fe0c08a4f2
Inspired by the zulip conversation about how `Layout` should better enforce `size < isize::MAX as usize`, this uses an N-variant enum on N-bit platforms to require at the validity level that the existing invariant of "must be a power of two" is upheld. This was MIRI can catch it, and means there's a more-specific type for `Layout` to store than just `NonZeroUsize`.
32 lines
1.1 KiB
Rust
32 lines
1.1 KiB
Rust
use core::alloc::Layout;
|
|
use core::ptr::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(ALIGN as *mut u8));
|
|
}
|
|
|
|
#[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);
|
|
}
|
|
}
|