tree 8b3b814272a75e985d5c6ab334c173adb44d2921
parent 40332688e0185b6ea6f1ba7286958d7bea1b18e8
author Nicholas Nethercote <n.nethercote@gmail.com> 1778831901 +1000
committer Nicholas Nethercote <n.nethercote@gmail.com> 1778930195 +1000

Split `LintExpectationId`

`LintExpectationId` has two variants, `Unstable` and `Stable`. There are
some places where both variants are possible, but there are also places
where only one of `Unstable` or `Stable` is possible.

This commit encodes this into the type system by introducing
new types `UnstableLintExpectationId` and `StableLintExpectationId`. The
variants of `LintExpectationId` now enclose these. This makes it clearer
what values are possible where.

Other things of note:
- `LintLevelsProvider` gets an associated type and some method changes.
- `LintContext` gets an associated type.
- `LevelSpec` is made generic. `UnstableLevelSpec` and `StableLevelSpec`
  typedefs are added.
- The unstable types are now guaranteed by the type system to never be
  stably hashed. Previously this was a runtime check.