// Dual-mode build (stable ⇄ nightly): nightly-only `#![feature]` attributes
// in this crate are written as `#![cfg_attr(bao_nightly, feature(...))]` and
// the fast paths that need them are `#[cfg(bao_nightly)]`-gated; stable
// builds compile against the `allocator_api2` mirror (see `core_alloc` in
// lib.rs). The channel is detected from the compiler version string
// (nightlies carry "-nightly").
use env;
use Command;