[−][src]Struct rustc_mir::borrow_check::nll::region_infer::TypeTest
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A "type test" corresponds to an outlives constraint between a type
and a lifetime, like T: 'x
or <T as Foo>::Bar: 'x
. They are
translated from the Verify
region constraints in the ordinary
inference context.
These sorts of constraints are handled differently than ordinary
constraints, at least at present. During type checking, the
InferCtxt::process_registered_region_obligations
method will
attempt to convert a type test like T: 'x
into an ordinary
outlives constraint when possible (for example, &'a T: 'b
will
be converted into 'a: 'b
and registered as a Constraint
).
In some cases, however, there are outlives relationships that are not converted into a region constraint, but rather into one of these "type tests". The distinction is that a type test does not influence the inference result, but instead just examines the values that we ultimately inferred for each region variable and checks that they meet certain extra criteria. If not, an error can be issued.
One reason for this is that these type tests typically boil down
to a check like 'a: 'x
where 'a
is a universally quantified
region -- and therefore not one whose value is really meant to be
inferred, precisely (this is not always the case: one can have a
type test like <Foo as Trait<'?0>>::Bar: 'x
, where '?0
is an
inference variable). Another reason is that these type tests can
involve disjunction -- that is, they can be satisfied in more
than one way.
For more information about this translation, see
InferCtxt::process_registered_region_obligations
and
InferCtxt::type_must_outlive
in rustc::infer::outlives
.
Fields
generic_kind: GenericKind<'tcx>
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The type T
that must outlive the region.
lower_bound: RegionVid
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The region 'x
that the type must outlive.
locations: Locations
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Where did this constraint arise and why?
test: RegionTest
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A test which, if met by the region 'x
, proves that this type
constraint is satisfied.
Trait Implementations
impl<'tcx> Clone for TypeTest<'tcx>
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impl<'tcx> Clone for TypeTest<'tcx>
fn clone(&self) -> TypeTest<'tcx>
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fn clone(&self) -> TypeTest<'tcx>
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
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fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
impl<'tcx> Debug for TypeTest<'tcx>
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impl<'tcx> Debug for TypeTest<'tcx>
Auto Trait Implementations
Blanket Implementations
impl<T> ToOwned for T where
T: Clone,
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impl<T> ToOwned for T where
T: Clone,
type Owned = T
fn to_owned(&self) -> T
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fn to_owned(&self) -> T
Creates owned data from borrowed data, usually by cloning. Read more
fn clone_into(&self, target: &mut T)
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fn clone_into(&self, target: &mut T)
🔬 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> From for T
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impl<T> From for T
impl<T, U> Into for T where
U: From<T>,
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impl<T, U> Into for T where
U: From<T>,
impl<T, U> TryFrom for T where
T: From<U>,
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impl<T, U> TryFrom for T where
T: From<U>,
type Error = !
try_from
)The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
try_from
)Performs the conversion.
impl<T> Borrow for T where
T: ?Sized,
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impl<T> Borrow for T where
T: ?Sized,
ⓘImportant traits for &'a mut Rfn borrow(&self) -> &T
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fn borrow(&self) -> &T
Immutably borrows from an owned value. Read more
impl<T, U> TryInto for T where
U: TryFrom<T>,
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impl<T, U> TryInto for T where
U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
try_from
)The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
try_from
)Performs the conversion.
impl<T> BorrowMut for T where
T: ?Sized,
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impl<T> BorrowMut for T where
T: ?Sized,
ⓘImportant traits for &'a mut Rfn borrow_mut(&mut self) -> &mut T
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fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
impl<T> Any for T where
T: 'static + ?Sized,
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impl<T> Any for T where
T: 'static + ?Sized,
fn get_type_id(&self) -> TypeId
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fn get_type_id(&self) -> TypeId
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)
this method will likely be replaced by an associated static
Gets the TypeId
of self
. Read more
impl<E> SpecializationError for E
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impl<E> SpecializationError for E
fn not_found<S, T>(trait_name: &'static str, method_name: &'static str) -> E where
T: ?Sized,
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fn not_found<S, T>(trait_name: &'static str, method_name: &'static str) -> E where
T: ?Sized,
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instead?
Create an error for a missing method specialization. Defaults to panicking with type, trait & method names. S
is the encoder/decoder state type, T
is the type being encoded/decoded, and the arguments are the names of the trait and method that should've been overridden. Read more
impl<T> Erased for T
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impl<T> Erased for T
impl<T> Send for T where
T: ?Sized,
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impl<T> Send for T where
T: ?Sized,
impl<T> Sync for T where
T: ?Sized,
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impl<T> Sync for T where
T: ?Sized,
impl<T> Erased for T
impl<T> Erased for T
impl<T> MaybeResult for T
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impl<T> MaybeResult for T
fn from_ok(x: T) -> T
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fn from_ok(x: T) -> T
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fn map_same<F>(self, f: F) -> T where
F: FnOnce(T) -> T,
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fn map_same<F>(self, f: F) -> T where
F: FnOnce(T) -> T,
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impl<'a, T> Captures for T where
T: ?Sized,
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impl<'a, T> Captures for T where
T: ?Sized,