517: gracefully handle cycles in crate graph r=matklad a=matklad
518: Add an explanatory message when we use the Query fallback r=matklad a=DJMcNab
Fixes https://github.com/rust-analyzer/rust-analyzer/issues/269.
There is no good way to explain it for go_to_def, so I've just fallen back on to_vec.
Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>
Co-authored-by: DJMcNab <36049421+djmcnab@users.noreply.github.com>