Remove braces when fixing a nested use tree into a single item
[Back in 2019](https://github.com/rust-lang/rust/pull/56645) I added rustfix support for the `unused_imports` lint, to automatically remove them when running `cargo fix`. For the most part this worked great, but when removing all but one childs of a nested use tree it turned `use foo::{Unused, Used}` into `use foo::{Used}`. This is slightly annoying, because it then requires you to run `rustfmt` to get `use foo::Used`.
This PR automatically removes braces and the surrouding whitespace when all but one child of a nested use tree are unused. To get it done I had to add the span of the nested use tree to the AST, and refactor a bit the code I wrote back then.
A thing I noticed is, there doesn't seem to be any `//@ run-rustfix` test for fixing the `unused_imports` lint. I created a test in `tests/suggestions` (is that the right directory?) that for now tests just what I added in the PR. I can followup in a separate PR to add more tests for fixing `unused_lints`.
This PR is best reviewed commit-by-commit.
Fix insufficient logic when searching for the underlying allocation
This PR fixes the logic inside the `invalid_reference_casting` lint, when trying to lint on bigger memory layout casts.
More specifically when looking for the "underlying allocation" we were wrongly assuming that when we got `&mut slice[index]` that `slice[index]` was the allocation, but it's not.
Fixes https://github.com/rust-lang/rust/issues/124685
Handle normalization failure in `struct_tail_erasing_lifetimes`
Fixes#113272
The ICE occurred because the struct being normalized had an error. This PR adds some defensive code to guard against that.
Do not ICE on `AnonConst`s in `diagnostic_hir_wf_check`
Fixes#122989
Below is the snippet from #122989 that ICEs:
```rust
trait Traitor<const N: N<2> = 1, const N: N<2> = N> {
fn N(&N) -> N<2> {
M
}
}
trait N<const N: Traitor<2> = 12> {}
```
The `AnonConst` that triggers the ICE is the `2` in the param `const N: N<2> = 1`. The currently existing code in `diagnostic_hir_wf_check` deals only with `AnonConst`s that are default values of some param, but the `2` is not a default value. It is just an `AnonConst` HIR node inside a `TraitRef` HIR node corresponding to `N<2>`. Therefore the existing code cannot handle it and this PR ensures that it does.
Rollup of 5 pull requests
Successful merges:
- #124738 (rustdoc: dedup search form HTML)
- #124827 (generalize hr alias: avoid unconstrainable infer vars)
- #124832 (narrow down visibilities in `rustc_parse::lexer`)
- #124842 (replace another Option<Span> by DUMMY_SP)
- #124846 (Don't ICE when we cannot eval a const to a valtree in the new solver)
r? `@ghost`
`@rustbot` modify labels: rollup
Don't ICE when we cannot eval a const to a valtree in the new solver
Use `const_eval_resolve` instead of `try_const_eval_resolve` because naming aside, the former doesn't ICE when a value can't be evaluated to a valtree.
r? lcnr
never patterns: lower never patterns to `Unreachable` in MIR
This lowers a `!` pattern to "goto Unreachable". Ideally I'd like to read from the place to make it clear that the UB is coming from an invalid value, but that's tricky so I'm leaving it for later.
r? `@compiler-errors` how do you feel about a lil bit of MIR lowering
borrowck: prepopulate opaque storage more eagerly
otherwise we ICE due to ambiguity when normalizing while computing implied bounds.
r? ``@compiler-errors``
Record impl args in the proof tree in new solver
Rather than rematching them during select.
Also use `ImplSource::Param` instead of `ImplSource::Builtin` for alias-bound candidates, so we don't ICE in `Instance::resolve`.
r? lcnr
Rollup of 4 pull requests
Successful merges:
- #124520 (Document that `create_dir_all` calls `mkdir`/`CreateDirW` multiple times)
- #124724 (Prefer lower vtable candidates in select in new solver)
- #124771 (Don't consider candidates with no failing where clauses when refining obligation causes in new solver)
- #124808 (Use `super_fold` in `RegionsToStatic` visitor)
r? `@ghost`
`@rustbot` modify labels: rollup
Don't consider candidates with no failing where clauses when refining obligation causes in new solver
Improves error messages when we have param-env candidates that don't deeply unify (i.e. after alias-bounds).
r? lcnr
Prefer lower vtable candidates in select in new solver
Also, adjust the select visitor to only winnow when the *parent* goal is `Certainty::Yes`. This means that we won't winnow in cases when we have any ambiguous inference guidance from two candidates.
r? lcnr
Add constants for f16 and f128
- Commit 1 adds associated constants for `f16`, excluding NaN and infinities as these are implemented using arithmetic for `f32` and `f64`.
- Commit 2 adds associated constants for `f128`, excluding NaN and infinities.
- Commit 3 adds constants in `std::f16::consts`.
- Commit 4 adds constants in `std::f128::consts`.
Improve check-cfg CLI errors with more structured diagnostics
This PR improve check-cfg CLI errors with more structured diagnostics.
In particular it now shows the statement where the error occurred, what kind lit it is, as well as pointing users to the doc for more details.
`@rustbot` label +F-check-cfg
Rollup of 6 pull requests
Successful merges:
- #124148 (rustdoc-search: search for references)
- #124668 (Fix bootstrap panic when build from tarball)
- #124736 (compiler: upgrade time from 0.3.34 to 0.3.36)
- #124748 (Fix unwinding on 32-bit watchOS ARM (v2))
- #124749 (Stabilize exclusive_range_pattern (v2))
- #124750 (Document That `f16` And `f128` Hardware Support is Limited (v2))
r? `@ghost`
`@rustbot` modify labels: rollup
Remove suggestion about iteration count in coerce
Fixes#122561
The iteration count-centric suggestion was implemented in PR #100094, but it was based on the wrong assumption that the type mismatch error depends on the number of times the loop iterates. As it turns out, that is not true (see this comment for details: https://github.com/rust-lang/rust/pull/122679#issuecomment-2017432531)
This PR attempts to remedy the situation by changing the suggestion from the one centered on iteration count to a simple suggestion to add a return value.
It should also fix#100285 by simply making it redundant.
Implement `do_not_recommend` in the new solver
Put the test into `diagnostic_namespace` test folder even though it's not in the diagnostic namespace, because it should be soon.
r? lcnr
cc `@weiznich`
Update Cargo specific diagnostics in check-cfg
This PR updates the Cargo specific diagnostics for check-cfg/`unexpected_cfgs` lint.
Specifically it update to new url and use the double-column (instead of one) in the Cargo directive suggestion.
`@rustbot` label +F-check-cfg
cc `@weihanglo`
We do not coerce `&mut &mut T -> *mut mut T`
Resolves#34117 by declaring it to be "working as intended" until someone RFCs it or whatever other lang proposal would be required. It seems a bit of a footgun, but perhaps there are strong reasons to allow it anyways. Seeing as how I often have to be mindful to not allow a pointer to coerce the wrong way in my FFI work, I am inclined to think not, but perhaps it's fine in some use-case and that's actually more common?
