rustc_errors: let `DiagnosticBuilder::emit` return a "guarantee of emission".
That is, `DiagnosticBuilder` is now generic over the return type of `.emit()`, so we'll now have:
* `DiagnosticBuilder<ErrorReported>` for error (incl. fatal/bug) diagnostics
* can only be created via a `const L: Level`-generic constructor, that limits allowed variants via a `where` clause, so not even `rustc_errors` can accidentally bypass this limitation
* asserts `diagnostic.is_error()` on emission, just in case the construction restriction was bypassed (e.g. by replacing the whole `Diagnostic` inside `DiagnosticBuilder`)
* `.emit()` returns `ErrorReported`, as a "proof" token that `.emit()` was called
(though note that this isn't a real guarantee until after completing the work on
#69426)
* `DiagnosticBuilder<()>` for everything else (warnings, notes, etc.)
* can also be obtained from other `DiagnosticBuilder`s by calling `.forget_guarantee()`
This PR is a companion to other ongoing work, namely:
* #69426
and it's ongoing implementation:
#93222
the API changes in this PR are needed to get statically-checked "only errors produce `ErrorReported` from `.emit()`", but doesn't itself provide any really strong guarantees without those other `ErrorReported` changes
* #93244
would make the choices of API changes (esp. naming) in this PR fit better overall
In order to be able to let `.emit()` return anything trustable, several changes had to be made:
* `Diagnostic`'s `level` field is now private to `rustc_errors`, to disallow arbitrary "downgrade"s from "some kind of error" to "warning" (or anything else that doesn't cause compilation to fail)
* it's still possible to replace the whole `Diagnostic` inside the `DiagnosticBuilder`, sadly, that's harder to fix, but it's unlikely enough that we can paper over it with asserts on `.emit()`
* `.cancel()` now consumes `DiagnosticBuilder`, preventing `.emit()` calls on a cancelled diagnostic
* it's also now done internally, through `DiagnosticBuilder`-private state, instead of having a `Level::Cancelled` variant that can be read (or worse, written) by the user
* this removes a hazard of calling `.cancel()` on an error then continuing to attach details to it, and even expect to be able to `.emit()` it
* warnings were switched to *only* `can_emit_warnings` on emission (instead of pre-cancelling early)
* `struct_dummy` was removed (as it relied on a pre-`Cancelled` `Diagnostic`)
* since `.emit()` doesn't consume the `DiagnosticBuilder` <sub>(I tried and gave up, it's much more work than this PR)</sub>,
we have to make `.emit()` idempotent wrt the guarantees it returns
* thankfully, `err.emit(); err.emit();` can return `ErrorReported` both times, as the second `.emit()` call has no side-effects *only* because the first one did do the appropriate emission
* `&mut Diagnostic` is now used in a lot of function signatures, which used to take `&mut DiagnosticBuilder` (in the interest of not having to make those functions generic)
* the APIs were already mostly identical, allowing for low-effort porting to this new setup
* only some of the suggestion methods needed some rework, to have the extra `DiagnosticBuilder` functionality on the `Diagnostic` methods themselves (that change is also present in #93259)
* `.emit()`/`.cancel()` aren't available, but IMO calling them from an "error decorator/annotator" function isn't a good practice, and can lead to strange behavior (from the caller's perspective)
* `.downgrade_to_delayed_bug()` was added, letting you convert any `.is_error()` diagnostic into a `delay_span_bug` one (which works because in both cases the guarantees available are the same)
This PR should ideally be reviewed commit-by-commit, since there is a lot of fallout in each.
r? `@estebank` cc `@Manishearth` `@nikomatsakis` `@mark-i-m`
better ObligationCause for normalization errors in `can_type_implement_copy`
Some logic is needed so we can point to the field when given totally nonsense types like `struct Foo(<u32 as Iterator>::Item);`
Fixes#93687
Don't lint `match` expressions with `cfg`ed arms
Somehow there are no open issues related to this for any of the affected lints. At least none that I could fine from a quick search.
changelog: Don't lint `match` expressions with `cfg`ed arms in many cases
Fix `await_holding_lock` not linting `parking_lot` Mutex/RwLock
This adds tests for `RwLock` and `parking_lot::{Mutex, RwLock}`, which were added before in 2dc8c083f5, but never tested in UI tests. I noticed this while reading [fasterthanli.me](https://fasterthanli.me/articles/a-rust-match-made-in-hell) latest blog post, complaining that Clippy doesn't catch this for `parking_lot`. (Too many people read his blog, he's too powerful)
Some more things:
- Adds a test for #6446
- Improves the lint message
changelog: [`await_holding_lock`]: Now also lints for `parking_lot::{Mutex, RwLock}`
Even though the FP for that the lints were moved to pedantic isn't fixed
yet, running the lintcheck tool over the most popular 279 crates didn't
trigger this lint once. I would say that this lint is valuable enough,
despite the known FP, to be warn-by-default. Especially since a pretty
nice workaround exists.
Improve `redundant_slicing` lint
fixes#7972fixes#7257
This can supersede #7976
changelog: Fix suggestion for `redundant_slicing` when re-borrowing for a method call
changelog: New lint `deref_as_slicing`
Don't lint `needless_borrow` in method receiver positions
fixes#8408fixes#8407fixes#8391fixes#8367fixes#8380
This is a temporary fix for `needless_borrow`. The proper fix is included in #8355.
This should probably be merged into rustc before beta branches on Friday. This issue has been reported six or seven times in the past couple of weeks.
changelog: Fix various issues with `needless_borrow` n´. Note to changelog writer: those issues might have been introduced in this release cycle, so this might not matter in the changelog.
Don't lint Default::default if it is the udpate syntax base
changelog: Don't lint `Default::default` it is part of the update syntax
Current clippy warns about this:
```
warning: calling `Foo::default()` is more clear than this expression
--> src/main.rs:12:11
|
12 | ..Default::default()
| ^^^^^^^^^^^^^^^^^^ help: try: `Foo::default()`
|
```
With these changes, it will not lint that particular expression anymore.
Correctly mark the span of captured arguments in `format_args!()`
It should not include the braces, or misspelling suggestions will be wrong.
Fixes#94010.
Move transmute_undefined_repr back to nursery
There's still open discussion if this lint is ready to be enabled by
default. We want to give us more time to figure this out and prevent
this lint from getting to stable as an enabled-by-default lint.
cc https://github.com/rust-lang/rust-clippy/pull/8432
r? `@Manishearth` `@dtolnay`
I think this is the way to go here. We can re-enable this lint with the next sync, if we should decide to do so. But I would hold of for this release.
We have until Friday (beta branching) to decide if we want to merge this.
There's still open discussion if this lint is ready to be enabled by
default. We want to give us more time to figure this out and prevent
this lint from getting to stable as an enabled-by-default lint.
Specifically, rename the `Const` struct as `ConstS` and re-introduce `Const` as
this:
```
pub struct Const<'tcx>(&'tcx Interned<ConstS>);
```
This now matches `Ty` and `Predicate` more closely, including using
pointer-based `eq` and `hash`.
Notable changes:
- `mk_const` now takes a `ConstS`.
- `Const` was copy, despite being 48 bytes. Now `ConstS` is not, so need a
we need separate arena for it, because we can't use the `Dropless` one any
more.
- Many `&'tcx Const<'tcx>`/`&Const<'tcx>` to `Const<'tcx>` changes
- Many `ct.ty` to `ct.ty()` and `ct.val` to `ct.val()` changes.
- Lots of tedious sigil fiddling.
Specifically, change `Region` from this:
```
pub type Region<'tcx> = &'tcx RegionKind;
```
to this:
```
pub struct Region<'tcx>(&'tcx Interned<RegionKind>);
```
This now matches `Ty` and `Predicate` more closely.
Things to note
- Regions have always been interned, but we haven't been using pointer-based
`Eq` and `Hash`. This is now happening.
- I chose to impl `Deref` for `Region` because it makes pattern matching a lot
nicer, and `Region` can be viewed as just a smart wrapper for `RegionKind`.
- Various methods are moved from `RegionKind` to `Region`.
- There is a lot of tedious sigil changes.
- A couple of types like `HighlightBuilder`, `RegionHighlightMode` now have a
`'tcx` lifetime because they hold a `Ty<'tcx>`, so they can call `mk_region`.
- A couple of test outputs change slightly, I'm not sure why, but the new
outputs are a little better.
