[clang] [APINotes] Add SWIFT_RETURNS_(UN)RETAINED support to APINotes (PR #118938)

[Egor Zhdan via cfe-commits]

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@@ -511,6 +511,10 @@ static void ProcessAPINotes(Sema &S, FunctionOrMethod AnyFunc,
       AnyTypeChanged = true;
   }
 
+  // returns_(un)retained
+  if (!Info.SwiftReturnOwnership.empty())
+    D->addAttr(SwiftAttrAttr::Create(S.Context, Info.SwiftReturnOwnership));
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egorzhdan wrote:

I think we would want to construct a string `"returns_" + Info.SwiftReturnOwnership` here.

https://github.com/llvm/llvm-project/pull/118938