diff --git a/library/coretests/tests/alloc.rs b/library/coretests/tests/alloc.rs index 72fdf82c1f8cf..a4af6fd32a11d 100644 --- a/library/coretests/tests/alloc.rs +++ b/library/coretests/tests/alloc.rs @@ -55,6 +55,30 @@ fn layout_array_edge_cases() { } } +#[test] +fn layout_errors() { + let layout = Layout::new::<[u8; 2]>(); + // Should error if the alignment is not a power of two. + assert!(layout.align_to(3).is_err()); + + // The remaining assertions ensure that the methods error on arithmetic overflow as the + // alignment cannot overflow `isize`. + let size = layout.size(); + let size_max = isize::MAX as usize; + let align_max = size_max / size; + + assert!(layout.align_to(size_max + 1).is_err()); + + assert!(layout.repeat(align_max).is_ok()); + assert!(layout.repeat(align_max + 1).is_err()); + + assert!(layout.repeat_packed(align_max).is_ok()); + assert!(layout.repeat_packed(align_max + 1).is_err()); + + let next = Layout::from_size_align(size_max, 1).unwrap(); + assert!(layout.extend(next).is_err()); +} + #[test] fn layout_debug_shows_log2_of_alignment() { // `Debug` is not stable, but here's what it does right now