The AST generator creates a reference enum for each syntax group — an
enum where each variant contains a reference to the relevant syntax
node. Previously you could customize the name of the reference enum for
a group — primarily because there was an existing `ExpressionRef` type
that wouldn't have lined up with the auto-derived name `ExprRef`. This
follow-up PR is a simple search/replace to switch over to the
auto-derived name, so that we can remove this customization point.
While looking into potential AST optimizations, I noticed the `AstNode`
trait and `AnyNode` type aren't used anywhere in Ruff or Red Knot. It
looks like they might be historical artifacts of previous ways of
consuming AST nodes?
- `AstNode::cast`, `AstNode::cast_ref`, and `AstNode::can_cast` are not
used anywhere.
- Since `cast_ref` isn't needed anymore, the `Ref` associated type isn't
either.
This is a pure refactoring, with no intended behavior changes.
This PR replaces most of the hard-coded AST definitions with a
generation script, similar to what happens in `rust_python_formatter`.
I've replaced every "rote" definition that I could find, where the
content is entirely boilerplate and only depends on what syntax nodes
there are and which groups they belong to.
This is a pretty massive diff, but it's entirely a refactoring. It
should make absolutely no changes to the API or implementation. In
particular, this required adding some configuration knobs that let us
override default auto-generated names where they don't line up with
types that we created previously by hand.
## Test plan
There should be no changes outside of the `rust_python_ast` crate, which
verifies that there were no API changes as a result of the
auto-generation. Aggressive `cargo clippy` and `uvx pre-commit` runs
after each commit in the branch.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
