Enum Error 

#[non_exhaustive]
pub enum Error {
    EmptyGroup {
        type_name: &'static str,
    },
    GroupMemberTypeMismatch {
        expected: &'static str,
        actual: &'static str,
    },
    AlreadyProvided(&'static str),
    AlreadyProvidedPrivate {
        module: &'static str,
        type_name: &'static str,
    },
    Cycle(String),
    NotConstructed(&'static str),
    MissingProvider {
        type_name: &'static str,
        module: &'static str,
    },
    ProviderMissingDep {
        provider: &'static str,
        module: &'static str,
        dependency: &'static str,
    },
    InvokerMissingDep {
        module: &'static str,
        dependency: &'static str,
    },
    Downcast(&'static str),
    ConstructorFailed {
        type_name: &'static str,
        source: BoxError,
    },
    InvokerFailed {
        name: &'static str,
        source: BoxError,
    },
    AppendAfterStart,
    AppendWhileStopping,
    BuildTimeout(Duration),
    StartTimeout(Duration),
    StopTimeout(Duration),
    UnwindTimeout(Duration),
    TaskFailedDuringStart,
    SigintListen(Error),
    SigtermListen(Error),
    SignalListen(Error),
    MultipleStop(MultipleStopError),
    CleanupAfterFailure {
        cleanup: Box<Error>,
        earlier: Box<Error>,
    },
    Hook {
        name: &'static str,
        source: BoxError,
    },
    Io {
        context: String,
        source: Error,
    },
}

Errors produced while wiring, starting, or stopping an application.

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.

EmptyGroup

A required group has no members.

Fields

type_name: &'static str

Group type name shown in diagnostics (Group<T>).

GroupMemberTypeMismatch

A group member provider’s result type does not match the declared element type.

Fields

expected: &'static str

Element type the caller declared.

actual: &'static str

Result type reported by the erased provider.

AlreadyProvided(&'static str)

A public type was registered more than once.

AlreadyProvidedPrivate

A private type was registered more than once in the same module.

Fields

module: &'static str

Module name shown in diagnostics.

type_name: &'static str

Type name that collided.

Cycle(String)

The dependency graph contains a cycle.

NotConstructed(&'static str)

A value was requested before it had been constructed.

MissingProvider

No provider exists for a requested type.

Fields

type_name: &'static str

Missing type.

module: &'static str

Scope that requested it.

ProviderMissingDep

A provider depends on something nothing registers.

Fields

provider: &'static str

Provider result type.

module: &'static str

Module that owns the provider.

dependency: &'static str

Missing dependency type.

InvokerMissingDep

An invoker depends on something nothing registers.

Fields

module: &'static str

Module that owns the invoker.

dependency: &'static str

Missing dependency type.

Downcast(&'static str)

Internal downcast of a cached value failed.

ConstructorFailed

A fallible constructor returned an error.

Fields

type_name: &'static str

Type being constructed.

source: BoxError

The user error from the constructor.

InvokerFailed

A fallible invoker returned an error.

Fields

name: &'static str

Rust type name of the invoker function.

source: BoxError

The user error from the invoker.

AppendAfterStart

Hook registration after start completed.

AppendWhileStopping

Hook registration while stopping.

BuildTimeout(Duration)

Graph construction exceeded its budget.

StartTimeout(Duration)

Start phase exceeded its budget.

StopTimeout(Duration)

Stop phase exceeded its budget.

UnwindTimeout(Duration)

Unwind after a failed/cancelled start exceeded its budget.

TaskFailedDuringStart

A background crate::task failed while start was still running, and unwind did not surface a more specific join error.

SigintListen(Error)

Failed to install a SIGINT listener.

SigtermListen(Error)

Failed to install a SIGTERM listener.

SignalListen(Error)

Failed to install a process-signal listener (non-Unix platforms).

MultipleStop(MultipleStopError)

Several OnStop hooks failed; see MultipleStopError::errors.

CleanupAfterFailure

Cleanup failed after an earlier phase error; both are retained.

Fields

cleanup: Box<Error>

Error from stop/unwind.

earlier: Box<Error>

Error from the earlier phase.

Hook

An application hook returned this failure.

Prefer Error::hook rather than constructing this variant directly. crate::Lifecycle overwrites Self::Hook::name with the registering hook’s Hook::name when start/stop returns this variant. Error::Io and other variants are left unchanged.

Fields

name: &'static str

crate::Hook::name; defaults to "unnamed" from Error::hook until crate::Lifecycle attaches the registering hook’s name.

source: BoxError

The user error from the hook.

Io

I/O failure with a short context label (e.g. bind / serve).

Prefer Error::io rather than constructing this variant directly.

Fields

context: String

What was being done when I/O failed.

source: Error

Underlying I/O error.

Implementations

impl Error

pub fn hook(err: impl Into<BoxError>) -> Self

Wrap a hook failure, keeping the original error as std::error::Error::source.

Accepts anything convertible to BoxError, including &str, String, std::io::Error, and types that implement std::error::Error. crate::Lifecycle overwrites Self::Hook::name with the registering hook’s Hook::name when start/stop returns this variant.

pub fn io(context: impl Into<String>, source: Error) -> Self

Wrap an I/O failure with a short context label (e.g. "bind 127.0.0.1:3000").

There is no From<std::io::Error> impl, so listener.bind().await? does not compile in a modrun::Result function — map with this helper instead.

Trait Implementations

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.