Struct HeadUsages 

struct HeadUsages {
    inductive: u32,
    unknown: u32,
    coinductive: u32,
    forced_ambiguity: u32,
}

The kinds of cycles a cycle head was involved in.

This is used to avoid rerunning a cycle if there’s just a single usage kind and the final result matches its provisional result.

While it tracks the amount of usages using u32, we only ever care whether there are any. We only count them to be able to ignore usages from irrelevant candidates while evaluating a goal.

This cares about how nested goals relied on a cycle head. It does not care about how frequently the nested goal relied on it.

Fields

inductive: u32

unknown: u32

coinductive: u32

forced_ambiguity: u32

Implementations

impl HeadUsages

fn add_usage(&mut self, path: PathKind)

fn add_usages_from_nested(&mut self, usages: HeadUsages)

This adds the usages which occurred while computing a nested goal.

We don’t actually care about how frequently the nested goal relied on its cycle heads, only whether it did.

fn ignore_usages(&mut self, usages: HeadUsages)

fn is_empty(self) -> bool

Trait Implementations

impl Clone for HeadUsages

fn clone(&self) -> HeadUsages

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for HeadUsages

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

Formats the value using the given formatter.

impl Default for HeadUsages

fn default() -> HeadUsages

Returns the “default value” for a type.

impl PartialEq for HeadUsages

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

impl Eq for HeadUsages

impl StructuralPartialEq for HeadUsages

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: 16 bytes