Initial advisory for owning_ref unsoundness

[Shnatsel]

I would appreciate an opinion on whether this should be informational = unsound or not.

Addresses part of #1174 (the unmaintained advisory is still TODO)

[Shnatsel]

@noamtashma could you take a look and see if the summary is accurate?

Suggestions or edits are also very welcome.

[noamtashma]

Hi! Looks good to me.
You seem to be missing this issue: Kimundi/owning-ref-rs#71
About an unsoundness regarding implicit constraints in the map functions.

[pinkforest]

@Shnatsel would you be open if I push a commit into your branch to address the comment to get this merged -

Otherwise lgtm from me - We've pinged the author - Kimundi/owning-ref-rs#81

[Shnatsel]

I'll see if I can get around to it. FWIW @pinkforest you should have the rights to push to this branch, it's on this repo instead of a private fork.

[pinkforest]

Thanks - Fixed it - looks good to merge :)

[Shnatsel]

Thanks!