Struct rustc_infer::traits::Obligation
source · pub struct Obligation<'tcx, T> {
pub cause: ObligationCause<'tcx>,
pub param_env: ParamEnv<'tcx>,
pub predicate: T,
pub recursion_depth: usize,
}
Expand description
An Obligation
represents some trait reference (e.g., i32: Eq
) for
which the “impl_source” must be found. The process of finding an “impl_source” is
called “resolving” the Obligation
. This process consists of
either identifying an impl
(e.g., impl Eq for i32
) that
satisfies the obligation, or else finding a bound that is in
scope. The eventual result is usually a Selection
(defined below).
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: T
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§
source§impl<'tcx> Obligation<'tcx, Predicate<'tcx>>
impl<'tcx> Obligation<'tcx, Predicate<'tcx>>
sourcepub fn flip_polarity(
&self,
tcx: TyCtxt<'tcx>
) -> Option<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
.
source§impl<'tcx> Obligation<'tcx, Binder<'tcx, TraitPredicate<'tcx>>>
impl<'tcx> Obligation<'tcx, Binder<'tcx, TraitPredicate<'tcx>>>
pub fn derived_cause( &self, variant: impl FnOnce(DerivedObligationCause<'tcx>) -> ObligationCauseCode<'tcx> ) -> ObligationCause<'tcx>
source§impl<'tcx, O> Obligation<'tcx, O>
impl<'tcx, O> Obligation<'tcx, O>
pub fn new( tcx: TyCtxt<'tcx>, cause: ObligationCause<'tcx>, param_env: ParamEnv<'tcx>, predicate: impl ToPredicate<'tcx, O> ) -> Obligation<'tcx, O>
sourcepub fn set_depth_from_parent(&mut self, parent_depth: usize)
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 ToPredicate<'tcx, O> ) -> Obligation<'tcx, O>
pub fn misc( tcx: TyCtxt<'tcx>, span: Span, body_id: LocalDefId, param_env: ParamEnv<'tcx>, trait_ref: impl ToPredicate<'tcx, O> ) -> Obligation<'tcx, O>
pub fn with<P>( &self, tcx: TyCtxt<'tcx>, value: impl ToPredicate<'tcx, P> ) -> Obligation<'tcx, P>
source§impl<'tcx> Obligation<'tcx, Binder<'tcx, TraitPredicate<'tcx>>>
impl<'tcx> Obligation<'tcx, Binder<'tcx, TraitPredicate<'tcx>>>
Trait Implementations§
source§impl<'tcx, T: Clone> Clone for Obligation<'tcx, T>
impl<'tcx, T: Clone> Clone for Obligation<'tcx, T>
source§fn clone(&self) -> Obligation<'tcx, T>
fn clone(&self) -> Obligation<'tcx, T>
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresource§impl<'tcx, O: Debug> Debug for Obligation<'tcx, O>
impl<'tcx, O: Debug> Debug for Obligation<'tcx, O>
source§impl<'tcx, P> From<Obligation<'tcx, P>> for Goal<'tcx, P>
impl<'tcx, P> From<Obligation<'tcx, P>> for Goal<'tcx, P>
source§fn from(value: Obligation<'tcx, P>) -> Self
fn from(value: Obligation<'tcx, P>) -> Self
source§impl<T: Hash> Hash for Obligation<'_, T>
impl<T: Hash> Hash for Obligation<'_, T>
source§impl<'tcx, T: PartialEq> PartialEq<Obligation<'tcx, T>> for Obligation<'tcx, T>
impl<'tcx, T: PartialEq> PartialEq<Obligation<'tcx, T>> for Obligation<'tcx, T>
source§fn eq(&self, other: &Obligation<'tcx, T>) -> bool
fn eq(&self, other: &Obligation<'tcx, T>) -> bool
self
and other
values to be equal, and is used
by ==
.source§impl<'tcx, O: TypeFoldable<TyCtxt<'tcx>>> TypeFoldable<TyCtxt<'tcx>> for Obligation<'tcx, O>
impl<'tcx, O: TypeFoldable<TyCtxt<'tcx>>> TypeFoldable<TyCtxt<'tcx>> for Obligation<'tcx, O>
source§fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
folder: &mut F
) -> Result<Self, F::Error>
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>( self, folder: &mut F ) -> Result<Self, F::Error>
source§fn fold_with<F>(self, folder: &mut F) -> Selfwhere
F: TypeFolder<I>,
fn fold_with<F>(self, folder: &mut F) -> Selfwhere F: TypeFolder<I>,
try_fold_with
for use with infallible
folders. Do not override this method, to ensure coherence with
try_fold_with
.source§impl<'tcx, O: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>> for Obligation<'tcx, O>
impl<'tcx, O: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>> for Obligation<'tcx, O>
source§fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
&self,
visitor: &mut V
) -> ControlFlow<V::BreakTy>
fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>( &self, visitor: &mut V ) -> ControlFlow<V::BreakTy>
impl<T: Eq> Eq for Obligation<'_, T>
Auto Trait Implementations§
impl<'tcx, T> !RefUnwindSafe for Obligation<'tcx, T>
impl<'tcx, T> !Send for Obligation<'tcx, T>
impl<'tcx, T> !Sync for Obligation<'tcx, T>
impl<'tcx, T> Unpin for Obligation<'tcx, T>where T: Unpin,
impl<'tcx, T> !UnwindSafe for Obligation<'tcx, T>
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Layout§
Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.