Enum AllowTwoPhase 

pub enum AllowTwoPhase {
    Yes,
    No,
}

At least for initial deployment, we want to limit two-phase borrows to only a few specific cases. Right now, those are mostly “things that desugar” into method calls:

• using x.some_method() syntax, where some_method takes &mut self,
• using Foo::some_method(&mut x, ...) syntax,
• binary assignment operators (+=, -=, *=, etc.).

Anything else should be rejected until generalized two-phase borrow support is implemented. Right now, dataflow can’t handle the general case where there is more than one use of a mutable borrow, and we don’t want to accept too much new code via two-phase borrows, so we try to limit where we create two-phase capable mutable borrows. See #49434 for tracking.

Variants

Yes

No

Trait Implementations

impl Clone for AllowTwoPhase

fn clone(&self) -> AllowTwoPhase

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AllowTwoPhase

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

Formats the value using the given formatter.

impl Hash for AllowTwoPhase

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for AllowTwoPhase

fn eq(&self, other: &AllowTwoPhase) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for AllowTwoPhase

impl Eq for AllowTwoPhase

impl StructuralPartialEq for AllowTwoPhase