Enum Refusal 

pub enum Refusal {
    Widened {
        atom: Box<GrantAtom>,
        parent: Box<GrantSet>,
    },
    UndecidableContainment {
        atom: Box<GrantAtom>,
        against: Box<GrantAtom>,
        reason: Undecidable,
    },
    Interference(Box<Conflict>),
    UndecidableDisjointness {
        conflict: Box<Conflict>,
        reason: Undecidable,
    },
}

Why the solver refused a flow.

Grant payloads are boxed. Refusal is the error half of the compiler’s Results, so its size is paid on the success path too, and a pair of atoms plus a set is well past the point where that starts to cost. The constructors hide the boxing; only exhaustive matches see it.

Variants

Widened

A grant widened along an edge. Law I forbids it.

Fields

atom: Box<GrantAtom>

The atom that escaped.

parent: Box<GrantSet>

What the parent actually permits.

UndecidableContainment

Containment could not be decided, so the flow is refused.

Fields

atom: Box<GrantAtom>

The atom that could not be compared.

against: Box<GrantAtom>

The parent atom it was compared against.

reason: Undecidable

Why the comparison could not be made.

Interference(Box<Conflict>)

Two branches were proved to interfere.

UndecidableDisjointness

Two branches could not be proved not to interfere.

Fields

conflict: Box<Conflict>

The pair that could not be decided.

reason: Undecidable

Why the comparison could not be made.

Implementations

impl Refusal

pub fn is_proved(&self) -> bool

Whether this refusal is a proved violation rather than a solver gap.

Both refuse the flow. The distinction is for diagnostics: a proved violation means the flow is wrong, an undecided one means the flow may be fine but is spelled in a way the solver cannot check.

pub fn suggestion(&self) -> &'static str

A suggested fix, phrased for the author.

Trait Implementations

impl Clone for Refusal

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Refusal

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

Formats the value using the given formatter.

impl Display for Refusal

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

Formats the value using the given formatter.

impl Eq for Refusal

impl Error for Refusal

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for Refusal

fn eq(&self, other: &Self) -> bool

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Refusal