pub enum BoundVarIndexKind {
Bound(DebruijnIndex),
Canonical,
}
Expand description
Okay, we do something fun for Bound
types/regions/consts:
Specifically, we distinguish between canonically bound things and
for<>
bound things. And, really, it comes down to caching during
canonicalization and instantiation.
To understand why we do this, imagine we have a type (T, for<> fn(T))
.
If we just tracked canonically bound types with a DebruijnIndex
(as we
used to), then the canonicalized type would be something like
for<0> (^0.0, for<> fn(^1.0))
and so we can’t cache T -> ^0.0
,
we have to also factor in binder level. (Of course, we don’t cache that
exactly, but rather the entire enclosing type, but the point stands.)
Of course, this is okay because we don’t ever nest canonicalization, so
BoundVarIndexKind::Canonical
is unambiguous. We, alternatively, could
have some sentinel DebruijinIndex
, but that just seems too scary.
This doesn’t seem to have a huge perf swing either way, but in the next
solver, canonicalization is hot and there are some pathological cases where
this is needed (post-mono-higher-ranked-hang
).
Variants§
Bound(DebruijnIndex)
Canonical
Trait Implementations§
Source§impl Clone for BoundVarIndexKind
impl Clone for BoundVarIndexKind
Source§fn clone(&self) -> BoundVarIndexKind
fn clone(&self) -> BoundVarIndexKind
1.0.0 · Source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moreSource§impl Debug for BoundVarIndexKind
impl Debug for BoundVarIndexKind
Source§impl<__D: Decoder> Decodable<__D> for BoundVarIndexKind
impl<__D: Decoder> Decodable<__D> for BoundVarIndexKind
Source§impl<__E: Encoder> Encodable<__E> for BoundVarIndexKind
impl<__E: Encoder> Encodable<__E> for BoundVarIndexKind
Source§impl Hash for BoundVarIndexKind
impl Hash for BoundVarIndexKind
Source§impl<__CTX> HashStable<__CTX> for BoundVarIndexKind
impl<__CTX> HashStable<__CTX> for BoundVarIndexKind
fn hash_stable(&self, __hcx: &mut __CTX, __hasher: &mut StableHasher)
Source§impl PartialEq for BoundVarIndexKind
impl PartialEq for BoundVarIndexKind
Source§impl<I> TypeFoldable<I> for BoundVarIndexKindwhere
I: Interner,
impl<I> TypeFoldable<I> for BoundVarIndexKindwhere
I: Interner,
Source§fn try_fold_with<__F: FallibleTypeFolder<I>>(
self,
__folder: &mut __F,
) -> Result<Self, __F::Error>
fn try_fold_with<__F: FallibleTypeFolder<I>>( self, __folder: &mut __F, ) -> Result<Self, __F::Error>
Source§impl<I> TypeVisitable<I> for BoundVarIndexKindwhere
I: Interner,
impl<I> TypeVisitable<I> for BoundVarIndexKindwhere
I: Interner,
Source§fn visit_with<__V: TypeVisitor<I>>(&self, __visitor: &mut __V) -> __V::Result
fn visit_with<__V: TypeVisitor<I>>(&self, __visitor: &mut __V) -> __V::Result
impl Copy for BoundVarIndexKind
impl Eq for BoundVarIndexKind
impl StructuralPartialEq for BoundVarIndexKind
Auto Trait Implementations§
impl DynSend for BoundVarIndexKind
impl DynSync for BoundVarIndexKind
impl Freeze for BoundVarIndexKind
impl RefUnwindSafe for BoundVarIndexKind
impl Send for BoundVarIndexKind
impl Sync for BoundVarIndexKind
impl Unpin for BoundVarIndexKind
impl UnwindSafe for BoundVarIndexKind
Blanket Implementations§
Source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
Source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Source§impl<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
Source§impl<T, R> CollectAndApply<T, R> for T
impl<T, R> CollectAndApply<T, R> for T
Source§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
Source§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
Source§fn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
key
and return true
if they are equal.Source§impl<T> Instrument for T
impl<T> Instrument for T
Source§fn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
Source§fn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
Source§impl<T> IntoEither for T
impl<T> IntoEither for T
Source§fn into_either(self, into_left: bool) -> Either<Self, Self>
fn into_either(self, into_left: bool) -> Either<Self, Self>
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 moreSource§fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
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 moreSource§impl<T> Pointable for T
impl<T> Pointable for T
Source§impl<I, T> TypeVisitableExt<I> for Twhere
I: Interner,
T: TypeVisitable<I>,
impl<I, T> TypeVisitableExt<I> for Twhere
I: Interner,
T: TypeVisitable<I>,
fn has_type_flags(&self, flags: TypeFlags) -> bool
Source§fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool
fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool
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 error_reported(&self) -> Result<(), <I as Interner>::ErrorGuaranteed>
Source§fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool
fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool
true
if this type has any regions that escape binder
(and
hence are not bound by it).Source§fn has_escaping_bound_vars(&self) -> bool
fn has_escaping_bound_vars(&self) -> bool
true
if this type has regions that are not a part of the type.
For example, for<'a> fn(&'a i32)
return false
, while fn(&'a i32)
would return true
. The latter can occur when traversing through the
former. Read morefn has_aliases(&self) -> bool
fn has_opaque_types(&self) -> bool
fn has_coroutines(&self) -> bool
fn references_error(&self) -> bool
fn has_non_region_param(&self) -> bool
fn has_infer_regions(&self) -> bool
fn has_infer_types(&self) -> bool
fn has_non_region_infer(&self) -> bool
fn has_infer(&self) -> bool
fn has_placeholders(&self) -> bool
fn has_non_region_placeholders(&self) -> bool
fn has_param(&self) -> bool
Source§fn has_free_regions(&self) -> bool
fn has_free_regions(&self) -> bool
fn has_erased_regions(&self) -> bool
Source§fn has_erasable_regions(&self) -> bool
fn has_erasable_regions(&self) -> bool
Source§fn is_global(&self) -> bool
fn is_global(&self) -> bool
Source§fn has_bound_regions(&self) -> bool
fn has_bound_regions(&self) -> bool
Source§fn has_non_region_bound_vars(&self) -> bool
fn has_non_region_bound_vars(&self) -> bool
Source§fn has_bound_vars(&self) -> bool
fn has_bound_vars(&self) -> bool
Source§fn still_further_specializable(&self) -> bool
fn still_further_specializable(&self) -> bool
impl
specialization.Source§impl<I, T, U> Upcast<I, U> for Twhere
U: UpcastFrom<I, T>,
impl<I, T, U> Upcast<I, U> for Twhere
U: UpcastFrom<I, T>,
Source§impl<I, T> UpcastFrom<I, T> for T
impl<I, T> UpcastFrom<I, T> for T
fn upcast_from(from: T, _tcx: I) -> T
Source§impl<T> WithSubscriber for T
impl<T> WithSubscriber for T
Source§fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
Source§fn with_current_subscriber(self) -> WithDispatch<Self>
fn with_current_subscriber(self) -> WithDispatch<Self>
impl<T> ErasedDestructor for Twhere
T: 'static,
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: 4 bytes
Size for each variant:
Bound
: 4 bytesCanonical
: 0 bytes