Struct Lifetime

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pub struct Lifetime {
    pub hir_id: HirId,
    pub ident: Ident,
    pub kind: LifetimeKind,
    pub source: LifetimeSource,
    pub syntax: LifetimeSyntax,
}
Expand description

A lifetime. The valid field combinations are non-obvious and not all combinations are possible. The following example shows some of them. See also the comments on LifetimeKind and LifetimeSource.

#[repr(C)]
struct S<'a>(&'a u32);       // res=Param, name='a, source=Reference, syntax=Named
unsafe extern "C" {
    fn f1(s: S);             // res=Param, name='_, source=Path, syntax=Hidden
    fn f2(s: S<'_>);         // res=Param, name='_, source=Path, syntax=Anonymous
    fn f3<'a>(s: S<'a>);     // res=Param, name='a, source=Path, syntax=Named
}

struct St<'a> { x: &'a u32 } // res=Param, name='a, source=Reference, syntax=Named
fn f() {
    _ = St { x: &0 };        // res=Infer, name='_, source=Path, syntax=Hidden
    _ = St::<'_> { x: &0 };  // res=Infer, name='_, source=Path, syntax=Anonymous
}

struct Name<'a>(&'a str);    // res=Param,  name='a, source=Reference, syntax=Named
const A: Name = Name("a");   // res=Static, name='_, source=Path, syntax=Hidden
const B: &str = "";          // res=Static, name='_, source=Reference, syntax=Hidden
static C: &'_ str = "";      // res=Static, name='_, source=Reference, syntax=Anonymous
static D: &'static str = ""; // res=Static, name='static, source=Reference, syntax=Named

trait Tr {}
fn tr(_: Box<dyn Tr>) {}     // res=ImplicitObjectLifetimeDefault, name='_, source=Other, syntax=Hidden

fn capture_outlives<'a>() ->
    impl FnOnce() + 'a       // res=Param, ident='a, source=OutlivesBound, syntax=Named
{
    || {}
}

fn capture_precise<'a>() ->
    impl FnOnce() + use<'a>  // res=Param, ident='a, source=PreciseCapturing, syntax=Named
{
    || {}
}

// (commented out because these cases trigger errors)
// struct S1<'a>(&'a str);   // res=Param, name='a, source=Reference, syntax=Named
// struct S2(S1);            // res=Error, name='_, source=Path, syntax=Hidden
// struct S3(S1<'_>);        // res=Error, name='_, source=Path, syntax=Anonymous
// struct S4(S1<'a>);        // res=Error, name='a, source=Path, syntax=Named

Some combinations that cannot occur are LifetimeSyntax::Hidden with LifetimeSource::OutlivesBound or LifetimeSource::PreciseCapturing — there’s no way to “elide” these lifetimes.

Fields§

§hir_id: HirId§ident: Ident

Either a named lifetime definition (e.g. 'a, 'static) or an anonymous lifetime ('_, either explicitly written, or inserted for things like &type).

§kind: LifetimeKind

Semantics of this lifetime.

§source: LifetimeSource

The context in which the lifetime occurred. See Lifetime::suggestion for example use.

§syntax: LifetimeSyntax

The syntax that the user used to declare this lifetime. See Lifetime::suggestion for example use.

Implementations§

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impl Lifetime

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pub fn new( hir_id: HirId, ident: Ident, kind: LifetimeKind, source: LifetimeSource, syntax: LifetimeSyntax, ) -> Lifetime

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pub fn is_elided(&self) -> bool

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pub fn is_anonymous(&self) -> bool

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pub fn is_syntactically_hidden(&self) -> bool

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pub fn is_syntactically_anonymous(&self) -> bool

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pub fn is_static(&self) -> bool

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pub fn suggestion(&self, new_lifetime: &str) -> (Span, String)

Trait Implementations§

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impl Clone for Lifetime

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fn clone(&self) -> Lifetime

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Lifetime

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

Formats the value using the given formatter. Read more
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impl Display for Lifetime

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

Formats the value using the given formatter. Read more
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impl<__CTX> HashStable<__CTX> for Lifetime
where __CTX: HashStableContext,

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fn hash_stable(&self, __hcx: &mut __CTX, __hasher: &mut StableHasher)

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impl Copy for Lifetime

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impl<T> Aligned for T

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const ALIGN: Alignment

Alignment of Self.
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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

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fn allocate_on(self, arena: &'tcx Arena<'tcx>) -> &'tcx mut T

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fn allocate_from_iter( arena: &'tcx Arena<'tcx>, iter: impl IntoIterator<Item = T>, ) -> &'tcx mut [T]

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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dest. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts 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 more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts 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 more
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impl<T> Pointable for T

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const ALIGN: usize

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same for T

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type Output = T

Should always be Self
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T> ToString for T
where T: Display + ?Sized,

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fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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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
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fn with_current_subscriber(self) -> WithDispatch<Self>

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

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: 28 bytes