Type inference for overloadable operators

[flodiebold]

Follow-up to #390. We don't support overloads of the binary operators in the type system yet, e.g. handling custom Add implementations etc.. We have all the necessary systems in place to do this, but I don't know if it makes sense to try doing it before we've got a solution for rust-lang/chalk#234, since that would probably prevent many cases from working anyway.

[flodiebold]

This is mostly implemented, except for some bugs (#7150).

[rben01]

If RA reports that the inferred type of 1_u32 / 2_u32 is <u32 as Div<u32>>::Output, does that fall under this issue, or should I submit a separate issue? (I'd expect u32 due to the trait implementation here, which AFAIK is unambiguous.)

[Veykril]

That seems to be a problem with your rust setup or project