rustc_type_ir::relate::solver_relating

Struct SolverRelating

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pub struct SolverRelating<'infcx, Infcx, I: Interner> {
    infcx: &'infcx Infcx,
    structurally_relate_aliases: StructurallyRelateAliases,
    param_env: I::ParamEnv,
    ambient_variance: Variance,
    goals: Vec<Goal<I, I::Predicate>>,
    cache: DelayedSet<(Variance, I::Ty, I::Ty)>,
}
Expand description

Enforce that a is equal to or a subtype of b.

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§infcx: &'infcx Infcx§structurally_relate_aliases: StructurallyRelateAliases§param_env: I::ParamEnv§ambient_variance: Variance§goals: Vec<Goal<I, I::Predicate>>§cache: DelayedSet<(Variance, I::Ty, I::Ty)>

The cache only tracks the ambient_variance as it’s the only field which is mutable and which meaningfully changes the result when relating types.

The cache does not track whether the state of the Infcx has been changed or whether we’ve added any goals to self.goals. Whether a goal is added once or multiple times is not really meaningful.

Changes in the inference state may delay some type inference to the next fulfillment loop. Given that this loop is already necessary, this is also not a meaningful change. Consider the following three relations:

Vec<?0> sub Vec<?1>
?0 eq u32
Vec<?0> sub Vec<?1>

Without a cache, the second Vec<?0> sub Vec<?1> would eagerly constrain ?1 to u32. When using the cache entry from the first time we’ve related these types, this only happens when later proving the Subtype(?0, ?1) goal from the first relation.

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impl<'infcx, Infcx, I> SolverRelating<'infcx, Infcx, I>
where Infcx: InferCtxtLike<Interner = I>, I: Interner,

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pub fn new( infcx: &'infcx Infcx, structurally_relate_aliases: StructurallyRelateAliases, ambient_variance: Variance, param_env: I::ParamEnv, ) -> Self

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impl<Infcx, I> PredicateEmittingRelation<Infcx> for SolverRelating<'_, Infcx, I>
where Infcx: InferCtxtLike<Interner = I>, I: Interner,

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fn span(&self) -> I::Span

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fn param_env(&self) -> I::ParamEnv

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fn structurally_relate_aliases(&self) -> StructurallyRelateAliases

Whether aliases should be related structurally. This is pretty much always No unless you’re equating in some specific locations of the new solver. See the comments in these use-cases for more details.
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fn register_predicates( &mut self, obligations: impl IntoIterator<Item: Upcast<I, I::Predicate>>, )

Register predicates that must hold in order for this relation to hold. This uses the default param_env of the obligation.
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fn register_goals( &mut self, obligations: impl IntoIterator<Item = Goal<I, I::Predicate>>, )

Register obligations that must hold in order for this relation to hold
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fn register_alias_relate_predicate(&mut self, a: I::Ty, b: I::Ty)

Register AliasRelate obligation(s) that both types must be related to each other.
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impl<Infcx, I> TypeRelation<I> for SolverRelating<'_, Infcx, I>
where Infcx: InferCtxtLike<Interner = I>, I: Interner,

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fn cx(&self) -> I

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fn relate_item_args( &mut self, item_def_id: I::DefId, a_arg: I::GenericArgs, b_arg: I::GenericArgs, ) -> RelateResult<I, I::GenericArgs>

Relate the two args for the given item. The default is to look up the variance for the item and proceed accordingly.
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fn relate_with_variance<T: Relate<I>>( &mut self, variance: Variance, _info: VarianceDiagInfo<I>, a: T, b: T, ) -> RelateResult<I, T>

Switch variance for the purpose of relating a and b.
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fn tys(&mut self, a: I::Ty, b: I::Ty) -> RelateResult<I, I::Ty>

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

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

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fn binders<T>( &mut self, a: Binder<I, T>, b: Binder<I, T>, ) -> RelateResult<I, Binder<I, T>>
where T: Relate<I>,

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fn relate<T: Relate<I>>(&mut self, a: T, b: T) -> RelateResult<I, T>

Generic relation routine suitable for most anything.

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impl<'infcx, Infcx, I> DynSend for SolverRelating<'infcx, Infcx, I>
where <I as Interner>::ParamEnv: DynSend, Infcx: DynSync, <I as Interner>::Predicate: DynSend, <I as Interner>::Ty: DynSend,

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impl<'infcx, Infcx, I> DynSync for SolverRelating<'infcx, Infcx, I>
where <I as Interner>::ParamEnv: DynSync, Infcx: DynSync, <I as Interner>::Predicate: DynSync, <I as Interner>::Ty: DynSync,

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impl<'infcx, Infcx, I> Freeze for SolverRelating<'infcx, Infcx, I>
where <I as Interner>::ParamEnv: Freeze,

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impl<'infcx, Infcx, I> RefUnwindSafe for SolverRelating<'infcx, Infcx, I>

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impl<'infcx, Infcx, I> Send for SolverRelating<'infcx, Infcx, I>
where <I as Interner>::ParamEnv: Send, Infcx: Sync, <I as Interner>::Predicate: Send, <I as Interner>::Ty: Send,

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impl<'infcx, Infcx, I> Sync for SolverRelating<'infcx, Infcx, I>
where <I as Interner>::ParamEnv: Sync, Infcx: Sync, <I as Interner>::Predicate: Sync, <I as Interner>::Ty: Sync,

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impl<'infcx, Infcx, I> Unpin for SolverRelating<'infcx, Infcx, I>
where <I as Interner>::ParamEnv: Unpin, <I as Interner>::Predicate: Unpin, <I as Interner>::Ty: Unpin,

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impl<'infcx, Infcx, I> UnwindSafe for SolverRelating<'infcx, Infcx, I>

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impl<T> Aligned for T

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const ALIGN: Alignment = _

Alignment of Self.
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where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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where T: ?Sized,

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fn borrow(&self) -> &T

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

Mutably borrows from an owned value. Read more
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impl<T, R> CollectAndApply<T, R> for T

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fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to f(&iter.collect::<Vec<_>>()).

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type Output = R

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fn from(t: T) -> T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
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Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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const ALIGN: usize = _

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type Output = T

Should always be Self
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Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.