1 files changed, 29 insertions, 0 deletions
diff --git a/tests/ui/mir/alignment/packed.rs b/tests/ui/mir/alignment/packed.rs
new file mode 100644
index 000000000..754698591
--- /dev/null
+++ b/tests/ui/mir/alignment/packed.rs
@@ -0,0 +1,29 @@
+// run-pass
+// compile-flags: -C debug-assertions
+
+#![feature(strict_provenance, pointer_is_aligned)]
+
+#[repr(packed)]
+struct Misaligner {
+    _head: u8,
+    tail: u64,
+}
+
+fn main() {
+    let memory = [Misaligner { _head: 0, tail: 0}, Misaligner { _head: 0, tail: 0}];
+    // Test that we can use addr_of! to get the address of a packed member which according to its
+    // type is not aligned, but because it is a projection from a packed type is a valid place.
+    let ptr0 = std::ptr::addr_of!(memory[0].tail);
+    let ptr1 = std::ptr::addr_of!(memory[0].tail);
+    // Even if ptr0 happens to be aligned by chance, ptr1 is not.
+    assert!(!ptr0.is_aligned() || !ptr1.is_aligned());
+
+    // And also test that we can get the addr of a packed struct then do a member read from it.
+    unsafe {
+        let ptr = std::ptr::addr_of!(memory[0]);
+        let _tail = (*ptr).tail;
+
+        let ptr = std::ptr::addr_of!(memory[1]);
+        let _tail = (*ptr).tail;
+    }
+}