Enum MutblCap

enum MutblCap {
    Not,
    WeaklyNot(Option<Span>),
    Mut,
}

ref mut bindings (explicit or match-ergonomics) are not allowed behind an & reference. Normally, the borrow checker enforces this, but for (currently experimental) match ergonomics, we track this when typing patterns for two purposes:

• For RFC 3627’s Rule 3, when this would prevent us from binding with ref mut, we limit the default binding mode to be by shared ref when it would otherwise be ref mut.

• For RFC 3627’s Rule 5, we allow & patterns to match against &mut references, treating them as if they were shared references. Since the scrutinee is mutable in this case, the borrow checker won’t catch if we bind with ref mut, so we need to throw an error ourselves.

Variants

Not

Mutability restricted to immutable.

WeaklyNot(Option<Span>)

Mutability restricted to immutable, but only because of the pattern (not the scrutinee type).

The contained span, if present, points to an & pattern that is the reason for the restriction, and which will be reported in a diagnostic.

Mut

No restriction on mutability

Implementations

impl MutblCap

fn cap_to_weakly_not(self, span: Option<Span>) -> Self

fn as_mutbl(self) -> Mutability

Trait Implementations

impl Clone for MutblCap

fn clone(&self) -> MutblCap

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for MutblCap

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

Formats the value using the given formatter.

impl PartialEq for MutblCap

fn eq(&self, other: &MutblCap) -> 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 MutblCap

impl Eq for MutblCap

impl StructuralPartialEq for MutblCap

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: 12 bytes

Size for each variant:

• Not: 0 bytes
• WeaklyNot: 12 bytes
• Mut: 0 bytes