rust/tests/run-pass/slices.rs

248 lines
8.4 KiB
Rust

#![feature(new_uninit)]
#![feature(slice_as_chunks)]
#![feature(slice_partition_dedup)]
use std::slice;
fn slice_of_zst() {
fn foo<T>(v: &[T]) -> Option<&[T]> {
let mut it = v.iter();
for _ in 0..5 {
it.next();
}
Some(it.as_slice())
}
fn foo_mut<T>(v: &mut [T]) -> Option<&mut [T]> {
let mut it = v.iter_mut();
for _ in 0..5 {
it.next();
}
Some(it.into_slice())
}
// In a slice of zero-size elements the pointer is meaningless.
// Ensure iteration still works even if the pointer is at the end of the address space.
let slice: &[()] = unsafe { slice::from_raw_parts(-5isize as *const (), 10) };
assert_eq!(slice.len(), 10);
assert_eq!(slice.iter().count(), 10);
// .nth() on the iterator should also behave correctly
let mut it = slice.iter();
assert!(it.nth(5).is_some());
assert_eq!(it.count(), 4);
// Converting Iter to a slice should never have a null pointer
assert!(foo(slice).is_some());
// Test mutable iterators as well
let slice: &mut [()] = unsafe { slice::from_raw_parts_mut(-5isize as *mut (), 10) };
assert_eq!(slice.len(), 10);
assert_eq!(slice.iter_mut().count(), 10);
{
let mut it = slice.iter_mut();
assert!(it.nth(5).is_some());
assert_eq!(it.count(), 4);
}
assert!(foo_mut(slice).is_some())
}
fn test_iter_ref_consistency() {
use std::fmt::Debug;
fn test<T : Copy + Debug + PartialEq>(x : T) {
let v : &[T] = &[x, x, x];
let v_ptrs : [*const T; 3] = match v {
[ref v1, ref v2, ref v3] => [v1 as *const _, v2 as *const _, v3 as *const _],
_ => unreachable!()
};
let len = v.len();
// nth(i)
for i in 0..len {
assert_eq!(&v[i] as *const _, v_ptrs[i]); // check the v_ptrs array, just to be sure
let nth = v.iter().nth(i).unwrap();
assert_eq!(nth as *const _, v_ptrs[i]);
}
assert_eq!(v.iter().nth(len), None, "nth(len) should return None");
// stepping through with nth(0)
{
let mut it = v.iter();
for i in 0..len {
let next = it.nth(0).unwrap();
assert_eq!(next as *const _, v_ptrs[i]);
}
assert_eq!(it.nth(0), None);
}
// next()
{
let mut it = v.iter();
for i in 0..len {
let remaining = len - i;
assert_eq!(it.size_hint(), (remaining, Some(remaining)));
let next = it.next().unwrap();
assert_eq!(next as *const _, v_ptrs[i]);
}
assert_eq!(it.size_hint(), (0, Some(0)));
assert_eq!(it.next(), None, "The final call to next() should return None");
}
// next_back()
{
let mut it = v.iter();
for i in 0..len {
let remaining = len - i;
assert_eq!(it.size_hint(), (remaining, Some(remaining)));
let prev = it.next_back().unwrap();
assert_eq!(prev as *const _, v_ptrs[remaining-1]);
}
assert_eq!(it.size_hint(), (0, Some(0)));
assert_eq!(it.next_back(), None, "The final call to next_back() should return None");
}
}
fn test_mut<T : Copy + Debug + PartialEq>(x : T) {
let v : &mut [T] = &mut [x, x, x];
let v_ptrs : [*mut T; 3] = match v {
[ref v1, ref v2, ref v3] =>
[v1 as *const _ as *mut _, v2 as *const _ as *mut _, v3 as *const _ as *mut _],
_ => unreachable!()
};
let len = v.len();
// nth(i)
for i in 0..len {
assert_eq!(&mut v[i] as *mut _, v_ptrs[i]); // check the v_ptrs array, just to be sure
let nth = v.iter_mut().nth(i).unwrap();
assert_eq!(nth as *mut _, v_ptrs[i]);
}
assert_eq!(v.iter().nth(len), None, "nth(len) should return None");
// stepping through with nth(0)
{
let mut it = v.iter();
for i in 0..len {
let next = it.nth(0).unwrap();
assert_eq!(next as *const _, v_ptrs[i]);
}
assert_eq!(it.nth(0), None);
}
// next()
{
let mut it = v.iter_mut();
for i in 0..len {
let remaining = len - i;
assert_eq!(it.size_hint(), (remaining, Some(remaining)));
let next = it.next().unwrap();
assert_eq!(next as *mut _, v_ptrs[i]);
}
assert_eq!(it.size_hint(), (0, Some(0)));
assert_eq!(it.next(), None, "The final call to next() should return None");
}
// next_back()
{
let mut it = v.iter_mut();
for i in 0..len {
let remaining = len - i;
assert_eq!(it.size_hint(), (remaining, Some(remaining)));
let prev = it.next_back().unwrap();
assert_eq!(prev as *mut _, v_ptrs[remaining-1]);
}
assert_eq!(it.size_hint(), (0, Some(0)));
assert_eq!(it.next_back(), None, "The final call to next_back() should return None");
}
}
// Make sure iterators and slice patterns yield consistent addresses for various types,
// including ZSTs.
test(0u32);
test(());
test([0u32; 0]); // ZST with alignment > 0
test_mut(0u32);
test_mut(());
test_mut([0u32; 0]); // ZST with alignment > 0
}
fn uninit_slice() {
let mut values = Box::<[Box<u32>]>::new_uninit_slice(3);
let values = unsafe {
// Deferred initialization:
values[0].as_mut_ptr().write(Box::new(1));
values[1].as_mut_ptr().write(Box::new(2));
values[2].as_mut_ptr().write(Box::new(3));
values.assume_init()
};
assert_eq!(values.iter().map(|x| **x).collect::<Vec<_>>(), vec![1, 2, 3])
}
/// Regression tests for slice methods in the Rust core library where raw pointers are obtained
/// from mutable references.
fn test_for_invalidated_pointers() {
let mut buffer = [0usize; 64];
let len = buffer.len();
// These regression tests (indirectly) call every slice method which contains a `buffer.as_mut_ptr()`.
// `<[T]>::as_mut_ptr(&mut self)` takes a mutable reference (tagged Unique), which will invalidate all
// the other pointers that were previously derived from it according to the Stacked Borrows model.
// An example of where this could go wrong is a prior bug inside `<[T]>::copy_within`:
//
// unsafe {
// core::ptr::copy(self.as_ptr().add(src_start), self.as_mut_ptr().add(dest), count);
// }
//
// The arguments to `core::ptr::copy` are evaluated from left to right. `self.as_ptr()` creates
// an immutable reference (which is tagged as `SharedReadOnly` by Stacked Borrows) to the array
// and derives a valid `*const` pointer from it. When jumping to the next argument,
// `self.as_mut_ptr()` creates a mutable reference (tagged as `Unique`) to the array, which
// invalidates the existing `SharedReadOnly` reference and any pointers derived from it.
// The invalidated `*const` pointer (the first argument to `core::ptr::copy`) is then used
// after the fact when `core::ptr::copy` is called, which triggers undefined behavior.
unsafe { assert_eq!(0, *buffer.as_mut_ptr_range().start ); }
// Check that the pointer range is in-bounds, while we're at it
let range = buffer.as_mut_ptr_range();
unsafe { assert_eq!(*range.start, *range.end.sub(len)); }
buffer.reverse();
// Calls `fn as_chunks_unchecked_mut` internally (requires unstable `#![feature(slice_as_chunks)]`):
assert_eq!(2, buffer.as_chunks_mut::<32>().0.len());
// Calls `fn split_at_mut_unchecked` internally:
let split_mut = buffer.split_at_mut(32);
assert_eq!(split_mut.0, split_mut.1);
// Calls `fn partition_dedup_by` internally (requires unstable `#![feature(slice_partition_dedup)]`):
assert_eq!(1, buffer.partition_dedup().0.len());
buffer.rotate_left(8);
buffer.rotate_right(16);
buffer.copy_from_slice(&[1usize; 64]);
buffer.swap_with_slice(&mut [2usize; 64]);
assert_eq!(0, unsafe { buffer.align_to_mut::<u8>().1[1] });
buffer.copy_within(1.., 0);
}
fn main() {
slice_of_zst();
test_iter_ref_consistency();
uninit_slice();
test_for_invalidated_pointers();
}