Fills in server information.
Derives CodeAction capabilities from the client. If code action literals
are unsupported we fall back to the "simple support" which just sends back
commands (this is already supported in our config). The difference being
that we did not adjust our server capabilities so that if the client was
checking for `CodeActionProvider: "true"` in the response that would have failed.
4501: Querify `importable_locations_in_crate` r=jonas-schievink a=jonas-schievink
This brings the time needed to compute the `add_missing_impl_members` assist down from ~5 minutes to 20 seconds on my test workload (which is editing within an impl of a MIR [`MutVisitor`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/visit/trait.MutVisitor.html))
cc #4498
Co-authored-by: Jonas Schievink <jonasschievink@gmail.com>
4497: Create LowerCtx on the fly r=matklad a=edwin0cheng
Previously we create `LowerCtx` at the beginning of lowering, however, the hygiene content is in fact changing between macro expression expanding.
This PR change it to create the `LowerCtx` on the fly to fix above bug.
However, #4465 is not fixed by this PR, the goto-def is still not work yet. It only fixed the infer part.
Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>
4493: Provide builtin impls of Fn traits for fn-pointers r=flodiebold a=hban
Meant to be, but isn't actually a fix for #2880.
Consider this snippet:
```rust
use std::marker::PhantomData;
use std::ops::Deref;
struct Lazy<T, F/* = fn() -> T*/>(F, PhantomData<T>);
impl<T, F> Lazy<T, F> {
pub fn new(f: F) -> Lazy<T, F> {
Lazy(f, PhantomData)
}
}
impl<T, F: FnOnce() -> T> Deref for Lazy<T, F> {
type Target = T;
fn deref(&self) -> &T { todo!() }
}
fn test() {
let lazy1: Lazy<u32, _> = Lazy::new(|| 0u32);
let r1 = lazy1.to_string();
fn make_u32_fn() -> u32 { todo!() }
let make_u32_fn_ptr: fn() -> u32 = make_u32_fn;
let lazy2: Lazy<u32, _> = Lazy::new(make_u32_fn_ptr);
let r2 = lazy2.to_string();
}
```
* On current master:
* When type default is commented-out, `r1` is correctly inferred, `r2` in _{unknown}_.
* When type default is not commented-out, both `r1` and `r2` are _{unknown}_.
* With this PR:
* When type default is commented-out, both `r1` and `r2` are correctly inferred.
* When type default is not commented-out, both `r1` and `r2` are _{unknown}_.
Well, it's a improvement at least. I guess this thing with type defaults is a different problem.
I also tried add Fn impls for fn items, but wasn't successful. So this PR only adds those impls for fn pointers.
Co-authored-by: Hrvoje Ban <hban@users.noreply.github.com>
4489: Memory allocation optimization r=matklad a=simonvandel
I did some profiling using DHAT, and this was what I could easily optimize without much knowledge of the codebase.
This speeds up analysis-stats on rust-analyser by ~4% on my local machine.
**Benchmark**
➜ rust-analyzer-base git:(master) hyperfine --min-runs=2 '/home/simon/Documents/rust-analyzer/target/release/rust-analyzer analysis-stats .' '/home/simon/Documents/rust-analyzer-base/target/release/rust-analyzer analysis-stats .'
Benchmark #1: /home/simon/Documents/rust-analyzer/target/release/rust-analyzer analysis-stats .
Time (mean ± σ): 49.621 s ± 0.317 s [User: 48.725 s, System: 0.792 s]
Range (min … max): 49.397 s … 49.846 s 2 runs
Benchmark #2: /home/simon/Documents/rust-analyzer-base/target/release/rust-analyzer analysis-stats .
Time (mean ± σ): 51.764 s ± 0.045 s [User: 50.882 s, System: 0.756 s]
Range (min … max): 51.733 s … 51.796 s 2 runs
Summary
'/home/simon/Documents/rust-analyzer/target/release/rust-analyzer analysis-stats .' ran
1.04 ± 0.01 times faster than '/home/simon/Documents/rust-analyzer-base/target/release/rust-analyzer analysis-stats .'
Co-authored-by: Simon Vandel Sillesen <simon.vandel@gmail.com>
4484: Allow calling dyn trait super trait methods without the super trait in scope r=flodiebold a=flodiebold
This also removes some vestiges of the old impl trait support which I think aren't currently in use.
Co-authored-by: Florian Diebold <flodiebold@gmail.com>
4472: Fix path resolution for module and function with same name r=hasali19 a=hasali19
This fixes#3970 and also fixes completion for the same issue.
Co-authored-by: Hasan Ali <git@hasali.co.uk>
4448: Generate configuration for launch.json r=vsrs a=vsrs
This PR adds two new commands: `"rust-analyzer.debug"` and `"rust-analyzer.newDebugConfig"`. The former is a supplement to the existing `"rust-analyzer.run"` command and works the same way: asks for a runnable and starts new debug session. The latter allows adding a new configuration to **launch.json** (or to update an existing one).
If the new option `"rust-analyzer.debug.useLaunchJson"` is set to true then `"rust-analyzer.debug"` and Debug Lens will first look for existing debug configuration in **launch.json**. That is, it has become possible to specify startup arguments, env variables, etc.
`"rust-analyzer.debug.useLaunchJson"` is false by default, but it might be worth making true the default value. Personally I prefer true, but I'm not sure if it is good for all value.
----
I think that this PR also solves https://github.com/rust-analyzer/rust-analyzer/issues/3441.
Both methods to update launch.json mentioned in the issue do not work:
1. Menu. It is only possible to add a launch.json configuration template via a debug adapter. And anyway it's only a template and it is impossible to specify arguments from an extension.
2. DebugConfigurationProvider. The exact opposite situation: it is possible to specify all debug session settings, but it is impossible to export these settings to launch.json.
Separate `"rust-analyzer.newDebugConfig"` command looks better for me.
----
Fixes#4450Fixes#3441
Co-authored-by: vsrs <vit@conrlab.com>
Co-authored-by: vsrs <62505555+vsrs@users.noreply.github.com>
4273: Trigger add_vis assist on paths/record fields as well r=flodiebold a=TimoFreiberg
Resolves#4037.
- [x] Function defs
- [x] ADT defs
- [x] Enum variants
- [x] Consts
- [x] Statics
- [x] Traits
- [x] Type aliases
- [x] Modules
- [x] Record fields (using different implementation)
- [x] struct fields
- [x] enum variant fields
- ❌ union fields (`Semantics::resolve_record_field` seems to not work for union fields, so I think this can be handled in a future PR)
- [x] More tests?
- [x] Improve test fixture code and documentation a bit (see [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0/topic/resolve_path.20between.20fixture.20files))
Co-authored-by: Timo Freiberg <timo.freiberg@gmail.com>
4445: Correctly fill default type parameters r=flodiebold a=montekki
Fixes#3877
So, basically even if the parameters are omitted from the `impl` block, check the parameters in `trait` if they have a default type, and if they do go from `hir` to `ast::TypeArg`. I've added a helper for that but I am not sure that it's a proper way to go from `hir` to `ast` here.
Co-authored-by: Fedor Sakharov <fedor.sakharov@gmail.com>
4405: Make some stuff public so that they can be reused by other tools r=pksunkara a=pksunkara
So, my little experiment of building a code analysis tool using rust-analyzer is successful. I am going to proceed to build the tool now. This PR makes the needed things public.
I know there were some things about trying to change stuff regarding loading workspaces, which would make it more easier for other tools to reuse. But, until then, it should be okay using this `load_cargo` fn.
Btw, if I were publish my tool, I would need the `ra` crates to be released. Since @matklad told me that he doesn't want to care about breaking stuff, I would propose the following.
Every monday, during the weekly release, we release a new pre v1 minor version of all the crates. That way, we don't need to care about breaking stuff but still have rust-analyzer on crates.io.
I made https://github.com/pksunkara/cargo-workspaces to help release workspace crates easily.
So, coming week, we start with `0.1.0`, then week after that, we release `0.2.0` and then `0.3.0` etc.. until we decide on `1.0.0` which is probably when the compiler team also starts using the crates. There is no limit to the minor versions (we can even have `0.150.0` or `0.1500.0`), so I don't see anything wrong with this strategy.
Co-authored-by: Pavan Kumar Sunkara <pavan.sss1991@gmail.com>
4434: add more specific match postfix for Result and Option r=matklad a=bnjjj
In order to have the same behavior than `if let` and `while let`
Co-authored-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
4083: Smol documentation for ast nodes r=matklad a=Veetaha
There is a tremendous amount of TODOs to clarify the topics I am not certain about.
Please @matklad, @edwin0cheng review carefully, I even left some mentions of your names in todos to put your attention where you most probably can give comments.
In order to simplify the review, I separated the codegen (i.e. changes in `ast/generated/nodes.rs`) from `ast_src` changes (they in fact just duplicate one another) into two commits.
Also, I had to hack a little bit to let the docs be generated as doc comments and not as doc attributes because it's easier to read them this way and IIRC we don't support hints for `#[doc = ""]` attributes for now...
Closes#3682
Co-authored-by: veetaha <veetaha2@gmail.com>
This reverts commit 7a49165f5d.
MacroStmts ast node is not used by itself, but it pertains
to SyntaxNodeKind MACRO_STMTS that is used by ra_paser, so
even tho the node itself is not used, it is better to keep it
with a FIXME to actually add a doc comment when it becomes useful.
4423: add tests module snippet r=bnjjj a=bnjjj
Request from a friend coming from intellij Rust
Co-authored-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
4397: Textmate cooperation r=matklad a=georgewfraser
This PR tweaks the fallback TextMate scopes to make them more consistent with the existing grammar and other languages, and edits the builtin TextMate grammar to align with semantic coloring. Before is on the left, after is on the right:
<img width="855" alt="Screen Shot 2020-05-10 at 1 45 51 PM" src="https://user-images.githubusercontent.com/1369240/81512320-a8be7e80-92d4-11ea-8940-2c03f6769015.png">
**Use keyword.other for regular keywords instead of keyword**. This is a really peculiar quirk of TextMate conventions, but virtually *all* TextMate grammars use `keyword.other` (colored blue in VSCode Dark+) for regular keywords and `keyword.control` (colored purple in VSCode Dark+) for control keywords. The TextMate scope `keyword` is colored like control keywords, not regular keywords. It may seem strange that the `keyword` scope is not the right fallback for the `keyword` semantic token, but TextMate has a long and weird history. Note how keywords change from purple back to blue (what they were before semantic coloring was added):
**(1) Use punctuation.section.embedded for format specifiers**. This aligns with how Typescript colors formatting directives:
<img width="238" alt="Screen Shot 2020-05-09 at 10 54 01 AM" src="https://user-images.githubusercontent.com/1369240/81481258-93b5f280-91e3-11ea-99c2-c6d258c5bcad.png">
**(2) Consistently use `entity.name.type.*` scopes for type names**. Avoid using `entity.name.*` which gets colored like a keyword.
**(3) Use Property instead of Member for fields**. Property and Member are very similar, but if you look at the TextMate fallback scopes, it's clear that Member is intended for function-like-things (methods?) and Property is intended for variable-like-things.
**(4) Color `for` as a regular keyword when it's part of `impl Trait for Struct`**.
**(5) Use `variable.other.constant` for constants instead of `entity.name.constant`**. In the latest VSCode insiders, variable.other.constant has a subtly different color that differentiates constants from ordinary variables. It looks close to the green of types but it's not the same---it's a new color recently added to take advantage of semantic coloring.
I also made some minor changes that make the TextMate scopes better match the semantic scopes. The effect of this for the user is you observe less of a change when semantic coloring "activates". You can see the changes I made relative to the built-in TextMate grammar here:
a91d15c80c..97428b6d52 (diff-6966c729b862f79f79bf7258eb3e0885)
Co-authored-by: George Fraser <george@fivetran.com>
4421: Find references to a function outside module r=flodiebold a=montekki
Fixes#4188
Yet again, it looks like although the code in
da1f316b02/crates/ra_ide_db/src/search.rs (L128-L132)
may be wrong, it is not hit since the `vis` is `None` at this point. The fix is similar to the #4237 case: just add another special case to `Definition::visibility()`.
Co-authored-by: Fedor Sakharov <fedor.sakharov@gmail.com>
4394: Simplify r=matklad a=Veetaha
4414: Highlighting improvements r=matklad a=matthewjasper
- `static mut`s are highlighted as `mutable`.
- The name of the macro declared by `macro_rules!` is now highlighted.
Co-authored-by: veetaha <veetaha2@gmail.com>
Co-authored-by: Matthew Jasper <mjjasper1@gmail.com>
4406: Update cargo-metadata r=matklad a=edwin0cheng
This PR update `cargo-metadata` to 0.10.0 and it also relax the` serde-derive` deps to 1.0 for tests in `proc-macro-srv`.
cc @robojumper
r= @matklad , I think you would have something to say related to https://github.com/serde-rs/json/issues/647#issue-593788429 ?
4410: Improve wording in comment r=matklad a=edwin0cheng
4411: do not remove then block when you unwrap else block #4361 r=matklad a=bnjjj
close#4361
4417: Omit default types in HirDisplay SourceCode mode r=matklad a=TimoFreiberg
Closes#4390
Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>
Co-authored-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
Co-authored-by: Timo Freiberg <timo.freiberg@gmail.com>
This fixes an issue where the following code sample would fail to infer
the type contained in the option:
```rust
fn main() {
let mut end = None; // TODO: Fix inference for this in RA
loop {
end = Some(true);
}
}
```
4175: Introduce HirDisplay method for rendering source code & use it in add_function assist r=flodiebold a=TimoFreiberg
Next feature for #3639.
So far the only change in the new `HirDisplay` method is that paths are qualified, but more changes will be necessary (omitting the function name from function types, returning an error instead of printing `"{unknown}"`, probably more).
Is that approach okay?
Co-authored-by: Timo Freiberg <timo.freiberg@gmail.com>
This starts the transition to a new method of documenting the cfgs that are
enabled for a given crate in the json file. This is changing from a list
of atoms and a dict of key:value pairs, to a list of strings that is
equivalent to that returned by `rustc --print cfg ..`, and parsed in the
same manner by rust-analyzer.
This is the first of two changes, which adds the new field that contains
the list of strings. Next change will complete the transition and remove
the previous fields.
E.g. in
```rust
match x {
1 => function1,
2 => function2,
}
```
we need to try coercing both to pointers. Turns out this is a special case in
rustc as well (see the link in the comment).
4377: Implement better handling of divergence r=matklad a=flodiebold
Divergence here means that for some reason, the end of a block will not be reached. We tried to model this just using the never type, but that doesn't work fully (e.g. in `let x = { loop {}; "foo" };` x should still have type `&str`); so this introduces a `diverges` flag that the type checker keeps track of, like rustc does. We also add some checking for `break`, but no support for break-with-value or labeled breaks yet.
Co-authored-by: Florian Diebold <florian.diebold@freiheit.com>
Co-authored-by: Florian Diebold <flodiebold@gmail.com>
Divergence here means that for some reason, the end of a block will not be
reached. We tried to model this just using the never type, but that doesn't work
fully (e.g. in `let x = { loop {}; "foo" };` x should still have type `&str`);
so this introduces a `diverges` flag that the type checker keeps track of, like
rustc does.
4329: Look for `cargo`, `rustc`, and `rustup` in standard installation path r=matklad a=cdisselkoen
Discussed in #3118. This is approximately a 90% fix for the issue described there.
This PR creates a new crate `ra_env` with a function `get_path_for_executable()`; see docs there. `get_path_for_executable()` improves and generalizes the function `cargo_binary()` which was previously duplicated in the `ra_project_model` and `ra_flycheck` crates. (Both of those crates now depend on the new `ra_env` crate.) The new function checks (e.g.) `$CARGO` and `$PATH`, but also falls back on `~/.cargo/bin` manually before erroring out. This should allow most users to not have to worry about setting the `$CARGO` or `$PATH` variables for VSCode, which can be difficult e.g. on macOS as discussed in #3118.
I've attempted to replace all calls to `cargo`, `rustc`, and `rustup` in rust-analyzer with appropriate invocations of `get_path_for_executable()`; I don't think I've missed any in Rust code, but there is at least one invocation in TypeScript code which I haven't fixed. (I'm not sure whether it's affected by the same problem or not.) a4778ddb7a/editors/code/src/cargo.ts (L79)
I'm sure this PR could be improved a bunch, so I'm happy to take feedback/suggestions on how to solve this problem better, or just bikeshedding variable/function/crate names etc.
cc @Veetaha
Fixes#3118.
Co-authored-by: Craig Disselkoen <craigdissel@gmail.com>
Co-authored-by: veetaha <veetaha2@gmail.com>
4362: do not show runnables for main function outside of a binary target r=matklad a=bnjjj
close#4356
Co-authored-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
4346: Fix rename of enum variant visible from module r=matklad a=montekki
Probably fixes#4237
It looks like the ref is found correctly in this case but it's visibility is not correctly determined. I took a stab at fixing that by adding an implementation of `HasVisibility` for `EnumVariant` so it works more or less the same way it does for struct fields.
In other words, the `search_range` here does not contain the ref since it's not considered visible:
efd8e34c39/crates/ra_ide_db/src/search.rs (L209-L214)
Before that I tried to populate `ItemScope` with visible enum variants but that ended up with breaking tests all over the place and also it looked illogical in the end: `ItemScope` is not populated with, say, public struct fields and the same should be true for `enum` variants.
I've added two more or less identical tests: one for the case with a struct field rename and one for enum variant rename; the test for struct should probably be removed and the names should be changed.
Co-authored-by: Fedor Sakharov <fedor.sakharov@gmail.com>
4316: do not truncate display for hover r=matklad a=bnjjj
close#4311
4351: Fix Windows server path r=matklad a=lnicola
CC @Coder-256.
Co-authored-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
Co-authored-by: Laurențiu Nicola <lnicola@users.noreply.github.com>
4166: Defining a default target to support cross-compilation targets r=matklad a=FuriouZz
Related to #4163
Co-authored-by: Christophe MASSOLIN <christophe.massolin@gmail.com>
4306: Make incremental sync opt-out and fix line index rebuild r=matklad a=lnicola
4308: Update server binary paths in docs r=matklad a=Coder-256
Fixed incorrect macOS path and converted to a list. Also, should the Windows path include `matklad.rust-analyzer`? (I can't check)
Co-authored-by: Laurențiu Nicola <lnicola@dend.ro>
Co-authored-by: Jacob Greenfield <jacob@jacobgreenfield.me>
No tests fail, and quick manual testing shows that there are no
false-positives. In general, each completion contributor should be
independent from the others.
4269: add support of use alias semantic in definition r=matklad a=bnjjj
close#4202
4293: no doctests for flycheck r=matklad a=matklad
bors r+
🤖
Co-authored-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>
4285: add support of cfg attributes on enum variants r=edwin0cheng a=bnjjj
close#4279
Co-authored-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
4286: Make incremental sync opt-in r=matklad a=lnicola
@matklad do you want to merge this? I'd make it opt-out, but it's fine to test it more.
Co-authored-by: Laurențiu Nicola <lnicola@dend.ro>
4280: Add documents owner for ImplDef and SourceFile r=matklad a=edwin0cheng
When working on #3182, I found that `ImplDef` and `SourceFile` do not implemet `DocCommentsOwer` trait, and I tested it in `cargo doc` that `impl` could has some doc-comments.
I am not so sure about `SourceFile` case, but in theory if that file is a crate root, the doc comment of it should represent the whole crate documentation, right ?
Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>
4276: Don't count start of non-ASCII characters as being inside of them r=matklad a=lnicola
I'm still not sure that `utf16_to_utf8_col` is correct for code points from Supplementary Planes. These have two UTF-16 code units, and I feel we're not going to count them correctly.
Fixes the crash in https://github.com/rust-analyzer/rust-analyzer/issues/4263#issuecomment-622988258.
Co-authored-by: Laurențiu Nicola <lnicola@dend.ro>
4207: Add unwrap block assist #4156 r=matklad a=bnjjj
close issue #4156
4253: Remove `workspaceLoaded` setting r=matklad a=eminence
The `workspaceLoaded` notification setting was originally designed to
control the display of a popup message that said:
"workspace loaded, {} rust packages"
This popup was removed and replaced by a much sleeker message in the
VSCode status bar that provides a real-time status while loading:
rust-analyzer: {}/{} packages
This was done as part of #3587
The change in this PR simply renames this setting from `workspaceLoaded` to
`progress` to better describe what it actually controls. At the moment,
the only type of progress message that is controlled by this setting is
the initial load messages, but in theory other messages could also be
controlled by this setting.
Reviewer notes:
* If we didn't like the idea of causing minor breaking to user's config, we could keep the setting name as `workspaceLoaded`
* I think we can now close both #2719 and #3176 since the notification dialog in question no longer exists (actually I think you can close those issues even if you reject this PR 😄 )
Co-authored-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>
Co-authored-by: Andrew Chin <achin@eminence32.net>
The `workspaceLoaded` notification setting was originally designed to
control the display of a popup message that said:
"workspace loaded, {} rust packages"
This popup was removed and replaced by a much sleeker message in the
VSCode status bar that provides a real-time status while loading:
rust-analyzer: {}/{} packages
This was done as part of #3587
The new status-bar indicator is unobtrusive and shouldn't need to be
disabled. So this setting is removed.
4244: Show unsafe trait in hover r=matklad a=DianaNites
Following on #2450 and #4210, for traits.
`unsafe` is the only qualifier they can have, though.
Co-authored-by: Diana <5275194+DianaNites@users.noreply.github.com>
4246: Validate uses of self and super r=matklad a=djrenren
This change follows on the validation of the `crate` keyword in paths. It verifies the following things:
`super`:
- May only be preceded by other `super` segments
- If in a `UseItem` then all semantically preceding paths also consist only of `super`
`self`
- May only be the start of a path
Just a note, a couple times while working on this I found myself really wanting a Visitor of some sort so that I could traverse descendants while skipping sub-trees that are unimportant. Iterators don't really work for this, so as you can see I reached for recursion. Considering paths are generally small a fancy debounced visitor probably isn't important but figured I'd say something in case we had something like this lying around and I wasn't using it.
Co-authored-by: John Renner <john@jrenner.net>
4153: Add support for incremental text synchronization r=matklad a=lnicola
Fixes#3762.
This still needs a `ra_vfs` PR, but I want to know I'm on the right track. I tested the change and it didn't crash horribly, but YMMV.
Co-authored-by: Laurențiu Nicola <lnicola@dend.ro>
4227: Report invalid, nested, multi-segment crate-paths r=matklad a=djrenren
There was a bug in the previous path-validating code that didn't detect multi-segment paths that started with `crate`.
```rust
// Successfully reported
use foo::{crate};
// BUG: was not being reported
use foo::{crate::bar};
```
This was due to my confusion about path-associativity. That is, the path with no qualifier is the innermost path, not the outermost. I've updated the code with a lot of comments to explain what's going on.
This bug was discovered when I found an erroneous `ok` test which I reported here:
https://github.com/rust-analyzer/rust-analyzer/issues/4226
This test now fails and has been modified, hopefully in the spirit of the original test, to be correct. Sorry about submitting the bug in the first place!
Co-authored-by: John Renner <john@jrenner.net>
4178: Validate the location of `crate` in paths r=matklad a=djrenren
**This solution does not fully handle `use` statements. See below**
This pull requests implements simple validation of usages of the `crate` keyword in `Path`s. Specifically it validates that:
- If a `PathSegment` is starts with the `crate` keyword, it is also the first segment of the `Path`
- All other usages of `crate` in `Path`s are considered errors.
This aligns with `rustc`'s rules. Unlike rustc this implementation does not issue a special error message in the case of `::crate` but it does catch the error.
Furthermore, this change does not cover all error cases. Specifically the following is not caught:
```rust
use foo::{crate}
```
This is because this check is context sensitive. From an AST perspective, `crate` is the root of the `Path`. Only by inspecting the full `UseItem` do we see that it is not in fact the root. This problem becomes worse because `UseTree`s are allowed to be arbitrarily nested:
```rust
use {crate, {{crate, foo::{crate}}}
```
So this is a hard problem to solve without essentially a breadth-first search. In a traditional compiler, I'd say this error is most easily found during the AST -> HIR conversion pass but within rust-analyzer I'm not sure where it belongs.
Under the implementation in this PR, such errors are ignored so we're *more correct* just not *entirely correct*.
Co-authored-by: John Renner <john@jrenner.net>