This lint detects inefficient or useless `{std,core}::mem::swap()` calls
such as:
```rust
// Should be `a = temp();`
swap(&mut a, &mut temp());
// Should be `*b = temp();`
swap(b, &mut temp());
// Should be `temp1(); temp2();` if we want to keep the side effects
swap(&mut temp1(), &mut temp2());
```
It also takes care of using a form appropriate for a `()` context if
`swap()` is part of a larger expression (don't ask me why this wouldn't
happen, I have no idea), by suggesting `{ x = y; }` (statement in block)
or `{std,core}::mem::drop((temp1(), temp2())`.
changelog: [`swap_with_temporary`]: new lint
Close#1968
This PR has started as an effort to proceed from the feedback in
rust-lang/rust-clippy#12861.
- Checks test functions (functions marked with `#[test]` annotation) for
redundant "test_" prefix.
- Auto-fix is supported (and handles collisions gracefully, see below).
- If removing "test_" prefix from, say, `test_foo()` results in a name
collision (either because function `foo()` is already defined within the
current scope, or because the `foo()` call exists within function --
thus creating an unwanted recursion), lint suggests function rename,
warning the user that a simple trimming of `test_` prefix will result in
a name collision.
- If removing "test_" prefix results in invalid identifier (consider
`test_const`, `test_`, `test_42`), then again no auto-fix is suggested,
user is asked to rename function, with a note that a simple prefix
trimming will result in an invalid function name.
(`Applicability::HasPlaceholders` is used and user is suggested to: drop
`test_` prefix + add `_works` suffix, i.e. `test_foo` becomes
`foo_works` -- but again, user has to apply those changes manually).
- If trimmed version of the function name is a valid identifier, doesn't
result in name collision or unwanted recursion, then user is able to run
auto-fix.
fixesrust-lang/rust-clippy#8931
changelog: new lint: [`redundant_test_prefix`]
This lint does more harm than good: in its description, it proposes to
rewrite `match` on `Vec<_>` indexes or slices by a version which cannot
panic but masks the failure by choosing the default variant.
The `clippy::indexing_slicing` restriction lint covers those cases more
safely, by suggesting to use a non-panicking version to retrieve the
value from the container, without suggesting to fallback to the default
success variant in case of failure.
This PR is an (opposite) alternative to #14208 (which will add a
suggestion to the lint matching the lint description). Discussion on
both PRs can be found [on
Zulip](https://rust-lang.zulipchat.com/#narrow/channel/257328-clippy/topic/Suggestions.20that.20suppress.20panics).
changelog: [`match_on_vec_items`]: deprecate lint
changelog: [`manual_abs_diff`]: Initial implementation
Hey, first time writing a new lint for clippy, hope I got it right. I
think it's pretty self-explanatory!
Added a few `fixme` test cases, where the lint can be improved to catch
more (probably rare) patterns, but opening a PR with this initial
implementation to make sure I'm on the right track, and that this lint
is acceptable at all.
😁
This lint does more harm than good: in its description, it proposes to
rewrite `match` on `Vec<_>` indexes or slices by a version which cannot
panic but masks the failure by choosing the default variant.
The `clippy::indexing_slicing` restriction lint covers those cases more
safely, by suggesting to use a non-panicking version to retrieve the
value from the container, without suggesting to fallback to the default
success variant in case of failure.
Both lints share a lot of characteristics but were implemented in
unrelated ways. This unifies them, saving around 100 SLOC in the
process, and making one more test trigger the lint. Also, this removes
useless blocks in suggestions.
Fixes https://github.com/rust-lang/rust-clippy/issues/12163
I decided to initially make this a restriction lint because it felt a
bit niche and opinionated to be a warn-by-default style lint. It may be
appropriate as a style lint if the standard or convention *is* to use
`\` as doc comment linebreaks - not sure if they are!
The wording on the help message could be improved, as well as the name
of the lint itself since it's a bit wordy - suggestions welcome.
This lint works on both `///` and `//!` doc comments.
changelog: new lint: `doc_comment_double_space_linebreaks`
fix typo
change replacement character in example, remove extraneous space from suggested change
add additional testcases; check doc comment not from expansion
do not lint on macros, add more testcases
fix wording, remove commented out code, add additonal testcase
uibless
fix doc comments, use optional snippets
Remove unneeded additional space
Checks for functions with method calls to `.map(_)` on an arg of type
`Option` as the outermost expression.
Fixes#774
```
changelog: [`single_option_map`]: Checks for functions with method calls to `.map(_)` on an arg of type `Option` as the outermost expression.
```
While extending the `option_map_or_err_ok` lint (warn by default,
"style") to recognize η-expanded forms of `Ok`, as in
```rust
// Should suggest `opt.ok_or("foobar")`
let _ = opt.map_or(Err("foobar"), |x| Ok(x));
```
I discovered that the `manual_ok_or` lint (allow by default, "pedantic")
already covered exactly the cases handled by `option_map_or_err_ok`,
including the one I was adding. Apparently, `option_map_or_err_ok` was
added without realizing that the lint already existed under the
`manual_ok_or` name. As a matter of fact, artifacts of this second lint
were even present in the first lint `stderr` file and went unnoticed for
more than a year.
This PR:
- deprecates `option_map_or_err_ok` with a message saying to use
`manual_ok_or`
- moves `manual_ok_or` from "pedantic" to "style" (the category in which
`option_map_or_err_ok` was)
In addition, I think that this lint, which is short, machine applicable,
and leads to shorter and clearer code with less arguments (`Ok`
disappears) and the removal of one level of call (`Err(x)` is replaced
by `x`), is a reason by itself to be in "style".
changelog: [`option_map_or_err_ok` and `manual_ok_or`]: move
`manual_ok_or` from "pedantic" to "style", and deprecate the redundant
style lint `option_map_or_err_ok`.
Hey folks. It's been a while since I added the `as_slice` method to
`Option`, and I totally forgot about a lint to suggest it. Well, I had
some time around Christmas, so here it is now.
---
changelog: add [`manual_option_as_slice`] lint
