Type Alias PredicateObligation

pub type PredicateObligation<'tcx> = Obligation<'tcx, Predicate<'tcx>>;

Aliased Type

struct PredicateObligation<'tcx> {
    pub cause: ObligationCause<'tcx>,
    pub param_env: ParamEnv<'tcx>,
    pub predicate: Predicate<'tcx>,
    pub recursion_depth: usize,
}

Fields

cause: ObligationCause<'tcx>

The reason we have to prove this thing.

param_env: ParamEnv<'tcx>

The environment in which we should prove this thing.

predicate: Predicate<'tcx>

The thing we are trying to prove.

recursion_depth: usize

If we started proving this as a result of trying to prove something else, track the total depth to ensure termination. If this goes over a certain threshold, we abort compilation – in such cases, we can not say whether or not the predicate holds for certain. Stupid halting problem; such a drag.

Implementations

impl<'tcx> PredicateObligation<'tcx>

pub fn flip_polarity( &self, tcx: TyCtxt<'tcx>, ) -> Option<PredicateObligation<'tcx>>

Flips the polarity of the inner predicate.

Given T: Trait predicate it returns T: !Trait and given T: !Trait returns T: Trait.

impl<'tcx, O> Obligation<'tcx, O>

pub fn new( tcx: TyCtxt<'tcx>, cause: ObligationCause<'tcx>, param_env: ParamEnv<'tcx>, predicate: impl Upcast<TyCtxt<'tcx>, O>, ) -> Obligation<'tcx, O>

pub fn set_depth_from_parent(&mut self, parent_depth: usize)

We often create nested obligations without setting the correct depth.

To deal with this evaluate and fulfill explicitly update the depth of nested obligations using this function.

pub fn with_depth( tcx: TyCtxt<'tcx>, cause: ObligationCause<'tcx>, recursion_depth: usize, param_env: ParamEnv<'tcx>, predicate: impl Upcast<TyCtxt<'tcx>, O>, ) -> Obligation<'tcx, O>

pub fn misc( tcx: TyCtxt<'tcx>, span: Span, body_id: LocalDefId, param_env: ParamEnv<'tcx>, trait_ref: impl Upcast<TyCtxt<'tcx>, O>, ) -> Obligation<'tcx, O>

pub fn with<P>( &self, tcx: TyCtxt<'tcx>, value: impl Upcast<TyCtxt<'tcx>, P>, ) -> Obligation<'tcx, P>

Trait Implementations

impl<'tcx> Elaboratable<TyCtxt<'tcx>> for PredicateObligation<'tcx>

For Obligation, a sub-obligation is combined with the current obligation’s param-env and cause code.

fn predicate(&self) -> Predicate<'tcx>

fn child(&self, clause: Clause<'tcx>) -> Self

fn child_with_derived_cause( &self, clause: Clause<'tcx>, span: Span, parent_trait_pred: PolyTraitPredicate<'tcx>, index: usize, ) -> Self

impl<'tcx, T: Clone> Clone for Obligation<'tcx, T>

fn clone(&self) -> Obligation<'tcx, T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'tcx, O: Debug> Debug for Obligation<'tcx, O>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Hash> Hash for Obligation<'_, T>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<'tcx, T: PartialEq> PartialEq for Obligation<'tcx, T>

fn eq(&self, other: &Obligation<'tcx, T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'tcx, O: TypeFoldable<TyCtxt<'tcx>>> TypeFoldable<TyCtxt<'tcx>> for Obligation<'tcx, O>

fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>( self, folder: &mut F, ) -> Result<Self, F::Error>

The entry point for folding. To fold a value t with a folder f call: t.try_fold_with(f).

fn fold_with<F>(self, folder: &mut F) -> Self

where F: TypeFolder<I>,

A convenient alternative to try_fold_with for use with infallible folders. Do not override this method, to ensure coherence with try_fold_with.

impl<'tcx, O: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>> for Obligation<'tcx, O>

fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result

The entry point for visiting. To visit a value t with a visitor v call: t.visit_with(v).

impl<T: Eq> Eq for Obligation<'_, T>

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: 48 bytes