//! Building a value requires a live `Runtime`.
//!
//! Its own test binary on purpose: this is about a process where no runtime was
//! ever created, which cannot be arranged in a file that also runs tests that
//! build one.
//!
//! Nothing here used to fail. `ray_alloc` lazily mmaps a thread-local heap when
//! none exists (core `heap.c:1386-1390`), so a constructor with no runtime
//! quietly allocated into an orphan heap instead of crashing — which is why the
//! hole survived so long.