pub struct SubRelations {
    map: FxHashMap<TyVid, SubId>,
    table: UnificationTableStorage<SubId>,
}
Expand description

When reporting ambiguity errors, we sometimes want to treat all inference vars which are subtypes of each others as if they are equal. For this case we compute the transitive closure of our subtype obligations here.

E.g. when encountering ambiguity errors, we want to suggest specifying some method argument or to add a type annotation to a local variable. Because subtyping cannot change the shape of a type, it’s fine if the cause of the ambiguity error is only related to the suggested variable via subtyping.

Even for something like let x = returns_arg(); x.method(); the type of x is only a supertype of the argument of returns_arg. We still want to suggest specifying the type of the argument.

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§map: FxHashMap<TyVid, SubId>§table: UnificationTableStorage<SubId>

Implementations§

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impl SubRelations

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fn get_id<'tcx>(&mut self, infcx: &InferCtxt<'tcx>, vid: TyVid) -> SubId

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pub fn add_constraints<'tcx>( &mut self, infcx: &InferCtxt<'tcx>, obls: impl IntoIterator<Item = Predicate<'tcx>>, )

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pub fn unified<'tcx>( &mut self, infcx: &InferCtxt<'tcx>, a: TyVid, b: TyVid, ) -> bool

Trait Implementations§

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impl Default for SubRelations

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fn default() -> SubRelations

Returns the “default value” for a type. Read more

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impl<T> Aligned for T

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const ALIGN: Alignment = _

Alignment of Self.
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where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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Immutably borrows from an owned value. Read more
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type Output = R

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fn filterable( self, filter_name: &'static str, ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

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Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 56 bytes