project-model: when using `rust-project.json`, prefer the sysroot-defined rustc over discovery in `$PATH`
At the moment, rust-analyzer discovers `rustc` via the `$PATH` even if the `sysroot` field is defined in a `rust-project.json`. However, this does not work for users who do not have rustup installed, resulting in any `cfg`-based inference in rust-analzyer not working correctly. In my (decently naive!) opinion, it makes more sense to rely on the `sysroot` field in the `rust-project.json`.
One might ask "why not add `rustc` to the `$PATH`?" That is a reasonable question, but that doesn't work for my use case:
- The path to the sysroot in my employer's monorepo changes depending on which platform a user is on. For example, if they're on Linux, they'd want to use the sysroot defined at path `a`, whereas if they're on macOS, they'd want to use the sysroot at path `b` (I wrote the sysroot resolution functionality [here](765da4ca1e/integrations/rust-project/src/sysroot.rs (L39)), if you're curious).
- The location of the sysroot can (and does!) change, especially as people figure out how to make Rust run successfully on non-Linux platforms (e.g., iOS, Android, etc.) in a monorepo. Updating people's `$PATH` company-wide is hard while updating a config inside a CLI is pretty easy.
## Testing
I've created a `rust-project.json` using [rust-project](https://github.com/facebook/buck2/tree/main/integrations/rust-project) and was able to successfully load a project with and without the `sysroot`/`sysroot_src` fields—without those fields, rust-analyzer fell back to the `$PATH` based approach, as evidenced by `[DEBUG project_model::rustc_cfg] using rustc from env rustc="rustc"` showing up in the logs.
Resolve inlay hint data
Part of https://github.com/rust-lang/rust-analyzer/issues/13962
Support https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#inlayHint_resolve better, by omitting all inlay hint fields specified in the client hint resolve capabilities.
Current list of all capabilities possible to resolve later:
```
"textEdits"
"tooltip"
"label.tooltip"
"label.location"
"label.command"
```
and every one specified in the client capabilities is now resolved by r-a, being omitted in the initial response.
--------------
When editing `inlay_hints.rs` file around line `457` with no resolve capabilities, I get
<details>
<summary>resolved json, 10803 characters</summary>
```json
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```
</details>
for the visible editor range alone, pretty much repeated on every consequent edit.
With this patch and all inlay hint resolve capabilities enabled, for the same example I observe quite a footprint reduction:
<details>
<summary>unresolved json, 4142 characters</summary>
```json
{"jsonrpc":"2.0","id":49,"result":[{"position":{"line":477,"character":1},"label":[{"value":"fn inlay_hints"}],"paddingLeft":true,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":451,"character":10},"label":[{"value":": "},{"value":"ProfileSpan"},{"value":""}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":451,"character":27},"label":[{"value":"label:"}],"kind":2,"paddingLeft":false,"paddingRight":true,"data":{"file_id":0}},{"position":{"line":452,"character":12},"label":[{"value":": "},{"value":"Semantics"},{"value":"<'_, "},{"value":"RootDatabase"},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":453,"character":12},"label":[{"value":": "},{"value":"SourceFile"},{"value":""}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":454,"character":12},"label":[{"value":": &"},{"value":"SyntaxNode"},{"value":"<"},{"value":"RustLanguage"},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":456,"character":12},"label":": i32","kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":458,"character":15},"label":[{"value":": "},{"value":"Vec"},{"value":"<"},{"value":"InlayHint"},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":460,"character":21},"label":[{"value":": "},{"value":"SemanticsScope"},{"value":"<'_>"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":460,"character":36},"label":[{"value":"node:"}],"kind":2,"paddingLeft":false,"paddingRight":true,"data":{"file_id":0}},{"position":{"line":461,"character":23},"label":[{"value":": "},{"value":"FamousDefs"},{"value":"<'_, '_>"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":463,"character":17},"label":[{"value":": impl FnMut("},{"value":"SyntaxNode"},{"value":"<"},{"value":"RustLanguage"},{"value":">)"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":463,"character":25},"label":[{"value":": "},{"value":"SyntaxNode"},{"value":"<"},{"value":"RustLanguage"},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":463,"character":33},"label":[{"value":"hints:"}],"kind":2,"paddingLeft":false,"paddingRight":true,"data":{"file_id":0}},{"position":{"line":465,"character":22},"label":[{"value":": "},{"value":"TextRange"},{"value":""}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":467,"character":35},"label":[{"value":": "},{"value":"SyntaxNode"},{"value":"<"},{"value":"RustLanguage"},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":469,"character":92},"label":[{"value":"impl "},{"value":"Iterator"},{"value":"<"},{"value":"Item"},{"value":" = "},{"value":"SyntaxNode"},{"value":"<"},{"value":"RustLanguage"},{"value":">>"}],"kind":1,"paddingLeft":true,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":468,"character":34},"label":[{"value":"impl "},{"value":"Iterator"},{"value":"<"},{"value":"Item"},{"value":" = "},{"value":"SyntaxNode"},{"value":"<"},{"value":"RustLanguage"},{"value":">>"},{"value":""}],"kind":1,"paddingLeft":true,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":467,"character":41},"label":[{"value":""},{"value":"SyntaxNode"},{"value":"<"},{"value":"RustLanguage"},{"value":">"}],"kind":1,"paddingLeft":true,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":469,"character":40},"label":" -> bool","kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":469,"character":39},"label":[{"value":": &"},{"value":"SyntaxNode"},{"value":"<"},{"value":"RustLanguage"},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}}]}
```
</details>
with all unresolved parts needing only for navigation, hover or applying the hint edit — dynamic parts that are made after mouse hover or similar events, that resolve the hint data.
Enable `rust_analyzer` for cfgs when code is being analyzed by rust-analyzer
This allows one to have r-a skip analysis/replace macros that work not well with r-a at all by gating them behind this cfg (an example being the `quote` macro which r-a struggles with in terms of performance).
Do not send inlay hint refresh requests on file edits
See https://github.com/rust-lang/rust-analyzer/issues/13369#issuecomment-1695306870
Editor itself is able to invalidate hints after edits, and /refresh was sent after editor reports changes to the language server. This forces the editor to either query & invalidate the hints twice after every edit, or wait for /refresh to come before querying the hints.
Both options are rather useless, so instead, send a request on server startup only: client editors do not know when the server actually starts up, this will help to query the initial hints after editor was open and the server was still starting up.
Bind unused parameter assistant
This PR introduces a new **Bind unused parameter assistant**.
While we do have a QuickFix from `rustc` (prefixing the parameter with an underscore), it's sometimes more convenient to suppress the warning using the following approach:
```rust
fn some_function(unused: i32) {}
```
->
```rust
fn some_function(unused: i32) {
let _ = unused;
}
```
code: remove `rust-analyzer.discoverProjectCommand` in favor of a companion extension
I think it's time to remove this functionality from the `rust-analyzer` and move it into a dedicated extension responsible for this. Selfishly, this changes makes it tenable to do progress reporting to the editor and potentially do some more complicated things around managing _which_ workspaces are being used.
