Enum StreamError 

#[non_exhaustive]
pub enum StreamError {
    Spawn {
        program: String,
        source: Error,
    },
    PipeNotCaptured {
        stream: &'static str,
    },
    CancelLockPoisoned,
}

Why spawn_streaming or ProcessHandle::cancel failed.

Carries the real underlying std::io::Error as a source (via std::error::Error::source) rather than a pre-formatted string, so a caller can downcast or inspect the OS error (e.g. distinguish NotFound — the binary isn’t on PATH — from PermissionDenied). #[non_exhaustive] so adding a variant later isn’t a breaking change.

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.

Spawn

The child process could not be spawned: the binary isn’t on PATH, isn’t executable, or the OS refused. source is the spawn io::Error (commonly NotFound).

Fields

program: String

The program that failed to launch (as passed to the engine).

source: Error

The OS error from Command::spawn.

PipeNotCaptured

The spawned child didn’t expose a piped stdout/stderr. Shouldn’t happen given the engine requests Stdio::piped(), but Child’s pipe accessors return Option, so the case is represented rather than unwrapped.

Fields

stream: &'static str

Which stream was missing — "stdout" or "stderr".

CancelLockPoisoned

Cancellation couldn’t acquire the child lock because it was poisoned (a thread panicked while holding it). The process may still be running; the caller can retry or give up.

Trait Implementations

impl Debug for StreamError

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

Formats the value using the given formatter.

impl Display for StreamError

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

Formats the value using the given formatter.

impl Error for StreamError

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.