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Show variance of parameters on hover

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This commit is contained in:
Lukas Wirth 2024-12-28 20:31:20 +01:00
parent 60e28c6bd9
commit bb921fbe94
5 changed files with 69 additions and 12 deletions
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20
crates/hir/src/lib.rs
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@ -101,7 +101,6 @@ pub use crate::{
PathResolution, Semantics, SemanticsImpl, SemanticsScope, TypeInfo, VisibleTraits,
},
};
pub use hir_ty::method_resolution::TyFingerprint;
// Be careful with these re-exports.
//
@ -151,8 +150,9 @@ pub use {
display::{ClosureStyle, HirDisplay, HirDisplayError, HirWrite},
dyn_compatibility::{DynCompatibilityViolation, MethodViolationCode},
layout::LayoutError,
method_resolution::TyFingerprint,
mir::{MirEvalError, MirLowerError},
CastError, FnAbi, PointerCast, Safety,
CastError, FnAbi, PointerCast, Safety, Variance,
},
// FIXME: Properly encapsulate mir
hir_ty::{mir, Interner as ChalkTyInterner},
@ -3957,6 +3957,22 @@ impl GenericParam {
GenericParam::LifetimeParam(it) => it.id.parent.into(),
}
}
pub fn variance(self, db: &dyn HirDatabase) -> Option<Variance> {
let parent = match self {
GenericParam::TypeParam(it) => it.id.parent(),
// const parameters are always invariant
GenericParam::ConstParam(_) => return None,
GenericParam::LifetimeParam(it) => it.id.parent,
};
let generics = hir_ty::generics::generics(db.upcast(), parent);
let index = match self {
GenericParam::TypeParam(it) => generics.type_or_const_param_idx(it.id.into())?,
GenericParam::ConstParam(_) => return None,
GenericParam::LifetimeParam(it) => generics.lifetime_idx(it.id)?,
};
db.variances_of(parent)?.get(index).copied()
}
}
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]