Function build_native_executable 

pub fn build_native_executable(
    spec: &NativeExecutableSpec<'_>,
    cargo: impl FnMut() -> Command,
    diagnostics: impl Write,
    admit: impl FnMut() -> Result<()>,
) -> Result<NativeExecutable, Box<dyn Error + Send + Sync>>

Build a selected native target and return Cargo’s reported executable.

The factory supplies the same Cargo prefix, working directory, environment and network/tool policy for metadata and build. Commands add --locked, exact package/target selection and Cargo’s JSON diagnostics format. Stdout is a bounded-per-message protocol; rendered compiler diagnostics and piped stderr stream to diagnostics. Other stderr configurations remain intact. Stdin is null. This owns direct-child completion, not process-group or signal policy. admit runs before each command factory, so caller interruption can refuse another dispatch after metadata. In-flight commands still run to completion.

Callers exclude source/config/tool mutation and retain artifact custody. No cache, installation, release admission, retry or elapsed-time default is added. Interrupted or rejected capture uses Host’s direct-child cleanup evidence.

Errors

Refuses invalid selection before command effects, missing/ambiguous metadata or artifacts, malformed/oversized messages, sink failures and command failures. Original Host execution/status/cleanup causes remain downcastable.