1.36.0 (4 July, 2019) #

Language #

• Non-Lexical Lifetimes are now enabled on the 2015 edition.
• The order of traits in trait objects no longer affects the semantics of that object. e.g. dyn Send + fmt::Debug is now equivalent to dyn fmt::Debug + Send, where this was previously not the case.

Libraries #

• HashMap’s implementation has been replaced with hashbrown::HashMap implementation.
• TryFromSliceError now implements From<Infallible>.
• mem::needs_drop is now available as a const fn.
• alloc::Layout::from_size_align_unchecked is now available as a const fn.
• String now implements BorrowMut<str>.
• io::Cursor now implements Default.
• Both NonNull::{dangling, cast} are now const fns.
• The alloc crate is now stable. alloc allows you to use a subset of std (e.g. Vec, Box, Arc) in #![no_std] environments if the environment has access to heap memory allocation.
• String now implements From<&String>.
• You can now pass multiple arguments to the dbg! macro. dbg! will return a tuple of each argument when there is multiple arguments.
• Result::{is_err, is_ok} are now #[must_use] and will produce a warning if not used.

Stabilized APIs #

• VecDeque::rotate_left
• VecDeque::rotate_right
• Iterator::copied
• io::IoSlice
• io::IoSliceMut
• Read::read_vectored
• Write::write_vectored
• str::as_mut_ptr
• mem::MaybeUninit
• pointer::align_offset
• future::Future
• task::Context
• task::RawWaker
• task::RawWakerVTable
• task::Waker
• task::Poll

Cargo #

• Cargo will now produce an error if you attempt to use the name of a required dependency as a feature.
• You can now pass the --offline flag to run cargo without accessing the network.

You can find further change’s in Cargo’s 1.36.0 release notes.

Clippy #

There have been numerous additions and fixes to clippy, see Clippy’s 1.36.0 release notes for more details.

Misc #

Compatibility Notes #

• With the stabilisation of mem::MaybeUninit, mem::uninitialized use is no longer recommended, and will be deprecated in 1.39.0.