1error: unsupported &mut [T] element type: opaque C++ type is not supported yet 2 --> tests/ui/slice_unsupported.rs:6:17 3 | 46 | fn f(_: &mut [Opaque]); 5 | ^^^^^^^^^^^^^ 6 7error: needs a cxx::ExternType impl in order to be used as a slice element in &mut [Opaque] 8 --> tests/ui/slice_unsupported.rs:4:9 9 | 104 | type Opaque; 11 | ^^^^^^^^^^^ 12