readd capture disjoint fields gate
This readds a feature gate guard that was added in PR #83521. (Basically, there were unintended consequences to the code exposed by removing the feature gate guard.)
The root bug still remains to be resolved, as discussed in issue #85561. This is just a band-aid suitable for a beta backport.
Cc issue #85435
Note that the latter issue is unfixed until we backport this (or another fix) to 1.53 beta
stabilize member constraints
Stabilizes the use of "member constraints" in solving `impl Trait` bindings. This is a step towards stabilizing a "MVP" of "named impl Trait".
# Member constraint stabilization report
| Info | |
| --- | --- |
| Tracking issue | [rust-lang/rust#61997](https://github.com/rust-lang/rust/issues/61997) |
| Implementation history | [rust-lang/rust#61775] |
| rustc-dev-guide coverage | [link](https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/member_constraints.html) |
| Complications | [rust-lang/rust#61773] |
[rust-lang/rust#61775]: https://github.com/rust-lang/rust/pull/61775
[rust-lang/rust#61773]: https://github.com/rust-lang/rust/issues/61773
## Background
Member constraints are an extension to our region solver that was introduced to make async fn region solving tractable. There are used in situations like the following:
```rust
fn foo<'a, 'b>(...) -> impl Trait<'a, 'b> { .. }
```
The problem here is that every region R in the hidden type must be equal to *either* `'a` *or* `'b` (or `'static`). This cannot be expressed simply via 'outlives constriants' like `R: 'a`. Therefore, we introduce a 'member constraint' `R member of ['a, 'b]`.
These constraints were introduced in [rust-lang/rust#61775]. At the time, we kept them feature gated and used them only for `impl Trait` return types that are derived from `async fn`. The intention, however, was always to support them in other contexts once we had time to gain more experience with them.
**In the time since their introduction, we have encountered no surprises or bugs due to these member constraints.** They are tested extensively as part of every async function that involves multiple unrelated lifetimes in its arguments.
## Tests
The behavior of member constraints is covered by the following tests:
* [`src/test/ui/async-await/multiple-lifetimes`](20e032e650/src/test/ui/async-await/multiple-lifetimes) -- tests using the async await, which are mostly already stabilized
* [`src/test/ui/impl-trait/multiple-lifetimes.rs`](20e032e650/src/test/ui/impl-trait/multiple-lifetimes.rs)
* [`src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.rs`](20e032e650/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.rs)
* [`src/test/ui/async-await/multiple-lifetimes/ret-impl-trait-fg.rs`](20e032e650/src/test/ui/async-await/multiple-lifetimes/ret-impl-trait-fg.rs)
* [`src/test/ui/async-await/multiple-lifetimes/ret-impl-trait-one.rs`](20e032e650/src/test/ui/async-await/multiple-lifetimes/ret-impl-trait-one.rs)
These tests cover a number of scenarios:
* `-> implTrait<'a, 'b>` with unrelated lifetimes `'a` and `'b`, as described above
* `async fn` that returns an `impl Trait` like the previous case, which desugars to a kind of "nested" impl trait like `impl Future<Output = impl Trait<'a, 'b>>`
## Potential concerns
There is a potential interaction with `impl Trait` on local variables, described in [rust-lang/rust#61773]. The challenge is that if you have a program like:
```rust=
trait Foo<'_> { }
impl Foo<'_> for &u32 { }
fn bar() {
let x: impl Foo<'_> = &44; // let's call the region variable for `'_` `'1`
}
```
then we would wind up with `'0 member of ['1, 'static]`, where `'0` is the region variable in the hidden type (`&'0 u32`) and `'1` is the region variable in the bounds `Foo<'1>`. This is tricky because both `'0` and `'1` are being inferred -- so making them equal may have other repercussions.
That said, `impl Trait` in bindings are not stable, and the implementation is pretty far from stabilization. Moreover, the difficulty highlighted here is not due to the presence of member constraints -- it's inherent to the design of the language. In other words, stabilizing member constraints does not actually cause us to accept anything that would make this problem any harder.
So I don't see this as a blocker to stabilization of member constraints; it is potentially a blocker to stablization of `impl trait` in let bindings.
E0599 suggestions and elision of generic argument if no canditate is found
fixes#81576
changes: In error E0599 (method not found) generic argument are eluded if the method was not found anywhere. If the method was found in another inherent implementation suggest that it was found elsewhere.
Example
```rust
struct Wrapper<T>(T);
struct Wrapper2<T> {
x: T,
}
impl Wrapper2<i8> {
fn method(&self) {}
}
fn main() {
let wrapper = Wrapper(i32);
wrapper.method();
let wrapper2 = Wrapper2{x: i32};
wrapper2.method();
}
```
```
Error[E0599]: no method named `method` found for struct `Wrapper<_>` in the current scope
....
error[E0599]: no method named `method` found for struct `Wrapper2<i32>` in the current scope
...
= note: The method was found for Wrapper2<i8>.
```
I am not very happy with the ```no method named `test` found for struct `Vec<_, _>` in the current scope```. I think it might be better to show only one generic argument `Vec<_>` if there is a default one. But I haven't yet found a way to do that,
fix `matches!` and `assert_matches!` on edition 2021
Previously this code failed to compile on edition 2021. [(Playground)](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=53960f2f051f641777b9e458da747707)
```rust
fn main() {
matches!((), ());
}
```
```
Compiling playground v0.0.1 (/playground)
error: `$pattern:pat` may be followed by `|`, which is not allowed for `pat` fragments
|
= note: allowed there are: `=>`, `,`, `=`, `if` or `in`
error: aborting due to previous error
error: could not compile `playground`
To learn more, run the command again with --verbose.
```
Post-monomorphization errors traces MVP
This PR works towards better diagnostics for the errors encountered in #85155 and similar.
We can encounter post-monomorphization errors (PMEs) when collecting mono items. The current diagnostics are confusing for these cases when they happen in a dependency (but are acceptable when they happen in the local crate).
These kinds of errors will be more likely now that `stdarch` uses const generics for its intrinsics' immediate arguments, and validates these const arguments with a mechanism that triggers such PMEs.
(Not to mention that the errors happen during codegen, so only when building code that actually uses these code paths. Check builds don't trigger them, neither does unused code)
So in this PR, we detect these kinds of errors during the mono item graph walk: if any error happens while collecting a node or its neighbors, we print a diagnostic about the current collection step, so that the user has at least some context of which erroneous code and dependency triggered the error.
The diagnostics for issue #85155 now have this note showing the source of the erroneous const argument:
```
note: the above error was encountered while instantiating `fn std::arch::x86_64::_mm_blend_ps::<51_i32>`
--> issue-85155.rs:11:24
|
11 | let _blended = _mm_blend_ps(a, b, 0x33);
| ^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error
```
Note that #85155 is a reduced version of a case happening in the wild, to indirect users of the `rustfft` crate, as seen in https://github.com/ejmahler/RustFFT/issues/74. The crate had a few of these out-of-range immediates. Here's how the diagnostics in this PR would have looked on one of its examples before it was fixed:
<details>
```
error[E0080]: evaluation of constant value failed
--> ./stdarch/crates/core_arch/src/macros.rs:8:9
|
8 | assert!(IMM >= MIN && IMM <= MAX, "IMM value not in expected range");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'IMM value not in expected range', ./stdarch/crates/core_arch/src/macros.rs:8:9
|
= note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
note: the above error was encountered while instantiating `fn _mm_blend_ps::<51_i32>`
--> /tmp/RustFFT/src/avx/avx_vector.rs:1314:23
|
1314 | let blended = _mm_blend_ps(rows[0], rows[2], 0x33);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: the above error was encountered while instantiating `fn _mm_permute_pd::<5_i32>`
--> /tmp/RustFFT/src/avx/avx_vector.rs:1859:9
|
1859 | _mm_permute_pd(self, 0x05)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
note: the above error was encountered while instantiating `fn _mm_permute_pd::<15_i32>`
--> /tmp/RustFFT/src/avx/avx_vector.rs:1863:32
|
1863 | (_mm_movedup_pd(self), _mm_permute_pd(self, 0x0F))
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0080`.
error: could not compile `rustfft`
To learn more, run the command again with --verbose.
```
</details>
I've developed and discussed this with them, so maybe r? `@oli-obk` -- but feel free to redirect to someone else of course.
(I'm not sure we can say that this PR definitely closes issue 85155, as it's still unclear exactly which diagnostics and information would be interesting to report in such cases -- and we've discussed printing backtraces before. I have prototypes of some complete and therefore noisy backtraces I showed Oli, but we decided to not include them in this PR for now)
Disallow shadowing const parameters
This pull request fixes#85348. Trying to shadow a `const` parameter as follows:
```rust
fn foo<const N: i32>() {
let N @ _ = 0;
}
```
currently causes an ICE. With my changes, I get:
```
error[E0530]: let bindings cannot shadow const parameters
--> test.rs:2:9
|
1 | fn foo<const N: i32>() {
| - the const parameter `N` is defined here
2 | let N @ _ = 0;
| ^ cannot be named the same as a const parameter
error: aborting due to previous error
```
This is the same error you get when trying to shadow a constant:
```rust
const N: i32 = 0;
let N @ _ = 0;
```
```
error[E0530]: let bindings cannot shadow constants
--> src/lib.rs:3:5
|
2 | const N: i32 = 0;
| ----------------- the constant `N` is defined here
3 | let N @ _ = 0;
| ^ cannot be named the same as a constant
error: aborting due to previous error
```
The reason for disallowing shadowing in both cases is described [here](https://github.com/rust-lang/rust/issues/33118#issuecomment-233962221) (the comment there only talks about constants, but the same reasoning applies to `const` parameters).
Avoid CJK legacy fonts in Windows
As metioned in #84035, the default serif CJK font in Windows is meh-looking.
To avoid this, we should use sans-serif font or provide CJK glyph supported font in `rustdoc.css`.
This test reproduces post-monomorphization errors one can encounter
when using incorrect immediate arguments to some of the stdarch
intrinsics using const generics.
deal with `const_evaluatable_checked` in `ConstEquate`
Failing to evaluate two constants which do not contain inference variables should not result in ambiguity.
Use TargetTriple::from_path in rustdoc
This fixes the problem reported in https://github.com/Rust-for-Linux/linux/pull/272 where rustdoc requires the absolute path of a target spec json instead of accepting a relative path like rustc.
Make building THIR a stealable query
This PR creates a stealable `thir_body` query so that we can build the THIR only once for THIR unsafeck and MIR build.
Blocked on #83842.
r? `@nikomatsakis`
Replace more "NULL" with "null"
Error messages in THIR unsafeck still contain "NULL", make them lowercase to be consistent with MIR unsafeck (cc #84842).
Extend `rustc_on_implemented` to improve more `?` error messages
`_Self` could match the generic definition; this adds that functionality for matching the generic definition of type parameters too.
Your advice welcome on the wording of all these messages, and which things belong in the message/label/note.
r? `@estebank`
rustdoc: render `<Self as X>::Y` type casts properly
Rustdoc didn't render any `<Self as X>` casts which causes invalid code inside the documentation. This is fixed by this PR by checking if the target type `X` is different from `Self`, and if so, it will render a typecast.
Resolves#85454
This sets their toggles to be closed in the HTML (matching the default
setting), and opens them if the setting indicates to do so.
This distinguishes between implementations and implementors based on
being descendants of certain named elements.
Rollup of 4 pull requests
Successful merges:
- #85506 (Reset "focusedByTab" field when doing another search)
- #85548 (Remove dead toggle JS code)
- #85550 (facepalm: operator precedence fail on my part.)
- #85555 (Check for more things in THIR unsafeck)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
