part of https://github.com/rust-lang/rust-clippy/issues/9100
The `obfuscated_if_else` lint currently only triggers for the pattern
`.then_some(..).unwrap_or(..)`, but there're other cases where this lint
should be triggered, one of which is `.then(..).unwrap_or(..)`.
changelog: [`obfuscated_if_else`]: trigger lint for the
`.then(..).unwrap_or(..)` pattern as well
changelog: none
`x & 15 == 0` is not equivalent to `x.trailing_zeros() > 4`, as `x =
0b10000` is true for the former and false for the latter.
In fact, clippy itself suggests the following:
```rust
pub fn src(x: i32) -> bool {
x & 15 == 0 // ~error: bit mask could be simplified with a call to `trailing_zeros`
^^^^^^^^^^^ help: try: `x.trailing_zeros() >= 4`
}
```
I ran across this message while writing code and thought it was quite
odd. I've simplified it and hopefully made it clearer for non-native
English speakers.
changelog: clarify message for non-obvious precedence
Without this check, the lint would suggest that
```rust
match test {
true if option == 5 => 10,
_ => 1,
};
```
is replaced by `if test { 10 } else { 1 }`.
changelog: [`match_bool`]: omit suggestion when guards are present in
`match` expression
Before edition 2024, some temporaries used in scrutinees of a `match`
used as the last expression of a block may outlive some referenced local
variables. Prevent those cases from happening by checking that alive
temporaries with significant drop do have a static lifetime.
The check is performed only for edition 2021 and earlier, and for the
last statement if it would become the last expression of the block.
changelog: [`unnecessary_semicolon`]: prevent borrow errors in editions
lower than 2024
r? @y21
Using `Vec::extend(std::iter::repeat_n(item, N))` allows to use the more
natural number of elements to add `N`, as is probably done in the
original loop, instead of computing the difference between the existing
number of elements and the wanted one.
Before MSRV 1.82, the older suggestion to use `Vec::resize()` is still
issued.
Inspired by #6156 (which predates `repeat_n()`).
changelog: [`same_item_push`]: recommend using `Vec::extend()` to extend
a vector
Before edition 2024, some temporaries used in scrutinees in a `match`
used as the last expression of a block may outlive some referenced
local variables. Prevent those cases from happening by checking that
alive temporaries with significant drop do have a static lifetime.
The check is performed only for edition 2021 and earlier, and for the
last statement if it would become the last expression of the block.
- The lint no longer triggers if one of the operands in the boolean
expression comes from a macro expansion.
- Parenthesis are now removed inside the generated block if they are no
longer necessary.
- Error markers have been added.
changelog: [`short_circuit_statement`]: better handling of macros and
better looking suggestions
changelog: none
`x & 15 == 0` is not equivalent to `x.trailing_zeros() > 4`, as `x = 0b10000` is true for
the former and false for the latter.
In fact, clippy itself suggests the following:
```rust
pub fn src(x: i32) -> bool {
x & 15 == 0 // ~error: bit mask could be simplified with a call to `trailing_zeros`
^^^^^^^^^^^ help: try: `x.trailing_zeros() >= 4`
}
```
- The lint no longer triggers if the expression comes from macro
expansion
- Parenthesis are now removed inside the generated block if they are no
longer necessary.
This PR fixes an issue with the `significant_drop_in_scrutinee`, where
the lint generates invalid Rust syntax when suggesting fixes for match
expressions that are part of larger expressions, such as in assignment
contexts. For example:
```rust
let mutex = Mutex::new(State {});
let _ = match mutex.lock().unwrap().foo() {
true => 0,
false => 1,
};
```
would suggest:
```rust
let _ = let value = mutex.lock().unwrap().foo();
match value {
```
With this PR, it now suggests:
```rust
let value = mutex.lock().unwrap().foo();
let _ = match value {
```
closes: #13986
changelog: [`significant_drop_in_scrutinee`] Fix incorrect suggestion
for `significant_drop_in_scrutinee` lint in expression context
Without this check, the lint would suggest that
```rust
match test {
true if option == 5 => 10,
_ => 1,
};
```
is replaced by `if test { 10 } else { 1 }`.
This lint detects and removes the unnecessary semicolon after a `match`
or `if` statement returning `()`. It seems to be quite a common
"mistake", given the number of hits (88) we had in the Clippy sources
themselves.
The lint doesn't bother about loops, as `rustfmt` already removes the
extra semicolon. It doesn't handle blocks either, as an extra block
level, followed or not by a semicolon, is likely intentional.
I propose to put the lint in `pedantic`, as putting it in `style` seems
quite hazardous given the number of hits.
Note: there exists a `redundant-semicolon` lint in the compiler, but it
is an early lint and cannot check that the expression evaluates to `()`,
so it ignores the cases we're handling here.
----
changelog: [`unnecessary_semicolon`]: new lint
A multipart suggestion will be used whenever the method call can be
replaced by another one with the first argument removed. It helps place
the new method call in context, especially when it is part of a larger
expression.
This fixes#13995 by applying a suggestion made by @y21.
r? @y21
changelog: [`unnecessary_map_or`]: better representation of suggestions
by placing them in context
This PR changes literal_string_with_formatting_args category from
`suspicious` to `nursery` since there are thousands of false positive on
GitHub.
Closes#13989 since it's no longer problematic with such false positive
with ~~`pedantic`~~ `nursery` category.
changelog: [`literal_string_with_formatting_args` ] change category to
`nursery` from `suspicious`
A multipart suggestion will be used whenever the method call can be
replaced by another one with the first argument removed. It helps place
the new method call in context, especially when it is part of a larger
expression.
Using `Vec::extend(std::iter::repeat_n(item, N))` allows to use the more
natural number of elements to add `N`, as is probably done in the original
loop, instead of computing the difference between the existing number of
elements and the wanted one.
Before MSRV 1.82, the older suggestion to use `Vec::resize()` is still
issued.
changelog: [`useless-nonzero-new_unchecked`]: new lint
Close#13991
### What it does
Checks for `NonZero*::new_unchecked(<literal>)` being used in a `const`
context.
### Why is this bad?
Using `NonZero*::new_unchecked()` is an `unsafe` function and requires
an `unsafe` context. When used with an
integer literal in a `const` context, `NonZero*::new().unwrap()` will
provide the same result with identical
runtime performances while not requiring `unsafe`.
### Example
```no_run
const PLAYERS: NonZeroUsize = unsafe { NonZeroUsize::new_unchecked(3) };
```
Use instead:
```no_run
const PLAYERS: NonZeroUsize = NonZeroUsize::new(3).unwrap();
```
Commit 9ef6e2199c introduced a check to
ensure that Clippy doesn't consider a lifetime present in an explicit
self types as being the default for an elided output lifetime. For
example, elision did not work in the case like:
```rust
fn func(self: &Rc<Self>, &str) -> &str { … }
```
Since Rust 1.81.0, the lifetime in the self type is now considered the
default for elision. Elision should then be suggested when appropriate.
changelog: [`needless_lifetimes`]: suggest elision of lifetimes present
in explicit self types as well
r? @Alexendoo
because of #8278
Temporaries created inside the expansion of `.await` will be dropped and
need no checking. Looking inside the expansion will trigger false
positives.
changelog: [`significant_drop_in_scrutinee`]: do not falsely warn for
temporaries created by `.await` expansion
Fix#13927
Commit 9ef6e2199c introduced a check to
ensure that Clippy doesn't consider a lifetime present in an explicit
self type as being the default for an elided output lifetime. For
example, elision did not work in the case like:
```rust
fn func(self: &Rc<Self>, &str) -> &str { … }
```
Since Rust 1.81.0, the lifetime in the self type is now considered
the default for elision. Elision should then be suggested when
appropriate.
changelog: [`slow_vector_initialization`]: auto-fix when appropriate
I made a change for `slow_vector_initialization` lint suggestion to use
`vec!` with size and remove the unneeded `resize` (or similar one) call
in #13912, while only the former one was suggested in the previous
implementation. Now, I think this lint can be automatically fixed with
no unnecessary code in some cases. I wrote “in some cases” because if
there are comments between vector declaration and `resize`, Clippy
shouldn't apply auto-fix because the comment may informational.
