Charlie Marsh 89e4e038b0 Store expression hierarchy in semantic model snapshots (#6345) ... ## Summary When we iterate over the AST for analysis, we often process nodes in a "deferred" manner. For example, if we're analyzing a function, we push the function body onto a deferred stack, along with a snapshot of the current semantic model state. Later, when we analyze the body, we restore the semantic model state from the snapshot. This ensures that we know the correct scope, hierarchy of statement parents, etc., when we go to analyze the function body. Historically, we _haven't_ included the _expression_ hierarchy in the model snapshot -- so we track the current expression parents in the visitor, but we never save and restore them when processing deferred nodes. This can lead to subtle bugs, in that methods like `expr_parent()` aren't guaranteed to be correct, if you're in a deferred visitor. This PR migrates expression tracking to mirror statement tracking exactly. So we push all expressions onto an `IndexVec`, and include the current expression on the snapshot. This ensures that `expr_parent()` and related methods are "always correct" rather than "sometimes correct". There's a performance cost here, both at runtime and in terms of memory consumption (we now store an additional pointer for every expression). In my hyperfine testing, it's about a 1% performance decrease for all-rules on CPython (up to 533.8ms, from 528.3ms) and a 4% performance decrease for default-rules on CPython (up to 212ms, from 204ms). However... I think this is worth it given the incorrectness of our current approach. In the future, we may want to reconsider how we do these upward traversals (e.g., with something like a red-green tree). (**Note**: in https://github.com/astral-sh/ruff/pull/6351, the slowdown seems to be entirely removed.)		2023-08-07 09:42:04 -04:00
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src	Store expression hierarchy in semantic model snapshots (#6345)	2023-08-07 09:42:04 -04:00
Cargo.toml	Pull in RustPython parser (#6099)	2023-07-27 09:29:11 +00:00