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.
Disallow ambiguous attributes on expressions
This implements the suggestion in [#15701](https://github.com/rust-lang/rust/issues/15701#issuecomment-2033124217) to disallow ambiguous outer attributes on expressions. This should resolve one of the concerns blocking the stabilization of `stmt_expr_attributes`.
Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`)
Implements `impl use<'a, 'b, T, U> Sized` syntax that allows users to explicitly list the captured parameters for an opaque, rather than inferring it from the opaque's bounds (or capturing *all* lifetimes under 2024-edition capture rules). This allows us to exclude some implicit captures, so this syntax may be used as a migration strategy for changes due to #117587.
We represent this list of captured params as `PreciseCapturingArg` in AST and HIR, resolving them between `rustc_resolve` and `resolve_bound_vars`. Later on, we validate that the opaques only capture the parameters in this list.
We artificially limit the feature to *require* mentioning all type and const parameters, since we don't currently have support for non-lifetime bivariant generics. This can be relaxed in the future.
We also may need to limit this to require naming *all* lifetime parameters for RPITIT, since GATs have no variance. I have to investigate this. This can also be relaxed in the future.
r? `@oli-obk`
Tracking issue:
- https://github.com/rust-lang/rust/issues/123432
Cleanup: Rename `ModSep` to `PathSep`
`::` is usually referred to as the *path separator* (citation needed).
The existing name `ModSep` for *module separator* is a bit misleading since it in fact separates the segments of arbitrary path segments, not only ones resolving to modules. Let me just give a shout-out to associated items (`T::Assoc`, `<Ty as Trait>::function`) and enum variants (`Option::None`).
Motivation: Reduce friction for new contributors, prevent potential confusion.
cc `@petrochenkov`
r? nnethercote or compiler
conditionally ignore fatal diagnostic in the SilentEmitter
This change is primarily meant to allow rustfmt to ignore all diagnostics when using the `SilentEmitter`. Back in #121301 the `SilentEmitter` was shared between rustc and rustfmt. This changed rustfmt's behavior from ignoring all diagnostic to emitting fatal diagnostics, which lead to https://github.com/rust-lang/rustfmt/issues/6109.
These changes allow rustfmt to maintain its previous behaviour when using the `SilentEmitter`, while allowing rustc code to still emit fatal diagnostics.
Experimental feature postfix match
This has a basic experimental implementation for the RFC postfix match (rust-lang/rfcs#3295, #121618). [Liaison is](https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/Postfix.20Match.20Liaison/near/423301844) ```@scottmcm``` with the lang team's [experimental feature gate process](https://github.com/rust-lang/lang-team/blob/master/src/how_to/experiment.md).
This feature has had an RFC for a while, and there has been discussion on it for a while. It would probably be valuable to see it out in the field rather than continue discussing it. This feature also allows to see how popular postfix expressions like this are for the postfix macros RFC, as those will take more time to implement.
It is entirely implemented in the parser, so it should be relatively easy to remove if needed.
This PR is split in to 5 commits to ease review.
1. The implementation of the feature & gating.
2. Add a MatchKind field, fix uses, fix pretty.
3. Basic rustfmt impl, as rustfmt crashes upon seeing this syntax without a fix.
4. Add new MatchSource to HIR for Clippy & other HIR consumers
This change is primarily meant to allow rustfmt to ignore all
diagnostics when using the `SilentEmitter`. Back in PR 121301 the
`SilentEmitter` was shared between rustc and rustfmt. This changed
rustfmt's behavior from ignoring all diagnostic to emitting fatal
diagnostics.
These changes allow rustfmt to maintain it's previous behaviour when
using the SilentEmitter, while allowing rustc code to still emit fatal
diagnostics.
Rework `untranslatable_diagnostic` lint
Currently it only checks calls to functions marked with `#[rustc_lint_diagnostics]`. This PR changes it to check calls to any function with an `impl Into<{D,Subd}iagnosticMessage>` parameter. This greatly improves its coverage and doesn't rely on people remembering to add `#[rustc_lint_diagnostics]`. It also lets us add `#[rustc_lint_diagnostics]` to a number of functions that don't have an `impl Into<{D,Subd}iagnosticMessage>`, such as `Diag::span`.
r? ``@davidtwco``
Currently it only checks calls to functions marked with
`#[rustc_lint_diagnostics]`. This commit changes it to check calls to
any function with an `impl Into<{D,Subd}iagMessage>` parameter. This
greatly improves its coverage and doesn't rely on people remembering to
add `#[rustc_lint_diagnostics]`.
The commit also adds `#[allow(rustc::untranslatable_diagnostic)`]
attributes to places that need it that are caught by the improved lint.
These places that might be easy to convert to translatable diagnostics.
Finally, it also:
- Expands and corrects some comments.
- Does some minor formatting improvements.
- Adds missing `DecorateLint` cases to
`tests/ui-fulldeps/internal-lints/diagnostics.rs`.
Existing names for values of this type are `sess`, `parse_sess`,
`parse_session`, and `ps`. `sess` is particularly annoying because
that's also used for `Session` values, which are often co-located, and
it can be difficult to know which type a value named `sess` refers to.
(That annoyance is the main motivation for this change.) `psess` is nice
and short, which is good for a name used this much.
The commit also renames some `parse_sess_created` values as
`psess_created`.
Detect empty leading where clauses on type aliases
1. commit: refactor the AST of type alias where clauses
* I could no longer bear the look of `.0.1` and `.1.0`
* Arguably moving `split` out of `TyAlias` into a substruct might not make that much sense from a semantic standpoint since it reprs an index into `TyAlias.predicates` but it's alright and it cleans up the usage sites of `TyAlias`
2. commit: fix an oversight: An empty leading where clause is still a leading where clause
* semantically reject empty leading where clauses on lazy type aliases
* e.g., on `#![feature(lazy_type_alias)] type X where = ();`
* make empty leading where clauses on assoc types trigger lint `deprecated_where_clause_location`
* e.g., `impl Trait for () { type X where = (); }`
Emitter cleanups
Some cleanups I made when reading emitter code. In particular, `HumanEmitter` and `JsonEmitter` have gone from three constructors to one.
r? `@oli-obk`
I removed it in #121206 because I thought thought it wasn't necessary.
But then I had to add an `emit_stashed_diagnostics` call elsewhere in
rustfmt to avoid the assertion failure (which took two attempts to get
right, #121487 and #121615), and now there's an assertion failure in
clippy as well (https://github.com/rust-lang/rust-clippy/issues/12364).
So this commit just reinstates the call in `DiagCtxtInner::drop`. It
also reverts the rustfmt changes from #121487 and #121615, though it
keeps the tests added for those PRs.
Rollup of 6 pull requests
Successful merges:
- #121389 (llvm-wrapper: fix few warnings)
- #121493 (By changing some attributes to only_local, reducing encoding attributes in the crate metadate.)
- #121615 (Move `emit_stashed_diagnostic` call in rustfmt.)
- #121617 (Actually use the right closure kind when checking async Fn goals)
- #121628 (Do not const prop unions)
- #121629 (fix some references to no-longer-existing ReprOptions.layout_seed)
r? `@ghost`
`@rustbot` modify labels: rollup
Move `emit_stashed_diagnostic` call in rustfmt.
This call was added to `parse_crate_mod` in #121487, to fix a case where a stashed diagnostic wasn't emitted. But there is another path where a stashed diagnostic might fail to be emitted if there's a parse error, if the `build` call in `parse_crate_inner` fails before `parse_crate_mod` is reached.
So this commit moves the `emit_stashed_diagnostic` call outwards, from `parse_crate_mod` to `format_project`, just after the `Parser::parse_crate` call. This should be far out enough to catch any parsing errors.
Fixes#121517.
r? `@oli-obk`
cc `@ytmimi`
This call was added to `parse_crate_mod` in #121487, to fix a case where
a stashed diagnostic wasn't emitted. But there is another path where a
stashed diagnostic might fail to be emitted if there's a parse error, if
the `build` call in `parse_crate_inner` fails before `parse_crate_mod`
is reached.
So this commit moves the `emit_stashed_diagnostic` call outwards, from
`parse_crate_mod` to `format_project`, just after the
`Parser::parse_crate` call. This should be far out enough to catch any
parsing errors.
Fixes#121517.
Commit 72b172b in #121206 changed things so that
`emit_stashed_diagnostics` is only called from `run_compiler`. But
rustfmt doesn't use `run_compiler`, so it needs to call
`emit_stashed_diagnostics` itself to avoid an abort in
`DiagCtxtInner::drop` when stashed diagnostics occur.
Fixes#121450.
errors: only eagerly translate subdiagnostics
Subdiagnostics don't need to be lazily translated, they can always be eagerly translated. Eager translation is slightly more complex as we need to have a `DiagCtxt` available to perform the translation, which involves slightly more threading of that context.
This slight increase in complexity should enable later simplifications - like passing `DiagCtxt` into `AddToDiagnostic` and moving Fluent messages into the diagnostic structs rather than having them in separate files (working on that was what led to this change).
r? ```@nnethercote```
Subdiagnostics don't need to be lazily translated, they can always be
eagerly translated. Eager translation is slightly more complex as we need
to have a `DiagCtxt` available to perform the translation, which involves
slightly more threading of that context.
This slight increase in complexity should enable later simplifications -
like passing `DiagCtxt` into `AddToDiagnostic` and moving Fluent messages
into the diagnostic structs rather than having them in separate files
(working on that was what led to this change).
Signed-off-by: David Wood <david@davidtw.co>
This makes it more like `hir::TyKind::Err`, and avoids a
`span_delayed_bug` call in `LoweringContext::lower_ty_direct`.
It also requires adding `ast::TyKind::Dummy`, now that
`ast::TyKind::Err` can't be used for that purpose in the absence of an
error emission.
There are a couple of cases that aren't as neat as I would have liked,
marked with `FIXME` comments.
Format `async` trait bounds in rustfmt
r? `@ytmimi` or `@calebcartwright`
This PR opts to do formatting in the rust-lang/rust tree because otherwise we'd have to wait until a full sync, and rustfmt is currently totally removing the `async` keyword.
cc https://github.com/rust-lang/rustfmt/issues/6070
