pub struct FulfillmentContext<'tcx> {
    predicates: ObligationForest<PendingPredicateObligation<'tcx>>,
    usable_in_snapshot: usize,
}
Expand description

The fulfillment context is used to drive trait resolution. It consists of a list of obligations that must be (eventually) satisfied. The job is to track which are satisfied, which yielded errors, and which are still pending. At any point, users can call select_where_possible, and the fulfillment context will try to do selection, retaining only those obligations that remain ambiguous. This may be helpful in pushing type inference along. Once all type inference constraints have been generated, the method select_all_or_error can be used to report any remaining ambiguous cases as errors.

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§predicates: ObligationForest<PendingPredicateObligation<'tcx>>

A list of all obligations that have been registered with this fulfillment context.

§usable_in_snapshot: usize

The snapshot in which this context was created. Using the context outside of this snapshot leads to subtle bugs if the snapshot gets rolled back. Because of this we explicitly check that we only use the context in exactly this snapshot.

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impl<'tcx> FulfillmentContext<'tcx>

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pub(super) fn new(infcx: &InferCtxt<'tcx>) -> FulfillmentContext<'tcx>

Creates a new fulfillment context.

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fn select( &mut self, selcx: SelectionContext<'_, 'tcx> ) -> Vec<FulfillmentError<'tcx>>

Attempts to select obligations using selcx.

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impl<'tcx> TraitEngine<'tcx> for FulfillmentContext<'tcx>

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fn register_predicate_obligation( &mut self, infcx: &InferCtxt<'tcx>, obligation: PredicateObligation<'tcx> )

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fn collect_remaining_errors( &mut self, _infcx: &InferCtxt<'tcx> ) -> Vec<FulfillmentError<'tcx>>

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fn select_where_possible( &mut self, infcx: &InferCtxt<'tcx> ) -> Vec<FulfillmentError<'tcx>>

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fn drain_unstalled_obligations( &mut self, infcx: &InferCtxt<'tcx> ) -> Vec<PredicateObligation<'tcx>>

Among all pending obligations, collect those are stalled on a inference variable which has changed since the last call to select_where_possible. Those obligations are marked as successful and returned.
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fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>>

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fn register_bound( &mut self, infcx: &InferCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>, def_id: DefId, cause: ObligationCause<'tcx> )

Requires that ty must implement the trait with def_id in the given environment. This trait must not have any type parameters (except for Self).

Auto Trait Implementations§

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impl<'tcx> !RefUnwindSafe for FulfillmentContext<'tcx>

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impl<'tcx> !Send for FulfillmentContext<'tcx>

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impl<'tcx> !Sync for FulfillmentContext<'tcx>

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impl<'tcx> Unpin for FulfillmentContext<'tcx>

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impl<'tcx> !UnwindSafe for FulfillmentContext<'tcx>

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<'tcx, T> TraitEngineExt<'tcx> for Twhere T: TraitEngine<'tcx> + ?Sized,

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fn register_predicate_obligations( &mut self, infcx: &InferCtxt<'tcx>, obligations: impl IntoIterator<Item = Obligation<'tcx, Predicate<'tcx>>> )

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fn select_all_or_error( &mut self, infcx: &InferCtxt<'tcx> ) -> Vec<FulfillmentError<'tcx>, Global>

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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

Layout§

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: 160 bytes