fix: Fix a bug in span map merge, and add explanations of how span maps are stored
Because it took me hours to figure out that contrary to common sense, the offset stored is the *end* of the node, and we search by the *start*. Which is why we need a convoluted `partition_point()` instead of a simple `binary_search()`. And this was not documented at all. Which made me make mistakes with my implementation of `SpanMap::merge()`.
The other bug fixed about span map merging is correctly keeping track of the current offset in presence of multiple sibling macro invocations. Unrelated, but because of the previous issue it took me hours to debug, so I figured out I'll put them together for posterity.
Fixes#18163.
fix: Fix name resolution when an import is resolved to some namespace and then later in the algorithm another namespace is added
The import is flagged as "indeterminate", and previously it was re-resolved, but only at the end of name resolution, when it's already too late for anything that depends on it.
This issue was tried to fix in https://github.com/rust-lang/rust-analyzer/pull/2466, but it was not fixed fully.
That PR is also why IDE features did work: the import at the end was resolved correctly, so IDE features that re-resolved the macro path resolved it correctly.
I was concerned about the performance of this, but this doesn't seem to regress `analysis-stats .`, so I guess it's fine to land this. I have no idea about the incremental perf however and I don't know how to measure that, although when typing in `zbus` (including creating a new function, which should recompute the def map) completion was fast enough.
I didn't check what rustc does, so maybe it does something more performant, like keeping track of only possibly problematic imports.
Fixes#18138.
Probably fixes#17630.
Because it took me hours to figure out that contrary to common sense, the offset stored is the *end* of the node, and we search by the *start*. Which is why we need a convoluted `partition_point()` instead of a simple `binary_search()`. And this was not documented at all. Which made me make mistakes with my implementation of `SpanMap::merge()`.
The other bug fixed about span map merging is correctly keeping track of the current offset in presence of multiple sibling macro invocations. Unrelated, but because of the previous issue it took me hours to debug, so I figured out I'll put them together for posterity.
The import is flagged as "indeterminate", and previously it was re-resolved, but only at the end of name resolution, when it's already too late for anything that depends on it.
This issue was tried to fix in https://github.com/rust-lang/rust-analyzer/pull/2466, but it was not fixed fully.
fix: Get rid of `$crate` in expansions shown to the user
Be it "Expand Macro Recursively", "Inline macro" or few other things.
We replace it with the crate name, as should've always been.
Probably fixes some issues, but I don't know what they are.
Previously some expansions were not cached, but were cached in the expansion cache, which caused panics when later queries tried to lookup the node from the expansion cache.
feat: render patterns in params for hovering
Fix#17858
This PR introduces an option to [hir-def/src/body/pretty.rs](08c7bbc2db/crates/hir-def/src/body/pretty.rs) to render the result as a single line, which is then reused for rendering patterns in parameters for hovering.
Always show error lifetime arguments as `'_`
Fixes#17947
Changed error lifetime argument presentation in non-test environment to `'_` and now showing them even if all of args are error lifetimes.
This also influenced some of the other tests like `extract_function.rs`, `predicate.rs` and `type_pos.rs`. Not sure whether I need to refrain from adding lifetimes args there. Happy to fix if needed
The search is used by IDE features such as rename and find all references.
The search is slow because we need to verify each candidate, and that requires analyzing it; the key to speeding it up is to avoid the analysis where possible.
I did that with a bunch of tricks that exploits knowledge about the language and its possibilities. The first key insight is that associated methods may only be referenced in the form `ContainerName::func_name` (parentheses are not necessary!) (Rust doesn't include a way to `use Container::func_name`, and even if it will in the future most usages are likely to stay in that form.
Searching for `::` will help only a bit, but searching for `Container` can help considerably, since it is very rare that there will be two identical instances of both a container and a method of it.
However, things are not as simple as they sound. In Rust a container can be aliased in multiple ways, and even aliased from different files/modules. If we will try to resolve the alias, we will lose any gain from the textual search (although very common method names such as `new` will still benefit, most will suffer because there are more instances of a container name than its associated item).
This is where the key trick enters the picture. The key insight is that there is still a textual property: a container namer cannot be aliased, unless its name is mentioned in the alias declaration, or a name of alias of it is mentioned in the alias declaration.
This becomes a fixpoint algorithm: we expand our list of aliases as we collect more and more (possible) aliases, until we eventually reach a fixpoint. A fixpoint is not guaranteed (and we do have guards for the rare cases where it does not happen), but it is almost so: most types have very few aliases, if at all.
We do use some semantic information while analyzing aliases. It's a balance: too much semantic analysis, and the search will become slow. But too few of it, and we will bring many incorrect aliases to our list, and risk it expands and expands and never reach a fixpoint. At the end, based on benchmarks, it seems worth to do a lot to avoid adding an alias (but not too much), while it is worth to do a lot to avoid the need to semantically analyze func_name matches (but again, not too much).
After we collected our list of aliases, we filter matches based on this list. Only if a match can be real, we do semantic analysis for it.
The results are promising: searching for all references on `new()` in `base-db` in the rust-analyzer repository, which previously took around 60 seconds, now takes as least as two seconds and a half (roughly), while searching for `Vec::new()`, almost an upper bound to how much a symbol can be used, that used to take 7-9 minutes(!) now completes in 100-120 seconds, and with less than half of non-verified results (aka. false positives).
This is the less strictly correct (but faster) of this patch; it can miss some (rare) cases (there is a test for that - `goto_ref_on_short_associated_function_complicated_type_magic_can_confuse_our_logic()`). There is another branch that have no false negatives but is slower to search (`Vec::new()` never reaches a fixpoint in aliases collection there). I believe it is possible to create a strategy that will have the best of both worlds, but it will involve significant complexity and I didn't bother, especially considering that in the vast majority of the searches the other branch will be more than enough. But all in all, I decided to bring this branch (of course if the maintainers will agree), since our search is already not 100% accurate (it misses macros), and I believe there is value in the additional perf.
