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
{"jsonrpc":"2.0","id":55,"result":[{"position":{"line":477,"character":1},"label":[{"value":"fn inlay_hints","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/ide/src/inlay_hints.rs","range":{"start":{"line":445,"character":14},"end":{"line":445,"character":25}}}}],"paddingLeft":true,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":451,"character":10},"label":[{"value":": "},{"value":"ProfileSpan","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/profile/src/hprof.rs","range":{"start":{"line":85,"character":11},"end":{"line":85,"character":22}}}},{"value":""}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":451,"character":27},"label":[{"value":"label:","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/profile/src/hprof.rs","range":{"start":{"line":60,"character":12},"end":{"line":60,"character":17}}}}],"kind":2,"paddingLeft":false,"paddingRight":true,"data":{"file_id":0}},{"position":{"line":452,"character":12},"label":[{"value":": "},{"value":"Semantics","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/hir/src/semantics.rs","range":{"start":{"line":108,"character":11},"end":{"line":108,"character":20}}}},{"value":"<'_, "},{"value":"RootDatabase","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/ide-db/src/lib.rs","range":{"start":{"line":75,"character":11},"end":{"line":75,"character":23}}}},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":453,"character":12},"label":[{"value":": "},{"value":"SourceFile","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/ast/generated/nodes.rs","range":{"start":{"line":223,"character":11},"end":{"line":223,"character":21}}}},{"value":""}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":454,"character":12},"label":[{"value":": &"},{"value":"SyntaxNode","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rowan-0.15.11/src/api.rs","range":{"start":{"line":15,"character":11},"end":{"line":15,"character":21}}}},{"value":"<"},{"value":"RustLanguage","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/syntax_node.rs","range":{"start":{"line":15,"character":9},"end":{"line":15,"character":21}}}},{"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","location":{"uri":"file:///Users/someonetoignore/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/vec/mod.rs","range":{"start":{"line":395,"character":11},"end":{"line":395,"character":14}}}},{"value":"<"},{"value":"InlayHint","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/ide/src/inlay_hints.rs","range":{"start":{"line":149,"character":11},"end":{"line":149,"character":20}}}},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":460,"character":21},"label":[{"value":": "},{"value":"SemanticsScope","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/hir/src/semantics.rs","range":{"start":{"line":1651,"character":11},"end":{"line":1651,"character":25}}}},{"value":"<'_>"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":460,"character":36},"label":[{"value":"node:","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/hir/src/semantics.rs","range":{"start":{"line":482,"character":24},"end":{"line":482,"character":28}}}}],"kind":2,"paddingLeft":false,"paddingRight":true,"data":{"file_id":0}},{"position":{"line":461,"character":23},"label":[{"value":": "},{"value":"FamousDefs","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/ide-db/src/famous_defs.rs","range":{"start":{"line":20,"character":11},"end":{"line":20,"character":21}}}},{"value":"<'_, '_>"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":463,"character":17},"label":[{"value":": impl FnMut("},{"value":"SyntaxNode","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rowan-0.15.11/src/api.rs","range":{"start":{"line":15,"character":11},"end":{"line":15,"character":21}}}},{"value":"<"},{"value":"RustLanguage","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/syntax_node.rs","range":{"start":{"line":15,"character":9},"end":{"line":15,"character":21}}}},{"value":">)"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":463,"character":25},"label":[{"value":": "},{"value":"SyntaxNode","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rowan-0.15.11/src/api.rs","range":{"start":{"line":15,"character":11},"end":{"line":15,"character":21}}}},{"value":"<"},{"value":"RustLanguage","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/syntax_node.rs","range":{"start":{"line":15,"character":9},"end":{"line":15,"character":21}}}},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":463,"character":33},"label":[{"value":"hints:","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/ide/src/inlay_hints.rs","range":{"start":{"line":480,"character":4},"end":{"line":480,"character":9}}}}],"kind":2,"paddingLeft":false,"paddingRight":true,"data":{"file_id":0}},{"position":{"line":465,"character":22},"label":[{"value":": "},{"value":"TextRange","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/text-size-1.1.0/src/range.rs","range":{"start":{"line":14,"character":11},"end":{"line":14,"character":20}}}},{"value":""}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":467,"character":35},"label":[{"value":": "},{"value":"SyntaxNode","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rowan-0.15.11/src/api.rs","range":{"start":{"line":15,"character":11},"end":{"line":15,"character":21}}}},{"value":"<"},{"value":"RustLanguage","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/syntax_node.rs","range":{"start":{"line":15,"character":9},"end":{"line":15,"character":21}}}},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":469,"character":92},"label":[{"value":"impl "},{"value":"Iterator","location":{"uri":"file:///Users/someonetoignore/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/iter/traits/iterator.rs","range":{"start":{"line":72,"character":10},"end":{"line":72,"character":18}}}},{"value":"<"},{"value":"Item","location":{"uri":"file:///Users/someonetoignore/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/iter/traits/iterator.rs","range":{"start":{"line":76,"character":9},"end":{"line":76,"character":13}}}},{"value":" = "},{"value":"SyntaxNode","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rowan-0.15.11/src/api.rs","range":{"start":{"line":15,"character":11},"end":{"line":15,"character":21}}}},{"value":"<"},{"value":"RustLanguage","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/syntax_node.rs","range":{"start":{"line":15,"character":9},"end":{"line":15,"character":21}}}},{"value":">>"}],"kind":1,"paddingLeft":true,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":468,"character":34},"label":[{"value":"impl "},{"value":"Iterator","location":{"uri":"file:///Users/someonetoignore/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/iter/traits/iterator.rs","range":{"start":{"line":72,"character":10},"end":{"line":72,"character":18}}}},{"value":"<"},{"value":"Item","location":{"uri":"file:///Users/someonetoignore/.rustup/toolchains/stable-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/iter/traits/iterator.rs","range":{"start":{"line":76,"character":9},"end":{"line":76,"character":13}}}},{"value":" = "},{"value":"SyntaxNode","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rowan-0.15.11/src/api.rs","range":{"start":{"line":15,"character":11},"end":{"line":15,"character":21}}}},{"value":"<"},{"value":"RustLanguage","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/syntax_node.rs","range":{"start":{"line":15,"character":9},"end":{"line":15,"character":21}}}},{"value":">>"},{"value":""}],"kind":1,"paddingLeft":true,"paddingRight":false,"data":{"file_id":0}},{"position":{"line":467,"character":41},"label":[{"value":""},{"value":"SyntaxNode","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rowan-0.15.11/src/api.rs","range":{"start":{"line":15,"character":11},"end":{"line":15,"character":21}}}},{"value":"<"},{"value":"RustLanguage","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/syntax_node.rs","range":{"start":{"line":15,"character":9},"end":{"line":15,"character":21}}}},{"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","location":{"uri":"file:///Users/someonetoignore/.cargo/registry/src/index.crates.io-6f17d22bba15001f/rowan-0.15.11/src/api.rs","range":{"start":{"line":15,"character":11},"end":{"line":15,"character":21}}}},{"value":"<"},{"value":"RustLanguage","location":{"uri":"file:///Users/someonetoignore/work/rust-analyzer/crates/syntax/src/syntax_node.rs","range":{"start":{"line":15,"character":9},"end":{"line":15,"character":21}}}},{"value":">"}],"kind":1,"paddingLeft":false,"paddingRight":false,"data":{"file_id":0}}]}
```
</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.
On type format '(', by adding closing ')' automatically
If I understand right, `()` can surround pretty much the same `{}` can, so add another on type formatting pair for convenience: sometimes it's not that pleasant to write parenthesis in `Some(2).map(|i| (i, i+1))` cases and I would prefer r-a to do that for me.
One note: currently, b06503b6ec/crates/rust-analyzer/src/handlers/request.rs (L357) fires always.
Should we remove the assertion entirely now, since apparently things work in release despite that check?
Fix signature help of methods from macros
Currently the receiver type is copied from AST instead re-formatting through `HirDisplay`. Macro generated functions seem to have no spaces and their signature help are rendered like `fn foo(&'amutself)` instead of `fn foo(&'a mut self)`.
Support doc links that resolve to fields
Fixes#15331
Also removes `Resolver::resolve_module_path_in_trait_assoc_items()` and reimplements it in hir with other `Resolver` methods to decouple things a bit.
Handle `#[cfg]`s on generic parameters
Records attributes on generic parameters in the item tree and filters out generic parameters disabled by `#[cfg]`s in `generic_params_query`.
Closes#11756
SCIP requires symbols to be unique, but multiple functions may have a
parameter with the same name. Qualify parameters according to the
containing function.
Added remove unused imports assist
This resolves the most important part of #5131. I needed to make a couple of cosmetic changes to the search infrastructure to do this.
A few open questions:
* Should imports that don't resolve to anything be considered unused? I figured probably not, but it would be a trivial change to make if we want it.
* Is there a cleaner way to make the edits to the use list?
* Is there a cleaner way to get the list of uses that intersect the current selection?
* Is the performance acceptable? When testing this on itself, it takes a good couple seconds to perform the assist.
* Is there a way to hide the rustc diagnostics that overlap with this functionality?
internal: Defer structured snippet rendering to allow escaping snippet bits
Since we know exactly where snippets are, we can transparently escape snippet bits to the exact text edits that need it, and not have to do it for anything other text edits.
Also will eventually fix#11006 once all assists are migrated. This comes as a side-effect of text edits that don't have snippets get marked as having no insert formatting at all.
internal: Format let-else
As nightly finally got support for it I went ahead and formatted r-a with the latest nightly, then with the latest stable (in case other stuff changed)
Fix runnable detection for `#[tokio::test]`
fix#15141
It is hacky, and it wouldn't work for e.g. this case:
```Rust
use ::core::prelude;
#[prelude::v1::test]
fn foo() {
}
```
But it works for the tokio case. We should use the name resolution here somehow, and after that we should probably also get rid of the ast based `test_related_attribute` function.
internal: add `library` fixture meta
Currently, there is no way to specify `CrateOrigin` of a file fixture ([this] might be a bug?). This PR adds `library` meta to explicitly specify the fixture to be `CrateOrigin::Library` and also makes sure crates that belong to a library source root are set `CrateOrigin::Library`.
(`library` isn't really the best name. It essentially means that the crate is outside workspace but `non_workspace_member` feels a bit too long. Suggestions for the better name would be appreciated)
Additionally:
- documents the fixture meta syntax as thoroughly as possible
- refactors relevant code
[this]: 4b06d3c595/crates/base-db/src/fixture.rs (L450)
internal: Add run-tests command
This command is similar to `cargo test` except that it uses r-a to run tests instead of compiling and running them with rustc. This is slower than `cargo test` and it is only useful for me to see a bird view of what needs to be fixed. The current output is:
```
48 passed, 5028 failed, 2 ignored
All tests 174.74s, 648ginstr
```
48 is very low, but higher than what I originally thought.
Now that there is some passing tests, I can show the plan:
https://github.com/rust-lang/rust-analyzer/assets/45197576/76d7d777-1843-4ca4-b7fe-e463bdade6cb
That is, at the end, I want to be able to immediately re run every test after every change. (0.5s is not really immediate, but it's not finished yet, and it is way better than 8s that running a typical test in r-a will take on my system)
Added a test near positive extermes and two test near negative
extermes as well one for 0.
Added a test using the `as` cast and one with comparison with 0.
fix: Fix nav target calculation discarding file ids from differing macro upmapping
Fixes https://github.com/rust-lang/rust-analyzer/issues/14792
Turns out there was the assumption that upmapping from a macro will always end in the same root file, which is no longer the case thanks to `include!`
Add signature help for tuple patterns and expressions
~~These are somewhat wonky since their signature changes as you type depending on context but they help out nevertheless.~~ should be less wonky now with added parser and lowering recoveries
fix: Don't duplicate sysroot crates in rustc workspace
Since we handle `library` as the sysroot source directly in the rustc workspace, we now duplicate the crates there, once as sysroot and once as just plain workspace crate. This causes a variety of issues for `vec!` macros and similar that emit `$crate` tokens across crates.
Prioritize threads affected by user typing
To this end I’ve introduced a new custom thread pool type which can spawn threads using each QoS class. This way we can run latency-sensitive requests under one QoS class and everything else under another QoS class. The implementation is very similar to that of the `threadpool` crate (which is currently used by rust-analyzer) but with unused functionality stripped out.
I’ll have to rebase on master once #14859 is merged but I think everything else is alright :D
This code replaces the thread pool implementation we were using
previously (from the `threadpool` crate). By making the thread pool
aware of QoS, each job spawned on the thread pool can have a different
QoS class.
This commit also replaces every QoS class used previously with Default
as a temporary measure so that each usage can be chosen deliberately.
Specify thread types using Quality of Service API
<details>
<summary>Some background (in case you haven’t heard of QoS before)</summary>
Heterogenous multi-core CPUs are increasingly found in laptops and desktops (e.g. Alder Lake, Snapdragon 8cx Gen 3, M1). To maximize efficiency on this kind of hardware, it is important to provide the operating system with more information so threads can be scheduled on different core types appropriately.
The approach that XNU (the kernel of macOS, iOS, etc) and Windows have taken is to provide a high-level semantic API – quality of service, or QoS – which informs the OS of the program’s intent. For instance, you might specify that a thread is running a render loop for a game. This makes the OS provide this thread with as large a share of the system’s resources as possible. Specifying a thread is running an unimportant background task, on the other hand, is cause for it to be scheduled exclusively on high-efficiency cores instead of high-performance cores.
QoS APIs allows for easy configuration of many different parameters at once; for instance, setting QoS on XNU affects scheduling, timer latency, I/O priorities, and of course what core type the thread in question should run on. I don’t know any details on how QoS works on Windows, but I would guess it’s similar.
Hypothetically, taking advantage of these APIs would improve power consumption, thermals, battery life if applicable, etc.
</details>
# Relevance to rust-analyzer
From what I can tell the philosophy behind both the XNU and Windows QoS APIs is that _user interfaces should never stutter under any circumstances._ You can see this in the array of QoS classes which are available: the highest QoS class in both APIs is one intended explicitly for UI render loops.
Imagine rust-analyzer is performing CPU-intensive background work – maybe you just invoked Find Usages on `usize` or opened a large project – in this scenario the editor’s render loop should absolutely get higher priority than rust-analyzer, no matter what. You could view it in terms of “realtime-ness”: flight control software is hard realtime, audio software is soft realtime, GUIs are softer realtime, and rust-analyzer is not realtime at all. Of course, maximizing responsiveness is important, but respecting the rest of the system is more important.
# Implementation
I’ve tried my best to unify thread creation in `stdx`, where the new API I’ve introduced _requires_ specifying a QoS class. Different points along the performance/efficiency curve can make a great difference; the M1’s e-cores use around three times less power than the p-cores, so putting in this effort is worthwhile IMO.
It’s worth mentioning that Linux does not [yet](https://youtu.be/RfgPWpTwTQo) have a QoS API. Maybe translating QoS into regular thread priorities would be acceptable? From what I can tell the only scheduling-related code in rust-analyzer is Windows-specific, so ignoring QoS entirely on Linux shouldn’t cause any new issues. Also, I haven’t implemented support for the Windows QoS APIs because I don’t have a Windows machine to test on, and because I’m completely unfamiliar with Windows APIs :)
I noticed that rust-analyzer handles some requests on the main thread (using `.on_sync()`) and others on a threadpool (using `.on()`). I think it would make sense to run the main thread at the User Initiated QoS and the threadpool at Utility, but only if all requests that are caused by typing use `.on_sync()` and all that don’t use `.on()`. I don’t understand how the `.on_sync()`/`.on()` split that’s currently present was chosen, so I’ve let this code be for the moment. Let me know if changing this to what I proposed makes any sense.
To avoid having to change everything back in case I’ve misunderstood something, I’ve left all threads at the Utility QoS for now. Of course, this isn’t what I hope the code will look like in the end, but I figured I have to start somewhere :P
# References
<ul>
<li><a href="https://developer.apple.com/library/archive/documentation/Performance/Conceptual/power_efficiency_guidelines_osx/PrioritizeWorkAtTheTaskLevel.html">Apple documentation related to QoS</a></li>
<li><a href="67e155c940/include/pthread/qos.h">pthread API for setting QoS on XNU</a></li>
<li><a href="https://learn.microsoft.com/en-us/windows/win32/procthread/quality-of-service">Windows’s QoS classes</a></li>
<li>
<details>
<summary>Full documentation of XNU QoS classes. This documentation is only available as a huge not-very-readable comment in a header file, so I’ve reformatted it and put it here for reference.</summary>
<ul>
<li><p><strong><code>QOS_CLASS_USER_INTERACTIVE</code>: A QOS class which indicates work performed by this thread is interactive with the user.</strong></p><p>Such work is requested to run at high priority relative to other work on the system. Specifying this QOS class is a request to run with nearly all available system CPU and I/O bandwidth even under contention. This is not an energy-efficient QOS class to use for large tasks. The use of this QOS class should be limited to critical interaction with the user such as handling events on the main event loop, view drawing, animation, etc.</p></li>
<li><p><strong><code>QOS_CLASS_USER_INITIATED</code>: A QOS class which indicates work performed by this thread was initiated by the user and that the user is likely waiting for the results.</strong></p><p>Such work is requested to run at a priority below critical user-interactive work, but relatively higher than other work on the system. This is not an energy-efficient QOS class to use for large tasks. Its use should be limited to operations of short enough duration that the user is unlikely to switch tasks while waiting for the results. Typical user-initiated work will have progress indicated by the display of placeholder content or modal user interface.</p></li>
<li><p><strong><code>QOS_CLASS_DEFAULT</code>: A default QOS class used by the system in cases where more specific QOS class information is not available.</strong></p><p>Such work is requested to run at a priority below critical user-interactive and user-initiated work, but relatively higher than utility and background tasks. Threads created by <code>pthread_create()</code> without an attribute specifying a QOS class will default to <code>QOS_CLASS_DEFAULT</code>. This QOS class value is not intended to be used as a work classification, it should only be set when propagating or restoring QOS class values provided by the system.</p></li>
<li><p><strong><code>QOS_CLASS_UTILITY</code>: A QOS class which indicates work performed by this thread may or may not be initiated by the user and that the user is unlikely to be immediately waiting for the results.</strong></p><p>Such work is requested to run at a priority below critical user-interactive and user-initiated work, but relatively higher than low-level system maintenance tasks. The use of this QOS class indicates the work should be run in an energy and thermally-efficient manner. The progress of utility work may or may not be indicated to the user, but the effect of such work is user-visible.</p></li>
<li><p><strong><code>QOS_CLASS_BACKGROUND</code>: A QOS class which indicates work performed by this thread was not initiated by the user and that the user may be unaware of the results.</strong></p><p>Such work is requested to run at a priority below other work. The use of this QOS class indicates the work should be run in the most energy and thermally-efficient manner.</p></li>
<li><p><strong><code>QOS_CLASS_UNSPECIFIED</code>: A QOS class value which indicates the absence or removal of QOS class information.</strong></p><p>As an API return value, may indicate that threads or pthread attributes were configured with legacy API incompatible or in conflict with the QOS class system.</p></li>
</ul>
</details>
</li>
</ul>
Fix `preorder_expr` skipping the `else` block of let-else statements
Fixes exit/yield points not getting highlighted in such blocks for `highlight_related` (#14813; and possibly other bugs in features that use `preorder_expr`).
Fixes exit/yield points not getting highlighted in such blocks for `highlight_related` (#14813; and possibly other bugs in features that use `preorder_expr`).
MIR episode 5
This PR inits drop support (it is very broken at this stage, some things are dropped multiple time, drop scopes are wrong, ...) and adds stdout support (`println!` doesn't work since its expansion is dummy, but `stdout().write(b"hello world\n")` works if you use `RA_SYSROOT_HACK`) for interpreting. There is no useful unit test that it can interpret yet, but it is a good sign that it didn't hit a major road block yet.
In MIR lowering, it adds support for slice pattern and anonymous const blocks, and some fixes so that we can evaluate `SmolStr::new_inline` in const eval. With these changes, 57 failed mir body remains.
