exe_ctx.GetTargetRef().GetDebugger().GetAsyncOutputStream()->Printf("warning: `%s' is not accessible (subsituting 0)\n", object_name.AsCString());
             object_ptr = 0;
         }
 
@@ -661,8 +660,8 @@
                 cmd_ptr = 0;
             }
         }
-        if (object_ptr)
-            args.push_back(object_ptr);
+        
+        args.push_back(object_ptr);
 
         if (m_in_objectivec_method)
             args.push_back(cmd_ptr);