Struct rustc_middle::mir::query::ClosureRegionRequirements [−][src]
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
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
impl<'tcx> Clone for ClosureRegionRequirements<'tcx>
[src]
fn clone(&self) -> ClosureRegionRequirements<'tcx>
[src]
pub fn clone_from(&mut self, source: &Self)
1.0.0[src]
impl<'tcx> Debug for ClosureRegionRequirements<'tcx>
[src]
impl<'tcx, __D: TyDecoder<'tcx>> Decodable<__D> for ClosureRegionRequirements<'tcx>
[src]
impl<'tcx, __E: TyEncoder<'tcx>> Encodable<__E> for ClosureRegionRequirements<'tcx>
[src]
impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for ClosureRegionRequirements<'tcx>
[src]
fn hash_stable(
&self,
__hcx: &mut StableHashingContext<'__ctx>,
__hasher: &mut StableHasher
)
[src]
&self,
__hcx: &mut StableHashingContext<'__ctx>,
__hasher: &mut StableHasher
)
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]
T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
[src]
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]
T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
[src]
impl<'a, T> Captures<'a> for T where
T: ?Sized,
[src]
T: ?Sized,
impl<T> From<T> for T
[src]
impl<T, U> Into<U> for T where
U: From<T>,
[src]
U: From<T>,
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]
T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
[src]
pub fn clone_into(&self, target: &mut T)
[src]
impl<T, U> TryFrom<U> for T where
U: Into<T>,
[src]
U: Into<T>,
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]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
[src]
U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.