Struct rustc_middle::mir::query::ClosureRegionRequirements

source ·
pub struct ClosureRegionRequirements<'tcx> {
    pub num_external_vids: usize,
    pub outlives_requirements: Vec<ClosureOutlivesRequirement<'tcx>>,
}
Expand description

After we borrow check a closure, we are left with various requirements that we have inferred between the free regions that appear in the closure’s signature or on its field types. These requirements are then verified and proved by the closure’s creating function. This struct encodes those requirements.

The requirements are listed as being between various RegionVid. The 0th region refers to 'static; subsequent region vids refer to the free regions that appear in the closure (or coroutine’s) type, in order of appearance. (This numbering is actually defined by the UniversalRegions struct in the NLL region checker. See for example UniversalRegions::closure_mapping.) Note the free regions in the closure’s signature and captures are erased.

Example: If type check produces a closure with the closure args:

ClosureArgs = [
    'a,                                         // From the parent.
    'b,
    i8,                                         // the "closure kind"
    for<'x> fn(&'<erased> &'x u32) -> &'x u32,  // the "closure signature"
    &'<erased> String,                          // some upvar
]

We would “renumber” each free region to a unique vid, as follows:

ClosureArgs = [
    '1,                                         // From the parent.
    '2,
    i8,                                         // the "closure kind"
    for<'x> fn(&'3 &'x u32) -> &'x u32,         // the "closure signature"
    &'4 String,                                 // some upvar
]

Now the code might impose a requirement like '1: '2. When an instance of the closure is created, the corresponding free regions can be extracted from its type and constrained to have the given outlives relationship.

Fields§

§num_external_vids: usize

The number of external regions defined on the closure. In our example above, it would be 3 – one for 'static, then '1 and '2. This is just used for a sanity check later on, to make sure that the number of regions we see at the callsite matches.

§outlives_requirements: Vec<ClosureOutlivesRequirement<'tcx>>

Requirements between the various free regions defined in indices.

Trait Implementations§

source§

impl<'tcx> Clone for ClosureRegionRequirements<'tcx>

source§

fn clone(&self) -> ClosureRegionRequirements<'tcx>

Returns a copy of the value. Read more
1.0.0 · source§

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

Performs copy-assignment from source. Read more
source§

impl<'tcx> Debug for ClosureRegionRequirements<'tcx>

source§

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

Formats the value using the given formatter. Read more
source§

impl<'tcx, __D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<__D> for ClosureRegionRequirements<'tcx>

source§

fn decode(__decoder: &mut __D) -> Self

source§

impl<'tcx, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for ClosureRegionRequirements<'tcx>

source§

fn encode(&self, __encoder: &mut __E)

source§

impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for ClosureRegionRequirements<'tcx>

source§

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

Auto Trait Implementations§

§

impl<'tcx> Freeze for ClosureRegionRequirements<'tcx>

§

impl<'tcx> !RefUnwindSafe for ClosureRegionRequirements<'tcx>

§

impl<'tcx> !Send for ClosureRegionRequirements<'tcx>

§

impl<'tcx> !Sync for ClosureRegionRequirements<'tcx>

§

impl<'tcx> Unpin for ClosureRegionRequirements<'tcx>

§

impl<'tcx> !UnwindSafe for ClosureRegionRequirements<'tcx>

Blanket Implementations§

source§

impl<T> Aligned for T

source§

const ALIGN: Alignment = _

Alignment of Self.
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, R> CollectAndApply<T, R> for T

source§

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<_>>()).

§

type Output = R

source§

impl<Tcx, T> DepNodeParams<Tcx> for T
where Tcx: DepContext, T: for<'a> HashStable<StableHashingContext<'a>> + Debug,

source§

default fn fingerprint_style() -> FingerprintStyle

source§

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).
source§

default fn to_debug_str(&self, _: Tcx) -> String

source§

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 DepNodes 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.
source§

impl<T> Filterable for T

source§

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
source§

impl<T> From<T> for T

source§

fn from(t: T) -> T

Returns the argument unchanged.

source§

impl<T> Instrument for T

source§

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

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
source§

fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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<P> IntoQueryParam<P> for P

source§

impl<T> MaybeResult<T> for T

§

type Error = !

source§

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

source§

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

source§

impl<T> Same for T

§

type Output = T

Should always be Self
source§

impl<T> ToOwned for T
where T: Clone,

§

type Owned = T

The resulting type after obtaining ownership.
source§

fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
source§

fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
source§

impl<'tcx, T> ToPredicate<'tcx, T> for T

source§

fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T

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.
source§

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

source§

fn vzip(self) -> V

source§

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

source§

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

source§

impl<T> WithSubscriber for T

source§

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
source§

fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
source§

impl<'a, T> Captures<'a> for T
where T: ?Sized,

source§

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

source§

impl<T> MaybeSendSync for T

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: 32 bytes