This attribute allows to mark default body of a trait function as
unstable. This means that implementing the trait without implementing
the function will require enabling unstable feature.
This is useful in conjunction with `#[rustc_must_implement_one_of]`,
we may want to relax requirements for a trait, for example allowing
implementing either of `PartialEq::{eq, ne}`, but do so in a safe way
-- making implementation of only `PartialEq::ne` unstable.
If part of a feature is stabilized and a new feature is added for the
remaining parts, then the `implied_by` attribute can be used to indicate
which now-stable feature previously contained a item. If the now-stable
feature is still active (if the user has only just updated rustc, for
example) then there will not be an stability error for uses of the item
from the implied feature.
Signed-off-by: David Wood <david.wood@huawei.com>
When an unexpected meta item is provided to `#[stable]`, the diagnostic
lists "since" and "note" as expected meta-items, however the surrounding
code actually expects "feature" and "since".
Signed-off-by: David Wood <david.wood@huawei.com>
Always evaluate all cfg predicate in all() and any()
This pull-request adjust the handling of the `all()` and `any()` to always evaluate every cfg predicate because not doing so result in accepting incorrect `cfg`:
```rust
#[cfg(any(unix, foo::bar))] // Should error on foo::bar, but does not on unix platform (but does on non unix platform)
fn foo1() {}
#[cfg(all(foo, foo::bar))] // Should error on foo::bar, but does not
fn foo2() {}
#[cfg(all(foo::bar, foo))] // Correctly error on foo::bar
fn foo3() {}
#[cfg(any(foo::bar, foo))] // Correctly error on foo::bar
fn foo4() {}
```
This pull-request take the side to directly turn it into a hard error instead of having a future incompatibility lint because the combination to get this incorrect behavior is unusual and highly probable that some code have this without noticing.
A [search](https://cs.github.com/?scopeName=All+repos&scope=&q=lang%3Arust+%2Fany%5C%28%5Ba-zA-Z%5D%2C+%5Ba-zA-Z%5D%2B%3A%3A%5Ba-zA-Z%5D%2B%2F) on Github reveal no such instance nevertheless a Crater run should probably be done before merging this.
This was discover in https://github.com/rust-lang/rust/pull/94175 when trying to lint on the second predicate. Also note that this seems to have being introduce with Rust 1.27.0: https://rust.godbolt.org/z/KnfqKv15f.
r? `@petrochenkov`
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
This keeps `reason` around for the time being. This is necessary to
avoid breakage during the bootstrap process. This change, as a whole,
brings `#[rustc_deprecated]` more in line with `#[deprecated]`.
Improve `--check-cfg` implementation
This pull-request is a mix of improvements regarding the `--check-cfg` implementation:
- Simpler internal representation (usage of `Option` instead of separate bool)
- Add --check-cfg to the unstable book (based on the RFC)
- Improved diagnostics:
* List possible values when the value is unexpected
* Suggest if possible a name or value that is similar
- Add more tests (well known names, mix of combinations, ...)
r? ```@petrochenkov```
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.
