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use core::alloc::Layout;
use core::mem::size_of;
use core::ptr::{self, NonNull};
#[test]
fn const_unchecked_layout() {
const SIZE: usize = 0x2000;
const ALIGN: usize = 0x1000;
const LAYOUT: Layout = unsafe { Layout::from_size_align_unchecked(SIZE, ALIGN) };
const DANGLING: NonNull<u8> = LAYOUT.dangling();
assert_eq!(LAYOUT.size(), SIZE);
assert_eq!(LAYOUT.align(), ALIGN);
assert_eq!(Some(DANGLING), NonNull::new(ptr::invalid_mut(ALIGN)));
}
#[test]
fn layout_round_up_to_align_edge_cases() {
const MAX_SIZE: usize = isize::MAX as usize;
for shift in 0..usize::BITS {
let align = 1_usize << shift;
let edge = (MAX_SIZE + 1) - align;
let low = edge.saturating_sub(10);
let high = edge.saturating_add(10);
assert!(Layout::from_size_align(low, align).is_ok());
assert!(Layout::from_size_align(high, align).is_err());
for size in low..=high {
assert_eq!(
Layout::from_size_align(size, align).is_ok(),
size.next_multiple_of(align) <= MAX_SIZE,
);
}
}
}
#[test]
fn layout_array_edge_cases() {
for_type::<i64>();
for_type::<[i32; 0b10101]>();
for_type::<[u8; 0b1010101]>();
// Make sure ZSTs don't lead to divide-by-zero
assert_eq!(Layout::array::<()>(usize::MAX).unwrap(), Layout::from_size_align(0, 1).unwrap());
fn for_type<T>() {
const MAX_SIZE: usize = isize::MAX as usize;
let edge = (MAX_SIZE + 1) / size_of::<T>();
let low = edge.saturating_sub(10);
let high = edge.saturating_add(10);
assert!(Layout::array::<T>(low).is_ok());
assert!(Layout::array::<T>(high).is_err());
for n in low..=high {
assert_eq!(Layout::array::<T>(n).is_ok(), n * size_of::<T>() <= MAX_SIZE);
}
}
}
#[test]
fn layout_debug_shows_log2_of_alignment() {
// `Debug` is not stable, but here's what it does right now
let layout = Layout::from_size_align(24576, 8192).unwrap();
let s = format!("{:?}", layout);
assert_eq!(s, "Layout { size: 24576, align: 8192 (1 << 13) }");
}
// Running this normally doesn't do much, but it's also run in Miri, which
// will double-check that these are allowed by the validity invariants.
#[test]
fn layout_accepts_all_valid_alignments() {
for align in 0..usize::BITS {
let layout = Layout::from_size_align(0, 1_usize << align).unwrap();
assert_eq!(layout.align(), 1_usize << align);
}
}
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