Enum Error 

#[non_exhaustive]
pub enum Error {
    PermissionDenied {
        instructions: String,
    },
    AccessibilityNotEnabled {
        app: String,
        instructions: String,
    },
    SelectorNotMatched {
        selector: String,
        diagnosis: Option<Box<Diagnosis>>,
    },
    ElementStale {
        selector: String,
    },
    ActionNotSupported {
        action: String,
        role: Role,
    },
    TextValueNotSupported,
    Timeout {
        elapsed: Duration,
        diagnosis: Option<Box<Diagnosis>>,
    },
    InvalidSelector {
        selector: String,
        message: String,
    },
    InvalidActionData {
        message: String,
    },
    InvalidConfig {
        message: String,
    },
    NoElementBounds,
    Unsupported {
        feature: String,
    },
    Platform {
        code: i64,
        message: String,
    },
}

Structured error type for xa11y operations. Designed to be informative across FFI boundaries.

Construct SelectorNotMatched and Timeout through Error::selector_not_matched / Error::timeout and attach context with Error::diagnose — see the module docs for the diagnosis pattern.

#[non_exhaustive]: new failure modes arrive with every backend and platform quirk, so downstream match arms need a _ fallback. Before this attribute the bindings’ exhaustive matches were what forced a new variant to be mapped; that guard now lives in cargo xtask check-bindings-parity, which fails when a variant is not referenced by both binding error mappers (see [[types.variant_coverage]] in bindings/parity_allowlist.toml).

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

PermissionDenied

Accessibility permissions not granted.

Fields

instructions: String

AccessibilityNotEnabled

The target application advertises an accessibility tree but its content is empty because the app’s accessibility bridge is disabled (Chromium/Electron on Linux without --force-renderer-accessibility, for example).

Fields

app: String

instructions: String

SelectorNotMatched

No element matched the selector.

Doubles as the “not yet” retry signal inside poll loops, so bare construction stays cheap; terminal sites attach a Diagnosis.

Fields

selector: String

diagnosis: Option<Box<Diagnosis>>

ElementStale

The node’s platform handle is stale and re-traversal could not relocate it.

Fields

selector: String

ActionNotSupported

The requested action is not supported by this element.

Fields

action: String

role: Role

TextValueNotSupported

Text value input is not supported for this element on this platform.

Timeout

A wait operation exceeded its timeout.

Always carries what the wait was for via its Diagnosis — a bare “Timeout after Ns” tells the consumer nothing actionable (tenet 6).

Fields

elapsed: Duration

diagnosis: Option<Box<Diagnosis>>

InvalidSelector

The selector string could not be parsed.

Fields

selector: String

message: String

InvalidActionData

Invalid argument to an action method.

Fields

message: String

InvalidConfig

Process-wide configuration is invalid (e.g. an unparsable XA11Y_DEFAULT_TIMEOUT environment variable).

Fields

message: String

NoElementBounds

The element has no bounds (e.g. an off-screen or virtual node), so a screen point can’t be computed for input simulation.

Unsupported

The requested operation has no implementation on this platform/session (e.g. pointer warp on Wayland without a portal grant).

Fields

feature: String

Platform

A platform-specific error occurred.

Fields

code: i64

message: String

Implementations

impl Error

pub fn selector_not_matched(selector: impl Into<String>) -> Self

Construct a bare Error::SelectorNotMatched (no diagnosis).

This is the cheap form for poll-loop retry signals; attach context at the terminal site with diagnose.

pub fn timeout(elapsed: Duration) -> Self

Construct a bare Error::Timeout (no diagnosis).

Prefer attaching a Diagnosis with diagnose before the error reaches a consumer — see tenet 6.

pub fn diagnose(self, diagnosis: Diagnosis) -> Self

Attach (or replace) a Diagnosis on errors that carry one.

Supported variants: SelectorNotMatched and Timeout. Other variants are returned unchanged — their primary fields already identify the failure, and silently growing a diagnosis field on them would not be rendered. An empty diagnosis is normalized to None.

pub fn diagnosis(&self) -> Option<&Diagnosis>

The attached Diagnosis, if this error carries one. Bindings use this to expose structured fields on their exception types.

Trait Implementations

impl Clone for Error

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 Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

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.