1.40.0 (August 30th, 2024)

Added

• io: add util::SimplexStream (#6589)
• process: stabilize Command::process_group (#6731)
• sync: add {TrySendError,SendTimeoutError}::into_inner (#6755)
• task: add JoinSet::join_all (#6784)

Added (unstable)

• runtime: add Builder::{on_task_spawn, on_task_terminate} (#6742)

Changed

• io: use vectored io for write_all_buf when possible (#6724)
• runtime: prevent niche-optimization to avoid triggering miri (#6744)
• sync: mark mpsc types as UnwindSafe (#6783)
• sync,time: make Sleep and BatchSemaphore instrumentation explicit roots (#6727)
• task: use NonZeroU64 for task::Id (#6733)
• task: include panic message when printing JoinError (#6753)
• task: add #[must_use] to JoinHandle::abort_handle (#6762)
• time: eliminate timer wheel allocations (#6779)

Documented

• docs: clarify that [build] section doesn't go in Cargo.toml (#6728)
• io: clarify zero remaining capacity case (#6790)
• macros: improve documentation for select! (#6774)
• sync: document mpsc channel allocation behavior (#6773)