Add more methods for resolving definitions from AST to their corresponding HIR types
In order to be able to add these methods with consistent naming I had to also rename two existing methods that would otherwise be conflicting/confusing:
`Semantics::to_module_def(&self, file: FileId) -> Option<Module>` (before)
`Semantics::file_to_module_def(&self, file: FileId) -> Option<Module>` (after)
`Semantics::to_module_defs(&self, file: FileId) -> impl Iterator<Item = Module>` (before)
`Semantics::file_to_module_defs(&self, file: FileId) -> impl Iterator<Item = Module>` (after)
(the PR is motivated by an outside use of the `ra_ap_hir` crate that would benefit from being able to walk a `hir::Function`'s AST, resolving its exprs/stmts/items to their HIR equivalents)
Export `SemanticsImpl` from `ra_ap_hir` crate, since it's already exposed via `Semantics.deref()`
The `SemanticsImpl` type is already de-facto exposed via `<Semantics as Deref>::Target`.
By not being part of the public crate interface it however doesn't get included in the documentation, resulting in a massive blind spot when it comes to `ra_ap_hir`'s type resolution APIs.
Add public function for resolving callable AST exprs to their HIR equivalents
(the PR is motivated by an outside use of the `ra_ap_hir` crate that would benefit from being able to walk a `hir::Function`'s AST, resolving callable exprs within to their HIR equivalents)
Derive `PartialEq`, `Eq` & `Hash` for `hir::Param`
Since `hir::SelfParam`, as well as all members of `hir::Param` already implement `PartialEq`, `Eq` & `Hash` it seems reasonable to also make `hir::Param` implement those.
(the change is motivated by an outside use of the `ra_ap_hir` crate that would benefit from being able to collect params in a `HashSet`)
feat: Add "make tuple" tactic to term search
Follow up to https://github.com/rust-lang/rust-analyzer/pull/16092
Now term search also supports tuples.
```rust
let a: i32 = 1;
let b: f64 = 0.0;
let c: (i32, (f64, i32)) = todo!(); // Finds (a, (b, a))
```
In addition to new tactic that handles tuples I changed how the generics are handled.
Previously it tried all possible options from types we had in scope but now it only tries useful ones that help us directly towards the goal or at least towards calling some other function.
This changes O(2^n) to O(n^2) where n is amount of rounds which in practice allows using types that take generics for multiple rounds (previously limited to 1). Average case that also used to be exponential is now roughly linear.
This means that deeply nested generics also work.
````rust
// Finds all valid combos, including `Some(Some(Some(...)))`
let a: Option<Option<Option<bool>>> = todo!();
````
_Note that although the complexity is smaller allowing more types with generics the search overall slows down considerably. I hope it's fine tho as the autocomplete is disabled by default and for code actions it's not super slow. Might have to tweak the depth hyper parameter tho_
This resulted in a huge increase of results found (benchmarks on `ripgrep` crate):
Before
````
Tail Expr syntactic hits: 149/1692 (8%)
Tail Exprs found: 749/1692 (44%)
Term search avg time: 18ms
```
After
```
Tail Expr syntactic hits: 291/1692 (17%)
Tail Exprs found: 1253/1692 (74%)
Term search avg time: 139ms
````
Most changes are local to term search except some tuple related stuff on `hir::Type`.
performance: Speed up Method Completions By Taking Advantage of Orphan Rules
(Continues https://github.com/rust-lang/rust-analyzer/pull/16498)
This PR speeds up method completions by doing two things without regressing `analysis-stats`[^1]:
- Filter candidate traits prior to calling `iterate_path_candidates` by relying on orphan rules (see below for a slightly more in-depth explanation). When generating completions [on `slog::Logger`](5e9e59c312/common/src/ledger.rs (L78)) in `oxidecomputer/omicron` as a test, this PR halved my completion times—it's now 454ms cold and 281ms warm. Before this PR, it was 808ms cold and 579ms warm.
- Inline some of the method candidate checks into `is_valid_method_candidate` and remove some unnecessary visibility checks. This was suggested by `@Veykril` in [this comment](https://github.com/rust-lang/rust-analyzer/pull/16498#issuecomment-1929864427).
We filter candidate traits by taking advantage of orphan rules. For additional details, I'll rely on `@WaffleLapkin's` explanation [from Zulip](https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Frust-analyzer/topic/Trait.20Checking/near/420942417):
> A type `A` can only implements traits which
> 1. Have a blanket implementation (`impl<T> Trait for T {}`)
> 2. Have implementation for `A` (`impl Trait for A {}`)
>
> Blanket implementation can only exist in `Trait`'s crate. Implementation for `A` can only exist in `A`'s or `Trait`'s crate.
Big thanks to Waffle for its keen observation!
---
I think some additional improvements are possible:
- `for_trait_and_self_ty` seemingly does not distinguish between `&T`, `&mut T`, or `T`, resulting in seemingly irrelevant traits like `tokio::io::AsyncWrite` being being included for, e.g., `&slog::Logger`. I don't know they're being considered due to the [autoref/autoderef behavior](a02a219773/crates/hir-ty/src/method_resolution.rs (L945-L962)), but I wonder if it'd make sense to filter by mutability earlier and not consider trait implementations that require `&mut T` when we only have a `&T`.
- The method completions [spend a _lot_ of time in unification](https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Frust-analyzer/topic/Trait.20Checking/near/421072356), and while there might be low-hanging fruit there, it might make more sense to wait for the new trait solver in `rustc`. I dunno.
[^1]: The filtering occurs outside of typechecking, after all.
fix: Don't panic on synthetic syntax in inference diagnostics
Temporary fix for https://github.com/rust-lang/rust-analyzer/issues/16682
We ought to rethink how we attach diagnostics to things, as IDs don't work for `format_args` like that!
