Struct rustc_middle::ty::sty::Binder

pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);

Binder is a binder for higher-ranked lifetimes or types. It is part of the compiler’s representation for things like for<'a> Fn(&'a isize) (which would be represented by the type PolyTraitRef == Binder<'tcx, TraitRef>). Note that when we instantiate, erase, or otherwise “discharge” these bound vars, we change the type from Binder<'tcx, T> to just T (see e.g., liberate_late_bound_regions).

Decodable and Encodable are implemented for Binder<T> using the impl_binder_encode_decode! macro.

Tuple Fields

0: T

1: &'tcx List<BoundVariableKind>

Implementations

impl<'tcx> Binder<'tcx, TraitRef<'tcx>>

pub fn print_only_trait_path(
    self
) -> Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>

impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>>

pub fn with_self_ty(
    &self,
    tcx: TyCtxt<'tcx>,
    self_ty: Ty<'tcx>
) -> Predicate<'tcx>

impl<'tcx> Binder<'tcx, TraitRef<'tcx>>

pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>>

pub fn def_id(&self) -> DefId

pub fn to_poly_trait_predicate(&self) -> PolyTraitPredicate<'tcx>

impl<'tcx> Binder<'tcx, ExistentialTraitRef<'tcx>>

pub fn def_id(&self) -> DefId

pub fn with_self_ty(
    &self,
    tcx: TyCtxt<'tcx>,
    self_ty: Ty<'tcx>
) -> PolyTraitRef<'tcx>

Object types don’t have a self type specified. Therefore, when we convert the principal trait-ref into a normal trait-ref, you must give some self type. A common choice is mk_err() or some placeholder type.

impl<'tcx, T> Binder<'tcx, T> where
    T: TypeFoldable<'tcx>, 

pub fn dummy(value: T) -> Binder<'tcx, T>

Wraps value in a binder, asserting that value does not contain any bound vars that would be bound by the binder. This is commonly used to ‘inject’ a value T into a different binding level.

pub fn bind_with_vars(
    value: T,
    vars: &'tcx List<BoundVariableKind>
) -> Binder<'tcx, T>

impl<'tcx, T> Binder<'tcx, T>

pub fn skip_binder(self) -> T

Skips the binder and returns the “bound” value. This is a risky thing to do because it’s easy to get confused about De Bruijn indices and the like. It is usually better to discharge the binder using no_bound_vars or replace_late_bound_regions or something like that. skip_binder is only valid when you are either extracting data that has nothing to do with bound vars, you are doing some sort of test that does not involve bound regions, or you are being very careful about your depth accounting.

Some examples where skip_binder is reasonable:

• extracting the DefId from a PolyTraitRef;
• comparing the self type of a PolyTraitRef to see if it is equal to a type parameter X, since the type X does not reference any regions

pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind>

pub fn as_ref(&self) -> Binder<'tcx, &T>

pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U> where
    F: FnOnce(&T) -> U, 

pub fn map_bound_ref<F, U: TypeFoldable<'tcx>>(&self, f: F) -> Binder<'tcx, U> where
    F: FnOnce(&T) -> U, 

pub fn map_bound<F, U: TypeFoldable<'tcx>>(self, f: F) -> Binder<'tcx, U> where
    F: FnOnce(T) -> U, 

pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U> where
    U: TypeFoldable<'tcx>, 

Wraps a value in a binder, using the same bound variables as the current Binder. This should not be used if the new value changes the bound variables. Note: the (old or new) value itself does not necessarily need to name all the bound variables.

This currently doesn’t do anything different than bind, because we don’t actually track bound vars. However, semantically, it is different because bound vars aren’t allowed to change here, whereas they are in bind. This may be (debug) asserted in the future.

pub fn no_bound_vars(self) -> Option<T> where
    T: TypeFoldable<'tcx>, 

Unwraps and returns the value within, but only if it contains no bound vars at all. (In other words, if this binder – and indeed any enclosing binder – doesn’t bind anything at all.) Otherwise, returns None.

(One could imagine having a method that just unwraps a single binder, but permits late-bound vars bound by enclosing binders, but that would require adjusting the debruijn indices, and given the shallow binding structure we often use, would not be that useful.)

pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>) where
    F: FnOnce(T) -> (U, V), 

Splits the contents into two things that share the same binder level as the original, returning two distinct binders.

f should consider bound regions at depth 1 to be free, and anything it produces with bound regions at depth 1 will be bound in the resulting return values.

impl<'tcx, T> Binder<'tcx, Option<T>>

pub fn transpose(self) -> Option<Binder<'tcx, T>>

impl<'tcx> Binder<'tcx, FnSig<'tcx>>

pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]>

pub fn input(&self, index: usize) -> Binder<'tcx, Ty<'tcx>>

pub fn inputs_and_output(&self) -> Binder<'tcx, &'tcx List<Ty<'tcx>>>

pub fn output(&self) -> Binder<'tcx, Ty<'tcx>>

pub fn c_variadic(&self) -> bool

pub fn unsafety(&self) -> Unsafety

pub fn abi(&self) -> Abi

impl<'tcx> Binder<'tcx, ExistentialProjection<'tcx>>

pub fn with_self_ty(
    &self,
    tcx: TyCtxt<'tcx>,
    self_ty: Ty<'tcx>
) -> PolyProjectionPredicate<'tcx>

pub fn item_def_id(&self) -> DefId

impl<'tcx> Binder<'tcx, TraitPredicate<'tcx>>

pub fn def_id(self) -> DefId

pub fn self_ty(self) -> Binder<'tcx, Ty<'tcx>>

impl<'tcx> Binder<'tcx, ProjectionPredicate<'tcx>>

pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId

Returns the DefId of the trait of the associated item being projected.

pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx>

Get the PolyTraitRef required for this projection to be well formed. Note that for generic associated types the predicates of the associated type also need to be checked.

pub fn ty(&self) -> Binder<'tcx, Ty<'tcx>>

pub fn projection_def_id(&self) -> DefId

The DefId of the TraitItem for the associated type.

Note that this is not the DefId of the TraitRef containing this associated type, which is in tcx.associated_item(projection_def_id()).container.

Trait Implementations

impl<'tcx> Borrow<Binder<'tcx, PredicateKind<'tcx>>> for Interned<'tcx, PredicateInner<'tcx>>

fn borrow<'a>(&'a self) -> &'a Binder<'tcx, PredicateKind<'tcx>>

Immutably borrows from an owned value.

impl<'tcx, T: Clone> Clone for Binder<'tcx, T>

fn clone(&self) -> Binder<'tcx, T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx, T: Debug> Debug for Binder<'tcx, T>

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

Formats the value using the given formatter.

impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Binder<'tcx, PredicateKind<'tcx>>

fn decode(
    decoder: &mut D
) -> Result<Binder<'tcx, PredicateKind<'tcx>>, D::Error>

impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Binder<'tcx, &'tcx List<Ty<'tcx>>>

fn decode(decoder: &mut D) -> Result<Self, D::Error>

impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Binder<'tcx, FnSig<'tcx>>

fn decode(decoder: &mut D) -> Result<Self, D::Error>

impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Binder<'tcx, ExistentialPredicate<'tcx>>

fn decode(decoder: &mut D) -> Result<Self, D::Error>

impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Binder<'tcx, TraitRef<'tcx>>

fn decode(decoder: &mut D) -> Result<Self, D::Error>

impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Binder<'tcx, Vec<GeneratorInteriorTypeCause<'tcx>>>

fn decode(decoder: &mut D) -> Result<Self, D::Error>

impl<'tcx> Display for Binder<'tcx, ExistentialPredicate<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, TraitRef<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, OutlivesPredicate<Region<'tcx>, Region<'tcx>>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, ExistentialTraitRef<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, TraitRefPrintOnlyTraitPath<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, TraitRefPrintOnlyTraitName<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, FnSig<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, TraitPredicate<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, SubtypePredicate<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, ProjectionPredicate<'tcx>>

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

Formats the value using the given formatter.

impl<'tcx> Display for Binder<'tcx, OutlivesPredicate<Ty<'tcx>, Region<'tcx>>>

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

Formats the value using the given formatter.

impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Binder<'tcx, PredicateKind<'tcx>>

fn encode(&self, e: &mut E) -> Result<(), E::Error>

impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Binder<'tcx, &'tcx List<Ty<'tcx>>>

fn encode(&self, e: &mut E) -> Result<(), E::Error>

impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Binder<'tcx, FnSig<'tcx>>

fn encode(&self, e: &mut E) -> Result<(), E::Error>

impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Binder<'tcx, ExistentialPredicate<'tcx>>

fn encode(&self, e: &mut E) -> Result<(), E::Error>

impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Binder<'tcx, TraitRef<'tcx>>

fn encode(&self, e: &mut E) -> Result<(), E::Error>

impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Binder<'tcx, Vec<GeneratorInteriorTypeCause<'tcx>>>

fn encode(&self, e: &mut E) -> Result<(), E::Error>

impl<'tcx, T: Hash> Hash for Binder<'tcx, T>

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, 

Feeds a slice of this type into the given Hasher.

impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for Binder<'tcx, T> where
    T: HashStable<StableHashingContext<'a>>, 

fn hash_stable(
    &self,
    hcx: &mut StableHashingContext<'a>,
    hasher: &mut StableHasher
)

impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for Binder<'a, T> where
    <T as Lift<'tcx>>::Lifted: TypeFoldable<'tcx>, 

type Lifted = Binder<'tcx, T::Lifted>

fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>

impl<'tcx, T: Ord> Ord for Binder<'tcx, T>

fn cmp(&self, other: &Binder<'tcx, T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<'tcx, T: PartialEq> PartialEq<Binder<'tcx, T>> for Binder<'tcx, T>

fn eq(&self, other: &Binder<'tcx, T>) -> bool

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

fn ne(&self, other: &Binder<'tcx, T>) -> bool

This method tests for !=.

impl<'tcx, T: PartialOrd> PartialOrd<Binder<'tcx, T>> for Binder<'tcx, T>

fn partial_cmp(&self, other: &Binder<'tcx, T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

This method tests less than (for self and other) and is used by the < operator.

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

This method tests less than or equal to (for self and other) and is used by the <= operator.

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

This method tests greater than (for self and other) and is used by the > operator.

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

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'tcx, T, P: PrettyPrinter<'tcx>> Print<'tcx, P> for Binder<'tcx, T> where
    T: Print<'tcx, P, Output = P, Error = P::Error> + TypeFoldable<'tcx>, 

type Output = P

type Error = P::Error

fn print(&self, cx: P) -> Result<Self::Output, Self::Error>

impl<'tcx, T: Relate<'tcx>> Relate<'tcx> for Binder<'tcx, T>

fn relate<R: TypeRelation<'tcx>>(
    relation: &mut R,
    a: Binder<'tcx, T>,
    b: Binder<'tcx, T>
) -> RelateResult<'tcx, Binder<'tcx, T>>

impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>>

fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>

impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Binder<'tcx, T>

fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self

fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self

fn super_visit_with<V: TypeVisitor<'tcx>>(
    &self,
    visitor: &mut V
) -> ControlFlow<V::BreakTy>

fn visit_with<V: TypeVisitor<'tcx>>(
    &self,
    visitor: &mut V
) -> ControlFlow<V::BreakTy>

fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool

Returns true if self has any late-bound regions that are either bound by binder or bound by some binder outside of binder. If binder is ty::INNERMOST, this indicates whether there are any late-bound regions that appear free.

fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool

Returns true if this self has any regions that escape binder (and hence are not bound by it).

fn has_escaping_bound_vars(&self) -> bool

fn definitely_has_type_flags(&self, tcx: TyCtxt<'tcx>, flags: TypeFlags) -> bool

fn has_type_flags(&self, flags: TypeFlags) -> bool

fn has_projections(&self) -> bool

fn has_opaque_types(&self) -> bool

fn references_error(&self) -> bool

fn potentially_has_param_types_or_consts(&self) -> bool

fn definitely_has_param_types_or_consts(&self, tcx: TyCtxt<'tcx>) -> bool

fn has_infer_regions(&self) -> bool

fn has_infer_types(&self) -> bool

fn has_infer_types_or_consts(&self) -> bool

fn needs_infer(&self) -> bool

fn has_placeholders(&self) -> bool

fn potentially_needs_subst(&self) -> bool

fn definitely_needs_subst(&self, tcx: TyCtxt<'tcx>) -> bool

fn has_free_regions(&self, tcx: TyCtxt<'tcx>) -> bool

“Free” regions in this context means that it has any region that is not (a) erased or (b) late-bound.

fn has_erased_regions(&self) -> bool

fn has_erasable_regions(&self, tcx: TyCtxt<'tcx>) -> bool

True if there are any un-erased free regions.

fn is_known_global(&self) -> bool

Indicates whether this value definitely references only ‘global’ generic parameters that are the same regardless of what fn we are in. This is used for caching.

fn is_global(&self, tcx: TyCtxt<'tcx>) -> bool

Indicates whether this value references only ‘global’ generic parameters that are the same regardless of what fn we are in. This is used for caching.

fn has_late_bound_regions(&self) -> bool

True if there are any late-bound regions

fn still_further_specializable(&self) -> bool

Indicates whether this value still has parameters/placeholders/inference variables which could be replaced later, in a way that would change the results of impl specialization.

impl<'tcx, T: Copy> Copy for Binder<'tcx, T>

impl<'tcx, T: Eq> Eq for Binder<'tcx, T>

impl<'tcx, T> StructuralEq for Binder<'tcx, T>

impl<'tcx, T> StructuralPartialEq for Binder<'tcx, T>

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.