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](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](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!
fix: panic when inlining callsites inside macros' parameters
Close#16660, #12429, #10695.
When `inline_into_callers` encounters callsites in macros parameters, it can lead to panics. Since there is no perfect way to handle macros, this PR directly filters out these cases.
internal: Remove salsa compile_fail tests
I can't figure out how to reproduce them, but hopefully fixes these:
Prioritise rustup sysroots over system ones
`get_path_for_executable` will now first check `$CARGO_HOME` before falling back to searching `$PATH`.
`rustup` is the recommended way to manage rust toolchains, therefore should be picked before the system toolchain.
Closes#16661
Document nvim 0.10 `inlay_hint`
It took me a few hours to figure out how to enable inlay type hints on Nvim 0.10 with `lspconfig`. `rustaceanvim` has already dropped support for them (https://github.com/mrcjkb/rustaceanvim/discussions/46#discussioncomment-7518669) and most other plugins, like `rust-tools`, are depreciated in favor of `rustaceanvim`.
This PR documents how to enable the inlay hints on Neovim 0.10 and later. I've tested this and changing the `on_attach` function is the only step that is required.
`get_path_for_executable` will now first check `$CARGO_HOME` before falling back to searching `$PATH`.
rustup is the recommended way to manage rust toolchains, therefore should be picked before the
system toolchain.
Add short flag -V for consistency with other rust tooling
Minor change to add the `-V` short flag to `rust-analyzer` to bring it in-line with other rust tooling such as:
> rustc -V
```bash
rustc 1.76.0 (07dca489a 2024-02-04)
```
> rustup -V
```bash
rustup 1.26.0 (5af9b9484 2023-04-05)
info: This is the version for the rustup toolchain manager, not the rustc compiler.
info: The currently active `rustc` version is `rustc 1.76.0 (07dca489a 2024-02-04)`
```
> cargo -V
```bash
cargo 1.76.0 (c84b36747 2024-01-18)
```
fix: Recompiles due to RUSTC_BOOTSTRAP
Some packages (e.g. thiserror) force a recompile if the value of the `RUSTC_BOOTSTRAP` env var changes. RA sets the variable to 1 in order to enable rustc / cargo unstable options. This causes flapping recompiles when building outside of RA.
Fixes#15057
internal: Optimize salsa memory usage
Reduces memory on self by ~20mb for me, there is a few more mb to save here if we made LRU caching opt-in, as currently every entry in a memoized query will store an `AtomicUsize` for the LRU.
