unimplement `PointerLike` for trait objects
Values of type `dyn* PointerLike` or `dyn PointerLike` are not pointer-like so these types should not implement `PointerLike`.
After https://github.com/rust-lang/rust/pull/133226, `PointerLike` allows user implementations, so we can't just mark it with `#[rustc_deny_explicit_impl(implement_via_object = false)]`. Instead, this PR splits the `#[rustc_deny_explicit_impl(implement_via_object = ...)]` attribute into two separate attributes `#[rustc_deny_explicit_impl]` and `#[rustc_do_not_implement_via_object]` so that we opt out of the automatic `impl PointerLike for dyn PointerLike` and still allow user implementations.
For traits that are marked with `#[do_not_implement_via_object]` but not `#[rustc_deny_explicit_impl]` I've also made it possible to add a manual `impl Trait for dyn Trait`. There is no immediate need for this, but it was one line to implement and seems nice to have.
fixes https://github.com/rust-lang/rust/issues/134545
fixes https://github.com/rust-lang/rust/issues/134543
r? `@compiler-errors`
This commit splits the `#[rustc_deny_explicit_impl(implement_via_object = ...)]` attribute
into two attributes `#[rustc_deny_explicit_impl]` and `#[rustc_do_not_implement_via_object]`.
This allows us to have special traits that can have user-defined impls but do not have the
automatic trait impl for trait objects (`impl Trait for dyn Trait`).
Fix logical error with what text is considered whitespace.
There appears to be a logical issue around what counts as leading white-space. There is code which does a subtraction assuming that no errors will be reported inside the leading whitespace. However we compute the length of that whitespace with std::char::is_whitespace and not rustc_lexer::is_whitespace. The former will include a no-break space while later will excluded it. We can only safely make the assumption that no errors will be reported in whitespace if it is all "Rust Standard" whitespace. Indeed an error does occur in unicode whitespace if it contains a no-break space. In that case the subtraction will cause a ICE (for a compiler in debug mode) as described in https://github.com/rust-lang/rust/issues/132918.
The arbitrary self types v2 work introduces a check for shadowed
methods, whereby a method in some "outer" smart pointer type may called
in preference to a method in the inner referent. This is bad if the
outer pointer adds a method later, as it may change behavior, so we
ensure we error in this circumstance.
It was intended that this new shadowing detection system only comes into
play for users who enable the `arbitrary_self_types` feature (or of
course everyone later if it's stabilized). It was believed that the
new deshadowing code couldn't be reached without building the custom
smart pointers that `arbitrary_self_types` enables, and therefore there
was no risk of this code impacting existing users.
However, it turns out that cunning use of `Pin::get_ref` can cause
this type of shadowing error to be emitted now. This commit adds a test
for this case.
Remove a duplicated check that doesn't do anything anymore.
fixes#134005
This code didn't actually `lub` the type of the previous expressions, but just the current type over and over again. Changing it to using the actual expression type does not change anything either, so may as well remove the entire loop.
Arbitrary self types v2 attempts to detect cases where methods in an
"outer" type (e.g. a smart pointer) might "shadow" methods in the
referent.
There are a couple of cases where the current code makes no attempt to
detect such shadowing. Both of these cases only apply if other unstable
features are enabled.
Add a test, mostly for illustrative purposes, so we can see the
shadowing cases that can occur.
Forbid overwriting types in typeck
While trying to figure out some type setting logic in https://github.com/rust-lang/rust/pull/134248 I realized that we sometimes set a type twice. While hopefully that would have been the same type, we didn't ensure that at all and just silently accepted it. So now we reject setting it twice, unless errors are happening, then we don't care.
Best reviewed commit by commit.
No behaviour change is intended.
cleanup region handling: add `LateParamRegionKind`
The second commit is to enable a split between `BoundRegionKind` and `LateParamRegionKind`, by avoiding `BoundRegionKind` where it isn't necessary.
The third comment then adds `LateParamRegionKind` to avoid having the same late-param region for separate bound regions. This fixes#124021.
r? `@compiler-errors`
Point at lint name instead of whole attr for gated lints
```
warning: unknown lint: `test_unstable_lint`
--> $DIR/warn-unknown-unstable-lint-inline.rs:4:10
|
LL | #![allow(test_unstable_lint, another_unstable_lint)]
| ^^^^^^^^^^^^^^^^^^
|
= note: the `test_unstable_lint` lint is unstable
= help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
note: the lint level is defined here
--> $DIR/warn-unknown-unstable-lint-inline.rs:3:9
|
LL | #![warn(unknown_lints)]
| ^^^^^^^^^^^^^
warning: unknown lint: `test_unstable_lint`
--> $DIR/warn-unknown-unstable-lint-inline.rs:4:29
|
LL | #![allow(test_unstable_lint, another_unstable_lint)]
| ^^^^^^^^^^^^^^^^^^^^^
|
= note: the `another_unstable_lint` lint is unstable
= help: add `#![feature(another_unstable_lint)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
```
This is particularly relevant when there are multiple lints in the same `warn` attribute. Pointing at the smaller span makes it clearer which one the warning is complaining about.
Advent of `tests/ui` (misc cleanups and improvements) [3/N]
Part of #133895.
Misc improvements to some ui tests immediately under `tests/ui/`.
Best reviewed commit-by-commit. Each commit's commit message contains further elaboration and rationale for changes.
r? compiler
-Znext-solver: modify candidate preference rules
This implements the design proposed in the FCP in #132325 and matches the old solver behavior. I hope the inline comments are all sufficiently clear, I personally think this is a fairly clear improvement over the existing approach using `fn discard_impls_shadowed_by_env`. This fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/96.
This also fixes#133639 which encounters an ICE in negative coherence when evaluating the where-clause. Given the features required to trigger this ICE 🤷
r? ``@compiler-errors``
Stabilize `#[diagnostic::do_not_recommend]`
This PR seeks to stabilize the `#[diagnostic::do_not_recommend]`attribute.
This attribute was first proposed as `#[do_not_recommend`] attribute in RFC 2397 (https://github.com/rust-lang/rfcs/pull/2397). It gives the crate authors the ability to not suggest to the compiler to not show certain traits in its error messages.
With the presence of the `#[diagnostic]` tool attribute namespace it was decided to move the attribute there, as that lowers the amount of guarantees the compiler needs to give about the exact way this influences error messages. It turns the attribute into a hint which can be ignored. In addition to the original proposed functionality this attribute now also hides the marked trait in help messages ("This trait is implemented by: ").
The attribute does not accept any argument and can only be placed on trait implementations. If it is placed somewhere else a lint warning is emitted and the attribute is otherwise ignored. If an argument is detected a lint warning is emitted and the argument is ignored. This follows the rules outlined by the diagnostic namespace.
This attribute allows crates like diesel to improve their error messages drastically. The most common example here is the following error message:
```
error[E0277]: the trait bound `&str: Expression` is not satisfied
--> /home/weiznich/Documents/rust/rust/tests/ui/diagnostic_namespace/do_not_recommend.rs:53:15
|
LL | SelectInt.check("bar");
| ^^^^^ the trait `Expression` is not implemented for `&str`, which is required by `&str: AsExpression<Integer>`
|
= help: the following other types implement trait `Expression`:
Bound<T>
SelectInt
note: required for `&str` to implement `AsExpression<Integer>`
--> /home/weiznich/Documents/rust/rust/tests/ui/diagnostic_namespace/do_not_recommend.rs:26:13
|
LL | impl<T, ST> AsExpression<ST> for T
| ^^^^^^^^^^^^^^^^ ^
LL | where
LL | T: Expression<SqlType = ST>,
| ------------------------ unsatisfied trait bound introduced here
```
By applying the new attribute to the wild card trait implementation of
`AsExpression` for `T: Expression` the error message becomes:
```
error[E0277]: the trait bound `&str: AsExpression<Integer>` is not satisfied
--> $DIR/as_expression.rs:55:15
|
LL | SelectInt.check("bar");
| ^^^^^ the trait `AsExpression<Integer>` is not implemented for `&str`
|
= help: the trait `AsExpression<Text>` is implemented for `&str`
= help: for that trait implementation, expected `Text`, found `Integer`
```
which makes it much easier for users to understand that they are facing a type mismatch.
Other explored example usages include:
* This standard library error message: https://github.com/rust-lang/rust/pull/128008
* That bevy derived example:
e1f3068995/tests/ui/diagnostic_namespace/do_not_recommend/supress_suggestions_in_help.rs (No
more tuple pyramids)
Fixes#51992
r? ``@compiler-errors``
This PR also adds a few more tests, makes sure that all the tests are run for the old and new trait solver and adds a check that the attribute does not contain arguments.
```
warning: unknown lint: `test_unstable_lint`
--> $DIR/warn-unknown-unstable-lint-inline.rs:4:10
|
LL | #![allow(test_unstable_lint, another_unstable_lint)]
| ^^^^^^^^^^^^^^^^^^
|
= note: the `test_unstable_lint` lint is unstable
= help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
note: the lint level is defined here
--> $DIR/warn-unknown-unstable-lint-inline.rs:3:9
|
LL | #![warn(unknown_lints)]
| ^^^^^^^^^^^^^
warning: unknown lint: `test_unstable_lint`
--> $DIR/warn-unknown-unstable-lint-inline.rs:4:29
|
LL | #![allow(test_unstable_lint, another_unstable_lint)]
| ^^^^^^^^^^^^^^^^^^^^^
|
= note: the `test_unstable_lint` lint is unstable
= help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
note: the lint level is defined here
--> $DIR/warn-unknown-unstable-lint-inline.rs:3:9
|
LL | #![warn(unknown_lints)]
| ^^^^^^^^^^^^^
```
This is particularly relevant when there are multiple lints in the same `warn` attribute. Pointing at the smaller span makes it clearer which one the warning is complaining about.
Clarify the match ergonomics 2024 migration lint's output
This makes a few changes:
- Rather than using the whole pattern as a span for the lint, this collects spans for each problematic default binding mode reset and labels them with why they're problems.
- The lint's suggestions are now verbose-styled, so that it's clear what's being suggested vs. what's problematic.
- The wording is now less technical, and the hard error version of this diagnostic now links to the same reference material as the lint (currently an unwritten page of the edition guide).
I'm not totally confident in the wording or formatting, so I'd appreciate feedback on that in particular. I tried to draw a connection with word choice between the labels and the suggestion, but it might be imprecise, unclear, or cluttered. If so, it might be worth making the labels more terse and adding notes that explain them, but that's harder to read in a way too.
cc ```@Nadrieril``` ```@Jules-Bertholet```
Closes#133854. For reference, the error from that issue becomes:
```
error: pattern uses features incompatible with edition 2024
--> $DIR/remove-me.rs:6:25
|
LL | map.iter().filter(|(&(_x, _y), &_c)| false);
| ^ ^ cannot implicitly match against multiple layers of reference
| |
| cannot implicitly match against multiple layers of reference
|
help: make the implied reference pattern explicit
|
LL | map.iter().filter(|&(&(_x, _y), &_c)| false);
| +
```
This commit seeks to stabilize the `#[diagnostic::do_not_recommend]`
attribute.
This attribute was first proposed as `#[do_not_recommend`] attribute in
RFC 2397 (https://github.com/rust-lang/rfcs/pull/2397). It gives the
crate authors the ability to not suggest to the compiler to not show
certain traits in it's error messages. With the presence of the
`#[diagnostic]` tool attribute namespace it was decided to move the
attribute there, as that lowers the amount of guarantees the compiler
needs to give about the exact way this influences error messages. It
turns the attribute into a hint which can be ignored. In addition to the
original proposed functionality this attribute now also hides the marked
trait in help messages ("This trait is implemented by: ").
The attribute does not accept any argument and can only be placed on
trait implementations. If it is placed somewhere else a lint warning is
emitted and the attribute is otherwise ignored. If an argument is
detected a lint warning is emitted and the argument is ignored. This
follows the rules outlined by the diagnostic namespace.
This attribute allows crates like diesel to improve their error messages
drastically. The most common example here is the following error
message:
```
error[E0277]: the trait bound `&str: Expression` is not satisfied
--> /home/weiznich/Documents/rust/rust/tests/ui/diagnostic_namespace/do_not_recommend.rs:53:15
|
LL | SelectInt.check("bar");
| ^^^^^ the trait `Expression` is not implemented for `&str`, which is required by `&str: AsExpression<Integer>`
|
= help: the following other types implement trait `Expression`:
Bound<T>
SelectInt
note: required for `&str` to implement `AsExpression<Integer>`
--> /home/weiznich/Documents/rust/rust/tests/ui/diagnostic_namespace/do_not_recommend.rs:26:13
|
LL | impl<T, ST> AsExpression<ST> for T
| ^^^^^^^^^^^^^^^^ ^
LL | where
LL | T: Expression<SqlType = ST>,
| ------------------------ unsatisfied trait bound introduced here
```
By applying the new attribute to the wild card trait implementation of
`AsExpression` for `T: Expression` the error message becomes:
```
error[E0277]: the trait bound `&str: AsExpression<Integer>` is not satisfied
--> $DIR/as_expression.rs:55:15
|
LL | SelectInt.check("bar");
| ^^^^^ the trait `AsExpression<Integer>` is not implemented for `&str`
|
= help: the trait `AsExpression<Text>` is implemented for `&str`
= help: for that trait implementation, expected `Text`, found `Integer`
```
which makes it much easier for users to understand that they are facing
a type mismatch.
Other explored example usages included
* This standard library error message: https://github.com/rust-lang/rust/pull/128008
* That bevy derived example:
e1f3068995/tests/ui/diagnostic_namespace/do_not_recommend/supress_suggestions_in_help.rs (No
more tuple pyramids)
Fixes#51992
This PR aims to improve the testing coverage for
`#[diagnostic::do_not_recommend]`. It ensures that all tests are run for
the old and new solver to verify that the behaviour is the same for both
variants. It also adds two new tests:
* A test with 4 traits having wild card impl for each other, with
alternating `#[diagnostic::do_not_recommend]` attributse
* A test with a lifetime dependend wild card impl, which is something
that's not supported yet
bootstrap: use specific-purpose ui test path for `test_valid` self-test
I wanted to move some ui tests around in #134418, which broke `test_valid` since it was referencing two non-specific-purpose ui tests. This PR instead adds two dummy tests under `tests/ui/bootstrap/self-test/`, for that purpose specifically.
r? bootstrap
- Move `tests/ui/attrs-resolution.rs` to `tests/ui/resolve/`.
- Document test intent.
- Rename test to `non-macro-attrs-accepted.rs` to better reflect test
intent.
- Move `tests/ui/attrs-resolution-errors.rs` to `tests/ui/resolve/`.
- Document test intent.
- Rename test to `attr-macros-positional-rejection.rs` to better reflect
test intent.
- Move `tests/ui/attr-usage-inline.rs` to `tests/ui/attributes/inline/`.
- Briefly document test intent.
- Drop unnecessary `#[allow(dead_code)]` as this is allowed-by-default
for ui test suite.
- Move `tests/ui/attr-shebang.rs` to `tests/ui/attributes/`.
- Downgrade test to `check-pass`, this would fail very early if the
parser did not accept `#![..]` attributes.
- Briefly document test intent.
