Trait rustc_trait_selection::infer::nll_relate::TypeRelatingDelegate

pub trait TypeRelatingDelegate<'tcx> {
    pub fn push_outlives(
        &mut self, 
        sup: &'tcx RegionKind, 
        sub: &'tcx RegionKind
    );
    pub fn const_equate(&mut self, a: &'tcx Const<'tcx>, b: &'tcx Const<'tcx>);
    pub fn create_next_universe(&mut self) -> UniverseIndex;
    pub fn next_existential_region_var(
        &mut self, 
        was_placeholder: bool
    ) -> &'tcx RegionKind;
    pub fn next_placeholder_region(
        &mut self, 
        placeholder: Placeholder<BoundRegion>
    ) -> &'tcx RegionKind;
    pub fn generalize_existential(
        &mut self, 
        universe: UniverseIndex
    ) -> &'tcx RegionKind;
    pub fn normalization() -> NormalizationStrategy;
    pub fn forbid_inference_vars() -> bool;
}

Required methods

pub fn push_outlives(&mut self, sup: &'tcx RegionKind, sub: &'tcx RegionKind)

Push a constraint sup: sub -- this constraint must be satisfied for the two types to be related. sub and sup may be regions from the type or new variables created through the delegate.

pub fn const_equate(&mut self, a: &'tcx Const<'tcx>, b: &'tcx Const<'tcx>)

pub fn create_next_universe(&mut self) -> UniverseIndex

Creates a new universe index. Used when instantiating placeholders.

pub fn next_existential_region_var(
    &mut self,
    was_placeholder: bool
) -> &'tcx RegionKind

Creates a new region variable representing a higher-ranked region that is instantiated existentially. This creates an inference variable, typically.

So e.g., if you have for<'a> fn(..) <: for<'b> fn(..), then we will invoke this method to instantiate 'a with an inference variable (though 'b would be instantiated first, as a placeholder).

pub fn next_placeholder_region(
    &mut self,
    placeholder: Placeholder<BoundRegion>
) -> &'tcx RegionKind

Creates a new region variable representing a higher-ranked region that is instantiated universally. This creates a new region placeholder, typically.

So e.g., if you have for<'a> fn(..) <: for<'b> fn(..), then we will invoke this method to instantiate 'b with a placeholder region.

pub fn generalize_existential(
    &mut self,
    universe: UniverseIndex
) -> &'tcx RegionKind

Creates a new existential region in the given universe. This is used when handling subtyping and type variables -- if we have that ?X <: Foo<'a>, for example, we would instantiate ?X with a type like Foo<'?0> where '?0 is a fresh existential variable created by this function. We would then relate Foo<'?0> with Foo<'a> (and probably add an outlives relation stating that '?0: 'a).

pub fn normalization() -> NormalizationStrategy

Define the normalization strategy to use, eager or lazy.

pub fn forbid_inference_vars() -> bool

Enables some optimizations if we do not expect inference variables in the RHS of the relation.

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Implementors

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