Removed trailing whitespace, added Object Safety clause
@@ -168,7 +168,7 @@ an implementation of `Unsize<U>` for `T` will be provided:
* `[T; n]` to `[T]`.
-* `T` to `dyn U`, when `T` implements `U + Sized`
+* `T` to `dyn U`, when `T` implements `U + Sized`, and `U` is [object safe].
* `Foo<..., T, ...>` to `Foo<..., U, ...>`, when:
* `Foo` is a struct.
@@ -188,6 +188,7 @@ unsized coercion to `Foo<U>`.
[RFC 401]: https://github.com/rust-lang/rfcs/blob/master/text/0401-coercions.md
[RFC 1558]: https://github.com/rust-lang/rfcs/blob/master/text/1558-closure-to-fn-coercion.md
[subtype]: subtyping.md
+[object safe]: items/traits.md#object-safety
[as]: expressions/operator-expr.md#type-cast-expressions
[`Unsize`]: ../std/marker/trait.Unsize.html
[`CoerceUnsized`]: ../std/ops/trait.CoerceUnsized.html
