Faster, more compact implementation of std::borrow::Cow
Cow<str> (#47), thanks to @Nilstrieb.Deserialize implementation for beef::Cow<str> using the impl_serde feature is now specialized, and will produced a borrowed variant if possible, which is particularly useful for serde_json (see #44).const_fn feature is internally using a narrower unstable feature gate const_fn_trait_bound (see #41).beef::lean::Cow is two words wide on 64-bit architectures only.Sync and Send markers (#37, #38. #39).Unpin impl (#39).Default on Cow (#32).PartialOrd and Ord, and fixed Eq impls (#28, #29).const_str and const_slice are now available for both beef::Cow and beef::lean::Cow.const_str no longer requires nightly and is available without a feature flag.unwrap_borrowed method, thanks @Licenser (#20).beef::lean::Cow, found thanks to Miri and @RalfJung.impl_serde feature which provides a Serialize and Deserialize trait implementations.is_borrowed and is_owned methods.beef::Cow<'a, T> is now a type alias to beef::generic::Cow<'a, T, Wide> where Wide is private. This doesn't change anything, merely hides Option<NonZeroUsize> as implementation detail and makes errors more readable.const_fn feature now adds two separate functions instead of one: const_str and const_slice for borrowing &'static str and &'static [T] respectively. This is the only breaking change this release.beef::Cow<'a, T> is now a type alias for beef::generic::Cow<'a, T, Option<NonZeroUsize>>.beef::lean::Cow<'a, T> which is a type alias for beef::generic::Cow<'a, T, Lean>, where Lean is a 0-sized struct. This version of the Cow stores length and capacity together on a single usize, and is only available for 64-bit targets.const_fn now adds Cow::const_borrowed as a separate function. This is not available for beef::lean::Cow.Beef trait has been made private.owned_from_parts.