Move lint level source explanation to the bottom
So, uhhhhh
r? `@estebank`
## User-facing change
"note: `#[warn(...)]` on by default" and such are moved to the bottom of the diagnostic:
```diff
- = note: `#[warn(unsupported_calling_conventions)]` on by default
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #87678 <https://github.com/rust-lang/rust/issues/87678>
+ = note: `#[warn(unsupported_calling_conventions)]` on by default
```
Why warning is enabled is the least important thing, so it shouldn't be the first note the user reads, IMO.
## Developer-facing change
`struct_span_lint` and similar methods have a different signature.
Before: `..., impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>)`
After: `..., impl Into<DiagnosticMessage>, impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>) -> &'b mut DiagnosticBuilder<'a, ()>`
The reason for this is that `struct_span_lint` needs to edit the diagnostic _after_ `decorate` closure is called. This also makes lint code a little bit nicer in my opinion.
Another option is to use `impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>) -> DiagnosticBuilder<'a, ()>` altough I don't _really_ see reasons to do `let lint = lint.build(message)` everywhere.
## Subtle problem
By moving the message outside of the closure (that may not be called if the lint is disabled) `format!(...)` is executed earlier, possibly formatting `Ty` which may call a query that trims paths that crashes the compiler if there were no warnings...
I don't think it's that big of a deal, considering that we move from `format!(...)` to `fluent` (which is lazy by-default) anyway, however this required adding a workaround which is unfortunate.
## P.S.
I'm sorry, I do not how to make this PR smaller/easier to review. Changes to the lint API affect SO MUCH 😢
doc: make the usage of clippy.toml more clear
Added a subsection for it, and move it after `Allowing/denying lints` which is more frequently used.
fix https://github.com/rust-lang/rust-clippy/issues/9265
*Please write a short comment explaining your change (or "none" for internal only changes)*
changelog: none
[`unnecessary_lazy_evaluations`] Do not suggest switching to early evaluation when type has custom `Drop`
fix#9427
changelog: [`unnecessary_lazy_evaluations`] Do not suggest switching to early evaluation when type has custom `Drop`
`Res::SelfTy` currently has two `Option`s. When the second one is `Some`
the first one is never consulted. So we can split it into two variants,
`Res::SelfTyParam` and `Res::SelfTyAlias`, reducing the size of `Res`
from 24 bytes to 12. This then shrinks `hir::Path` and
`hir::PathSegment`, which are the HIR types that take up the most space.
fix [`needless_borrow`], [`explicit_auto_deref`] FPs on unions
fix https://github.com/rust-lang/rust-clippy/issues/9383
changelog: fix [`needless_borrow`] false positive on unions
changelog: fix [`explicit_auto_deref`] false positive on unions
Left a couple debug derived impls on purpose I needed to debug as I don't think it's noise
Don't lint unstable moves in `std_instead_of_core`
Fixes#9515
changelog: [`std_instead_of_core`]: No longer suggests unstable modules such as `core::error`
add `box-default` lint
This adds a `box-default` lint to suggest using `Box::default()` instead of `Box::new(Default::default())`, which offers less moving parts and potentially better performance according to [the perf book](https://nnethercote.github.io/perf-book/standard-library-types.html#box).
---
changelog: add [`box_default`] lint
[`needless_return`] Recursively remove unneeded semicolons
fix#8336,
fix#8156,
fix https://github.com/rust-lang/rust-clippy/issues/7358,
fix#9192,
fix https://github.com/rust-lang/rust-clippy/issues/9503
changelog: [`needless_return`] Recursively remove unneeded semicolons
For now the suggestion about removing the semicolons are hidden because they would be very noisy and should be obvious if the user wants to apply the lint manually instead of using `--fix`. This could be an issue for beginner, but haven't found better way to display it.
[arithmetic-side-effects] Consider references
Takes into consideration integer references like `&i32::MAX` because currently things like `let _ = &1 + 0` trigger the lint.
changelog: FP: [`arithmetic_side_effects`]: Now ignores references
[9507](https://github.com/rust-lang/rust-clippy/pull/9507)
Don't lint `*_interior_mutable_const` on unions due to potential ICE.
fixes#9445
cc rust-lang/rust#101113
This started ICE'ing sometime last month due to stricter UB checks. I'm not sure how we could check the value of a union as MIRI doesn't seem to store which field is currently active.
changelog: Don't ICE on const unions containing a `!Freeze` type.
Silence [`question_mark`] in const context
fix https://github.com/rust-lang/rust-clippy/issues/9175
When `const_try` is stabilised can be turned into a MSRV
changelog: Silence [`question_mark`] in const context
new uninlined_format_args lint to inline explicit arguments
Implement https://github.com/rust-lang/rust-clippy/issues/8368 - a new lint to inline format arguments such as `print!("{}", var)` into `print!("{var}")`.
### Supported cases
code | suggestion | comment
---|---|---
`print!("{}", var)` | `print!("{var}")` | simple variables
`print!("{0}", var)` | `print!("{var}")` | positional variables
`print!("{v}", v=var)` | `print!("{var}")` | named variables
`print!("{0} {0}", var)` | `print!("{var} {var}")` | aliased variables
`print!("{0:1$}", var, width)` | `print!("{var:width$}")` | width support
`print!("{0:.1$}", var, prec)` | `print!("{var:.prec$}")` | precision support
`print!("{:.*}", prec, var)` | `print!("{var:.prec$}")` | asterisk support
### Known Problems
* There may be a false positive if the format string is wrapped in a macro call:
```rust
# let var = 42;
macro_rules! no_param_str { () => { "{}" }; }
macro_rules! pass_through { ($expr:expr) => { $expr }; }
println!(no_param_str!(), var);
println!(pass_through!("{}"), var);
```
* Format string uses an indexed argument that cannot be inlined.
Supporting this case requires re-indexing of the format string.
Until implemented, `print!("{0}={1}", var, 1+2)` should be changed to `print!("{var}={0}", 1+2)` by hand.
changelog: [`uninlined_format_args`]: A new lint to inline format arguments, i.e. `print!("{}", var)` into `print!("{var}")`
Stabilize const `BTree{Map,Set}::new`
The FCP was completed in #71835.
Since `len` and `is_empty` are not const stable yet, this also creates a new feature for them since they previously used the same `const_btree_new` feature.
Implement https://github.com/rust-lang/rust-clippy/issues/8368 - a new
lint to inline format arguments such as `print!("{}", var)` into
`print!("{var}")`.
code | suggestion | comment
---|---|---
`print!("{}", var)` | `print!("{var}")` | simple variables
`print!("{0}", var)` | `print!("{var}")` | positional variables
`print!("{v}", v=var)` | `print!("{var}")` | named variables
`print!("{0} {0}", var)` | `print!("{var} {var}")` | aliased variables
`print!("{0:1$}", var, width)` | `print!("{var:width$}")` | width
support
`print!("{0:.1$}", var, prec)` | `print!("{var:.prec$}")` | precision
support
`print!("{:.*}", prec, var)` | `print!("{var:.prec$}")` | asterisk
support
code | suggestion | comment
---|---|---
`print!("{0}={1}", var, 1+2)` | `print!("{var}={0}", 1+2)` | Format
string uses an indexed argument that cannot be inlined. Supporting this
case requires re-indexing of the format string.
changelog: [`uninlined_format_args`]: A new lint to inline format
arguments, i.e. `print!("{}", var)` into `print!("{var}")`
