e2aa38e6ab
Merge `PatParam`/`PatWithOr`, and `Expr`/`Expr2021`, for a few reasons. - It's conceptually nice, because the two pattern kinds and the two expression kinds are very similar. - With expressions in particular, there are several places where both expression kinds get the same treatment. - It removes one unreachable match arm. - Most importantly, for #124141 I will need to introduce a new type `MetaVarKind` that is very similar to `NonterminalKind`, but records a couple of extra fields for expression metavars. It's nicer to have a single `MetaVarKind::Expr` expression variant to hold those extra fields instead of duplicating them across two variants `MetaVarKind::{Expr,Expr2021}`. And then it makes sense for patterns to be treated the same way, and for `NonterminalKind` to also be treated the same way. I also clarified the comments, because I have long found them a little hard to understand. |
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| src | ||
| Cargo.toml | ||
| README.md | ||
The rustc_ast crate contains those things concerned purely with syntax
– that is, the AST ("abstract syntax tree"), along with some definitions for tokens and token streams, data structures/traits for mutating ASTs, and shared definitions for other AST-related parts of the compiler (like the lexer and macro-expansion).
For more information about how these things work in rustc, see the rustc dev guide: