error: mutable reference to C++ type requires a pin -- use Pin<&mut Opaque>
 --> tests/ui/pin_mut_opaque.rs:5:19
  |
5 |         fn f(arg: &mut Opaque);
  |                   ^^^^^^^^^^^

error: mutable reference to C++ type requires a pin -- use Pin<&mut CxxString>
 --> tests/ui/pin_mut_opaque.rs:8:17
  |
8 |         fn s(s: &mut CxxString);
  |                 ^^^^^^^^^^^^^^

error: mutable reference to C++ type requires a pin -- use Pin<&mut CxxVector<...>>
 --> tests/ui/pin_mut_opaque.rs:9:17
  |
9 |         fn v(v: &mut CxxVector<u8>);
  |                 ^^^^^^^^^^^^^^^^^^

error: needs a cxx::ExternType impl in order to be used as a non-pinned mutable reference in signature of `f`, `g`, `h`
 --> tests/ui/pin_mut_opaque.rs:4:9
  |
4 |         type Opaque;
  |         ^^^^^^^^^^^

error: mutable reference to opaque C++ type requires a pin -- use `self: Pin<&mut Opaque>`
 --> tests/ui/pin_mut_opaque.rs:6:14
  |
6 |         fn g(&mut self);
  |              ^^^^^^^^^

error: mutable reference to opaque C++ type requires a pin -- use `self: Pin<&mut Opaque>`
 --> tests/ui/pin_mut_opaque.rs:7:20
  |
7 |         fn h(self: &mut Opaque);
  |                    ^^^^^^^^^^^