Struct PotentialMutableBorrow

pub struct PotentialMutableBorrow<T: ?Sized>(/* private fields */);

A variant of MutableBorrow which represents a mutable borrow which can gracefully recover from borrow errors if they end up occurring.

Unlike a MutableBorrow, this token will not trigger a warning if a confounding borrow is potentially alive at the same time as it since, if the dynamic borrow this borrow guard backs ends up aliasing with something else, the error is assumed to be handled gracefully.

As with borrow_mutably and friends, setting T to Nothing causes this guard to have no effect on the statically-analyzed borrow counts.

If the error cannot be handled gracefully, one may construct a MutableBorrow and downgrade it to a PotentialMutableBorrow so that the static analyzer will start reporting these potentially aliasing borrows again.

See the Potential Borrows section of the crate documentation for more details.

Implementations

impl<T: ?Sized> PotentialMutableBorrow<T>

pub fn new() -> Self

Constructs a new PotentialMutableBorrow guard.

This function has no runtime cost but will cause the AuToken static analyzer to increment the number of mutable borrows of type T in scope. Note, however, that it will not cause the static analyzer to report aliases with potentially confounding borrow tokens. See the structure documentation for details.

Internally, this function calls:

autoken::assume_no_alias(|| MutableBorrow::<T>::new());

pub fn loan(&mut self) -> MutableBorrow<Nothing<'_>>

Creates a loaned MutableBorrow of this guard which has no effect on the static analysis borrow counters by itself, making it safe to use in conditional code.

This is typically used to construct the MutableBorrow guard for runtime borrow guards which were successfully created in fallible code.

See the Making Sense of Control Flow Errors section of the crate documentation for more details on loans.

pub fn assume_no_alias_loan(&self) -> MutableBorrow<Nothing<'_>>

Creates a loaned MutableBorrow of this guard which has no effect on the static analysis borrow counters by itself, making it safe to use in conditional code.

This is typically used to construct the MutableBorrow guard for runtime borrow guards which were successfully created in fallible code.

Unlike loan, this method takes an immutable reference to the loaning PotentialMutableBorrow, which makes it more prone to accidental borrow aliasing.

See the Making Sense of Control Flow Errors section of the crate documentation for more details on loans.

pub fn strip_lifetime_analysis(self) -> PotentialMutableBorrow<Nothing<'static>>

Transforms the type of T into Nothing, effectively making it as if this borrow guard no longer exists.

See the Making Sense of Control Flow Errors section of the crate documentation for more details on the utility of strip_lifetime_analysis.

Trait Implementations

impl<T: ?Sized> Clone for PotentialMutableBorrow<T>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: ?Sized> Debug for PotentialMutableBorrow<T>

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

Formats the value using the given formatter.

impl<T: ?Sized> Default for PotentialMutableBorrow<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T: ?Sized> Ord for PotentialMutableBorrow<T>

fn cmp(&self, _other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T: ?Sized> PartialEq for PotentialMutableBorrow<T>

fn eq(&self, _other: &Self) -> 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<T: ?Sized> PartialOrd for PotentialMutableBorrow<T>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: ?Sized> Eq for PotentialMutableBorrow<T>