Nicholas Nethercote 1a9a284ad2 Simplify HashStableContext. ...

`derive(HashStable_Generic)` generates impls like this:
```
impl<__CTX> HashStable<__CTX> for ExpnKind
where
    __CTX: crate::HashStableContext
{
    fn hash_stable(&self, hcx : &mut __CTX, __hasher: &mut StableHasher) {
        ...
    }
}
```
This is used for crates that are upstream of `rustc_middle`.

The `crate::HashStableContext` bound means every crate that uses
`derive(HashStable_Generic)` must provide (or import) a trait
`HashStableContext` which `rustc_middle` then impls. In `rustc_span`
this trait is sensible, with three methods. In other crates, this trait
is empty, and there is the following trait hierarchy:
```
rustc_session::HashStableContext
  |              |
  |   rustc_hir::HashStableContext
  |         /                   \
rustc_ast::HashStableContext   rustc_abi::HashStableContext
  |
rustc_span::HashStableContext
```
All very strange and unnecessary. This commit changes
`derive(HashStable_Generic)` to use `rustc_span::HashStableContext`
instead of `crate::HashStableContext`. This eliminates the need for all
the empty `HashStableContext` traits and impls. Much better.

2026-04-01 17:52:43 +11:00

..

src

Simplify HashStableContext.

2026-04-01 17:52:43 +11:00

Cargo.toml

parser/lexer: bump to Unicode 17, use faster unicode-ident

2025-12-27 11:20:24 +01:00