I.e. don't generate `let var_name = &foo()`.
Anything that creates a new value don't need a reference. That excludes mostly field accesses and indexing.
I had a thought that we can also not generate a reference for fields and indexing as long as the type is `Copy`, but sometimes people impl `Copy` even when they don't want to copy the values (e.g. a large type), so I didn't do that.
Expand proc-macros in workspace root, not package root
Should fix https://github.com/rust-lang/rust-analyzer/issues/17748. The approach is generally not perfect though as rust-project.json projects don't benefit from this (still, nothing changes in that regard)
fix: Fix "Unwrap block" assist with block modifiers
The assist just assumes the `{` will be the first character, which led to strange outputs such as `nsafe {`.
Fixes#17964.
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
fix: add extra_test_bin_args to test explorer test runner
`@HKalbasi` I thought I included this in #17470 but it appears not so I have created a new issue #17959 for this fix.
In most places where we set a search scope it is a single file, and so the fast path will actually harm performance, since it has to search for aliases in the whole project.
The only exception that qualifies for the fast path is SSR (there is an exception that don't qualify for the fast path as it search for `use` items). It sets the search scope to avoid dependencies. We could make it use the fast path, but I didn't bother.
perf: Speed up search for short associated functions, especially very common identifiers such as `new`
`@Veykril` said in https://github.com/rust-lang/rust-analyzer/pull/17908#issuecomment-2292958068 that people complain searches for `new()` are slow (they are right), so here I am to help!
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) branch 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.
You can find the strict branch at https://github.com/ChayimFriedman2/rust-analyzer/tree/speedup-new-usages-strict.
Should fix#7404, I guess (will check now).
fix: run flycheck without rev_deps when target is specified
Since querying for a crate's target is a call to salsa and therefore blocking, flycheck task is now deferred out of main thread by using `GlobalState`s `deferred_task_queue`. Fixes#17829 and https://github.com/rust-lang/rustlings/issues/2071
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.
This avoids the need to analyze the file when we are not inside a macro call.
This is especially important for the optimization in the next commit(s), as there the common case will be to descent into macros but then not analyze.
