analysis-stats --with-deps on r-a hits this
unimplemented!() call: https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/hir_ty/src/traits/chalk/mapping.rs#L234
Could this be due to const generics?
oh hm. we never pass const or lifetime params to Chalk, so I'm not sure
I mean, it has to be either a const or a lifetime, the question would be where it came from
there are already some situations where Chalk gives us a lifetime back in a solution, maybe this is the same thing
it's rather weird though, because what is this a substitution for -- we never tell Chalk that anything takes a non-type parameter...