Stabilize `cfg_boolean_literals`
Closes#131204
`@rustbot` labels +T-lang +I-lang-nominated
This will end up conflicting with the test in #138293 so whichever doesn't land first will need updating
--
# Stabilization Report
## General design
### What is the RFC for this feature and what changes have occurred to the user-facing design since the RFC was finalized?
[RFC 3695](https://github.com/rust-lang/rfcs/pull/3695), none.
### What behavior are we committing to that has been controversial? Summarize the major arguments pro/con.
None
### Are there extensions to this feature that remain unstable? How do we know that we are not accidentally committing to those?
None
## Has a call-for-testing period been conducted? If so, what feedback was received?
Yes; only positive feedback was received.
## Implementation quality
### Summarize the major parts of the implementation and provide links into the code (or to PRs)
Implemented in [#131034](https://github.com/rust-lang/rust/pull/131034).
### Summarize existing test coverage of this feature
- [Basic usage, including `#[cfg()]`, `cfg!()` and `#[cfg_attr()]`](6d71251cf9/tests/ui/cfg/true-false.rs)
- [`--cfg=true/false` on the command line being accessible via `r#true/r#false`](6d71251cf9/tests/ui/cfg/raw-true-false.rs)
- [Interaction with the unstable `#[doc(cfg(..))]` feature](https://github.com/rust-lang/rust/tree/6d71251/tests/rustdoc-ui/cfg-boolean-literal.rs)
- [Denying `--check-cfg=cfg(true/false)`](https://github.com/rust-lang/rust/tree/6d71251/tests/ui/check-cfg/invalid-arguments.rs)
- Ensuring `--cfg false` on the command line doesn't change the meaning of `cfg(false)`: `tests/ui/cfg/cmdline-false.rs`
- Ensuring both `cfg(true)` and `cfg(false)` on the same item result in it being disabled: `tests/ui/cfg/both-true-false.rs`
### What outstanding bugs in the issue tracker involve this feature? Are they stabilization-blocking?
The above mentioned issue; it should not block as it interacts with another unstable feature.
### What FIXMEs are still in the code for that feature and why is it ok to leave them there?
None
### Summarize contributors to the feature by name for recognition and assuredness that people involved in the feature agree with stabilization
- `@clubby789` (RFC)
- `@Urgau` (Implementation in rustc)
### Which tools need to be adjusted to support this feature. Has this work been done?
`rustdoc`'s unstable`#[doc(cfg(..)]` has been updated to respect it. `cargo` has been updated with a forward compatibility lint to enable supporting it in cargo once stabilized.
## Type system and execution rules
### What updates are needed to the reference/specification? (link to PRs when they exist)
A few lines to be added to the reference for configuration predicates, specified in the RFC.
This fixes two problems with the autofixes for the `unused_imports`
lint:
- `use std::collections::{HashMap, self as coll};` would suggest, when
`HashMap` is unused, the incorrect `use std::collections::self as coll;`
which does not compile.
- `use std::borrow::{self, Cow};` would suggest, when `self` is unused,
`use std::borrow::{Cow};`, which contains unnecessary brackets.
Lint `#[must_use]` attributes applied to methods in trait impls
The `#[must_use]` attribute has no effect when applied to methods in trait implementations. This PR adds it to the unused `#[must_use]` lint, and cleans the extra attributes in portable-simd and Clippy.
```
error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
--> $DIR/attempted-access-non-fatal.rs:7:15
|
LL | let _ = 2.l;
| ^
|
help: if intended to be a floating point literal, consider adding a `0` after the period and a `f64` suffix
|
LL - let _ = 2.l;
LL + let _ = 2.0f64;
|
```
Make unused_parens's suggestion considering expr's attributes.
For the expr with attributes,
like `let _ = (#[inline] || println!("Hello!"));`,
the suggestion's span should contains the attributes, or the suggestion will remove them.
fixes#129833
For the expr with attributes, like `let _ = (#[inline] || println!("Hello!"));`, the suggestion's span should contains the attributes, or the suggestion will remove them.
fixes#129833
expand: fix minor diagnostics bug
The error mentions `///`, when it's actually `//!`:
```
error[E0658]: attributes on expressions are experimental
--> test.rs:4:9
|
4 | //! wah
| ^^^^^^^
|
= note: see issue https://github.com/rust-lang/rust/issues/15701 <https://github.com/rust-lang/rust/issues/15701> for more information
= help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
= help: `///` is for documentation comments. For a plain comment, use `//`.
```
Some minor (English only) heroics are performed to print error messages
like "5th rule of macro `m` is never used". The form "rule #5 of macro
`m` is never used" is just as good and much simpler to implement.
The error mentions `///`, when it's actually `//!`:
error[E0658]: attributes on expressions are experimental
--> test.rs:4:9
|
4 | //! wah
| ^^^^^^^
|
= note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
= help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
= help: `///` is for documentation comments. For a plain comment, use `//`.
fixes#117448
For example unnecessary imports in std::prelude that can be eliminated:
```rust
use std::option::Option::Some;//~ WARNING the item `Some` is imported redundantly
use std::option::Option::None; //~ WARNING the item `None` is imported redundantly
```
Fix unused_parens issue when cast is followed LT
Fixes#117142
The original check only checks `a as (i32) < 0`, this fix extends it to handle `b + a as (i32) < 0`.
A better way is maybe we suggest `(a as i32) < 0` instead of suppressing the warning, maybe following PR could improve it.
