# Enum rustc_middle::ty::inhabitedness::inhabited_predicate::InhabitedPredicate

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    pub enum InhabitedPredicate<'tcx> {
        True,
        False,
        ConstIsZero(Const<'tcx>),
        NotInModule(DefId),
        GenericType(Ty<'tcx>),
        OpaqueType(OpaqueTypeKey<'tcx>),
        And(&'tcx [InhabitedPredicate<'tcx>; 2]),
        Or(&'tcx [InhabitedPredicate<'tcx>; 2]),
    }

Expand description

Represents whether some type is inhabited in a given context. Examples of uninhabited types are `!`, `enum Void {}`, or a struct containing either of those types. A type’s inhabitedness may depend on the `ParamEnv` as well as what types are visible in the current module.

## Variants§

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### True

Inhabited

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### False

Uninhabited

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### ConstIsZero(Const<'tcx>)

Uninhabited when a const value is non-zero. This occurs when there is an array of uninhabited items, but the array is inhabited if it is empty.

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### NotInModule(DefId)

Uninhabited if within a certain module. This occurs when an uninhabited type has restricted visibility.

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### GenericType(Ty<'tcx>)

Inhabited if some generic type is inhabited. These are replaced by calling `Self::instantiate`.

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### OpaqueType(OpaqueTypeKey<'tcx>)

Inhabited if either we don’t know the hidden type or we know it and it is inhabited.

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### And(&'tcx [InhabitedPredicate<'tcx>; 2])

A AND B

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### Or(&'tcx [InhabitedPredicate<'tcx>; 2])

A OR B

## Implementations§

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### impl<'tcx> InhabitedPredicate<'tcx>

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#### pub fn apply( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, module_def_id: DefId, ) -> bool

Returns true if the corresponding type is inhabited in the given `ParamEnv` and module.

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#### pub fn apply_revealing_opaque( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, module_def_id: DefId, reveal_opaque: &impl Fn(OpaqueTypeKey<'tcx>) -> Option<Ty<'tcx>>, ) -> bool

Returns true if the corresponding type is inhabited in the given `ParamEnv` and module, revealing opaques when possible.

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#### pub fn apply_any_module( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ) -> Option<bool>

Same as `apply`, but returns `None` if self contains a module predicate

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#### pub fn apply_ignore_module( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ) -> bool

Same as `apply`, but `NotInModule(_)` predicates yield `false`. That is, privately uninhabited types are considered always uninhabited.

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#### fn apply_inner<E: Debug>( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, eval_stack: &mut SmallVec<[Ty<'tcx>; 1]>, in_module: &impl Fn(DefId) -> Result<bool, E>, reveal_opaque: &impl Fn(OpaqueTypeKey<'tcx>) -> Option<Ty<'tcx>>, ) -> Result<bool, E>

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#### pub fn and(self, tcx: TyCtxt<'tcx>, other: Self) -> Self

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#### pub fn or(self, tcx: TyCtxt<'tcx>, other: Self) -> Self

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#### pub fn all(tcx: TyCtxt<'tcx>, iter: impl IntoIterator<Item = Self>) -> Self

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#### pub fn any(tcx: TyCtxt<'tcx>, iter: impl IntoIterator<Item = Self>) -> Self

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#### fn reduce_and(self, tcx: TyCtxt<'tcx>, other: Self) -> Option<Self>

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#### fn reduce_or(self, tcx: TyCtxt<'tcx>, other: Self) -> Option<Self>

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#### pub fn instantiate(self, tcx: TyCtxt<'tcx>, args: GenericArgsRef<'tcx>) -> Self

Replaces generic types with its corresponding predicate

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#### fn instantiate_opt( self, tcx: TyCtxt<'tcx>, args: GenericArgsRef<'tcx>, ) -> Option<Self>

## Trait Implementations§

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### impl<'tcx> Clone for InhabitedPredicate<'tcx>

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#### fn clone(&self) -> InhabitedPredicate<'tcx>

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl<'tcx> Debug for InhabitedPredicate<'tcx>

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

Formats the value using the given formatter. Read more
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### impl<'tcx> EraseType for InhabitedPredicate<'tcx>

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#### type Result = [u8; 16]

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### impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for InhabitedPredicate<'tcx>

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

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### impl<'tcx> PartialEq for InhabitedPredicate<'tcx>

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#### fn eq(&self, other: &InhabitedPredicate<'tcx>) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`.
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#### 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.
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### impl<'tcx> Copy for InhabitedPredicate<'tcx>

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### impl<'tcx> StructuralPartialEq for InhabitedPredicate<'tcx>

## Auto Trait Implementations§

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### impl<'tcx> DynSend for InhabitedPredicate<'tcx>

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### impl<'tcx> DynSync for InhabitedPredicate<'tcx>

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### impl<'tcx> Freeze for InhabitedPredicate<'tcx>

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### impl<'tcx> !RefUnwindSafe for InhabitedPredicate<'tcx>

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### impl<'tcx> Send for InhabitedPredicate<'tcx>

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### impl<'tcx> Sync for InhabitedPredicate<'tcx>

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### impl<'tcx> Unpin for InhabitedPredicate<'tcx>

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### impl<'tcx> !UnwindSafe for InhabitedPredicate<'tcx>

## Blanket Implementations§

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### impl<T> Aligned for T

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#### const ALIGN: Alignment = _

Alignment of `Self`.
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### impl<T> Any for T
where T: 'static + ?Sized,

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

Gets the `TypeId` of `self`. Read more
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### impl<T> AnyEq for T
where T: Any + PartialEq,

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#### fn equals(&self, other: &(dyn Any + 'static)) -> bool

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#### fn as_any(&self) -> &(dyn Any + 'static)

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### impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

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#### fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut T

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#### fn allocate_from_iter<'a>( arena: &'a Arena<'tcx>, iter: impl IntoIterator<Item = T>, ) -> &'a mut [T]

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### impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

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#### fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut T

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#### fn allocate_from_iter<'a>( arena: &'a Arena<'tcx>, iter: impl IntoIterator<Item = T>, ) -> &'a mut [T]

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

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

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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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> CloneToUninit for T
where T: Copy,

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#### unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (`clone_to_uninit`)
Performs copy-assignment from `self` to `dst`. Read more
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### impl<T> CloneToUninit for T
where T: Clone,

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#### default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (`clone_to_uninit`)
Performs copy-assignment from `self` to `dst`. 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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### impl<Tcx, T> DepNodeParams<Tcx> for T
where Tcx: DepContext, T: for<'a> HashStable<StableHashingContext<'a>> + Debug,

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#### default fn fingerprint_style() -> FingerprintStyle

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#### default fn to_fingerprint(&self, tcx: Tcx) -> Fingerprint

This method turns the parameters of a DepNodeConstructor into an opaque Fingerprint to be used in DepNode. Not all DepNodeParams support being turned into a Fingerprint (they don’t need to if the corresponding DepNode is anonymous).
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#### default fn to_debug_str(&self, _: Tcx) -> String

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#### default fn recover(_: Tcx, _: &DepNode) -> Option<T>

This method tries to recover the query key from the given `DepNode`, something which is needed when forcing `DepNode`s during red-green evaluation. The query system will only call this method if `fingerprint_style()` is not `FingerprintStyle::Opaque`. It is always valid to return `None` here, in which case incremental compilation will treat the query as having changed instead of forcing it.
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### impl<T> Filterable for T

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#### fn filterable( self, filter_name: &'static str, ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. Read more
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### impl<T> From<T> for T

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

Returns the argument unchanged.

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### impl<T> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided `Span`, returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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### impl<T, U> Into<U> for T
where U: From<T>,

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

Calls `U::from(self)`.

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

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### impl<T> IntoEither for 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>
where F: FnOnce(&Self) -> bool,

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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### impl<P> IntoQueryParam<P> for P

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#### fn into_query_param(self) -> P

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### impl<T> MaybeResult<T> for T

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#### type Error = !

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#### fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

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#### fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

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### impl<T> Pointable for T

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#### const ALIGN: usize = _

The alignment of pointer.
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#### type Init = T

The type for initializers.
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#### unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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#### unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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#### unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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#### unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<T> ToOwned for T
where T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<I, T, U> Upcast<I, U> for T
where U: UpcastFrom<I, T>,

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#### fn upcast(self, interner: I) -> U

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### impl<I, T> UpcastFrom<I, T> for T

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#### fn upcast_from(from: T, _tcx: I) -> T

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### impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

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#### default fn from_cycle_error( tcx: Tcx, cycle_error: &CycleError, _guar: ErrorGuaranteed, ) -> T

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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

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### impl<T> ErasedDestructor for T
where T: 'static,

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### impl<T> MaybeSendSync for T
where T: Send + Sync,

## 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: 16 bytes

Size for each variant:

- `True`: 0 bytes
- `False`: 0 bytes
- `ConstIsZero`: 8 bytes
- `NotInModule`: 8 bytes
- `GenericType`: 8 bytes
- `OpaqueType`: 16 bytes
- `And`: 8 bytes
- `Or`: 8 bytes