mention lint group in default level lint note
### Summary
This PR updates lint diagnostics so that default-level notes now mention the lint group they belong to, if any.
Fixes: rust-lang/rust#65464.
### Example
```rust
fn main() {
let x = 5;
}
```
Before:
```
= note: `#[warn(unused_variables)]` on by default
```
After:
```
= note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
```
### Unchanged Cases
Messages remain the same when the lint level is explicitly set, e.g.:
* Attribute on the lint `#[warn(unused_variables)]`:
```
note: the lint level is defined here
LL | #[warn(unused_variables)]
| ^^^^^^^^^^^^^^^^
```
* Attribute on the group `#[warn(unused)]:`:
```
= note: `#[warn(unused_variables)]` implied by `#[warn(unused)]`
```
* CLI option `-W unused`:
```
= note: `-W unused-variables` implied by `-W unused`
= help: to override `-W unused` add `#[allow(unused_variables)]`
```
* CLI option `-W unused-variables`:
```
= note: requested on the command line with `-W unused-variables`
```
Fix suggestion spans inside macros for the `unused_must_use` lint
This PR fixes the suggestion spans inside macros for the `unused_must_use` lint by trying to find the oldest ancestor span.
Fixes https://github.com/rust-lang/rust/issues/143025
Allow `#![doc(test(attr(..)))]` everywhere
This PR adds the ability to specify [`#![doc(test(attr(..)))]`](https://doc.rust-lang.org/nightly/rustdoc/write-documentation/the-doc-attribute.html#testattr) ~~at module level~~ everywhere in addition to allowing it at crate-root.
This is motivated by a recent PR #140323 (by ````@tgross35)```` where we have to duplicate 2 attributes to every single `f16` and `f128` doctests, by allowing `#![doc(test(attr(..)))]` at module level (and everywhere else) we can omit them entirely and just have (in both module):
```rust
#![doc(test(attr(feature(cfg_target_has_reliable_f16_f128))))]
#![doc(test(attr(expect(internal_features))))]
```
Those new attributes are appended to the one found at crate-root or at a previous module. Those "global" attributes are compatible with merged doctests (they already were before).
Given the small addition that this is, I'm proposing to insta-stabilize it, but I can feature-gate it if preferred.
Best reviewed commit by commit.
r? ````@GuillaumeGomez````
PR 138515, we insert a placeholder attribute so that checks for attributes can still know about the placement of `cfg` attributes. When we suggest removing items with `cfg_attr`s (fix Issue 56328) and make them verbose. We tweak the wording of the existing "unused `extern crate`" lint.
```
warning: unused extern crate
--> $DIR/removing-extern-crate.rs:9:1
|
LL | extern crate removing_extern_crate as foo;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/removing-extern-crate.rs:6:9
|
LL | #![warn(rust_2018_idioms)]
| ^^^^^^^^^^^^^^^^
= note: `#[warn(unused_extern_crates)]` implied by `#[warn(rust_2018_idioms)]`
help: remove the unused `extern crate`
|
LL - #[cfg_attr(test, macro_use)]
LL - extern crate removing_extern_crate as foo;
LL +
|
```
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.
