GCC5 buildbot made it to clang. Fix implicit conversions it found.
diff --git a/clang/lib/Basic/DiagnosticIDs.cpp b/clang/lib/Basic/DiagnosticIDs.cpp
index e30e375..6f8b544 100644
--- a/clang/lib/Basic/DiagnosticIDs.cpp
+++ b/clang/lib/Basic/DiagnosticIDs.cpp
@@ -289,7 +289,7 @@
 
       unsigned getOrCreateDiagID(DiagnosticIDs::Level L, StringRef Message,
                                  DiagnosticIDs &Diags) {
-        DiagDesc D(L, Message);
+        DiagDesc D(L, std::string(Message));
         // Check to see if it already exists.
         std::map<DiagDesc, unsigned>::iterator I = DiagIDs.lower_bound(D);
         if (I != DiagIDs.end() && I->first == D)