Use memmem when searching for usages in ide-db
We already have this dependency, so there is no reason not to use it as it is generally faster than std in our use case.
Further simplify the macros generated by `rustc_queries`
This doesn't actually move anything outside the macros, but it makes them simpler to read.
- Add a new `rustc_query_names` macro. This allows a much simpler syntax for the matchers in the macros passed to it as a callback.
- Convert `define_dep_nodes` and `alloc_once` to use `rustc_query_names`. This is possible because they only use the names
(despite the quite complicated matchers in `define_dep_nodes`, none of the other arguments are used).
- Get rid of `rustc_dep_node_append`.
r? `@cjgillot`
Refactor macro-by-example code
I had a look at the MBE code because of #7857. I found some easy readability wins, that might also _marginally_ improve perf.
Initial implementation of dyn*
This PR adds extremely basic and incomplete support for [dyn*](https://smallcultfollowing.com/babysteps//blog/2022/03/29/dyn-can-we-make-dyn-sized/). The goal is to get something in tree behind a flag to make collaboration easier, and also to make sure the implementation so far is not unreasonable. This PR does quite a few things:
* Introduce `dyn_star` feature flag
* Adds parsing for `dyn* Trait` types
* Defines `dyn* Trait` as a sized type
* Adds support for explicit casts, like `42usize as dyn* Debug`
* Including const evaluation of such casts
* Adds codegen for drop glue so things are cleaned up properly when a `dyn* Trait` object goes out of scope
* Adds codegen for method calls, at least for methods that take `&self`
Quite a bit is still missing, but this gives us a starting point. Note that this is never intended to become stable surface syntax for Rust, but rather `dyn*` is planned to be used as an implementation detail for async functions in dyn traits.
Joint work with `@nikomatsakis` and `@compiler-errors.`
r? `@bjorn3`
Simplify caching and storage for queries
I highly recommend reviewing commit-by-commit; each individual commit is quite small but it can be hard to see looking at the overall diff that the behavior is the same. Each commit depends on the previous.
r? `@cjgillot`
Update cargo
10 commits in 646e9a0b9ea8354cc409d05f10e8dc752c5de78e..082503982ea0fb7a8fd72210427d43a2e2128a63 2022-09-02 14:29:28 +0000 to 2022-09-13 17:49:38 +0000
- Take priority into account within the pending queue (rust-lang/cargo#11032)
- fix(add): Clarify which version the features are added for (rust-lang/cargo#11075)
- doc: clarify config-relative paths for `--config <path>` (rust-lang/cargo#11079)
- Do not add home bin path to PATH if it's already there (rust-lang/cargo#11023)
- Don't use `for` loop on an `Option` (rust-lang/cargo#11081)
- Remove dead code (rust-lang/cargo#11080)
- Change progress indicator for sparse registries (rust-lang/cargo#11068)
- chore(ci): Ensure intradoc links are valid (rust-lang/cargo#11055)
- Cache index files based on contents hash (rust-lang/cargo#11044)
- fix: specifies the max length for crate name (rust-lang/cargo#11051)
Rustdoc-Json: Don't loose subitems of foreign traits.
Previously, we'd clone the index, and extend it with foreign traits. But when doing this, traits would render their subitems without them going into the index being used in the output leading to dangling ID's.
r? `@GuillaumeGomez`
Allow configuration of annotation location.
I've added the ability to configure where lens annotations render relevant to the item they describe. Previously, these would render directly above the line the item is declared on. Now, there is the ability to render these annotations above the entire item (including doc comments, and attributes).
The names of the config options are up for debate, I did what seemed best to me but if anyone has better ideas let me know.
This is my first contribution so if I've missed anything please let me know.
Here's a preview of what the new option looks like:
<img width="577" alt="Screen Shot 2022-09-11 at 10 39 51 PM" src="https://user-images.githubusercontent.com/33100798/189570298-b4fcbf9c-ee49-4b79-aae6-1037ae4f26af.png">
closes https://github.com/rust-lang/rust-analyzer/issues/13218
fixup: remove unnecessary `Option`
Fixup for #13223, two things:
- `normalize_projection_query()` (and consequently `HirDatabase::normalize_projection()`) never returns `None` (well, it used to when I first wrote it...), so just return `Ty` instead of `Option<Ty>`
- When chalk cannot normalize projection uniquely, `normalize_trait_assoc_type()` used to return `None` before #13223, but not anymore because of the first point. I restored the behavior so its callers work as before.
Restructure `find_path` into a separate functions for modules and non-module items
Follow up to https://github.com/rust-lang/rust-analyzer/pull/13212
Also renames `prefer_core` imports config to `prefer_no_std` and changes the behavior of no_std path searching by preferring `core` paths `over` alloc
This PR turned into a slight rewrite, so it unfortunately does a few more things that I initially planned to (including a bug fix for enum variant paths)
Stabilize generic associated types
Closes#44265
r? `@nikomatsakis`
# ⚡ Status of the discussion ⚡
* [x] There have been several serious concerns raised, [summarized here](https://github.com/rust-lang/rust/pull/96709#issuecomment-1129311660).
* [x] There has also been a [deep-dive comment](https://github.com/rust-lang/rust/pull/96709#issuecomment-1167220240) explaining some of the "patterns of code" that are enabled by GATs, based on use-cases posted to this thread or on the tracking issue.
* [x] We have modeled some aspects of GATs in [a-mir-formality](https://github.com/nikomatsakis/a-mir-formality) to give better confidence in how they will be resolved in the future. [You can read a write-up here](https://github.com/rust-lang/types-team/blob/master/minutes/2022-07-08-implied-bounds-and-wf-checking.md).
* [x] The major points of the discussion have been [summarized on the GAT initiative repository](https://rust-lang.github.io/generic-associated-types-initiative/mvp.html).
* [x] [FCP has been proposed](https://github.com/rust-lang/rust/pull/96709#issuecomment-1129311660) and we are awaiting final decisions and discussion amidst the relevant team members.
# Stabilization proposal
This PR proposes the stabilization of `#![feature(generic_associated_types)]`. While there a number of future additions to be made and bugs to be fixed (both discussed below), properly doing these will require significant language design and will ultimately likely be backwards-compatible. Given the overwhelming desire to have some form of generic associated types (GATs) available on stable and the stability of the "simple" uses, stabilizing the current subset of GAT features is almost certainly the correct next step.
Tracking issue: #44265
Initiative: https://rust-lang.github.io/generic-associated-types-initiative/
RFC: https://github.com/rust-lang/rfcs/blob/master/text/1598-generic_associated_types.md
Version: 1.65 (2022-08-22 => beta, 2022-11-03 => stable).
## Motivation
There are a myriad of potential use cases for GATs. Stabilization unblocks probable future language features (e.g. async functions in traits), potential future standard library features (e.g. a `LendingIterator` or some form of `Iterator` with a lifetime generic), and a plethora of user use cases (some of which can be seen just by scrolling through the tracking issue and looking at all the issues linking to it).
There are a myriad of potential use cases for GATs. First, there are many users that have chosen to not use GATs primarily because they are not stable (some of which can be seen just by scrolling through the tracking issue and looking at all the issues linking to it). Second, while language feature desugaring isn't *blocked* on stabilization, it gives more confidence on using the feature. Likewise, library features like `LendingIterator` are not necessarily blocked on stabilization to be implemented unstably; however few, if any, public-facing APIs actually use unstable features.
This feature has a long history of design, discussion, and developement - the RFC was first introduced roughly 6 years ago. While there are still a number of features left to implement and bugs left to fix, it's clear that it's unlikely those will have backwards-incompatibility concerns. Additionally, the bugs that do exist do not strongly impede the most-common use cases.
## What is stabilized
The primary language feature stabilized here is the ability to have generics on associated types, as so. Additionally, where clauses on associated types will now be accepted, regardless if the associated type is generic or not.
```rust
trait ATraitWithGATs {
type Assoc<'a, T> where T: 'a;
}
trait ATraitWithoutGATs<'a, T> {
type Assoc where T: 'a;
}
```
When adding an impl for a trait with generic associated types, the generics for the associated type are copied as well. Note that where clauses are allowed both after the specified type and before the equals sign; however, the latter is a warn-by-default deprecation.
```rust
struct X;
struct Y;
impl ATraitWithGATs for X {
type Assoc<'a, T> = &'a T
where T: 'a;
}
impl ATraitWithGATs for Y {
type Assoc<'a, T>
where T: 'a
= &'a T;
}
```
To use a GAT in a function, generics are specified on the associated type, as if it was a struct or enum. GATs can also be specified in trait bounds:
```rust
fn accepts_gat<'a, T>(t: &'a T) -> T::Assoc<'a, T>
where for<'x> T: ATraitWithGATs<Assoc<'a, T> = &'a T> {
...
}
```
GATs can also appear in trait methods. However, depending on how they are used, they may confer where clauses on the associated type definition. More information can be found [here](https://github.com/rust-lang/rust/issues/87479). Briefly, where clauses are required when those bounds can be proven in the methods that *construct* the GAT or other associated types that use the GAT in the trait. This allows impls to have maximum flexibility in the types defined for the associated type.
To take a relatively simple example:
```rust
trait Iterable {
type Item<'a>;
type Iterator<'a>: Iterator<Item = Self::Item<'a>>;
fn iter<'x>(&'x self) -> Self::Iterator<'x>;
//^ We know that `Self: 'a` for `Iterator<'a>`, so we require that bound on `Iterator`
// `Iterator` uses `Self::Item`, so we also require a `Self: 'a` on `Item` too
}
```
A couple well-explained examples are available in a previous [blog post](https://blog.rust-lang.org/2021/08/03/GATs-stabilization-push.html).
## What isn't stabilized/implemented
### Universal type/const quantification
Currently, you can write a bound like `X: for<'a> Trait<Assoc<'a> = &'a ()>`. However, you cannot currently write `for<T> X: Trait<Assoc<T> = T>` or `for<const N> X: Trait<Assoc<N> = [usize; N]>`.
Here is an example where this is needed:
```rust
trait Foo {}
trait Trait {
type Assoc<F: Foo>;
}
trait Trait2: Sized {
fn foo<F: Foo, T: Trait<Assoc<F> = F>>(_t: T);
}
```
In the above example, the *caller* must specify `F`, which is likely not what is desired.
### Object-safe GATs
Unlike non-generic associated types, traits with GATs are not currently object-safe. In other words the following are not allowed:
```rust
trait Trait {
type Assoc<'a>;
}
fn foo(t: &dyn for<'a> Trait<Assoc<'a> = &'a ()>) {}
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not allowed
let ty: Box<dyn for<'a> Trait<Assoc<'a> = &'a ()>>;
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not allowed
```
### Higher-kinded types
You cannot write currently (and there are no current plans to implement this):
```rust
struct Struct<'a> {}
fn foo(s: for<'a> Struct<'a>) {}
```
## Tests
There are many tests covering GATs that can be found in `src/test/ui/generic-associated-types`. Here, I'll list (in alphanumeric order) tests highlight some important behavior or contain important patterns.
- `./parse/*`: Parsing of GATs in traits and impls, and the trait path with GATs
- `./collections-project-default.rs`: Interaction with associated type defaults
- `./collections.rs`: The `Collection` pattern
- `./const-generics-gat-in-trait-return-type-*.rs`: Const parameters
- `./constraint-assoc-type-suggestion.rs`: Emit correct syntax in suggestion
- `./cross-crate-bounds.rs`: Ensure we handles bounds across crates the same
- `./elided-in-expr-position.rs`: Disallow lifetime elision in return position
- `./gat-in-trait-path-undeclared-lifetime.rs`: Ensure we error on undeclared lifetime in trait path
- `./gat-in-trait-path.rs`: Base trait path case
- `./gat-trait-path-generic-type-arg.rs`: Don't allow shadowing of parameters
- `./gat-trait-path-parenthesised-args.rs`: Don't allow paranthesized args in trait path
- `./generic-associated-types-where.rs`: Ensure that we require where clauses from trait to be met on impl
- `./impl_bounds.rs`: Check that the bounds on GATs in an impl are checked
- `./issue-76826.rs`: `Windows` pattern
- `./issue-78113-lifetime-mismatch-dyn-trait-box.rs`: Implicit 'static diagnostics
- `./issue-84931.rs`: Ensure that we have a where clause on GAT to ensure trait parameter lives long enough
- `./issue-87258_a.rs`: Unconstrained opaque type with TAITs
- `./issue-87429-2.rs`: Ensure we can use bound vars in the bounds
- `./issue-87429-associated-type-default.rs`: Ensure bounds hold with associated type defaults, for both trait and impl
- `./issue-87429-specialization.rs`: Check that bounds hold under specialization
- `./issue-88595.rs`: Under the outlives lint, we require a bound for both trait and GAT lifetime when trait lifetime is used in function
- `./issue-90014.rs`: Lifetime bounds are checked with TAITs
- `./issue-91139.rs`: Under migrate mode, but not NLL, we don't capture implied bounds from HRTB lifetimes used in a function and GATs
- `./issue-91762.rs`: We used to too eagerly pick param env candidates when normalizing with GATs. We now require explicit parameters specified.
- `./issue-95305.rs`: Disallow lifetime elision in trait paths
- `./iterable.rs`: `Iterable` pattern
- `./method-unsatified-assoc-type-predicate.rs`: Print predicates with GATs correctly in method resolve error
- `./missing_lifetime_const.rs`: Ensure we must specify lifetime args (not elidable)
- `./missing-where-clause-on-trait.rs`: Ensure we don't allow stricter bounds on impl than trait
- `./parameter_number_and_kind_impl.rs`: Ensure paramters on GAT in impl match GAT in trait
- `./pointer_family.rs`: `PointerFamily` pattern
- `./projection-bound-cycle.rs`: Don't allow invalid cycles to prove bounds
- `./self-outlives-lint.rs`: Ensures that an e.g. `Self: 'a` is written on the traits GAT if that bound can be implied from the GAT usage in the trait
- `./shadowing.rs`: Don't allow lifetime shadowing in params
- `./streaming_iterator.rs`: `StreamingIterator`(`LendingIterator`) pattern
- `./trait-objects.rs`: Disallow trait objects for traits with GATs
- `./variance_constraints.rs`: Require that GAT substs be invariant
## Remaining bugs and open issues
A full list of remaining open issues can be found at: https://github.com/rust-lang/rust/labels/F-generic_associated_types
There are some `known-bug` tests in-tree at `src/test/ui/generic-associated-types/bugs`.
Here I'll categorize most of those that GAT bugs (or involve a pattern found more with GATs), but not those that include GATs but not a GAT issue in and of itself. (I also won't include issues directly for things listed elsewhere here.)
Using the concrete type of a GAT instead of the projection type can give errors, since lifetimes are chosen to be early-bound vs late-bound.
- #85533
- #87803
In certain cases, we can run into cycle or overflow errors. This is more generally a problem with associated types.
- #87755
- #87758
Bounds on an associatd type need to be proven by an impl, but where clauses need to be proven by the usage. This can lead to confusion when users write one when they mean the other.
- #87831
- #90573
We sometimes can't normalize closure signatures fully. Really an asociated types issue, but might happen a bit more frequently with GATs, since more obvious place for HRTB lifetimes.
- #88382
When calling a function, we assign types to parameters "too late", after we already try (and fail) to normalize projections. Another associated types issue that might pop up more with GATs.
- #88460
- #96230
We don't fully have implied bounds for lifetimes appearing in GAT trait paths, which can lead to unconstrained type errors.
- #88526
Suggestion for adding lifetime bounds can suggest unhelpful fixes (`T: 'a` instead of `Self: 'a`), but the next compiler error after making the suggested change is helpful.
- #90816
- #92096
- #95268
We can end up requiring that `for<'a> I: 'a` when we really want `for<'a where I: 'a> I: 'a`. This can leave unhelpful errors than effectively can't be satisfied unless `I: 'static`. Requires bigger changes and not only GATs.
- #91693
Unlike with non-generic associated types, we don't eagerly normalize with param env candidates. This is intended behavior (for now), to avoid accidentaly stabilizing picking arbitrary impls.
- #91762
Some Iterator adapter patterns (namely `filter`) require Polonius or unsafe to work.
- #92985
## Potential Future work
### Universal type/const quantification
No work has been done to implement this. There are also some questions around implied bounds.
### Object-safe GATs
The intention is to make traits with GATs object-safe. There are some design work to be done around well-formedness rules and general implementation.
### GATified std lib types
It would be helpful to either introduce new std lib traits (like `LendingIterator`) or to modify existing ones (adding a `'a` generic to `Iterator::Item`). There also a number of other candidates, like `Index`/`IndexMut` and `Fn`/`FnMut`/`FnOnce`.
### Reduce the need for `for<'a>`
Seen [here](https://github.com/rust-lang/rfcs/pull/1598#issuecomment-2611378730). One possible syntax:
```rust
trait Iterable {
type Iter<'a>: Iterator<Item = Self::Item<'a>>;
}
fn foo<T>() where T: Iterable, T::Item<let 'a>: Display { } //note the `let`!
```
### Better implied bounds on higher-ranked things
Currently if we have a `type Item<'a> where self: 'a`, and a `for<'a> T: Iterator<Item<'a> = &'a ()`, this requires `for<'a> Self: 'a`. Really, we want `for<'a where T: 'a> ...`
There was some mentions of this all the back in the RFC thread [here](https://github.com/rust-lang/rfcs/pull/1598#issuecomment-264340514).
## Alternatives
### Make generics on associated type in bounds a binder
Imagine the bound `for<'a> T: Trait<Item<'a>= &'a ()>`. It might be that `for<'a>` is "too large" and it should instead be `T: Trait<for<'a> Item<'a>= &'a ()>`. Brought up in RFC thread [here](https://github.com/rust-lang/rfcs/pull/1598#issuecomment-229443863) and in a few places since.
Another related question: Is `for<'a>` the right syntax? Maybe `where<'a>`? Also originally found in RFC thread [here](https://github.com/rust-lang/rfcs/pull/1598#issuecomment-261639969).
### Stabilize lifetime GATs first
This has been brought up a few times. The idea is to only allow GATs with lifetime parameters to in initial stabilization. This was probably most useful prior to actual implementation. At this point, lifetimes, types, and consts are all implemented and work. It feels like an arbitrary split without strong reason.
## History
* On 2016-04-30, [RFC opened](https://github.com/rust-lang/rfcs/pull/1598)
* On 2017-09-02, RFC merged and [tracking issue opened](https://github.com/rust-lang/rust/issues/44265)
* On 2017-10-23, [Move Generics from MethodSig to TraitItem and ImplItem](https://github.com/rust-lang/rust/pull/44766)
* On 2017-12-01, [Generic Associated Types Parsing & Name Resolution](https://github.com/rust-lang/rust/pull/45904)
* On 2017-12-15, [https://github.com/rust-lang/rust/pull/46706](https://github.com/rust-lang/rust/pull/46706)
* On 2018-04-23, [Feature gate where clauses on associated types](https://github.com/rust-lang/rust/pull/49368)
* On 2018-05-10, [Extend tests for RFC1598 (GAT)](https://github.com/rust-lang/rust/pull/49423)
* On 2018-05-24, [Finish implementing GATs (Chalk)](https://github.com/rust-lang/chalk/pull/134)
* On 2019-12-21, [Make GATs less ICE-prone](https://github.com/rust-lang/rust/pull/67160)
* On 2020-02-13, [fix lifetime shadowing check in GATs](https://github.com/rust-lang/rust/pull/68938)
* On 2020-06-20, [Projection bound validation](https://github.com/rust-lang/rust/pull/72788)
* On 2020-10-06, [Separate projection bounds and predicates](https://github.com/rust-lang/rust/pull/73905)
* On 2021-02-05, [Generic associated types in trait paths](https://github.com/rust-lang/rust/pull/79554)
* On 2021-02-06, [Trait objects do not work with generic associated types](https://github.com/rust-lang/rust/issues/81823)
* On 2021-04-28, [Make traits with GATs not object safe](https://github.com/rust-lang/rust/pull/84622)
* On 2021-05-11, [Improve diagnostics for GATs](https://github.com/rust-lang/rust/pull/82272)
* On 2021-07-16, [Make GATs no longer an incomplete feature](https://github.com/rust-lang/rust/pull/84623)
* On 2021-07-16, [Replace associated item bound vars with placeholders when projecting](https://github.com/rust-lang/rust/pull/86993)
* On 2021-07-26, [GATs: Decide whether to have defaults for `where Self: 'a`](https://github.com/rust-lang/rust/issues/87479)
* On 2021-08-25, [Normalize projections under binders](https://github.com/rust-lang/rust/pull/85499)
* On 2021-08-03, [The push for GATs stabilization](https://blog.rust-lang.org/2021/08/03/GATs-stabilization-push.html)
* On 2021-08-12, [Detect stricter constraints on gats where clauses in impls vs trait](https://github.com/rust-lang/rust/pull/88336)
* On 2021-09-20, [Proposal: Change syntax of where clauses on type aliases](https://github.com/rust-lang/rust/issues/89122)
* On 2021-11-06, [Implementation of GATs outlives lint](https://github.com/rust-lang/rust/pull/89970)
* On 2021-12-29. [Parse and suggest moving where clauses after equals for type aliases](https://github.com/rust-lang/rust/pull/92118)
* On 2022-01-15, [Ignore static lifetimes for GATs outlives lint](https://github.com/rust-lang/rust/pull/92865)
* On 2022-02-08, [Don't constrain projection predicates with inference vars in GAT substs](https://github.com/rust-lang/rust/pull/92917)
* On 2022-02-15, [Rework GAT where clause check](https://github.com/rust-lang/rust/pull/93820)
* On 2022-02-19, [Only mark projection as ambiguous if GAT substs are constrained](https://github.com/rust-lang/rust/pull/93892)
* On 2022-03-03, [Support GATs in Rustdoc](https://github.com/rust-lang/rust/pull/94009)
* On 2022-03-06, [Change location of where clause on GATs](https://github.com/rust-lang/rust/pull/90076)
* On 2022-05-04, [A shiny future with GATs blog post](https://jackh726.github.io/rust/2022/05/04/a-shiny-future-with-gats.html)
* On 2022-05-04, [Stabilization PR](https://github.com/rust-lang/rust/pull/96709)
New assist: move_format_string_arg
The name might need some improving.
```rust
fn main() {
print!("{x + 1}");
}
```
to
```rust
fn main() {
print!("{}"$0, x + 1);
}
```
fixes#13180
ref to #5988 for similar work
* extracted `format_like`'s parser to it's own module in `ide-db`
* reworked the parser's API to be more direct
* added assist to extract expressions in format args
fix: handle lifetime variables in projection normalization
Fixes#12674
The problem is that we've been skipping the binders of normalized projections assuming they should be empty, but the assumption is unfortunately wrong. We may get back lifetime variables and should handle them before returning them as normalized projections. For those who are curious why we get those even though we treat all lifetimes as 'static, [this comment in chalk](d875af0ff1/chalk-solve/src/infer/unify.rs (L888-L908)) may be interesting.
I thought using `InferenceTable` would be cleaner than the other ways as it already has the methods for canonicalization, normalizing projection, and resolving variables, so moved goal building and trait solving logic to a new `HirDatabase` query. I made it transparent query as the query itself doesn't do much work but the eventual call to `HirDatabase::trait_solve_query()` does.
Remove the toggleInlayHints command from VSCode
Inlay hints are no longer something specifc to r-a as it has been upstreamed into the LSP, we don't have a reason to give the config for this feature special treatment in regards to toggling. There are plenty of other options out there in the VSCode marketplace to create toggle commands/hotkeys for configurations in general which I believe we should nudge people towards instead.
fix: handle trait methods as inherent methods for trait-related types
Fixes#10677
When resolving methods for trait object types and placeholder types that are bounded by traits, we need to count the methods of the trait and its super traits as inherent methods. This matters because these trait methods have higher priority than the other traits' methods.
Relevant code in rustc: [`assemble_inherent_candidates_from_object()`](0631ea5d73/compiler/rustc_typeck/src/check/method/probe.rs (L783-L792)) for trait object types, [`assemble_inherent_candidates_from_param()`](0631ea5d73/compiler/rustc_typeck/src/check/method/probe.rs (L838-L847)) for placeholder types. Notice the second arg of `push_candidate()` is `is_inherent`.
Remove redundant 'resolve_obligations_as_possible' call
Hi! I was looking for a "good first issue" and saw this one: https://github.com/rust-lang/rust-analyzer/issues/7542. I like searching for performance improvements, so I wanted to try to find something useful there.
There are two tests in integrated_benchmarks.rs, I looked at 'integrated_highlighting_benchmark' (not the one discussed in the issue above).
Profile from that test looks like this:
```
$ RUN_SLOW_BENCHES=1 cargo test --release --package rust-analyzer --lib -- integrated_benchmarks::integrated_highlighting_benchmark --exact --nocapture
Finished release [optimized] target(s) in 0.06s
Running unittests src/lib.rs (target/release/deps/rust_analyzer-a80ca6bb8f877458)
running 1 test
workspace loading: 358.45ms
initial: 9.60s
change: 13.96µs
cpu profiling is disabled, uncomment `default = [ "cpu_profiler" ]` in Cargo.toml to enable.
273ms - highlight
143ms - infer:wait @ per_query_memory_usage
143ms - infer_query
0 - crate_def_map:wait (3165 calls)
4ms - deref_by_trait (967 calls)
96ms - resolve_obligations_as_possible (22106 calls)
0 - trait_solve::wait (2068 calls)
21ms - Semantics::analyze_impl (18 calls)
0 - SourceBinder::to_module_def (20 calls)
36ms - classify_name (19 calls)
19ms - classify_name_ref (308 calls)
0 - crate_def_map:wait (461 calls)
4ms - descend_into_macros (628 calls)
0 - generic_params_query (4 calls)
0 - impl_data_with_diagnostics_query (1 calls)
45ms - infer:wait (37 calls)
0 - resolve_obligations_as_possible (2 calls)
0 - source_file_to_def (1 calls)
0 - trait_solve::wait (42 calls)
after change: 275.23ms
test integrated_benchmarks::integrated_highlighting_benchmark ... ok
```
22106 calls to `resolve_obligations_as_possible` seem like the main issue there.
One thing I noticed (and fixed in this PR) is that `InferenceContext::resolve_ty_shallow` first calls `resolve_obligations_as_possible`, and then calls `InferenceTable::resolve_ty_shallow`. But `InferenceTable::resolve_ty_shallow` [inside](2e9f1204ca/crates/hir-ty/src/infer/unify.rs (L372)) again calls `resolve_obligations_as_possible`.
`resolve_obligations_as_possible` inside has a while loop, which works until it can't find any helpful information. So calling this function for the second time does nothing, so one of the calls could be safely removed.
`InferenceContext::resolve_ty_shallow` is actually quite a hot place, and after fixing it, the total number of `resolve_obligations_as_possible` in this test is reduced to 15516 (from 22106). "After change" time also improves from ~270ms to ~240ms, which is not a very huge win, but still something measurable.
Same profile after PR:
```
$ RUN_SLOW_BENCHES=1 cargo test --release --package rust-analyzer --lib -- integrated_benchmarks::integrated_highlighting_benchmark --exact --nocapture
Finished release [optimized] target(s) in 0.06s
Running unittests src/lib.rs (target/release/deps/rust_analyzer-a80ca6bb8f877458)
running 1 test
workspace loading: 339.86ms
initial: 9.28s
change: 10.69µs
cpu profiling is disabled, uncomment `default = [ "cpu_profiler" ]` in Cargo.toml to enable.
236ms - highlight
110ms - infer:wait @ per_query_memory_usage
110ms - infer_query
0 - crate_def_map:wait (3165 calls)
4ms - deref_by_trait (967 calls)
64ms - resolve_obligations_as_possible (15516 calls)
0 - trait_solve::wait (2068 calls)
21ms - Semantics::analyze_impl (18 calls)
0 - SourceBinder::to_module_def (20 calls)
34ms - classify_name (19 calls)
18ms - classify_name_ref (308 calls)
0 - crate_def_map:wait (461 calls)
3ms - descend_into_macros (628 calls)
0 - generic_params_query (4 calls)
0 - impl_data_with_diagnostics_query (1 calls)
45ms - infer:wait (37 calls)
0 - resolve_obligations_as_possible (2 calls)
0 - source_file_to_def (1 calls)
0 - trait_solve::wait (42 calls)
after change: 238.15ms
test integrated_benchmarks::integrated_highlighting_benchmark ... ok
```
The performance of this test could be further improved but at the cost of making code more complicated, so I wanted to check if such a change is desirable before sending another PR.
`resolve_obligations_as_possible` is actually called a lot of times even when no new information was provided. As I understand, `resolve_obligations_as_possible` could do something useful only if some variables/values were unified since the last check. We can store a boolean variable inside `InferenceTable`, which indicates if `try_unify` was called after last `resolve_obligations_as_possible`. If it wasn't called, we can safely not call `resolve_obligations_as_possible` again.
I tested this change locally, and it reduces the number of `resolve_obligations_as_possible` to several thousand (it is not shown in the profile anymore, so don't know the exact number), and the total time is reduced to ~180ms. Here is a generated profile:
```
$ RUN_SLOW_BENCHES=1 cargo test --release --package rust-analyzer --lib -- integrated_benchmarks::integrated_highlighting_benchmark --exact --nocapture
Finished release [optimized] target(s) in 0.06s
Running unittests src/lib.rs (target/release/deps/rust_analyzer-a80ca6bb8f877458)
running 1 test
workspace loading: 349.92ms
initial: 8.56s
change: 11.32µs
cpu profiling is disabled, uncomment `default = [ "cpu_profiler" ]` in Cargo.toml to enable.
175ms - highlight
21ms - Semantics::analyze_impl (18 calls)
0 - SourceBinder::to_module_def (20 calls)
33ms - classify_name (19 calls)
17ms - classify_name_ref (308 calls)
0 - crate_def_map:wait (461 calls)
3ms - descend_into_macros (628 calls)
0 - generic_params_query (4 calls)
0 - impl_data_with_diagnostics_query (1 calls)
97ms - infer:wait (38 calls)
0 - resolve_obligations_as_possible (2 calls)
0 - source_file_to_def (1 calls)
0 - trait_solve::wait (42 calls)
after change: 177.04ms
test integrated_benchmarks::integrated_highlighting_benchmark ... ok
```
Let me know if adding a new bool field seems like a reasonable tradeoff, so I can send a PR.
Previously, annotations would only appear above the name of an item (function signature, struct declaration, etc).
Now, rust-analyzer can be configured to show annotations either above the name or above the whole item (including doc comments and attributes).
