Tweak E0277 output when a candidate is available
*Follow up to #132086.*
Go from
```
error[E0277]: the trait bound `Then<Ignored<chumsky::combinator::Filter<chumsky::primitive::Any<&str, chumsky::extra::Full<EmptyErr, (), ()>>, {closure@src/main.rs:9:17: 9:27}>, char>, chumsky::combinator::Map<impl CSTParser<'a, O>, O, {closure@src/main.rs:11:24: 11:27}>, (), (), chumsky::extra::Full<EmptyErr, (), ()>>: CSTParser<'a>` is not satisfied
--> src/main.rs:7:50
|
7 | fn leaf<'a, O>(parser: impl CSTParser<'a, O>) -> impl CSTParser<'a, ()> {
| ^^^^^^^^^^^^^^^^^^^^^^ the trait `chumsky::private::ParserSealed<'_, &str, (), chumsky::extra::Full<EmptyErr, (), ()>>` is not implemented for `Then<Ignored<Filter<Any<&str, ...>, ...>, ...>, ..., ..., ..., ...>`, which is required by `Then<Ignored<chumsky::combinator::Filter<chumsky::primitive::Any<&str, chumsky::extra::Full<EmptyErr, (), ()>>, {closure@src/main.rs:9:17: 9:27}>, char>, chumsky::combinator::Map<impl CSTParser<'a, O>, O, {closure@src/main.rs:11:24: 11:27}>, (), (), chumsky::extra::Full<EmptyErr, (), ()>>: CSTParser<'a>`
|
= help: the trait `chumsky::private::ParserSealed<'_, &'a str, ((), ()), chumsky::extra::Full<EmptyErr, (), ()>>` is implemented for `Then<Ignored<chumsky::combinator::Filter<chumsky::primitive::Any<&str, chumsky::extra::Full<EmptyErr, (), ()>>, {closure@src/main.rs:9:17: 9:27}>, char>, chumsky::combinator::Map<impl CSTParser<'a, O>, O, {closure@src/main.rs:11:24: 11:27}>, (), (), chumsky::extra::Full<EmptyErr, (), ()>>`
= help: for that trait implementation, expected `((), ())`, found `()`
= note: required for `Then<Ignored<Filter<Any<&str, ...>, ...>, ...>, ..., ..., ..., ...>` to implement `Parser<'_, &str, ()>`
note: required for `Then<Ignored<Filter<Any<&str, ...>, ...>, ...>, ..., ..., ..., ...>` to implement `CSTParser<'a>`
--> src/main.rs:5:16
|
5 | impl<'a, O, T> CSTParser<'a, O> for T where T: Parser<'a, &'a str, O> {}
| ^^^^^^^^^^^^^^^^ ^ ---------------------- unsatisfied trait bound introduced here
= note: the full name for the type has been written to '/home/gh-estebank/longlong/target/debug/deps/longlong-0008f9a4f2023b08.long-type-13239977239800463552.txt'
= note: consider using `--verbose` to print the full type name to the console
= note: the full name for the type has been written to '/home/gh-estebank/longlong/target/debug/deps/longlong-0008f9a4f2023b08.long-type-13239977239800463552.txt'
= note: consider using `--verbose` to print the full type name to the console
```
to
```
error[E0277]: the trait bound `Then<Ignored<chumsky::combinator::Filter<chumsky::primitive::Any<&str, chumsky::extra::Full<EmptyErr, (), ()>>, {closure@src/main.rs:9:17: 9:27}>, char>, chumsky::combinator::Map<impl CSTParser<'a, O>, O, {closure@src/main.rs:11:24: 11:27}>, (), (), chumsky::extra::Full<EmptyErr, (), ()>>: CSTParser<'a>` is not satisfied
--> src/main.rs:7:50
|
7 | fn leaf<'a, O>(parser: impl CSTParser<'a, O>) -> impl CSTParser<'a, ()> {
| ^^^^^^^^^^^^^^^^^^^^^^ unsatisfied trait bound
...
11 | ws.then(parser.map(|_| ()))
| --------------------------- return type was inferred to be `Then<Ignored<..., ...>, ..., ..., ..., ...>` here
|
= help: the trait `ParserSealed<'_, &_, (), Full<_, _, _>>` is not implemented for `Then<Ignored<..., ...>, ..., ..., ..., ...>`
but trait `ParserSealed<'_, &'a _, ((), ()), Full<_, _, _>>` is implemented for it
= help: for that trait implementation, expected `((), ())`, found `()`
= note: required for `Then<Ignored<..., ...>, ..., ..., ..., ...>` to implement `Parser<'_, &str, ()>`
note: required for `Then<Ignored<..., ...>, ..., ..., ..., ...>` to implement `CSTParser<'a>`
--> src/main.rs:5:16
|
5 | impl<'a, O, T> CSTParser<'a, O> for T where T: Parser<'a, &'a str, O> {}
| ^^^^^^^^^^^^^^^^ ^ ---------------------- unsatisfied trait bound introduced here
= note: the full name for the type has been written to '/home/gh-estebank/longlong/target/debug/deps/longlong-df9d52be87eada65.long-type-1337037744507305372.txt'
= note: consider using `--verbose` to print the full type name to the console
```
* Remove redundant wording
* Introduce trait diff highlighting logic and use it
* Fix incorrect "long type written to path" logic (can be split off)
* Point at tail expression in more cases in E0277
* Avoid long primary span labels in E0277 by moving them to a `help`
Fix#132013.
There are individual commits that can be their own PR. If the review load is too big, happy to split them off.
Remove the "which is required by `{root_obligation}`" post-script in
"the trait `X` is not implemented for `Y`" explanation in E0277. This
information is already conveyed in the notes explaining requirements,
making it redundant while making the text (particularly in labels)
harder to read.
```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
--> $DIR/wf-static-type.rs:10:13
|
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`
|
= note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
--> $DIR/wf-static-type.rs:7:17
|
LL | struct IsCopy<T:Copy> { t: T }
| ^^^^ required by this bound in `IsCopy`
```
vs the prior
```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
--> $DIR/wf-static-type.rs:10:13
|
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`, which is required by `Option<NotCopy>: Copy`
|
= note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
--> $DIR/wf-static-type.rs:7:17
|
LL | struct IsCopy<T:Copy> { t: T }
| ^^^^ required by this bound in `IsCopy`
```
Do not call query to compute coroutine layout for synthetic body of async closure
There is code in the MIR validator that attempts to prevent query cycles when inlining a coroutine into itself, and will use the coroutine layout directly from the body when it detects that's the same coroutine as the one that's being validated. After #128506, this logic didn't take into account the fact that the coroutine def id will differ if it's the "by-move body" of an async closure. This PR implements that.
Fixes#129811
Fix projections when parent capture is by-ref but child capture is by-value in the `ByMoveBody` pass
This fixes a somewhat strange bug where we build the incorrect MIR in #129074. This one is weird, but I don't expect it to actually matter in practice since it almost certainly results in a move error in borrowck. However, let's not ICE.
Given the code:
```
#![feature(async_closure)]
// NOT copy.
struct Ty;
fn hello(x: &Ty) {
let c = async || {
*x;
//~^ ERROR cannot move out of `*x` which is behind a shared reference
};
}
fn main() {}
```
The parent coroutine-closure captures `x: &Ty` by-ref, resulting in an upvar of `&&Ty`. The child coroutine captures `x` by-value, resulting in an upvar of `&Ty`. When constructing the by-move body for the coroutine-closure, we weren't applying an additional deref projection to convert the parent capture into the child capture, resulting in an type error in assignment, which is a validation ICE.
As I said above, this only occurs (AFAICT) in code that eventually results in an error, because it is only triggered by HIR that attempts to move a non-copy value out of a ref. This doesn't occur if `Ty` is `Copy`, since we'd instead capture `x` by-ref in the child coroutine.
Fixes#129074
Fix `ElaborateBoxDerefs` on debug varinfo
Slightly simplifies the `ElaborateBoxDerefs` pass to fix cases where it was applying the wrong projections to debug var infos containing places that deref boxes.
From what I can tell[^1], we don't actually have any tests (or code anywhere, really) that exercise `debug x => *(...: Box<T>)`, and it's very difficult to trigger this in surface Rust, so I wrote a custom MIR test.
What happens is that the pass was turning `*(SOME_PLACE: Box<T>)` into `*(*((((SOME_PLACE).0: Unique<T>).0: NonNull<T>).0: *const T))` in debug var infos. In particular, notice the *double deref*, which was wrong.
This is the root cause of #128554, so this PR fixes#128554 as well. The reason that async closures was affected is because of the way that we compute the [`ByMove` body](https://github.com/rust-lang/rust/blob/master/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs), which resulted in `*(...: Box<T>)` in debug var info. But this really has nothing to do with async closures.
[^1]: Validated by literally replacing the `if elem == PlaceElem::Deref && base_ty.is_box() { ... }` innards with a `panic!()`, which compiled all of stage2 without panicking.
Don't implement `AsyncFn` for `FnDef`/`FnPtr` that wouldnt implement `Fn`
Due to unsafety, ABI, or the presence of target features, some `FnDef`/`FnPtr` types don't implement `Fn*`. Do the same for `AsyncFn*`.
Noticed this due to #128764, but this isn't really related to that ICE, which is fixed in #128792.
Implement simple, unstable lint to suggest turning closure-of-async-block into async-closure
We want to eventually suggest people to turn `|| async {}` to `async || {}`. This begins doing that. It's a pretty rudimentary lint, but I wanted to get something down so I wouldn't lose the code.
Tracking:
* #62290
Rollup of 7 pull requests
Successful merges:
- #125043 (reference type safety invariant docs: clarification)
- #125306 (Force the inner coroutine of an async closure to `move` if the outer closure is `move` and `FnOnce`)
- #125355 (Use Backtrace::force_capture instead of Backtrace::capture in rustc_log)
- #125382 (rustdoc: rename `issue-\d+.rs` tests to have meaningful names (part 7))
- #125391 (Minor serialize/span tweaks)
- #125395 (Remove unnecessary `.md` from the documentation sidebar)
- #125399 (Stop using `to_hir_binop` in codegen)
r? `@ghost`
`@rustbot` modify labels: rollup
Don't rely on upvars being assigned just because coroutine-closure kind is assigned
Previously, code relied on the implicit assumption that if a coroutine-closure's kind variable was constrained, then its upvars were also constrained. This is because we assign all of them at once at the end up upvar analysis.
However, there's another way that a coroutine-closure's kind can be constrained: from a signature hint in closure signature deduction. After #123350, we use these hints, which means the implicit assumption above no longer holds.
This PR adds the necessary checks so that we don't ICE.
r? oli-obk
