Enum chalk_ir::Constraint

pub enum Constraint<I: Interner> {
    LifetimeOutlives(Lifetime<I>, Lifetime<I>),
    TypeOutlives(Ty<I>, Lifetime<I>),
}

A constraint on lifetimes.

When we search for solutions within the trait system, we essentially ignore lifetime constraints, instead gathering them up to return with our solution for later checking. This allows for decoupling between type and region checking in the compiler.

Variants

LifetimeOutlives(Lifetime<I>, Lifetime<I>)

Outlives constraint 'a: 'b, indicating that the value of 'a must be a superset of the value of 'b.

TypeOutlives(Ty<I>, Lifetime<I>)

Type outlives constraint T: 'a, indicating that the type T must live at least as long as the value of 'a.

Trait Implementations

impl<I: Interner> CastTo<Constraint<I>> for Constraint<I>

fn cast_to( self, _interner: <Constraint<I> as HasInterner>::Interner ) -> Constraint<I>

Cast a value to type T.

impl<I: Clone + Interner> Clone for Constraint<I>

fn clone(&self) -> Constraint<I>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<I: Interner> Debug for Constraint<I>

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

Formats the value using the given formatter.

impl<I: Interner> HasInterner for Constraint<I>

type Interner = I

The interner associated with the type.

impl<I: Hash + Interner> Hash for Constraint<I>

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<I: PartialEq + Interner> PartialEq for Constraint<I>

fn eq(&self, other: &Constraint<I>) -> 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<I: Interner> TypeFoldable<I> for Constraint<I>

fn try_fold_with<E>( self, folder: &mut dyn FallibleTypeFolder<I, Error = E>, outer_binder: DebruijnIndex ) -> Result<Self, E>

Apply the given folder folder to self; binders is the number of binders that are in scope when beginning the folder. Typically binders starts as 0, but is adjusted when we encounter Binders<T> in the IR or other similar constructs.

fn fold_with( self, folder: &mut dyn TypeFolder<I>, outer_binder: DebruijnIndex ) -> Self

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<I: Interner> TypeVisitable<I> for Constraint<I>

fn visit_with<B>( &self, visitor: &mut dyn TypeVisitor<I, BreakTy = B>, outer_binder: DebruijnIndex ) -> ControlFlow<B>

Apply the given visitor visitor to self; binders is the number of binders that are in scope when beginning the visitor. Typically binders starts as 0, but is adjusted when we encounter Binders<T> in the IR or other similar constructs.

impl<I: Interner> Zip<I> for Constraint<I>

fn zip_with<Z: Zipper<I>>( zipper: &mut Z, variance: Variance, a: &Self, b: &Self ) -> Fallible<()>

Uses the zipper to walk through two values, ensuring that they match.

impl<I: Interner> Copy for Constraint<I>

where I::InternedLifetime: Copy, I::InternedType: Copy,

impl<I: Eq + Interner> Eq for Constraint<I>

impl<I: Interner> StructuralPartialEq for Constraint<I>