Elaborate `Future::Output` when printing opaque `impl Future` type
I would love to see the `Output =` type when printing type errors involving opaque `impl Future`.
[Test code](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=a800b481edd31575fbcaf5771a9c3678)
Before (cut relevant part of output):
```
note: while checking the return type of the `async fn`
--> /home/michael/test.rs:5:19
|
5 | async fn bar() -> usize {
| ^^^^^ checked the `Output` of this `async fn`, found opaque type
= note: expected type `usize`
found opaque type `impl Future`
```
After:
```
note: while checking the return type of the `async fn`
--> /home/michael/test.rs:5:19
|
5 | async fn bar() -> usize {
| ^^^^^ checked the `Output` of this `async fn`, found opaque type
= note: expected type `usize`
found opaque type `impl Future<Output = usize>`
```
Note the "found opaque type `impl Future<Output = usize>`" in the new output.
----
Questions:
1. We skip printing the output type when it's a projection, since I have been seeing some types like `impl Future<Output = <[static generator@/home/michael/test.rs:2:11: 2:21] as Generator<ResumeTy>>::Return>` which are not particularly helpful and leak implementation detail.
* Am I able to normalize this type within `rustc_middle::ty::print::pretty`? Alternatively, can we normalize it when creating the diagnostic? Otherwise, I'm fine with skipping it and falling back to the old output.
* Should I suppress any other types? I didn't encounter anything other than this generator projection type.
2. Not sure what the formatting of this should be. Do I include spaces in `Output = `?
Fix `non-constant value` ICE (#90878)
This also fixes the same suggestion, which was kind of broken, because it just searched for the last occurence of `const` to replace with a `let`. This works great in some cases, but when there is no const and a leading space to the file, it doesn't work and panic with overflow because it thought that it had found a const.
I also changed the suggestion to only trigger if the `const` and the non-constant value are on the same line, because if they aren't, the suggestion is very likely to be wrong.
Also don't trigger the suggestion if the found `const` is on line 0, because that triggers the ICE.
Asking Esteban to review since he was the last one to change the relevant code.
r? ``@estebank``
Fixes#90878
Clarify error messages caused by re-exporting `pub(crate)` visibility to outside
This PR clarifies error messages and suggestions caused by re-exporting pub(crate) visibility outside the crate.
Here is a small example ([Rust Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=e2cd0bd4422d4f20e6522dcbad167d3b)):
```rust
mod m {
pub(crate) enum E {}
}
pub use m::E;
fn main() {}
```
This code is compiled to:
```
error[E0365]: `E` is private, and cannot be re-exported
--> prog.rs:4:9
|
4 | pub use m::E;
| ^^^^ re-export of private `E`
|
= note: consider declaring type or module `E` with `pub`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0365`.
```
However, enum `E` is actually public to the crate, not private totally—nevertheless, rustc treats `pub(crate)` and private visibility as the same on the error messages. They are not clear and should be segmented distinctly.
By applying changes in this PR, the error message below will be the following message that would be clearer:
```
error[E0365]: `E` is only public to inside of the crate, and cannot be re-exported outside
--> prog.rs:4:9
|
4 | pub use m::E;
| ^^^^ re-export of crate public `E`
|
= note: consider declaring type or module `E` with `pub`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0365`.
```
Implement `clone_from` for `State`
Data flow engine uses `clone_from` for domain values. Providing an
implementation of `clone_from` will avoid some intermediate memory
allocations.
Extracted from #90413.
r? `@oli-obk`
fix CTFE/Miri simd_insert/extract on array-style repr(simd) types
The changed test would previously fail since `place_index` would just return the only field of `f32x4`, i.e., the array -- rather than *indexing into* the array which is what we have to do.
The new helper methods will also be needed for https://github.com/rust-lang/miri/issues/1912.
r? ``````@oli-obk``````
Rollup of 8 pull requests
Successful merges:
- #89258 (Make char conversion functions unstably const)
- #90578 (add const generics test)
- #90633 (Refactor single variant `Candidate` enum into a struct)
- #90800 (bootstap: create .cargo/config only if not present)
- #90942 (windows: Return the "Not Found" error when a path is empty)
- #90947 (Move some tests to more reasonable directories - 9.5)
- #90961 (Suggest removal of arguments for unit variant, not replacement)
- #90990 (Arenas cleanup)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Refactor single variant `Candidate` enum into a struct
`Candidate` enum has only a single `Ref` variant. Refactor it into a
struct and reduce overall indentation of the code by two levels.
No functional changes.
Try all stable method candidates first before trying unstable ones
Currently we try methods in this order in each step:
* Stable by value
* Unstable by value
* Stable autoref
* Unstable autoref
* ...
This PR changes it to first try pick methods without any unstable candidates, and if none is found, try again to pick unstable ones.
Fix#90320
CC #88971, hopefully would allow us to rename the "unstable_*" methods for integer impls back.
`@rustbot` label T-compiler T-libs-api
Rollup of 8 pull requests
Successful merges:
- #90386 (Add `-Zassert-incr-state` to assert state of incremental cache)
- #90438 (Clean up mess for --show-coverage documentation)
- #90480 (Mention `Vec::remove` in `Vec::swap_remove`'s docs)
- #90607 (Make slice->str conversion and related functions `const`)
- #90750 (rustdoc: Replace where-bounded Clean impl with simple function)
- #90895 (require full validity when determining the discriminant of a value)
- #90989 (Avoid suggesting literal formatting that turns into member access)
- #91002 (rustc: Remove `#[rustc_synthetic]`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
require full validity when determining the discriminant of a value
This resolves (for now) the semantic question that came up in https://github.com/rust-lang/rust/pull/89764: arguably, reading the discriminant of a value is 'using' that value, so we are in our right to demand full validity. Reading a discriminant is somewhat special in that it works for values of *arbitrary* type; all the other primitive MIR operations work on specific types (e.g. `bool` or an integer) and basically implicitly require validity as part of just "doing their job".
The alternative would be to just require that the discriminant itself is valid, if any -- but then what do we do for types that do not have a discriminant, which kind of validity do we check? [This code](81117ff930/compiler/rustc_codegen_ssa/src/mir/place.rs (L206-L215)) means we have to at least reject uninhabited types, but I would rather not special case that.
I don't think this can be tested in CTFE (since validity is not enforced there), I will add a compile-fail test to Miri:
```rust
#[allow(enum_intrinsics_non_enums)]
fn main() {
let i = 2u8;
std::mem::discriminant(unsafe { &*(&i as *const _ as *const bool) }); // UB
}
```
(I tried running the check even on the CTFE machines, but then it runs during ConstProp and that causes all sorts of problems. We could run it for ConstEval but not ConstProp, but that simply does not seem worth the effort currently.)
r? ``@oli-obk``
std: Get the standard library compiling for wasm64
This commit goes through and updates various `#[cfg]` as appropriate to
get the wasm64-unknown-unknown target behaving similarly to the
wasm32-unknown-unknown target. Most of this is just updating various
conditions for `target_arch = "wasm32"` to also account for `target_arch
= "wasm64"` where appropriate. This commit also lists `wasm64` as an
allow-listed architecture to not have the `restricted_std` feature
enabled, enabling experimentation with `-Z build-std` externally.
The main goal of this commit is to enable playing around with
`wasm64-unknown-unknown` externally via `-Z build-std` in a way that's
similar to the `wasm32-unknown-unknown` target. These targets are
effectively the same and only differ in their pointer size, but wasm64
is much newer and has much less ecosystem/library support so it'll still
take time to get wasm64 fully-fledged.
This function parameter attribute was introduced in https://github.com/rust-lang/rust/pull/44866 as an intermediate step in implementing `impl Trait`, it's not necessary or used anywhere by itself.
Improve ManuallyDrop suggestion
closes https://github.com/rust-lang/rust/issues/90585
* Fixes the recommended change to use ManuallyDrop as per the issue
* Changes the note to a help
* improves the span so it only points at the type.
Remove workaround for the forward progress handling in LLVM
this workaround was only needed for LLVM < 12 and the minimum LLVM version was updated to 12 in #90175
Fix span for non-satisfied trivial trait bounds
The spans for "trait bound not satisfied" errors in trivial trait bounds referenced the entire item (fn, impl, struct) before.
Now they only reference the obligation itself (`String: Copy`)
Address #90869
Print escaped string if char literal has multiple characters, but only one printable character
Fixes#90857
I'm not sure about the error message here, it could get rather long and *maybe* using the names of characters would be better? That wouldn't help the length any, though.
Improve diagnostics when a static lifetime is expected
Makes progress towards https://github.com/rust-lang/rust/issues/90600
The diagnostics here were previously entirely removed due to giving a misleading suggestion but if we instead provide an informative label in that same location it should better help the user understand the situation.
I included the example from the issue as it demonstrates an area where the diagnostics are still lacking.
Happy to remove that if its just adding noise atm.
warn on must_use use on async fn's
As referenced in #78149
This only works on `async` fn's for now, I can also look into if I can get `Box<dyn Future>` and `impl Future` working at this level (hir)
Alphabetize language features
This should significantly reduce the frequency of merge conflicts.
r? ````@joshtriplett````
````@rustbot```` label: +A-contributor-roadblock +S-waiting-on-review
Fix await suggestion on non-future type
Remove a match block that would suggest to add `.await` in the case where the expected type's `Future::Output` equals the found type. We only want to suggest `.await`ing in the opposite case (the found type's `Future::Output` equals the expected type).
The code sample is here: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=6ba6b83d4dddda263553b79dca9f6bcb
Before:
```
➜ ~ rustc --edition=2021 --crate-type=lib test.rs
error[E0308]: `match` arms have incompatible types
--> test.rs:4:14
|
2 | let x = match 1 {
| _____________-
3 | | 1 => other(),
| | ------- this is found to be of type `impl Future`
4 | | 2 => other().await,
| | ^^^^^^^^^^^^^ expected opaque type, found enum `Result`
5 | | };
| |_____- `match` arms have incompatible types
|
= note: expected type `impl Future`
found enum `Result<(), ()>`
help: consider `await`ing on the `Future`
|
4 | 2 => other().await.await,
| ++++++
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.
```
After:
```
➜ ~ rustc +stage1 --edition=2021 --crate-type=lib test.rs
error[E0308]: `match` arms have incompatible types
--> test.rs:4:14
|
2 | let x = match 1 {
| _____________-
3 | | 1 => other(),
| | ------- this is found to be of type `impl Future`
4 | | 2 => other().await,
| | ^^^^^^^^^^^^^ expected opaque type, found enum `Result`
5 | | };
| |_____- `match` arms have incompatible types
|
= note: expected type `impl Future`
found enum `Result<(), ()>`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.
```
Fixes#90931
Because it's always `'tcx`. In fact, some of them use a mixture of
passed-in `$tcx` and hard-coded `'tcx`, so no other lifetime would even
work.
This makes the code easier to read.
Remove `DropArena`.
Most arena-allocate types that impl `Drop` get their own `TypedArena`, but a
few infrequently used ones share a `DropArena`. This sharing adds complexity
but doesn't help performance or memory usage. Perhaps it was more effective in
the past prior to some other improvements to arenas.
This commit removes `DropArena` and the sharing of arenas via the `few`
attribute of the `arena_types` macro. This change removes over 100 lines of
code and nine uses of `unsafe` (one of which affects the parallel compiler) and
makes the remaining code easier to read.
Rollup of 8 pull requests
Successful merges:
- #86455 (check where-clause for explicit `Sized` before suggesting `?Sized`)
- #90801 (Normalize both arguments of `equate_normalized_input_or_output`)
- #90803 (Suggest `&str.chars()` on attempt to `&str.iter()`)
- #90819 (Fixes incorrect handling of TraitRefs when emitting suggestions.)
- #90910 (fix getting the discriminant of a zero-variant enum)
- #90925 (rustc_mir_build: reorder bindings)
- #90928 (Use a different server for checking clock drift)
- #90936 (Add a regression test for #80772)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
rustc_mir_build: reorder bindings
No functional changes intended.
I'm playing around with building compiler components using nightly rust
(2021-11-02) in a non-standard way. I encountered the following error while
trying to build rustc_mir_build:
```
error[E0597]: `wildcard` does not live long enough
--> rust/src/nightly/compiler/rustc_mir_build/src/build/matches/mod.rs:1767:82
|
1767 | let mut otherwise_candidate = Candidate::new(expr_place_builder.clone(), &wildcard, false);
| ^^^^^^^^^ borrowed value does not live long enough
...
1799 | }
| -
| |
| `wildcard` dropped here while still borrowed
| borrow might be used here, when `guard_candidate` is dropped and runs the destructor for type `Candidate<'_, '_>`
|
= note: values in a scope are dropped in the opposite order they are defined
```
I believe this flags an issue that may become an error in the future.
Swapping the order of `wildcard` and `guard_candidate` resolves it.
