Split rustc_mir
The `rustc_mir` crate is the second largest in the compiler.
This PR splits it up into 5 crates:
- rustc_borrowck;
- rustc_const_eval;
- rustc_mir_dataflow;
- rustc_mir_transform;
- rustc_monomorphize.
Suggest deriving traits if possible
This only applies to builtin derives as I don't think there is a
clean way to get the available derives in typeck.
Closes#85851
Remove `hir::GenericBound::Unsized`
Rather than "moving" the `?Sized` bounds to the param bounds, just also check where clauses in `astconv`. I also did some related cleanup here, but that's not strictly neccesary. Also going to do a perf run here.
r? `@estebank`
Improve structured tuple struct suggestion
Previously, the span was just for the constructor name, which meant it
would result in syntactically-invalid code when applied. Now, the span
is for the entire expression.
I also changed it to use `span_suggestion_verbose`, for two reasons:
1. Now that the suggestion span has been corrected, the output is a bit
cluttered and hard to read. Putting the suggestion its own window
creates more space.
2. It's easier to see what's being suggested, since now the version
after the suggestion is applied is shown.
r? `@davidtwco`
Avoid invoking the hir_crate query to traverse the HIR
Walking the HIR tree is done using the `hir_crate` query. However, this is unnecessary, since `hir_owner(CRATE_DEF_ID)` provides the same information. Since depending on `hir_crate` forces dependents to always be executed, this leads to unnecessary work.
By splitting HIR and attributes visits, we can avoid an edge to `hir_crate` when trying to visit the HIR tree.
The arguments to `span_suggestion` were in the wrong order, so the error
looked like this:
error[E0783]: trait objects without an explicit `dyn` are deprecated
--> src/test/ui/editions/dyn-trait-sugg-2021.rs:10:5
|
10 | Foo::hi(123);
| ^^^ help: <dyn Foo>: `use `dyn``
Now the error looks like this, as expected:
error[E0783]: trait objects without an explicit `dyn` are deprecated
--> src/test/ui/editions/dyn-trait-sugg-2021.rs:10:5
|
10 | Foo::hi(123);
| ^^^ help: use `dyn`: `<dyn Foo>`
This issue was only present in the 2021 error; the 2018 lint was
correct.
Correct doc comments inside `use_expr_visitor.rs`
Just a simple update. I haven't changed any content inside the comments, as they still seem correct. Have a wonderful rest of the day 🙃
For two reasons:
1. Now that the suggestion span has been corrected, the output is a bit
cluttered and hard to read. Putting the suggestion its own window
creates more space.
2. It's easier to see what's being suggested, since now the version
after the suggestion is applied is shown.
(And same for tuple variants.)
Previously, the span was just for the constructor name, which meant it
would result in syntactically-invalid code when applied. Now, the span
is for the entire expression.
Introduce `let...else`
Tracking issue: #87335
The trickiest part for me was enforcing the diverging else block with clear diagnostics. Perhaps the obvious solution is to expand to `let _: ! = ..`, but I decided against this because, when a "mismatched type" error is found in typeck, there is no way to trace where in the HIR the expected type originated, AFAICT. In order to pass down this information, I believe we should introduce `Expectation::LetElseNever(HirId)` or maybe add `HirId` to `Expectation::HasType`, but I left that as a future enhancement. For now, I simply assert that the block is `!` with a custom `ObligationCauseCode`, and I think this is clear enough, at least to start. The downside here is that the error points at the entire block rather than the specific expression with the wrong type. I left a todo to this effect.
Overall, I believe this PR is feature-complete with regard to the RFC.
Warn when [T; N].into_iter() is ambiguous in the new edition.
Fixes https://github.com/rust-lang/rust/issues/88475
In https://github.com/rust-lang/rust/issues/88475, a situation was found where `[T; N].into_iter()` becomes *ambiguous* in the new edition. This is different than the case where `(&[T; N]).into_iter()` resolves differently, which was the only case handled by the `array_into_iter` lint. This is almost identical to the new-traits-in-the-prelude problem. Effectively, due to the array-into-iter hack disappearing in Rust 2021, we effectively added `IntoIterator` to the 'prelude' in Rust 2021 specifically for arrays.
This modifies the prelude collisions lint to detect that case and emit a `array_into_iter` lint in that case.
Don't use `guess_head_span` in `predicates_of` for foreign span
Previously, the result of `predicates_of` for a foreign trait
would depend on the *current* state of the corresponding source
file in the foreign crate. This could lead to ICEs during incremental
compilation, since the on-disk contents of the upstream source file
could potentially change without the upstream crate being recompiled.
Additionally, this ensure that that the metadata we produce for a crate
only depends on its *compiled* upstream dependencies (e.g an rlib or
rmeta file), *not* the current on-disk state of the upstream crate
source files.
