Charlie Marsh 424b8d4ad2 Use a single node hierarchy to track statements and expressions (#6709) ... ## Summary This PR is a follow-up to the suggestion in https://github.com/astral-sh/ruff/pull/6345#discussion_r1285470953 to use a single stack to store all statements and expressions, rather than using separate vectors for each, which gives us something closer to a full-fidelity chain. (We can then generalize this concept to include all other AST nodes too.) This is in part made possible by the removal of the hash map from `&Stmt` to `StatementId` (#6694), which makes it much cheaper to store these using a single interface (since doing so no longer introduces the requirement that we hash all expressions). I'll follow-up with some profiling, but a few notes on how the data requirements have changed: - We now store a `BranchId` for every expression, not just every statement, so that's an extra `u32`. - We now store a single `NodeId` on every snapshot, rather than separate `StatementId` and `ExpressionId` IDs, so that's one fewer `u32` for each snapshot. - We're probably doing a few more lookups in general, since any calls to `current_statement()` etc. now have to iterate up the node hierarchy until they identify the first statement. ## Test Plan `cargo test`		2023-08-21 21:32:57 -04:00
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src	Use a single node hierarchy to track statements and expressions (#6709)	2023-08-21 21:32:57 -04:00
Cargo.toml	Add support for unions to our Python builtins type system (#6541)	2023-08-13 18:00:50 -04:00