5b82ea74b7
Recover wrong-cased keywords that start items (_this pr was inspired by [this tweet](https://twitter.com/Azumanga/status/1552982326409367561)_) r? `@estebank` We've talked a bit about this recovery, but I just wanted to make sure that this is the right approach :) For now I've only added the case insensitive recovery to `use`s, since most other items like `impl` blocks, modules, functions can start with multiple keywords which complicates the matter.
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: