Thanks to the observation (supported by counting) that the vast majority paths have neither generics no type anchors, and thanks to a new datastructure `ThinVecWithHeader` that is essentially `(T, Box<[U]>)` but with the size of a single pointer, we are able to reach this feat.
This (together with `ThinVecWithHeader`) makes the possibility to shrink `TypeRef`, because most types are paths.
Commit 6a06f6f72 (Deduplicate reference search results, 2022-11-07) deduplicates references
within each definition.
There is an edge case when requesting references of a macro argument. Apparently, our
descend_into_macros() stanza in references.rs produces a cartesian product of
- references inside the macro times
- times references outside the macro.
Since the above deduplication only applies to the references within a single definition, we
return them all, leading to many redundant references.
Work around this by deduplicating definitions as well. Perhaps there is a better fix to not
produce this cartesian product in the first place; but I think at least for definitions the
problem would remain; a macro can contain multiple definitions of the same name, but since the
navigation target will be the unresolved location, it's the same for all of them.
We can't use unique() because we don't want to drop references that don't have a declaration
(though I dont' have an example for this case).
I discovered this working with the "bitflags" macro from the crate of the same name.
Fixes#16357
This commit also adds `tracing` to NotificationDispatcher/RequestDispatcher,
bumps `rust-analyzer-salsa` to 0.17.0-pre.6, `always-assert` to 0.2, and
removes the homegrown `hprof` implementation in favor of a vendored
tracing-span-tree.
