OwningRef is included in the compiler despite known soundness problems. #109974
Description
The OwningRef module in rustc_data_structures, which seems to be a copy of this crate (perhaps with small additions?), has known soundness issues.
I wrote an article about the soundness problems here.
It's used in rustc in MetadataRef and related things. (I don't know if it's used anywhere else).
I don't know of any actual unsafe use of this crate in rustc, but I haven't actually tried to look for any.
IMO, in order to keep the code safe, either owning_ref should be replaced with something else, or otherwise, it should be updated to contain the known fixes to these soundness problems (here).