Enum rustc_trait_selection::infer::canonical::Certainty

pub enum Certainty {
    Proven,
    Ambiguous,
}

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

Variants

Proven

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

Ambiguous

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 unification 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.

Implementations

impl Certainty

pub fn is_proven(&self) -> bool

Trait Implementations

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<(), Error>

Formats the value using the given formatter.

impl<'__ctx> HashStable<StableHashingContext<'__ctx>> for Certainty

fn hash_stable( &self, __hcx: &mut StableHashingContext<'__ctx>, __hasher: &mut StableHasher<SipHasher128>, )

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

fn try_fold_with<F>( self, _: &mut F, ) -> Result<Certainty, <F as FallibleTypeFolder<TyCtxt<'tcx>>>::Error>

where F: FallibleTypeFolder<TyCtxt<'tcx>>,

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, _: &mut F) -> Certainty

where F: TypeFolder<TyCtxt<'tcx>>,

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> TypeVisitable<TyCtxt<'tcx>> for Certainty

fn visit_with<F>(&self, _: &mut F) -> <F as TypeVisitor<TyCtxt<'tcx>>>::Result

where F: TypeVisitor<TyCtxt<'tcx>>,

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

impl Copy for Certainty

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: 1 byte

Size for each variant:

• Proven: 0 bytes
• Ambiguous: 0 bytes