Nicholas Nethercote 5233bc91da Add an ErrorGuaranteed to ast::TyKind::Err.
This makes it more like `hir::TyKind::Err`, and avoids a
`span_delayed_bug` call in `LoweringContext::lower_ty_direct`.

It also requires adding `ast::TyKind::Dummy`, now that
`ast::TyKind::Err` can't be used for that purpose in the absence of an
error emission.

There are a couple of cases that aren't as neat as I would have liked,
marked with `FIXME` comments.
2024-02-15 09:35:11 +11:00
..
2024-02-13 21:03:34 +00:00

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: