Enum rustc::mir::BorrowKind [−][src]
pub enum BorrowKind { Shared, Unique, Mut { allow_two_phase_borrow: bool, }, }
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Variants
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Data must be immutable and is aliasable.
Unique
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Data must be immutable but not aliasable. This kind of borrow cannot currently be expressed by the user and is used only in implicit closure bindings. It is needed when you the closure is borrowing or mutating a mutable referent, e.g.:
let x: &mut isize = ...; let y = || *x += 5;
If we were to try to translate this closure into a more explicit form, we'd encounter an error with the code as written:
struct Env { x: & &mut isize } let x: &mut isize = ...; let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn fn fn_ptr(env: &mut Env) { **env.x += 5; }
This is then illegal because you cannot mutate a &mut
found
in an aliasable location. To solve, you'd have to translate with
an &mut
borrow:
struct Env { x: & &mut isize } let x: &mut isize = ...; let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x fn fn_ptr(env: &mut Env) { **env.x += 5; }
Now the assignment to **env.x
is legal, but creating a
mutable pointer to x
is not because x
is not mutable. We
could fix this by declaring x
as let mut x
. This is ok in
user code, if awkward, but extra weird for closures, since the
borrow is hidden.
So we introduce a "unique imm" borrow -- the referent is immutable, but not aliasable. This solves the problem. For simplicity, we don't give users the way to express this borrow, it's just used when translating closures.
Mut
🔬 This is a nightly-only experimental API. (rustc_private
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Data is mutable and not aliasable.
Fields of Mut
allow_two_phase_borrow: bool | 🔬 This is a nightly-only experimental API. ( |
Methods
impl BorrowKind
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impl BorrowKind
pub fn to_mutbl_lossy(self) -> Mutability
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pub fn to_mutbl_lossy(self) -> Mutability
🔬 This is a nightly-only experimental API. (rustc_private
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impl BorrowKind
[src]
impl BorrowKind
pub fn allows_two_phase_borrow(&self) -> bool
[src]
pub fn allows_two_phase_borrow(&self) -> bool
🔬 This is a nightly-only experimental API. (rustc_private
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Trait Implementations
impl<'a> HashStable<StableHashingContext<'a>> for BorrowKind
[src]
impl<'a> HashStable<StableHashingContext<'a>> for BorrowKind
fn hash_stable<W: StableHasherResult>(
&self,
hcx: &mut StableHashingContext<'a>,
hasher: &mut StableHasher<W>
)
[src]
fn hash_stable<W: StableHasherResult>(
&self,
hcx: &mut StableHashingContext<'a>,
hasher: &mut StableHasher<W>
)
🔬 This is a nightly-only experimental API. (rustc_private
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impl Copy for BorrowKind
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impl Copy for BorrowKind
impl Clone for BorrowKind
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impl Clone for BorrowKind
fn clone(&self) -> BorrowKind
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fn clone(&self) -> BorrowKind
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0[src]
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
impl Debug for BorrowKind
[src]
impl Debug for BorrowKind
fn fmt(&self, f: &mut Formatter) -> Result
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fn fmt(&self, f: &mut Formatter) -> Result
Formats the value using the given formatter. Read more
impl PartialEq for BorrowKind
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impl PartialEq for BorrowKind
fn eq(&self, other: &BorrowKind) -> bool
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fn eq(&self, other: &BorrowKind) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, other: &BorrowKind) -> bool
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fn ne(&self, other: &BorrowKind) -> bool
This method tests for !=
.
impl Eq for BorrowKind
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impl Eq for BorrowKind
fn assert_receiver_is_total_eq(&self)
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fn assert_receiver_is_total_eq(&self)
impl Encodable for BorrowKind
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impl Encodable for BorrowKind
fn encode<__S: Encoder>(&self, s: &mut __S) -> Result<(), __S::Error>
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fn encode<__S: Encoder>(&self, s: &mut __S) -> Result<(), __S::Error>
🔬 This is a nightly-only experimental API. (rustc_private
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impl Decodable for BorrowKind
[src]
impl Decodable for BorrowKind
Auto Trait Implementations
impl Send for BorrowKind
impl Send for BorrowKind
impl Sync for BorrowKind
impl Sync for BorrowKind