Rollup merge of #62959 - LukasKalbertodt:array-value-iter, r=scottmcm
Add by-value iterator for arrays
This adds an iterator that can iterate over arrays by value, yielding all elements by value. However, **this PR does _not_ add a corresponding `IntoIterator` impl for arrays**. The `IntoIterator` impl needs some discussion about backwards-compatibility that should take place in a separate PR. With this patch, this code should work (but there is currently still a bug):
```rust
#![feature(array_value_iter)]
use std::array::IntoIter;
let arr = [1, 2, 3];
for x in IntoIter::new(arr) {
println!("{}", x);
}
```
**TODO**:
- [x] Get initial feedback
- [x] Add tests
- [x] Figure out why stage1 produces weird bugs ([comment](https://github.com/rust-lang/rust/pull/62959#issuecomment-516016524))
- [x] Add UI tests as mentioned [here](https://github.com/rust-lang/rust/pull/62959#discussion_r307061894) (will do that soon-ish)
- [x] Fix [this new bug](https://github.com/rust-lang/rust/pull/62959#issuecomment-544732159)
**Notes for reviewers**
- Is the use of `MaybeUninit` correct here? I think it has to be used due to the `Clone` impl which has to fill the dead array elements with something, but cannot fill it with a correct instance.
- Are the unit tests sufficient?
CC #25725
This commit is contained in:
Mazdak Farrokhzad
GitHub
commit
a302155344
266
src/libcore/array/iter.rs
Normal file
266
src/libcore/array/iter.rs
Normal file
@ -0,0 +1,266 @@
|
||||
//! Defines the `IntoIter` owned iterator for arrays.
|
||||
|
||||
use crate::{
|
||||
fmt,
|
||||
iter::{ExactSizeIterator, FusedIterator, TrustedLen},
|
||||
mem::{self, MaybeUninit},
|
||||
ops::Range,
|
||||
ptr,
|
||||
};
|
||||
use super::LengthAtMost32;
|
||||
|
||||
|
||||
/// A by-value [array] iterator.
|
||||
///
|
||||
/// [array]: ../../std/primitive.array.html
|
||||
#[unstable(feature = "array_value_iter", issue = "0")]
|
||||
pub struct IntoIter<T, const N: usize>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{
|
||||
/// This is the array we are iterating over.
|
||||
///
|
||||
/// Elements with index `i` where `alive.start <= i < alive.end` have not
|
||||
/// been yielded yet and are valid array entries. Elements with indices `i
|
||||
/// < alive.start` or `i >= alive.end` have been yielded already and must
|
||||
/// not be accessed anymore! Those dead elements might even be in a
|
||||
/// completely uninitialized state!
|
||||
///
|
||||
/// So the invariants are:
|
||||
/// - `data[alive]` is alive (i.e. contains valid elements)
|
||||
/// - `data[..alive.start]` and `data[alive.end..]` are dead (i.e. the
|
||||
/// elements were already read and must not be touched anymore!)
|
||||
data: [MaybeUninit<T>; N],
|
||||
|
||||
/// The elements in `data` that have not been yielded yet.
|
||||
///
|
||||
/// Invariants:
|
||||
/// - `alive.start <= alive.end`
|
||||
/// - `alive.end <= N`
|
||||
alive: Range<usize>,
|
||||
}
|
||||
|
||||
impl<T, const N: usize> IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{
|
||||
/// Creates a new iterator over the given `array`.
|
||||
///
|
||||
/// *Note*: this method might never get stabilized and/or removed in the
|
||||
/// future as there will likely be another, preferred way of obtaining this
|
||||
/// iterator (either via `IntoIterator` for arrays or via another way).
|
||||
#[unstable(feature = "array_value_iter", issue = "0")]
|
||||
pub fn new(array: [T; N]) -> Self {
|
||||
// The transmute here is actually safe. The docs of `MaybeUninit`
|
||||
// promise:
|
||||
//
|
||||
// > `MaybeUninit<T>` is guaranteed to have the same size and alignment
|
||||
// > as `T`.
|
||||
//
|
||||
// The docs even show a transmute from an array of `MaybeUninit<T>` to
|
||||
// an array of `T`.
|
||||
//
|
||||
// With that, this initialization satisfies the invariants.
|
||||
|
||||
// FIXME(LukasKalbertodt): actually use `mem::transmute` here, once it
|
||||
// works with const generics:
|
||||
// `mem::transmute::<[T; {N}], [MaybeUninit<T>; {N}]>(array)`
|
||||
//
|
||||
// Until then, we do it manually here. We first create a bitwise copy
|
||||
// but cast the pointer so that it is treated as a different type. Then
|
||||
// we forget `array` so that it is not dropped.
|
||||
let data = unsafe {
|
||||
let data = ptr::read(&array as *const [T; N] as *const [MaybeUninit<T>; N]);
|
||||
mem::forget(array);
|
||||
data
|
||||
};
|
||||
|
||||
Self {
|
||||
data,
|
||||
alive: 0..N,
|
||||
}
|
||||
}
|
||||
|
||||
/// Returns an immutable slice of all elements that have not been yielded
|
||||
/// yet.
|
||||
fn as_slice(&self) -> &[T] {
|
||||
// This transmute is safe. As mentioned in `new`, `MaybeUninit` retains
|
||||
// the size and alignment of `T`. Furthermore, we know that all
|
||||
// elements within `alive` are properly initialized.
|
||||
let slice = &self.data[self.alive.clone()];
|
||||
unsafe {
|
||||
mem::transmute::<&[MaybeUninit<T>], &[T]>(slice)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
#[stable(feature = "array_value_iter_impls", since = "1.38.0")]
|
||||
impl<T, const N: usize> Iterator for IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{
|
||||
type Item = T;
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
||||
if self.alive.start == self.alive.end {
|
||||
return None;
|
||||
}
|
||||
|
||||
// Bump start index.
|
||||
//
|
||||
// From the check above we know that `alive.start != alive.end`.
|
||||
// Combine this with the invariant `alive.start <= alive.end`, we know
|
||||
// that `alive.start < alive.end`. Increasing `alive.start` by 1
|
||||
// maintains the invariant regarding `alive`. However, due to this
|
||||
// change, for a short time, the alive zone is not `data[alive]`
|
||||
// anymore, but `data[idx..alive.end]`.
|
||||
let idx = self.alive.start;
|
||||
self.alive.start += 1;
|
||||
|
||||
// Read the element from the array. This is safe: `idx` is an index
|
||||
// into the "alive" region of the array. Reading this element means
|
||||
// that `data[idx]` is regarded as dead now (i.e. do not touch). As
|
||||
// `idx` was the start of the alive-zone, the alive zone is now
|
||||
// `data[alive]` again, restoring all invariants.
|
||||
let out = unsafe { self.data.get_unchecked(idx).read() };
|
||||
|
||||
Some(out)
|
||||
}
|
||||
|
||||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||||
let len = self.len();
|
||||
(len, Some(len))
|
||||
}
|
||||
|
||||
fn count(self) -> usize {
|
||||
self.len()
|
||||
}
|
||||
|
||||
fn last(mut self) -> Option<Self::Item> {
|
||||
self.next_back()
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "array_value_iter_impls", since = "1.38.0")]
|
||||
impl<T, const N: usize> DoubleEndedIterator for IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{
|
||||
fn next_back(&mut self) -> Option<Self::Item> {
|
||||
if self.alive.start == self.alive.end {
|
||||
return None;
|
||||
}
|
||||
|
||||
// Decrease end index.
|
||||
//
|
||||
// From the check above we know that `alive.start != alive.end`.
|
||||
// Combine this with the invariant `alive.start <= alive.end`, we know
|
||||
// that `alive.start < alive.end`. As `alive.start` cannot be negative,
|
||||
// `alive.end` is at least 1, meaning that we can safely decrement it
|
||||
// by one. This also maintains the invariant `alive.start <=
|
||||
// alive.end`. However, due to this change, for a short time, the alive
|
||||
// zone is not `data[alive]` anymore, but `data[alive.start..alive.end
|
||||
// + 1]`.
|
||||
self.alive.end -= 1;
|
||||
|
||||
// Read the element from the array. This is safe: `alive.end` is an
|
||||
// index into the "alive" region of the array. Compare the previous
|
||||
// comment that states that the alive region is
|
||||
// `data[alive.start..alive.end + 1]`. Reading this element means that
|
||||
// `data[alive.end]` is regarded as dead now (i.e. do not touch). As
|
||||
// `alive.end` was the end of the alive-zone, the alive zone is now
|
||||
// `data[alive]` again, restoring all invariants.
|
||||
let out = unsafe { self.data.get_unchecked(self.alive.end).read() };
|
||||
|
||||
Some(out)
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "array_value_iter_impls", since = "1.38.0")]
|
||||
impl<T, const N: usize> Drop for IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{
|
||||
fn drop(&mut self) {
|
||||
// We simply drop each element via `for_each`. This should not incur
|
||||
// any significant runtime overhead and avoids adding another `unsafe`
|
||||
// block.
|
||||
self.by_ref().for_each(drop);
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "array_value_iter_impls", since = "1.38.0")]
|
||||
impl<T, const N: usize> ExactSizeIterator for IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{
|
||||
fn len(&self) -> usize {
|
||||
// Will never underflow due to the invariant `alive.start <=
|
||||
// alive.end`.
|
||||
self.alive.end - self.alive.start
|
||||
}
|
||||
fn is_empty(&self) -> bool {
|
||||
self.alive.is_empty()
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "array_value_iter_impls", since = "1.38.0")]
|
||||
impl<T, const N: usize> FusedIterator for IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{}
|
||||
|
||||
// The iterator indeed reports the correct length. The number of "alive"
|
||||
// elements (that will still be yielded) is the length of the range `alive`.
|
||||
// This range is decremented in length in either `next` or `next_back`. It is
|
||||
// always decremented by 1 in those methods, but only if `Some(_)` is returned.
|
||||
#[stable(feature = "array_value_iter_impls", since = "1.38.0")]
|
||||
unsafe impl<T, const N: usize> TrustedLen for IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{}
|
||||
|
||||
#[stable(feature = "array_value_iter_impls", since = "1.38.0")]
|
||||
impl<T: Clone, const N: usize> Clone for IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{
|
||||
fn clone(&self) -> Self {
|
||||
unsafe {
|
||||
// This creates a new uninitialized array. Note that the `assume_init`
|
||||
// refers to the array, not the individual elements. And it is Ok if
|
||||
// the array is in an uninitialized state as all elements may be
|
||||
// uninitialized (all bit patterns are valid). Compare the
|
||||
// `MaybeUninit` docs for more information.
|
||||
let mut new_data: [MaybeUninit<T>; N] = MaybeUninit::uninit().assume_init();
|
||||
|
||||
// Clone all alive elements.
|
||||
for idx in self.alive.clone() {
|
||||
// The element at `idx` in the old array is alive, so we can
|
||||
// safely call `get_ref()`. We then clone it, and write the
|
||||
// clone into the new array.
|
||||
let clone = self.data.get_unchecked(idx).get_ref().clone();
|
||||
new_data.get_unchecked_mut(idx).write(clone);
|
||||
}
|
||||
|
||||
Self {
|
||||
data: new_data,
|
||||
alive: self.alive.clone(),
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "array_value_iter_impls", since = "1.38.0")]
|
||||
impl<T: fmt::Debug, const N: usize> fmt::Debug for IntoIter<T, {N}>
|
||||
where
|
||||
[T; N]: LengthAtMost32,
|
||||
{
|
||||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||||
// Only print the elements that were not yielded yet: we cannot
|
||||
// access the yielded elements anymore.
|
||||
f.debug_tuple("IntoIter")
|
||||
.field(&self.as_slice())
|
||||
.finish()
|
||||
}
|
||||
}
|
||||
@ -14,6 +14,13 @@ use crate::hash::{Hash, self};
|
||||
use crate::marker::Unsize;
|
||||
use crate::slice::{Iter, IterMut};
|
||||
|
||||
#[cfg(not(bootstrap))]
|
||||
mod iter;
|
||||
|
||||
#[cfg(not(bootstrap))]
|
||||
#[unstable(feature = "array_value_iter", issue = "0")]
|
||||
pub use iter::IntoIter;
|
||||
|
||||
/// Utility trait implemented only on arrays of fixed size
|
||||
///
|
||||
/// This trait can be used to implement other traits on fixed-size arrays
|
||||
@ -1,4 +1,4 @@
|
||||
use core::array::FixedSizeArray;
|
||||
use core::array::{FixedSizeArray, IntoIter};
|
||||
use core::convert::TryFrom;
|
||||
|
||||
#[test]
|
||||
@ -40,3 +40,208 @@ fn array_try_from() {
|
||||
30 31 32
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
#[test]
|
||||
fn iterator_collect() {
|
||||
let arr = [0, 1, 2, 5, 9];
|
||||
let v: Vec<_> = IntoIter::new(arr.clone()).collect();
|
||||
assert_eq!(&arr[..], &v[..]);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_rev_collect() {
|
||||
let arr = [0, 1, 2, 5, 9];
|
||||
let v: Vec<_> = IntoIter::new(arr.clone()).rev().collect();
|
||||
assert_eq!(&v[..], &[9, 5, 2, 1, 0]);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_nth() {
|
||||
let v = [0, 1, 2, 3, 4];
|
||||
for i in 0..v.len() {
|
||||
assert_eq!(IntoIter::new(v.clone()).nth(i).unwrap(), v[i]);
|
||||
}
|
||||
assert_eq!(IntoIter::new(v.clone()).nth(v.len()), None);
|
||||
|
||||
let mut iter = IntoIter::new(v);
|
||||
assert_eq!(iter.nth(2).unwrap(), v[2]);
|
||||
assert_eq!(iter.nth(1).unwrap(), v[4]);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_last() {
|
||||
let v = [0, 1, 2, 3, 4];
|
||||
assert_eq!(IntoIter::new(v).last().unwrap(), 4);
|
||||
assert_eq!(IntoIter::new([0]).last().unwrap(), 0);
|
||||
|
||||
let mut it = IntoIter::new([0, 9, 2, 4]);
|
||||
assert_eq!(it.next_back(), Some(4));
|
||||
assert_eq!(it.last(), Some(2));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_clone() {
|
||||
let mut it = IntoIter::new([0, 2, 4, 6, 8]);
|
||||
assert_eq!(it.next(), Some(0));
|
||||
assert_eq!(it.next_back(), Some(8));
|
||||
let mut clone = it.clone();
|
||||
assert_eq!(it.next_back(), Some(6));
|
||||
assert_eq!(clone.next_back(), Some(6));
|
||||
assert_eq!(it.next_back(), Some(4));
|
||||
assert_eq!(clone.next_back(), Some(4));
|
||||
assert_eq!(it.next(), Some(2));
|
||||
assert_eq!(clone.next(), Some(2));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_fused() {
|
||||
let mut it = IntoIter::new([0, 9, 2]);
|
||||
assert_eq!(it.next(), Some(0));
|
||||
assert_eq!(it.next(), Some(9));
|
||||
assert_eq!(it.next(), Some(2));
|
||||
assert_eq!(it.next(), None);
|
||||
assert_eq!(it.next(), None);
|
||||
assert_eq!(it.next(), None);
|
||||
assert_eq!(it.next(), None);
|
||||
assert_eq!(it.next(), None);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_len() {
|
||||
let mut it = IntoIter::new([0, 1, 2, 5, 9]);
|
||||
assert_eq!(it.size_hint(), (5, Some(5)));
|
||||
assert_eq!(it.len(), 5);
|
||||
assert_eq!(it.is_empty(), false);
|
||||
|
||||
assert_eq!(it.next(), Some(0));
|
||||
assert_eq!(it.size_hint(), (4, Some(4)));
|
||||
assert_eq!(it.len(), 4);
|
||||
assert_eq!(it.is_empty(), false);
|
||||
|
||||
assert_eq!(it.next_back(), Some(9));
|
||||
assert_eq!(it.size_hint(), (3, Some(3)));
|
||||
assert_eq!(it.len(), 3);
|
||||
assert_eq!(it.is_empty(), false);
|
||||
|
||||
// Empty
|
||||
let it = IntoIter::new([] as [String; 0]);
|
||||
assert_eq!(it.size_hint(), (0, Some(0)));
|
||||
assert_eq!(it.len(), 0);
|
||||
assert_eq!(it.is_empty(), true);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_count() {
|
||||
let v = [0, 1, 2, 3, 4];
|
||||
assert_eq!(IntoIter::new(v.clone()).count(), 5);
|
||||
|
||||
let mut iter2 = IntoIter::new(v);
|
||||
iter2.next();
|
||||
iter2.next();
|
||||
assert_eq!(iter2.count(), 3);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_flat_map() {
|
||||
assert!((0..5).flat_map(|i| IntoIter::new([2 * i, 2 * i + 1])).eq(0..10));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_debug() {
|
||||
let arr = [0, 1, 2, 5, 9];
|
||||
assert_eq!(
|
||||
format!("{:?}", IntoIter::new(arr)),
|
||||
"IntoIter([0, 1, 2, 5, 9])",
|
||||
);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn iterator_drops() {
|
||||
use core::cell::Cell;
|
||||
|
||||
// This test makes sure the correct number of elements are dropped. The `R`
|
||||
// type is just a reference to a `Cell` that is incremented when an `R` is
|
||||
// dropped.
|
||||
|
||||
#[derive(Clone)]
|
||||
struct Foo<'a>(&'a Cell<usize>);
|
||||
|
||||
impl Drop for Foo<'_> {
|
||||
fn drop(&mut self) {
|
||||
self.0.set(self.0.get() + 1);
|
||||
}
|
||||
}
|
||||
|
||||
fn five(i: &Cell<usize>) -> [Foo<'_>; 5] {
|
||||
// This is somewhat verbose because `Foo` does not implement `Copy`
|
||||
// since it implements `Drop`. Consequently, we cannot write
|
||||
// `[Foo(i); 5]`.
|
||||
[Foo(i), Foo(i), Foo(i), Foo(i), Foo(i)]
|
||||
}
|
||||
|
||||
// Simple: drop new iterator.
|
||||
let i = Cell::new(0);
|
||||
{
|
||||
IntoIter::new(five(&i));
|
||||
}
|
||||
assert_eq!(i.get(), 5);
|
||||
|
||||
// Call `next()` once.
|
||||
let i = Cell::new(0);
|
||||
{
|
||||
let mut iter = IntoIter::new(five(&i));
|
||||
let _x = iter.next();
|
||||
assert_eq!(i.get(), 0);
|
||||
assert_eq!(iter.count(), 4);
|
||||
assert_eq!(i.get(), 4);
|
||||
}
|
||||
assert_eq!(i.get(), 5);
|
||||
|
||||
// Check `clone` and calling `next`/`next_back`.
|
||||
let i = Cell::new(0);
|
||||
{
|
||||
let mut iter = IntoIter::new(five(&i));
|
||||
iter.next();
|
||||
assert_eq!(i.get(), 1);
|
||||
iter.next_back();
|
||||
assert_eq!(i.get(), 2);
|
||||
|
||||
let mut clone = iter.clone();
|
||||
assert_eq!(i.get(), 2);
|
||||
|
||||
iter.next();
|
||||
assert_eq!(i.get(), 3);
|
||||
|
||||
clone.next();
|
||||
assert_eq!(i.get(), 4);
|
||||
|
||||
assert_eq!(clone.count(), 2);
|
||||
assert_eq!(i.get(), 6);
|
||||
}
|
||||
assert_eq!(i.get(), 8);
|
||||
|
||||
// Check via `nth`.
|
||||
let i = Cell::new(0);
|
||||
{
|
||||
let mut iter = IntoIter::new(five(&i));
|
||||
let _x = iter.nth(2);
|
||||
assert_eq!(i.get(), 2);
|
||||
let _y = iter.last();
|
||||
assert_eq!(i.get(), 3);
|
||||
}
|
||||
assert_eq!(i.get(), 5);
|
||||
|
||||
// Check every element.
|
||||
let i = Cell::new(0);
|
||||
for (index, _x) in IntoIter::new(five(&i)).enumerate() {
|
||||
assert_eq!(i.get(), index);
|
||||
}
|
||||
assert_eq!(i.get(), 5);
|
||||
|
||||
let i = Cell::new(0);
|
||||
for (index, _x) in IntoIter::new(five(&i)).rev().enumerate() {
|
||||
assert_eq!(i.get(), index);
|
||||
}
|
||||
assert_eq!(i.get(), 5);
|
||||
}
|
||||
|
||||
@ -31,6 +31,7 @@
|
||||
#![feature(slice_partition_dedup)]
|
||||
#![feature(int_error_matching)]
|
||||
#![feature(const_fn)]
|
||||
#![feature(array_value_iter)]
|
||||
#![feature(iter_partition_in_place)]
|
||||
#![feature(iter_is_partitioned)]
|
||||
#![feature(iter_order_by)]
|
||||
|
||||
@ -0,0 +1,41 @@
|
||||
// check-pass
|
||||
|
||||
#![feature(array_value_iter)]
|
||||
#![feature(trusted_len)]
|
||||
|
||||
use std::{
|
||||
array::IntoIter,
|
||||
fmt::Debug,
|
||||
iter::{ExactSizeIterator, FusedIterator, TrustedLen},
|
||||
};
|
||||
|
||||
pub fn yes_iterator() -> impl Iterator<Item = i32> {
|
||||
IntoIter::new([0i32; 32])
|
||||
}
|
||||
|
||||
pub fn yes_double_ended_iterator() -> impl DoubleEndedIterator {
|
||||
IntoIter::new([0i32; 32])
|
||||
}
|
||||
|
||||
pub fn yes_exact_size_iterator() -> impl ExactSizeIterator {
|
||||
IntoIter::new([0i32; 32])
|
||||
}
|
||||
|
||||
pub fn yes_fused_iterator() -> impl FusedIterator {
|
||||
IntoIter::new([0i32; 32])
|
||||
}
|
||||
|
||||
pub fn yes_trusted_len() -> impl TrustedLen {
|
||||
IntoIter::new([0i32; 32])
|
||||
}
|
||||
|
||||
pub fn yes_clone() -> impl Clone {
|
||||
IntoIter::new([0i32; 32])
|
||||
}
|
||||
|
||||
pub fn yes_debug() -> impl Debug {
|
||||
IntoIter::new([0i32; 32])
|
||||
}
|
||||
|
||||
|
||||
fn main() {}
|
||||
@ -0,0 +1,53 @@
|
||||
#![feature(array_value_iter)]
|
||||
#![feature(trusted_len)]
|
||||
|
||||
use std::{
|
||||
array::IntoIter,
|
||||
fmt::Debug,
|
||||
iter::{ExactSizeIterator, FusedIterator, TrustedLen},
|
||||
};
|
||||
|
||||
pub fn no_iterator() -> impl Iterator<Item = i32> {
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
IntoIter::new([0i32; 33])
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
}
|
||||
|
||||
pub fn no_double_ended_iterator() -> impl DoubleEndedIterator {
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
IntoIter::new([0i32; 33])
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
}
|
||||
|
||||
pub fn no_exact_size_iterator() -> impl ExactSizeIterator {
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
IntoIter::new([0i32; 33])
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
}
|
||||
|
||||
pub fn no_fused_iterator() -> impl FusedIterator {
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
IntoIter::new([0i32; 33])
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
}
|
||||
|
||||
pub fn no_trusted_len() -> impl TrustedLen {
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
IntoIter::new([0i32; 33])
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
}
|
||||
|
||||
pub fn no_clone() -> impl Clone {
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
IntoIter::new([0i32; 33])
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
}
|
||||
|
||||
pub fn no_debug() -> impl Debug {
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
IntoIter::new([0i32; 33])
|
||||
//~^ ERROR arrays only have std trait implementations for lengths 0..=32
|
||||
}
|
||||
|
||||
|
||||
fn main() {}
|
||||
@ -0,0 +1,122 @@
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:12:5
|
||||
|
|
||||
LL | IntoIter::new([0i32; 33])
|
||||
| ^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required by `std::array::IntoIter::<T, N>::new`
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:10:25
|
||||
|
|
||||
LL | pub fn no_iterator() -> impl Iterator<Item = i32> {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required because of the requirements on the impl of `std::iter::Iterator` for `std::array::IntoIter<i32, 33usize>`
|
||||
= note: the return type of a function must have a statically known size
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:18:5
|
||||
|
|
||||
LL | IntoIter::new([0i32; 33])
|
||||
| ^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required by `std::array::IntoIter::<T, N>::new`
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:16:38
|
||||
|
|
||||
LL | pub fn no_double_ended_iterator() -> impl DoubleEndedIterator {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required because of the requirements on the impl of `std::iter::DoubleEndedIterator` for `std::array::IntoIter<i32, 33usize>`
|
||||
= note: the return type of a function must have a statically known size
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:24:5
|
||||
|
|
||||
LL | IntoIter::new([0i32; 33])
|
||||
| ^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required by `std::array::IntoIter::<T, N>::new`
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:22:36
|
||||
|
|
||||
LL | pub fn no_exact_size_iterator() -> impl ExactSizeIterator {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required because of the requirements on the impl of `std::iter::ExactSizeIterator` for `std::array::IntoIter<i32, 33usize>`
|
||||
= note: the return type of a function must have a statically known size
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:30:5
|
||||
|
|
||||
LL | IntoIter::new([0i32; 33])
|
||||
| ^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required by `std::array::IntoIter::<T, N>::new`
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:28:31
|
||||
|
|
||||
LL | pub fn no_fused_iterator() -> impl FusedIterator {
|
||||
| ^^^^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required because of the requirements on the impl of `std::iter::FusedIterator` for `std::array::IntoIter<i32, 33usize>`
|
||||
= note: the return type of a function must have a statically known size
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:36:5
|
||||
|
|
||||
LL | IntoIter::new([0i32; 33])
|
||||
| ^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required by `std::array::IntoIter::<T, N>::new`
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:34:28
|
||||
|
|
||||
LL | pub fn no_trusted_len() -> impl TrustedLen {
|
||||
| ^^^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required because of the requirements on the impl of `std::iter::TrustedLen` for `std::array::IntoIter<i32, 33usize>`
|
||||
= note: the return type of a function must have a statically known size
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:42:5
|
||||
|
|
||||
LL | IntoIter::new([0i32; 33])
|
||||
| ^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required by `std::array::IntoIter::<T, N>::new`
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:40:22
|
||||
|
|
||||
LL | pub fn no_clone() -> impl Clone {
|
||||
| ^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required because of the requirements on the impl of `std::clone::Clone` for `std::array::IntoIter<i32, 33usize>`
|
||||
= note: the return type of a function must have a statically known size
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:48:5
|
||||
|
|
||||
LL | IntoIter::new([0i32; 33])
|
||||
| ^^^^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required by `std::array::IntoIter::<T, N>::new`
|
||||
|
||||
error[E0277]: arrays only have std trait implementations for lengths 0..=32
|
||||
--> $DIR/into-iter-no-impls-length-33.rs:46:22
|
||||
|
|
||||
LL | pub fn no_debug() -> impl Debug {
|
||||
| ^^^^^^^^^^ the trait `std::array::LengthAtMost32` is not implemented for `[i32; 33]`
|
||||
|
|
||||
= note: required because of the requirements on the impl of `std::fmt::Debug` for `std::array::IntoIter<i32, 33usize>`
|
||||
= note: the return type of a function must have a statically known size
|
||||
|
||||
error: aborting due to 14 previous errors
|
||||
|
||||
For more information about this error, try `rustc --explain E0277`.
|
||||
Loading…
x
Reference in New Issue
Block a user