Adds support for .await under the existing async_await feature gate.
Moves macro-like await! syntax to the await_macro feature gate.
Removes support for `await` as a non-keyword under the `async_await`
feature.
This commit extends the logic used to determine what the expected
signature of a closure is so that it can also determine the expected
signature of a generator. This improves a diagnostic where the fn
signature was blamed instead of the generator body. It doesn't fix
fix the diagnostic for `async fn`.
This commit adds a test for the current behaviour of signature deduction
of generators when there is a type mismatch between the return type of
the function body and the signature.
Improved error message when type must be bound due to generator.
Fixes#58930.
Keen to get some feedback - is this as minimal as we can get it or is there an existing visitor I could repurpose?
ignore higher-ranked object bound conditions created by WF
In the `issue-53548` test added in this PR, the `Box<dyn Trait>` type is expanded to `Box<dyn Trait + 'static>`, but the generator "witness" that results is `for<'r> { Box<dyn Trait + 'r> }`. The WF code was encountering an ICE (when debug-assertions were enabled) and an unexpected compilation error (without debug-asserions) when trying to process this `'r` region bound. In particular, to be WF, the region bound must meet the requirements of the trait, and hence we got `for<'r> { 'r: 'static }`. This would ICE because the `Binder` constructor we were using was assering that no higher-ranked regions were involved (because the WF code is supposed to skip those). The error (if debug-asserions were disabled) came because we obviously cannot prove that `'r: 'static` for any region `'r`. Pursuant with
our "lazy WF" strategy for higher-ranked regions, the fix is not to require that `for<'r> { 'r: 'static }` holds (this is also analogous to what we would do for higher-ranked regions appearing within the trait in other positions).
Fixes#53548
r? @pnkfelix
In the `issue-53548` test added in this commit, the `Box<dyn Trait>`
type is expanded to `Box<dyn Trait + 'static>`, but the generator
"witness" that results is `for<'r> { Box<dyn Trait + 'r> }`. The WF
code was encountering an ICE (when debug-assertions were enabled) and
an unexpected compilation error (without debug-asserions) when trying
to process this `'r` region bound. In particular, to be WF, the region
bound must meet the requirements of the trait, and hence we got
`for<'r> { 'r: 'static }`. This would ICE because the `Binder`
constructor we were using was assering that no higher-ranked regions
were involved (because the WF code is supposed to skip those). The
error (if debug-asserions were disabled) came because we obviously
cannot prove that `'r: 'static` for any region `'r`. Pursuant with
our "lazy WF" strategy for higher-ranked regions, the fix is not to
require that `for<'r> { 'r: 'static }` holds (this is also analogous
to what we would do for higher-ranked regions appearing within the
trait in other positions).
Add information to higher-ranked lifetimes conflicts error messages
Make these errors go through the new "placeholder error" code path, to have self tys displayed and make them hopefully less confusing.
Should fix#57362.
r? @nikomatsakis — so we can iterate on the specific wording you wanted.
This gives at least some explanation for why a borrow is expected to
last for a certain free region. Also:
* Reports E0373: "closure may outlive the current function" with NLL.
* Special cases the case of returning a reference to (or value
referencing) a local variable or temporary (E0515).
* Special case assigning a reference to a local variable in a closure
to a captured variable.
This commit extends existing special-casing of closures to highlight the
use of variables within generators that are causing the generator to
borrow them.
Give a special message when the later use is from a call. Use the span
of the callee instead of the whole expression. For conflicting borrow
messages say that the later use is of the first borrow.
(Presumably the place that borrow_check ends up reporting for the
error about is no longer the root `Local` itself, and thus the note
diagnostic here stops firing.)
Add `-Z borrowck=migrate`
This adds `-Z borrowck=migrate`, which represents the way we want to migrate to NLL under Rust versions to come. It also hooks this new mode into `--edition 2018`, which means we're officially turning NLL on in the 2018 edition.
The basic idea of `-Z borrowck=migrate` that there are cases where NLL is fixing old soundness bugs in the borrow-checker, but in order to avoid just breaking code by immediately rejecting the programs that hit those soundness bugs, we instead use the following strategy:
If your code is accepted by NLL, then we accept it.
If your code is rejected by both NLL and the old AST-borrowck, then we reject it.
If your code is rejected by NLL but accepted by the old AST-borrowck, then we emit the new NLL errors as **warnings**.
These warnings will be turned into hard errors in the future, and they say so in these diagnostics.
Fix#46908
As a driveby change, I made `#![feature(nll)]` *always* take
precedence over `-Z borrowck`. The main effect this had is that it
means tests with `#![feature(nll)]` will ignore uses of `-Z
borrowck=compare`. This affected only one test as far as I can tell,
and I think that test used `-Z borrowck=compare` only as a historical
accident.
Various changes to existing diagnostics
* [Add code to `invalid ABI` error, add span label, move list to help to make message shorter](https://github.com/rust-lang/rust/pull/51463/commits/23ae5af274defa9ff884f593e44a2bbcaf814a02):
```
error[E0697]: invalid ABI: found `路濫狼á́́`
--> $DIR/unicode.rs:11:8
|
LL | extern "路濫狼á́́" fn foo() {} //~ ERROR invalid ABI
| ^^^^^^^^^ invalid ABI
|
= help: valid ABIs: cdecl, stdcall, fastcall, vectorcall, thiscall, aapcs, win64, sysv64, ptx-kernel, msp430-interrupt, x86-interrupt, Rust, C, system, rust-intrinsic, rust-call, platform-intrinsic, unadjusted
```
* [Add code to incorrect `pub` restriction error](https://github.com/rust-lang/rust/pull/51463/commits/e96fdea8a38f39f99f8b9a4000a689187a457e08)
* [Add message to `rustc_on_unimplemented` attributes in core to have them set a custom message _and_ label](https://github.com/rust-lang/rust/pull/51463/commits/2cc7e5ed307aee936c20479cfdc7409d6b52a464):
```
error[E0277]: `W` does not have a constant size known at compile-time
--> $DIR/unsized-enum2.rs:33:8
|
LL | VA(W),
| ^ `W` does not have a constant size known at compile-time
|
= help: the trait `std::marker::Sized` is not implemented for `W`
= help: consider adding a `where W: std::marker::Sized` bound
= note: no field of an enum variant may have a dynamically sized type
```
```
error[E0277]: `Foo` cannot be sent between threads safely
--> $DIR/E0277-2.rs:26:5
|
LL | is_send::<Foo>();
| ^^^^^^^^^^^^^^ `Foo` cannot be sent between threads safely
|
= help: the trait `std::marker::Send` is not implemented for `Foo`
```
```
error[E0277]: can't compare `{integer}` with `std::string::String`
--> $DIR/binops.rs:16:7
|
LL | 5 < String::new();
| ^ no implementation for `{integer} < std::string::String` and `{integer} > std::string::String`
|
= help: the trait `std::cmp::PartialOrd<std::string::String>` is not implemented for `{integer}`
```
```
error[E0277]: can't compare `{integer}` with `std::result::Result<{integer}, _>`
--> $DIR/binops.rs:17:7
|
LL | 6 == Ok(1);
| ^^ no implementation for `{integer} == std::result::Result<{integer}, _>`
|
= help: the trait `std::cmp::PartialEq<std::result::Result<{integer}, _>>` is not implemented for `{integer}`
```
```
error[E0277]: a collection of type `i32` cannot be built from an iterator over elements of type `i32`
--> $DIR/type-check-defaults.rs:16:19
|
LL | struct WellFormed<Z = Foo<i32, i32>>(Z);
| ^ a collection of type `i32` cannot be built from `std::iter::Iterator<Item=i32>`
|
= help: the trait `std::iter::FromIterator<i32>` is not implemented for `i32`
note: required by `Foo`
--> $DIR/type-check-defaults.rs:15:1
|
LL | struct Foo<T, U: FromIterator<T>>(T, U);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
* [Add link to book for `Sized` errors](https://github.com/rust-lang/rust/pull/51463/commits/1244dc7c283323aea1a3457a4458d590a3e160c8):
```
error[E0277]: `std::fmt::Debug + std::marker::Sync + 'static` does not have a constant size known at compile-time
--> $DIR/const-unsized.rs:13:29
|
LL | const CONST_0: Debug+Sync = *(&0 as &(Debug+Sync));
| ^^^^^^^^^^^^^^^^^^^^^^ `std::fmt::Debug + std::marker::Sync + 'static` does not have a constant size known at compile-time
|
= help: the trait `std::marker::Sized` is not implemented for `std::fmt::Debug + std::marker::Sync + 'static`
= note: to learn more, visit <https://doc.rust-lang.org/book/second-edition/ch19-04-advanced-types.html#dynamically-sized-types--sized>
= note: constant expressions must have a statically known size
```
* [Point to previous line for single expected token not found](https://github.com/rust-lang/rust/pull/51463/commits/48165168fb0f059d8536cd4a2276b609d4a7f721) (if the current token is in a different line)
