`MultiSpan` contains labels, which are more complicated with the
introduction of diagnostic translation and will use types from
`rustc_errors` - however, `rustc_errors` depends on `rustc_span` so
`rustc_span` cannot use types like `DiagnosticMessage` without
dependency cycles. Introduce a new `rustc_error_messages` crate that can
contain `DiagnosticMessage` and `MultiSpan`.
Signed-off-by: David Wood <david.wood@huawei.com>
When encountering an unsatisfied trait bound, if there are no other
suggestions, mention all the types that *do* implement that trait:
```
error[E0277]: the trait bound `f32: Foo` is not satisfied
--> $DIR/impl_wf.rs:22:6
|
LL | impl Baz<f32> for f32 { }
| ^^^^^^^^ the trait `Foo` is not implemented for `f32`
|
= help: the following other types implement trait `Foo`:
Option<T>
i32
str
note: required by a bound in `Baz`
--> $DIR/impl_wf.rs:18:31
|
LL | trait Baz<U: ?Sized> where U: Foo { }
| ^^^ required by this bound in `Baz`
```
Mention implementers of traits in `ImplObligation`s.
Do not mention other `impl`s for closures, ranges and `?`.
Attempts to improve method name suggestions when a matching method name
is not found. The approach taken is use the Levenshtein distance and
account for substrings having a high distance but can sometimes be very
close to the intended method (eg. empty vs is_empty).
Spellchecking compiler comments
This PR cleans up the rest of the spelling mistakes in the compiler comments. This PR does not change any literal or code spelling issues.
async: Give predictable name to binding generated from .await expressions.
This name makes it to debuginfo and allows debuggers to identify such bindings and their captured versions in suspended async fns.
This will be useful for async stack traces, as discussed in https://internals.rust-lang.org/t/async-debugging-logical-stack-traces-setting-goals-collecting-examples/15547.
I don't know if this needs some discussion by ````@rust-lang/compiler,```` e.g. about the name of the binding (`__awaitee`) or about the fact that this PR introduces a (soft) guarantee about a compiler generated name. Although, regarding the later, I think the same reasoning applies here as it does for debuginfo in general.
r? ````@tmandry````
Add the generic_associated_types_extended feature
Right now, this only ignore obligations that reference new placeholders in `poly_project_and_unify_type`. In the future, this might do other things, like allowing object-safe GATs.
**This feature is *incomplete* and quite likely unsound. This is mostly just for testing out potential future APIs using a "relaxed" set of rules until we figure out *proper* rules.**
Also drive by cleanup of adding a `ProjectAndUnifyResult` enum instead of using a `Result<Result<Option>>`.
r? `@nikomatsakis`
[1/2] Implement macro meta-variable expressions
See https://github.com/rust-lang/rust/pull/93545#issuecomment-1050963295
The logic behind `length`, `index` and `count` was removed but the parsing code is still present, i.e., everything is simply ignored like `ignored`.
r? ``@petrochenkov``
Treat unstable lints as unknown
This change causes unstable lints to be ignored if the `unknown_lints`
lint is allowed. To achieve this, it also changes lints to apply as soon
as they are processed. Previously, lints in the same set were processed
as a batch and then all simultaneously applied.
Implementation of https://github.com/rust-lang/compiler-team/issues/469
Merge `#[deprecated]` and `#[rustc_deprecated]`
The first commit makes "reason" an alias for "note" in `#[rustc_deprecated]`, while still prohibiting it in `#[deprecated]`.
The second commit changes "suggestion" to not just be a feature of `#[rustc_deprecated]`. This is placed behind the new `deprecated_suggestion` feature. This needs a tracking issue; let me know if this PR will be approved and I can create one.
The third commit is what permits `#[deprecated]` to be used when `#![feature(staged_api)]` is enabled. This isn't yet used in stdlib (only tests), as it would require duplicating all deprecation attributes until a bootstrap occurs. I intend to submit a follow-up PR that replaces all uses and removes the remaining `#[rustc_deprecated]` code after the next bootstrap.
`@rustbot` label +T-libs-api +C-feature-request +A-attributes +S-waiting-on-review
Rollup of 8 pull requests
Successful merges:
- #91804 (Make some `Clone` impls `const`)
- #92541 (Mention intent of `From` trait in its docs)
- #93057 (Add Iterator::collect_into)
- #94739 (Suggest `if let`/`let_else` for refutable pat in `let`)
- #94754 (Warn users about `||` in let chain expressions)
- #94763 (Add documentation about lifetimes to thread::scope.)
- #94768 (Ignore `close_read_wakes_up` test on SGX platform)
- #94772 (Add miri to the well known conditional compilation names and values)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
This change causes unstable lints to be ignored if the `unknown_lints`
lint is allowed. To achieve this, it also changes lints to apply as soon
as they are processed. Previously, lints in the same set were processed
as a batch and then all simultaneously applied.
Implementation of https://github.com/rust-lang/compiler-team/issues/469
Remove ordering traits from `rustc_span::hygiene::LocalExpnId`
Part of work on #90317.
Also adds a negative impl block as a form of documentation and a roadblock to regression.
Add well known values to `--check-cfg` implementation
This pull-request adds well known values for the well known names via `--check-cfg=values()`.
[RFC 3013: Checking conditional compilation at compile time](https://rust-lang.github.io/rfcs/3013-conditional-compilation-checking.html#checking-conditional-compilation-at-compile-time) doesn't define this at all, but this seems a nice improvement.
The activation is done by a empty `values()` (new syntax) similar to `names()` except that `names(foo)` also activate well known names while `values(aa, "aa", "kk")` would not.
As stated this use a different activation logic because well known values for the well known names are not always sufficient.
In fact this is problematic for every `target_*` cfg because of non builtin targets, as the current implementation use those built-ins targets to create the list the well known values.
The implementation is straight forward, first we gather (if necessary) all the values (lazily or not) and then we apply them.
r? ```@petrochenkov```
ARM: Only allow using d16-d31 with asm! when supported by the target
Support can be determined by checking for the "d32" LLVM feature.
r? ```````````````@nagisa```````````````
Only create a single expansion for each inline integration.
The inlining integrator used to create one expansion for each span from the callee body.
This PR reverses the logic to create a single expansion for the whole call,
which is more consistent with how macro expansions work for macros.
This should remove the large memory regression in #91743.
Fix several asm! related issues
This is a combination of several fixes, each split into a separate commit. Splitting these into PRs is not practical since they conflict with each other.
Fixes#92378Fixes#85247
r? ``@nagisa``
The previous approach of checking for the reserve-r9 target feature
didn't actually work because LLVM only sets this feature very late when
initializing the per-function subtarget.
Adopt let else in more places
Continuation of #89933, #91018, #91481, #93046, #93590, #94011.
I have extended my clippy lint to also recognize tuple passing and match statements. The diff caused by fixing it is way above 1 thousand lines. Thus, I split it up into multiple pull requests to make reviewing easier. This is the biggest of these PRs and handles the changes outside of rustdoc, rustc_typeck, rustc_const_eval, rustc_trait_selection, which were handled in PRs #94139, #94142, #94143, #94144.
Add MemTagSanitizer Support
Add support for the LLVM [MemTagSanitizer](https://llvm.org/docs/MemTagSanitizer.html).
On hardware which supports it (see caveats below), the MemTagSanitizer can catch bugs similar to AddressSanitizer and HardwareAddressSanitizer, but with lower overhead.
On a tag mismatch, a SIGSEGV is signaled with code SEGV_MTESERR / SEGV_MTEAERR.
# Usage
`-Zsanitizer=memtag -C target-feature="+mte"`
# Comments/Caveats
* MemTagSanitizer is only supported on AArch64 targets with hardware support
* Requires `-C target-feature="+mte"`
* LLVM MemTagSanitizer currently only performs stack tagging.
# TODO
* Tests
* Example
Add a stack-`pin!`-ning macro to `core::pin`.
- https://github.com/rust-lang/rust/issues/93178
`pin!` allows pinning a value to the stack. Thanks to being implemented in the stdlib, which gives access to `macro` macros, and to the private `.pointer` field of the `Pin` wrapper, [it was recently discovered](https://rust-lang.zulipchat.com/#narrow/stream/187312-wg-async-foundations/topic/pin!.20.E2.80.94.20the.20.22definitive.22.20edition.20.28a.20rhs-compatible.20pin-nin.2E.2E.2E/near/268731241) ([archive link](https://zulip-archive.rust-lang.org/stream/187312-wg-async-foundations/topic/A.20rhs-compatible.20pin-ning.20macro.html#268731241)), contrary to popular belief, that it is actually possible to implement and feature such a macro:
```rust
let foo: Pin<&mut PhantomPinned> = pin!(PhantomPinned);
stuff(foo);
```
or, directly:
```rust
stuff(pin!(PhantomPinned));
```
- For context, historically, this used to require one of the two following syntaxes:
- ```rust
let foo = PhantomPinned;
pin!(foo);
stuff(foo);
```
- ```rust
pin! {
let foo = PhantomPinned;
}
stuff(foo);
```
This macro thus allows, for instance, doing things like:
```diff
fn block_on<T>(fut: impl Future<Output = T>) -> T {
// Pin the future so it can be polled.
- let mut fut = Box::pin(fut);
+ let mut fut = pin!(fut);
// Create a new context to be passed to the future.
let t = thread::current();
let waker = Arc::new(ThreadWaker(t)).into();
let mut cx = Context::from_waker(&waker);
// Run the future to completion.
loop {
match fut.as_mut().poll(&mut cx) {
Poll::Ready(res) => return res,
Poll::Pending => thread::park(),
}
}
}
```
- _c.f._, https://doc.rust-lang.org/1.58.1/alloc/task/trait.Wake.html
And so on, and so forth.
I don't think such an API can get better than that, barring full featured language support (`&pin` references or something), so I see no reason not to start experimenting with featuring this in the stdlib already 🙂
- cc `@rust-lang/wg-async-foundations` \[EDIT: this doesn't seem to have pinged anybody 😩, thanks `@yoshuawuyts` for the real ping\]
r? `@joshtriplett`
___
# Docs preview
https://user-images.githubusercontent.com/9920355/150605731-1f45c2eb-c9b0-4ce3-b17f-2784fb75786e.mp4
___
# Implementation
The implementation ends up being dead simple (so much it's embarrassing):
```rust
pub macro pin($value:expr $(,)?) {
Pin { pointer: &mut { $value } }
}
```
_and voilà_!
- The key for it working lies in [the rules governing the scope of anonymous temporaries](https://doc.rust-lang.org/1.58.1/reference/destructors.html#temporary-lifetime-extension).
<details><summary>Comments and context</summary>
This is `Pin::new_unchecked(&mut { $value })`, so, for starters, let's
review such a hypothetical macro (that any user-code could define):
```rust
macro_rules! pin {( $value:expr ) => (
match &mut { $value } { at_value => unsafe { // Do not wrap `$value` in an `unsafe` block.
$crate::pin::Pin::<&mut _>::new_unchecked(at_value)
}}
)}
```
Safety:
- `type P = &mut _`. There are thus no pathological `Deref{,Mut}` impls that would break `Pin`'s invariants.
- `{ $value }` is braced, making it a _block expression_, thus **moving** the given `$value`, and making it _become an **anonymous** temporary_.
By virtue of being anonynomous, it can no longer be accessed, thus preventing any attemps to `mem::replace` it or `mem::forget` it, _etc._
This gives us a `pin!` definition that is sound, and which works, but only in certain scenarios:
- If the `pin!(value)` expression is _directly_ fed to a function call:
`let poll = pin!(fut).poll(cx);`
- If the `pin!(value)` expression is part of a scrutinee:
```rust
match pin!(fut) { pinned_fut => {
pinned_fut.as_mut().poll(...);
pinned_fut.as_mut().poll(...);
}} // <- `fut` is dropped here.
```
Alas, it doesn't work for the more straight-forward use-case: `let` bindings.
```rust
let pinned_fut = pin!(fut); // <- temporary value is freed at the end of this statement
pinned_fut.poll(...) // error[E0716]: temporary value dropped while borrowed
// note: consider using a `let` binding to create a longer lived value
```
- Issues such as this one are the ones motivating https://github.com/rust-lang/rfcs/pull/66
This makes such a macro incredibly unergonomic in practice, and the reason most macros out there had to take the path of being a statement/binding macro (_e.g._, `pin!(future);`) instead of featuring the more intuitive ergonomics of an expression macro.
Luckily, there is a way to avoid the problem. Indeed, the problem stems from the fact that a temporary is dropped at the end of its enclosing statement when it is part of the parameters given to function call, which has precisely been the case with our `Pin::new_unchecked()`!
For instance,
```rust
let p = Pin::new_unchecked(&mut <temporary>);
```
becomes:
```rust
let p = { let mut anon = <temporary>; &mut anon };
```
However, when using a literal braced struct to construct the value, references to temporaries can then be taken. This makes Rust change the lifespan of such temporaries so that they are, instead, dropped _at the end of the enscoping block_.
For instance,
```rust
let p = Pin { pointer: &mut <temporary> };
```
becomes:
```rust
let mut anon = <temporary>;
let p = Pin { pointer: &mut anon };
```
which is *exactly* what we want.
Finally, we don't hit problems _w.r.t._ the privacy of the `pointer` field, or the unqualified `Pin` name, thanks to `decl_macro`s being _fully_ hygienic (`def_site` hygiene).
</details>
___
# TODO
- [x] Add compile-fail tests with attempts to break the `Pin` invariants thanks to the macro (_e.g._, try to access the private `.pointer` field, or see what happens if such a pin is used outside its enscoping scope (borrow error));
- [ ] Follow-up stuff:
- [ ] Try to experiment with adding `pin!` to the prelude: this may require to be handled with some extra care, as it may lead to issues reminiscent of those of `assert_matches!`: https://github.com/rust-lang/rust/issues/82913
- [x] Create the tracking issue.
