Struct rustc_middle::mir::query::ClosureRegionRequirements[][src]

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 generator’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 substs:

ClosureSubsts = [
    '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:

ClosureSubsts = [
    '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.

In some cases, we have to record outlives requirements between types and regions as well. In that case, if those types include any regions, those regions are recorded using their external names (ReStatic, ReEarlyBound, ReFree). We use these because in a query response we cannot use ReVar (which is what we use internally within the rest of the NLL code).

Fields

num_external_vids: usize
Expand description

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>>
Expand description

Requirements between the various free regions defined in indices.

Trait Implementations

impl<'tcx> Clone for ClosureRegionRequirements<'tcx>[src]

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

Returns a copy of the value. Read more

fn clone_from(&mut self, source: &Self)1.0.0[src]

Performs copy-assignment from source. Read more

impl<'tcx> Debug for ClosureRegionRequirements<'tcx>[src]

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

Formats the value using the given formatter. Read more

impl<'tcx, __D: TyDecoder<'tcx>> Decodable<__D> for ClosureRegionRequirements<'tcx>[src]

fn decode(__decoder: &mut __D) -> Result<Self, <__D as Decoder>::Error>[src]

impl<'tcx, __E: TyEncoder<'tcx>> Encodable<__E> for ClosureRegionRequirements<'tcx>[src]

fn encode(&self, __encoder: &mut __E) -> Result<(), <__E as Encoder>::Error>[src]

impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for ClosureRegionRequirements<'tcx>[src]

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

Auto Trait Implementations

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

impl<T> Any for T where
    T: 'static + ?Sized
[src]

pub fn type_id(&self) -> TypeId[src]

Gets the TypeId of self. Read more

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

pub fn borrow(&self) -> &T[src]

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

pub fn borrow_mut(&mut self) -> &mut T[src]

Mutably borrows from an owned value. Read more

impl<T> From<T> for T[src]

pub fn from(t: T) -> T[src]

Performs the conversion.

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

pub fn into(self) -> U[src]

Performs the conversion.

impl<T> MaybeResult<T> for T[src]

type Error = !

pub fn from(Result<T, <T as MaybeResult<T>>::Error>) -> T[src]

pub fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>[src]

impl<T> ToOwned for T where
    T: Clone
[src]

type Owned = T

The resulting type after obtaining ownership.

pub fn to_owned(&self) -> T[src]

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

pub fn clone_into(&self, target: &mut T)[src]

🔬 This is a nightly-only experimental API. (toowned_clone_into)

recently added

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

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>[src]

Performs the conversion.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

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

The type returned in the event of a conversion error.

pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>[src]

Performs the conversion.

impl<T> WithConstness for T[src]

fn with_constness(self, constness: Constness) -> ConstnessAnd<Self>[src]

fn with_const(self) -> ConstnessAnd<Self>[src]

fn without_const(self) -> ConstnessAnd<Self>[src]

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

Layout

Note: Most layout information is completely unstable and may be different between compiler versions and platforms. 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