1 files changed, 31 insertions, 0 deletions
diff --git a/library/core/tests/alloc.rs b/library/core/tests/alloc.rs
new file mode 100644
index 000000000..8a5a06b34
--- /dev/null
+++ b/library/core/tests/alloc.rs
@@ -0,0 +1,31 @@
+use core::alloc::Layout;
+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_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);
+    }
+}