Clarify the ownership semantics of the Diagnostic object used by

ASTUnit. Previously, we would end up with use-after-free errors
because the Diagnostic object would be creating in one place (say,
CIndex) and its ownership would not be transferred into the
ASTUnit. Fixes <rdar://problem/7818608>.

llvm-svn: 100464

clang/lib/Frontend/ASTMerge.cpp

@@ -37,7 +37,8 @@ void ASTMergeAction::ExecuteAction() {
   CI.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
                                        &CI.getASTContext());
   for (unsigned I = 0, N = ASTFiles.size(); I != N; ++I) {
-    ASTUnit *Unit = ASTUnit::LoadFromPCHFile(ASTFiles[I], CI.getDiagnostics(),
+    ASTUnit *Unit = ASTUnit::LoadFromPCHFile(ASTFiles[I], 
+                                             UnownedDiag(CI.getDiagnostics()),
                                              false);
     if (!Unit)
       continue;