Struct VarianceDep 

pub struct VarianceDep {
    pub position: VariancePosition,
    pub shape: &'static Shape,
}

A dependency for variance computation.

Represents a type that this type depends on, along with the position (covariant or contravariant) in which it appears.

Fields

position: VariancePosition

The position of this dependency (covariant or contravariant)

shape: &'static Shape

The shape of the dependency

Implementations

impl VarianceDep

pub const fn covariant(shape: &'static Shape) -> Self

Create a new variance dependency in covariant position.

pub const fn contravariant(shape: &'static Shape) -> Self

Create a new variance dependency in contravariant position.

pub const fn invariant(shape: &'static Shape) -> Self

Create a new variance dependency in invariant position.

Use this when the outer type is invariant with respect to this parameter, but you still want bivariant inner types to contribute nothing (rather than forcing the whole type to be invariant).

Example: &mut T is invariant with respect to T, but &mut i32 should be covariant with respect to its own lifetime when computing variance for some unrelated parameter (since i32 contributes Bivariant).

Trait Implementations

impl Clone for VarianceDep

fn clone(&self) -> VarianceDep

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for VarianceDep

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

Formats the value using the given formatter.

impl Copy for VarianceDep