let ty_b = field.ty(tcx, substs_b);
if let Ok(layout) = tcx.layout_of(param_env.and(ty_a)) {
- if layout.is_zst() {
- // ignore ZST fields
+ if layout.is_zst() && layout.details.align.abi.bytes() == 1 {
+ // ignore ZST fields with alignment of 1 byte
return None;
}
}
create_err(
"the trait `DispatchFromDyn` may only be implemented \
for structs containing the field being coerced, \
- ZST fields, and nothing else"
+ ZST fields with 1 byte alignment, and nothing else"
).note(
&format!(
"extra field `{}` of type `{}` is not allowed",
-error[E0378]: the trait `DispatchFromDyn` may only be implemented for structs containing the field being coerced, ZST fields, and nothing else
+error[E0378]: the trait `DispatchFromDyn` may only be implemented for structs containing the field being coerced, ZST fields with 1 byte alignment, and nothing else
--> $DIR/invalid_dispatch_from_dyn_impls.rs:10:1
|
LL | / impl<T, U> DispatchFromDyn<WrapperWithExtraField<U>> for WrapperWithExtraField<T>
LL | | {}
| |__^
-error: aborting due to 4 previous errors
+error[E0378]: the trait `DispatchFromDyn` may only be implemented for structs containing the field being coerced, ZST fields with 1 byte alignment, and nothing else
+ --> $DIR/invalid_dispatch_from_dyn_impls.rs:46:1
+ |
+LL | / impl<T: ?Sized, U: ?Sized> DispatchFromDyn<OverAligned<U>> for OverAligned<T>
+LL | | where
+LL | | T: Unsize<U>,
+LL | | {}
+ | |__^
+ |
+ = note: extra field `1` of type `OverAlignedZst` is not allowed
+
+error: aborting due to 5 previous errors
For more information about this error, try `rustc --explain E0378`.