Working with OwningRef

#1

I would like work with MetadataRef. I try implement rustc::middle::cstore::MetadataLoader, but I need create variable of MetadataRef.
How I can create variable of type MetadataRef=rustc_data_structures::owning_ref::OwningRef<Box<Erased>,[u8]?
I had tried to do this way: https://play.rust-lang.org/?version=nightly&mode=release&edition=2018&gist=ff147eaa994ee5c8ab8516b2ac65fd8e
But it’s does not compiled on my phone