From 9918693037dce8aa4bb6f08741b6812923486c18 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 19 Jun 2024 11:26:03 +0200
Subject: Merging upstream version 1.76.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 tests/ui/packed/issue-118537-field-offset-ice.rs | 39 ++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 tests/ui/packed/issue-118537-field-offset-ice.rs

(limited to 'tests/ui/packed/issue-118537-field-offset-ice.rs')

diff --git a/tests/ui/packed/issue-118537-field-offset-ice.rs b/tests/ui/packed/issue-118537-field-offset-ice.rs
new file mode 100644
index 000000000..657aec640
--- /dev/null
+++ b/tests/ui/packed/issue-118537-field-offset-ice.rs
@@ -0,0 +1,39 @@
+// run-pass
+#![feature(layout_for_ptr)]
+use std::mem;
+
+#[repr(packed(4))]
+struct Slice([u32]);
+
+#[repr(packed(2), C)]
+struct PackedSized {
+    f: u8,
+    d: [u32; 4],
+}
+
+#[repr(packed(2), C)]
+struct PackedUnsized {
+    f: u8,
+    d: Slice,
+}
+
+impl PackedSized {
+    fn unsize(&self) -> &PackedUnsized {
+        // We can't unsize via a generic type since then we get the error
+        // that packed structs with unsized tail don't work if the tail
+        // might need dropping.
+        let len = 4usize;
+        unsafe { mem::transmute((self, len)) }
+    }
+}
+
+fn main() { unsafe {
+    let p = PackedSized { f: 0, d: [1, 2, 3, 4] };
+    let p = p.unsize() as *const PackedUnsized;
+    // Make sure the size computation correctly adds exact 1 byte of padding
+    // in front of the `d` field.
+    assert_eq!(mem::size_of_val_raw(p), 1 + 1 + 4*4);
+    // And likewise for the offset computation.
+    let d = std::ptr::addr_of!((*p).d);
+    assert_eq!(d.cast::<u32>().read_unaligned(), 1);
+} }
-- 
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