Enum rustc_trait_selection::traits::solve::Certainty

pub enum Certainty {
    Yes,
    Maybe(MaybeCause),
}

Variants

Yes

Maybe(MaybeCause)

Implementations

impl Certainty

pub const AMBIGUOUS: Certainty = _

pub fn unify_with(self, other: Certainty) -> Certainty

Use this function to merge the certainty of multiple nested subgoals.

Given an impl like impl<T: Foo + Bar> Baz for T {}, we have 2 nested subgoals whenever we use the impl as a candidate: T: Foo and T: Bar. If evaluating T: Foo results in ambiguity and T: Bar results in success, we merge these two responses. This results in ambiguity.

If we unify ambiguity with overflow, we return overflow. This doesn’t matter inside of the solver as we do not distinguish ambiguity from overflow. It does however matter for diagnostics. If T: Foo resulted in overflow and T: Bar in ambiguity without changing the inference state, we still want to tell the user that T: Baz results in overflow.

pub const fn overflow(suggest_increasing_limit: bool) -> Certainty

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 Hash for Certainty

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

where __H: Hasher,

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

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

impl PartialEq for Certainty

fn eq(&self, other: &Certainty) -> bool

This method tests for self and other values to be equal, and is used by ==.

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

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

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

fn try_fold_with<__F>( self, __folder: &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, 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> TypeVisitable<TyCtxt<'tcx>> for Certainty

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

where __V: 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

impl Eq for Certainty

impl StructuralPartialEq 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:

• Yes: 0 bytes
• Maybe: 1 byte