Frontend: Sketch a LogDiagnosticPrinter object, and wire CC_LOG_DIAGNOSTICS to
it.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129089 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/LogDiagnosticPrinter.cpp b/lib/Frontend/LogDiagnosticPrinter.cpp
new file mode 100644
index 0000000..f148d5e
--- /dev/null
+++ b/lib/Frontend/LogDiagnosticPrinter.cpp
@@ -0,0 +1,39 @@
+//===--- LogDiagnosticPrinter.cpp - Log Diagnostic Printer ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Frontend/LogDiagnosticPrinter.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace clang;
+
+LogDiagnosticPrinter::LogDiagnosticPrinter(llvm::raw_ostream &os,
+                                           const DiagnosticOptions &diags,
+                                           bool _OwnsOutputStream)
+  : OS(os), LangOpts(0), DiagOpts(&diags),
+    OwnsOutputStream(_OwnsOutputStream) {
+}
+
+LogDiagnosticPrinter::~LogDiagnosticPrinter() {
+  if (OwnsOutputStream)
+    delete &OS;
+}
+
+void LogDiagnosticPrinter::HandleDiagnostic(Diagnostic::Level Level,
+                                             const DiagnosticInfo &Info) {
+  // Default implementation (Warnings/errors count).
+  DiagnosticClient::HandleDiagnostic(Level, Info);
+
+  // Write to a temporary string to ensure atomic write of diagnostic object.
+  llvm::SmallString<512> Msg;
+  llvm::raw_svector_ostream OS(Msg);
+
+  OS << "hello!\n";
+
+  this->OS << OS.str();
+}