Enum rustc_trait_selection::traits::select::EvaluationResult

pub enum EvaluationResult {
    EvaluatedToOk,
    EvaluatedToOkModuloRegions,
    EvaluatedToOkModuloOpaqueTypes,
    EvaluatedToAmbig,
    EvaluatedToAmbigStackDependent,
    EvaluatedToErr,
}

The result of trait evaluation. The order is important here as the evaluation of a list is the maximum of the evaluations.

The evaluation results are ordered: - EvaluatedToOk implies EvaluatedToOkModuloRegions implies EvaluatedToAmbig implies EvaluatedToAmbigStackDependent - the “union” of evaluation results is equal to their maximum - all the “potential success” candidates can potentially succeed, so they are noops when unioned with a definite error, and within the categories it’s easy to see that the unions are correct.

Variants

EvaluatedToOk

Evaluation successful.

EvaluatedToOkModuloRegions

Evaluation successful, but there were unevaluated region obligations.

EvaluatedToOkModuloOpaqueTypes

Evaluation successful, but need to rerun because opaque types got hidden types assigned without it being known whether the opaque types are within their defining scope

EvaluatedToAmbig

Evaluation is known to be ambiguous – it might hold for some assignment of inference variables, but it might not.

While this has the same meaning as EvaluatedToAmbigStackDependent – we can’t know whether this obligation holds or not – it is the result we would get with an empty stack, and therefore is cacheable.

EvaluatedToAmbigStackDependent

Evaluation failed because of recursion involving inference variables. We are somewhat imprecise there, so we don’t actually know the real result.

This can’t be trivially cached because the result depends on the stack results.

EvaluatedToErr

Evaluation failed.

Implementations

impl EvaluationResult

pub fn must_apply_considering_regions(self) -> bool

Returns true if this evaluation result is known to apply, even considering outlives constraints.

pub fn must_apply_modulo_regions(self) -> bool

Returns true if this evaluation result is known to apply, ignoring outlives constraints.

pub fn may_apply(self) -> bool

pub fn is_stack_dependent(self) -> bool

Trait Implementations

impl Clone for EvaluationResult

fn clone(&self) -> EvaluationResult

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for EvaluationResult

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

Formats the value using the given formatter.

impl EraseType for EvaluationResult

type Result = [u8; 1]

impl<'__ctx> HashStable<StableHashingContext<'__ctx>> for EvaluationResult

fn hash_stable( &self, __hcx: &mut StableHashingContext<'__ctx>, __hasher: &mut StableHasher<SipHasher128>, )

impl Ord for EvaluationResult

fn cmp(&self, other: &EvaluationResult) -> 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 + PartialOrd,

Restrict a value to a certain interval.

impl PartialEq for EvaluationResult

fn eq(&self, other: &EvaluationResult) -> 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 PartialOrd for EvaluationResult

fn partial_cmp(&self, other: &EvaluationResult) -> 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 Copy for EvaluationResult

impl Eq for EvaluationResult

impl StructuralPartialEq for EvaluationResult

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: 1 byte

Size for each variant:

• EvaluatedToOk: 0 bytes
• EvaluatedToOkModuloRegions: 0 bytes
• EvaluatedToOkModuloOpaqueTypes: 0 bytes
• EvaluatedToAmbig: 0 bytes
• EvaluatedToAmbigStackDependent: 0 bytes
• EvaluatedToErr: 0 bytes