enhance SMDiagnostic to also maintain a pointer to the SourceMgr.

Add a simplified constructor for clients that don't have locations
like "file not found" errors.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100538 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/SourceMgr.cpp

@@ -168,7 +168,7 @@ SMDiagnostic SourceMgr::GetMessage(SMLoc Loc, const std::string &Msg,
   }
   PrintedMsg += Msg;
 
-  return SMDiagnostic(Loc,
+  return SMDiagnostic(*this, Loc,
                       CurMB->getBufferIdentifier(), FindLineNumber(Loc, CurBuf),
                       Loc.getPointer()-LineStart, PrintedMsg,
                       LineStr, ShowLine);