Unsound component access using mutable queries about hecs HOT 2 CLOSED

Oh crap, good catch. We rely on Fetch::borrow to catch this case dynamically for shared queries, but of course that never gets called here.

probably via the tuple fetch combinator and the derive macro.

You mean, have these statically check that they don't directly contain duplicates? I don't think that would work, since queries can be arbitrarily nested; e.g. consider ((&mut A, &mut B), (&mut A, &mut C)). However, I think we can write a sanity-check which optimizes out reliably.

from hecs.

You mean, have these statically check that they don't directly contain duplicates?

I think it could but only with specialisation as this is necessary statically checking types for equality AFAIK.

I think we can write a sanity-check which optimizes out reliably.

But this is what I was thinking of as well.

from hecs.