# Struct rustc_infer::infer::relate::nll::TypeRelating

source ·

    pub struct TypeRelating<'me, 'tcx, D>where
        D: TypeRelatingDelegate<'tcx>,{
        infcx: &'me InferCtxt<'tcx>,
        delegate: D,
        ambient_variance: Variance,
        ambient_variance_info: VarianceDiagInfo<'tcx>,
    }

## Fields§

§`infcx: &'me InferCtxt<'tcx>`§`delegate: D`

Callback to use when we deduce an outlives relationship.

§`ambient_variance: Variance`

How are we relating `a` and `b`?

- Covariant means `a <: b`.
- Contravariant means `b <: a`.
- Invariant means `a == b`.
- Bivariant means that it doesn’t matter.

§`ambient_variance_info: VarianceDiagInfo<'tcx>`

## Implementations§

source§

### impl<'me, 'tcx, D> TypeRelating<'me, 'tcx, D>
where D: TypeRelatingDelegate<'tcx>,

source

#### pub fn new( infcx: &'me InferCtxt<'tcx>, delegate: D, ambient_variance: Variance ) -> Self

source

#### fn ambient_covariance(&self) -> bool

source

#### fn ambient_contravariance(&self) -> bool

source

#### fn push_outlives( &mut self, sup: Region<'tcx>, sub: Region<'tcx>, info: VarianceDiagInfo<'tcx> )

Push a new outlives requirement into our output set of constraints.

source

#### fn relate_ty_var<PAIR: VidValuePair<'tcx>>( &mut self, pair: PAIR ) -> RelateResult<'tcx, Ty<'tcx>>

Relate a type inference variable with a value type. This works by creating a “generalization” G of the value where all the lifetimes are replaced with fresh inference values. This generalization G becomes the value of the inference variable, and is then related in turn to the value. So e.g. if you had `vid = ?0` and `value = &'a u32`, we might first instantiate `?0` to a type like `&'0 u32` where `'0` is a fresh variable, and then relate `&'0 u32` with `&'a u32` (resulting in relations between `'0` and `'a`).

The variable `pair` can be either a `(vid, ty)` or `(ty, vid)` – in other words, it is always an (unresolved) inference variable `vid` and a type `ty` that are being related, but the vid may appear either as the “a” type or the “b” type, depending on where it appears in the tuple. The trait `VidValuePair` lets us work with the vid/type while preserving the “sidedness” when necessary – the sidedness is relevant in particular for the variance and set of in-scope things.

source

#### fn generalize( &mut self, ty: Ty<'tcx>, for_vid: TyVid ) -> RelateResult<'tcx, Ty<'tcx>>

source

#### fn relate_opaques( &mut self, a: Ty<'tcx>, b: Ty<'tcx> ) -> RelateResult<'tcx, Ty<'tcx>>

source

#### fn instantiate_binder_with_placeholders<T>( &mut self, binder: Binder<'tcx, T> ) -> T
where T: TypeFoldable<TyCtxt<'tcx>> + Copy,

source

#### fn instantiate_binder_with_existentials<T>( &mut self, binder: Binder<'tcx, T> ) -> T
where T: TypeFoldable<TyCtxt<'tcx>> + Copy,

## Trait Implementations§

source§

### impl<'tcx, D> ObligationEmittingRelation<'tcx> for TypeRelating<'_, 'tcx, D>
where D: TypeRelatingDelegate<'tcx>,

source§

#### fn param_env(&self) -> ParamEnv<'tcx>

source§

#### fn register_predicates( &mut self, obligations: impl IntoIterator<Item: ToPredicate<'tcx>> )

Register predicates that must hold in order for this relation to hold. Uses a default obligation cause, `ObligationEmittingRelation::register_obligations` should be used if control over the obligation causes is required.
source§

#### fn register_obligations(&mut self, obligations: PredicateObligations<'tcx>)

Register obligations that must hold in order for this relation to hold
source§

#### fn alias_relate_direction(&self) -> AliasRelationDirection

Relation direction emitted for `AliasRelate` predicates, corresponding to the direction of the relation.
source§

#### fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>)

Register an obligation that both types must be related to each other according to the `ty::AliasRelationDirection` given by `ObligationEmittingRelation::alias_relate_direction`
source§

### impl<'tcx, D> TypeRelation<'tcx> for TypeRelating<'_, 'tcx, D>
where D: TypeRelatingDelegate<'tcx>,

source§

#### fn tcx(&self) -> TyCtxt<'tcx>

source§

#### fn tag(&self) -> &'static str

Returns a static string we can use for printouts.
source§

#### fn a_is_expected(&self) -> bool

Returns `true` if the value `a` is the “expected” type in the relation. Just affects error messages.
source§

#### fn relate_with_variance<T: Relate<'tcx>>( &mut self, variance: Variance, info: VarianceDiagInfo<'tcx>, a: T, b: T ) -> RelateResult<'tcx, T>

Switch variance for the purpose of relating `a` and `b`.
source§

#### fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>>

source§

#### fn regions( &mut self, a: Region<'tcx>, b: Region<'tcx> ) -> RelateResult<'tcx, Region<'tcx>>

source§

#### fn consts( &mut self, a: Const<'tcx>, b: Const<'tcx> ) -> RelateResult<'tcx, Const<'tcx>>

source§

#### fn binders<T>( &mut self, a: Binder<'tcx, T>, b: Binder<'tcx, T> ) -> RelateResult<'tcx, Binder<'tcx, T>>
where T: Relate<'tcx>,

source§

#### fn with_cause<F, R>(&mut self, _cause: Cause, f: F) -> R
where F: FnOnce(&mut Self) -> R,

source§

#### fn relate<T>(&mut self, a: T, b: T) -> Result<T, TypeError<'tcx>>
where T: Relate<'tcx>,

Generic relation routine suitable for most anything.
source§

#### fn relate_item_args( &mut self, item_def_id: DefId, a_arg: &'tcx List<GenericArg<'tcx>>, b_arg: &'tcx List<GenericArg<'tcx>> ) -> Result<&'tcx List<GenericArg<'tcx>>, TypeError<'tcx>>

Relate the two args for the given item. The default is to look up the variance for the item and proceed accordingly.

## Auto Trait Implementations§

§

### impl<'me, 'tcx, D> !RefUnwindSafe for TypeRelating<'me, 'tcx, D>

§

### impl<'me, 'tcx, D> !Send for TypeRelating<'me, 'tcx, D>

§

### impl<'me, 'tcx, D> !Sync for TypeRelating<'me, 'tcx, D>

§

### impl<'me, 'tcx, D> Unpin for TypeRelating<'me, 'tcx, D>
where D: Unpin,

§

### impl<'me, 'tcx, D> !UnwindSafe for TypeRelating<'me, 'tcx, D>

## Blanket Implementations§

source§

### impl<T> Any for T
where T: 'static + ?Sized,

source§

#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
source§

### impl<T> Borrow<T> for T
where T: ?Sized,

source§

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
source§

### impl<T> BorrowMut<T> for T
where T: ?Sized,

source§

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
source§

### impl<T> From<T> for T

source§

#### fn from(t: T) -> T

Returns the argument unchanged.

source§

### impl<T, U> Into<U> for T
where U: From<T>,

source§

#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

source§

### impl<T, U> TryFrom<U> for T
where U: Into<T>,

§

#### type Error = Infallible

The type returned in the event of a conversion error.
source§

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
source§

### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

§

#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
source§

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

## 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.