Auto merge of #3227 - rust-lang:rustup-2023-12-15, r=RalfJung

Automatic Rustup

Author: bors

rust-version

@@ -1 +1 @@
-e6d1b0ec9859e6f5c29aaa3b6525fb625bf354ad
+604f185fae9a4b0edf7e28f616a0f53880f8f074

src/diagnostics.rs

@@ -512,7 +512,7 @@ pub fn report_msg<'tcx>(
         }
     }
 
-    handler.emit_diagnostic(&mut err);
+    handler.emit_diagnostic(err);
 }
 
 impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {

tests/pass/packed-struct-dyn-trait.rs

@@ -0,0 +1,21 @@
+// run-pass
+use std::ptr::addr_of;
+
+// When the unsized tail is a `dyn Trait`, its alignments is only dynamically known. This means the
+// packed(2) needs to be applied at runtime: the actual alignment of the field is `min(2,
+// usual_alignment)`. Here we check that we do this right by comparing size, alignment, and field
+// offset before and after unsizing.
+fn main() {
+    #[repr(C, packed(2))]
+    struct Packed<T: ?Sized>(u8, core::mem::ManuallyDrop<T>);
+
+    let p = Packed(0, core::mem::ManuallyDrop::new(1));
+    let p: &Packed<usize> = &p;
+    let sized = (core::mem::size_of_val(p), core::mem::align_of_val(p));
+    let sized_offset = unsafe { addr_of!(p.1).cast::<u8>().offset_from(addr_of!(p.0)) };
+    let p: &Packed<dyn Send> = p;
+    let un_sized = (core::mem::size_of_val(p), core::mem::align_of_val(p));
+    let un_sized_offset = unsafe { addr_of!(p.1).cast::<u8>().offset_from(addr_of!(p.0)) };
+    assert_eq!(sized, un_sized);
+    assert_eq!(sized_offset, un_sized_offset);
+}