Niko Matsakis

getting a weird #rustlang error about "borrowed value must be valid for lifetime '_#7r". never seen that lifetime specifier before... something internal? haven't yet figured out how to get the compiler to dump lifetimes to output so I can see where it came from

sounds like this might even be a compiler bug. Is it code you're comfortable sharing? If so, you could file an issue on it.

Cool, will do. It's also an error I don't expect to be getting (but of course could be my bad). I tried minimizing the repro, but compilation succeeded

There are only a few lifetimes with inteligible names, specifically 'static. The rest of the error message should show you where your borrow began, the lifetime began, and where the lifetime ends while your borrow is still held.