Crate standback

Expand description

Standback backports a number of methods, structs, and macros that have been stabilized in the Rust standard library since 1.36.0. This allows crate authors to depend on Standback rather than forcing downstream users to upgrade their compiler (or not use the new feature at all).

Due to a variety of restrictions in the Rust, it is not possible to implement everything that has been stabilized.

Usage

For most cases, importing the shims should suffice.

use standback::shim::*;

If you are using anything that would normally have to be imported, just use the standback crate instead of core, alloc, or std.

use standback::mem::take;

It is highly recommended to use #![allow(unstable_name_collisions)], as that’s the whole point of this crate. Just be extra-careful to not do it for anything that can’t be backported.

`#![no_std]` support

By default, there standard library is used where necessary. If support for #![no_std] is required, use default-features = false.

Items that require an allocator are gated under the alloc feature, which is enabled by default via the std feature.

Minimum supported Rust version

By default, this crate has a minimum supported Rust version of 1.36. If you do not require a MSRV this low, you can raise it by using default-features = false (be sure to re-enable std or alloc if you need it) and enabling a msrv-1.XX feature flag, substituting the appropriate version; the standback crate is not guaranteed to work (let alone produce a reasonable result) if no MSRV is declared when default-features = false. All versions up to the most recent stable release of a compiler are supported.

Note that items stabilized prior to the declared MSRV will not be re-exported.

Inherent items

The following methods and constants are available via the shim. For brevity, i* is i8, i16, i32, i64, i128, and isize; u* is u8, u16, u32, u64, u128, and usize.

1.60

u8::escape_ascii
Vec::spare_capacity_mut
MaybeUninit::assume_init_drop
MaybeUninit::assume_init_read
{i*, u*}::abs_diff

1.59

Result::copied
Result::cloned
NonZeroU*::is_power_of_two

1.58

Metadata::is_symlink
Path::is_symlink
{i*, u*}::saturating_div
Option::unwrap_unchecked
Result::unwrap_unchecked
Result::unwrap_err_unchecked
NonZeroU*::is_power_of_two
File::options

1.57

Iterator::map_while

1.56

None :(

1.55

prelude::rust_2015
prelude::rust_2018
prelude::rust_2021
Bounded::cloned
MaybeUninit::assume_init_mut
MaybeUninit::assume_init_ref
MaybeUninit::write

1.54

BTreeMap::into_keys
BTreeMap::into_values
HashMap::into_keys
HashMap::into_values
VecDeque::binary_search
VecDeque::binary_search_by
VecDeque::binary_search_by_key
VecDeque::partition_point

1.53

Ordering::is_eq
Duration::ZERO
Duration::is_zero
Duration::saturating_add
Duration::saturating_mul
Duration::saturating_sub
Option::insert
Ordering::is_eq
Ordering::is_ge
Ordering::is_gt
Ordering::is_le
Ordering::is_lt
Ordering::is_ne
OsStr::make_ascii_lowercase
OsStr::make_ascii_uppercase
OsStr::to_ascii_lowercase
OsStr::to_ascii_uppercase
OsStr::is_ascii
OsStr::eq_ignore_ascii_case
Rc::decrement_strong_count
Rc::increment_strong_count
Vec::extend_from_within
{f32, f64}::is_subnormal
{i*, u*}::BITS

1.52

char::MAX
char::REPLACEMENT_CHARACTER
char::UNICODE_VERSION
char::decode_utf16
char::from_digit
char::from_u32_unchecked
char::from_u32
slice::partition_point
str::rsplit_once
str::split_once

1.51

Arc::decrement_strong_count
Arc::increment_strong_count
Peekable::next_if_eq
Peekable::next_if
Seek::stream_position
slice::fill_with
slice::split_inclusive_mut
slice::split_inclusive
slice::strip_prefix
slice::strip_suffix
str::split_inclusive
i*::unsigned_abs
Poll::map_ok
Poll::map_err

1.50

bool::then
btree_map::Entry::or_insert_with_key
hash_map::Entry::or_insert_with_key
{f32, f64}::clamp
Ord::clamp
RefCell::take
slice::fill
UnsafeCell::get_mut

1.49

slice::select_nth_unstable
slice::select_nth_unstable_by
slice::select_nth_unstable_by_key

1.48

slice::as_ptr_range
slice::as_mut_ptr_range

1.47

Range::is_empty
Result::as_deref
Result::as_deref_mut
Vec::leak
f32::TAU
f64::TAU

1.46

{i*, u*}::leading_ones
{i*, u*}::trailing_ones
Option::zip

1.45

i*::saturating_abs
i*::saturating_neg
str::strip_prefix
str::strip_suffix

1.44

PathBuf::with_capacity
PathBuf::capacity
PathBuf::clear
PathBuf::reserve
PathBuf::reserve_exact
PathBuf::shrink_to_fit
Layout::align_to
Layout::pad_to_align
Layout::array
Layout::extend
{f32, f64}::to_int_unchecked

1.43

{f32, f64}::RADIX
{f32, f64}::MANTISSA_DIGITS
{f32, f64}::DIGITS
{f32, f64}::EPSILON
{f32, f64}::MIN
{f32, f64}::MIN_POSITIVE
{f32, f64}::MAX
{f32, f64}::MIN_EXP
{f32, f64}::MAX_EXP
{f32, f64}::MIN_10_EXP
{f32, f64}::MAX_10_EXP
{f32, f64}::NAN
{f32, f64}::INFINITY
{f32, f64}::NEG_INFINITY
{i*, u*}::MIN
{i*, u*}::MAX

1.42

CondVar::wait_while
CondVar::wait_timeout_while
ManuallyDrop::take

1.41

Result::map_or
Result::map_or_else

1.40

Option::as_deref
Option::as_deref_mut
{f32, f64}::to_be_bytes
{f32, f64}::to_le_bytes
{f32, f64}::to_ne_bytes
{f32, f64}::from_be_bytes
{f32, f64}::from_le_bytes
{f32, f64}::from_ne_bytes
slice::repeat

1.39

None :(

1.38

<*const T>::cast
<*mut T>::cast
Duration::as_secs_f32
Duration::as_secs_f64
Duration::div_f32
Duration::div_f64
Duration::from_secs_f32
Duration::from_secs_f64
Duration::mul_f32
Duration::mul_f64
{i*, u*}::rem_euclid
{i*, u*}::checked_rem_euclid
{i*, u*}::wrapping_rem_euclid
{i*, u*}::overflowing_rem_euclid
{i*, u*}::div_euclid
{i*, u*}::checked_div_euclid
{i*, u*}::wrapping_div_euclid
{i*, u*}::overflowing_div_euclid
{f32, f64}::rem_euclid
{f32, f64}::div_euclid

1.37

Cell::from_mut
Cell<[T]>::as_slice_of_cells
DoubleEndedIterator::nth_back
Option::xor
slice::copy_within

Free items

thread::available_parallelism // 1.59
iter::zip // 1.59
array::from_ref // 1.53
array::from_mut // 1.53
cmp::min_by // 1.53
cmp::max_by // 1.53
cmp::min_by_key // 1.53
cmp::max_by_key // 1.53
task::Wake // 1.51
future::pending // 1.48
iter::zip // 1.59
thread::available_parallelism // 1.59
future::ready // 1.48
{f32, f64}::consts::TAU // 1.47
char::UNICODE_VERSION // 1.45
{f32, f64}::consts::LOG10_2 // 1.43
{f32, f64}::consts::LOG2_10 // 1.43
iter::once_with // 1.43
mem::take // 1.40

Prelude macros (located in `standback::shim`)

matches! // 1.42
todo! // 1.39