[clang] [LifetimeSafety] Implement multi-level origins (PR #168344)

[Utkarsh Saxena via cfe-commits]

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@@ -52,41 +62,118 @@ struct Origin {
   }
 };
 
-/// Manages the creation, storage, and retrieval of origins for pointer-like
-/// variables and expressions.
-class OriginManager {
+/// A list of origins representing levels of indirection for pointer-like types.
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usx95 wrote:

Aah I see what you were referring to.

Yes, my idea is to move from an `OriginList` to `OriginTree` to support multiple inner pointers like `std::pair<int*, int*>` . This could be represented as a pre-order array but my initial preference is to have a Tree representation for better understanding.

https://github.com/llvm/llvm-project/pull/168344