Enum rustc::infer::canonical::Certainty

pub enum Certainty {
    Proven,
    Ambiguous,
}

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Indicates whether or not we were able to prove the query to be true.

Variants

Proven

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The query is known to be true, presuming that you apply the given var_values and the region-constraints are satisfied.

Ambiguous

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The query is not known to be true, but also not known to be false. The var_values represent either values that must hold in order for the query to be true, or helpful tips that might make it true. Currently rustc's trait solver cannot distinguish the two (e.g., due to our preference for where clauses over impls).

After some unifiations and things have been done, it makes sense to try and prove again -- of course, at that point, the canonical form will be different, making this a distinct query.

Methods

impl Certainty

pub fn is_proven(&self) -> bool

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pub fn is_ambiguous(&self) -> bool

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Trait Implementations

impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Certainty

fn hash_stable<W: StableHasherResult>(     &self,     __ctx: &mut StableHashingContext<'a>,     __hasher: &mut StableHasher<W> )

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impl Copy for Certainty

impl Clone for Certainty

fn clone(&self) -> Certainty

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Certainty

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

Formats the value using the given formatter.

impl<'tcx> TypeFoldable<'tcx> for Certainty

fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(     &self,     _: &mut F ) -> Certainty

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fn super_visit_with<F: TypeVisitor<'tcx>>(&self, _: &mut F) -> bool

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fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(     &self,     folder: &mut F ) -> Self

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

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fn has_regions_bound_at_or_above(&self, binder: DebruijnIndex) -> bool

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True if self has any late-bound regions that are either bound by binder or bound by some binder outside of binder. If binder is ty::INNERMOST, this indicates whether there are any late-bound regions that appear free.

fn has_regions_bound_above(&self, binder: DebruijnIndex) -> bool

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True if this self has any regions that escape binder (and hence are not bound by it).

fn has_escaping_regions(&self) -> bool

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fn has_type_flags(&self, flags: TypeFlags) -> bool

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fn has_projections(&self) -> bool

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fn references_error(&self) -> bool

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fn has_param_types(&self) -> bool

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fn has_self_ty(&self) -> bool

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fn has_infer_types(&self) -> bool

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fn needs_infer(&self) -> bool

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fn has_skol(&self) -> bool

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fn needs_subst(&self) -> bool

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fn has_re_skol(&self) -> bool

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fn has_closure_types(&self) -> bool

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fn has_free_regions(&self) -> bool

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"Free" regions in this context means that it has any region that is not (a) erased or (b) late-bound.

fn has_erasable_regions(&self) -> bool

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True if there any any un-erased free regions.

fn is_global(&self) -> bool

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Indicates whether this value references only 'global' types/lifetimes that are the same regardless of what fn we are in. This is used for caching.

fn has_late_bound_regions(&self) -> bool

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True if there are any late-bound regions

fn visit_tys_shallow(     &self,     visit: impl FnMut(Ty<'tcx>) -> bool ) -> bool

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A visitor that does not recurse into types, works like fn walk_shallow in Ty.

impl<'tcx> Lift<'tcx> for Certainty

type Lifted = Self

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fn lift_to_tcx<'a, 'gcx>(&self, _: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self>

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