Add map_err_ignore lint
In a large code base a lot of times errors are ignored by using something like:
```rust
foo.map_err(|_| Some::Enum)?;
```
This drops the original error in favor of a enum that will not have the original error's context. This lint helps catch throwing away the original error in favor of an enum without its context.
---
*Please keep the line below*
changelog: Added map_err_ignore lint
Add a new lint, `manual-strip`, that suggests using the `str::strip_prefix`
and `str::strip_suffix` methods introduced in Rust 1.45 when the same
functionality is performed 'manually'.
Closes#5734
Add lint panic in result
### Change
Adding a new "restriction" lint that will emit a warning when using "panic", "unimplemented" or "unreachable" in a function of type option/result.
### Motivation
Some codebases must avoid crashes at all costs, and hence functions of type option/result must return an error instead of crashing.
### Test plan
Running:
TESTNAME=panic_in_result cargo uitest ---
changelog: none
This catches bugs of the form
tokio::spawn(async move {
let f = some_async_thing();
f // Oh no I forgot to await f so that work will never complete.
});
Warn about assignments where left-hand side place expression is the same
as right-hand side value expression. For example, warn about assignment in:
```rust
pub struct Event {
id: usize,
x: i32,
y: i32,
}
pub fn copy_position(a: &mut Event, b: &Event) {
a.x = b.x;
a.y = a.y;
}
```
This lint catches cases where the last statement of a closure expecting
an instance of Ord has a trailing semi-colon. It compiles since the
closure ends up return () which also implements Ord but causes
unexpected results in cases such as sort_by_key.
Fixes#5080
reprise: rebase, update and address all concerns
Move range_minus_one to pedantic
This moves the range_minus_one lint to the pedantic category, so there
will not be any warnings emitted by default. This should work around
problems where the suggestion is impossible to resolve due to the range
consumer only accepting a specific range implementation, rather than the
`RangeBounds` trait (see #3307).
While it is possible to work around this by extracting the boundary into
a variable, I don't think clippy should encourage people to disable or
work around lints, but instead the lints should be fixable. So hopefully
this will help until a proper implementation checks what the range is
used for.
*Please keep the line below*
changelog: move [`range_minus_one`] to pedantic
Added restriction lint: pattern-type-mismatch
changelog: Added a new restriction lint `pattern-type-mismatch`. This lint is especially helpful for beginners learning about the magic behind pattern matching. (This explanation might be worth to include in the next changelog.)
#5626: lint iterator.map(|x| x)
changelog: adds a new lint for iterator.map(|x| x) (see https://github.com/rust-lang/rust-clippy/issues/5626)
The code also lints for result.map(|x| x) and option.map(|x| x). Also, I'm not sure if I'm checking for type adjustments correctly and I can't think of an example where .map(|x| x) would apply type adjustments.
let_and_return: avoid "does not live long enough" errors
EDIT: Add #3324 to the list of fixes
<details>
<summary>Description of old impl</summary>
<br>
Avoid suggesting turning the RHS expression of the last statement into the block tail expression if a temporary borrows from a local that would be destroyed before.
This is my first incursion into MIR so there's probably room for improvement!
</details>
Avoid linting if the return type of some method or function called in the last statement has a lifetime parameter.
changelog: Fix false positive in [`let_and_return`]
Fixes#3792Fixes#3324
New lint: iter_next_slice
Hello, this is a work-in-progress PR for issue: https://github.com/rust-lang/rust-clippy/issues/5572
I have implemented lint to replace `iter().next()` for `slice[index..]` and `array` with `get(index)` and `get(0)` respectively. However since I made a lot of changes, I would like to request some feedback before continuing so that I could fix mistakes.
Thank you!
---
changelog: implement `iter_next_slice` lint and test, and modify `needless_continues`, `for_loop_over_options_result` UI tests since they have `iter().next()`
New lint: `match_wildcard_for_single_variants`
changelog: Added a new lint match_wildcard_for_single_variants to warn on enum matches where a wildcard is used to match a single variant
Closes#5556
Rename lint `identity_conversion` to `useless_conversion`
Lint name `identity_conversion` was misleading, so this PR renames it to `useless_conversion`.
As decision has not really came up in the issue comments, this PR will probably need discussion.
fixes#3106
changelog: Rename lint `identity_conversion` to `useless_conversion`
Merge some lints together
This PR merges following lints:
- `block_in_if_condition_expr` and `block_in_if_condition_stmt` → `blocks_in_if_conditions`
- `option_map_unwrap_or`, `option_map_unwrap_or_else` and `result_map_unwrap_or_else` → `map_unwrap`
- `option_unwrap_used` and `result_unwrap_used` → `unwrap_used`
- `option_expect_used` and `result_expect_used` → `expect_used`
- `wrong_pub_self_convention` into `wrong_self_convention`
- `for_loop_over_option` and `for_loop_over_result` → `for_loops_over_fallibles`
Lints that have already been merged since the issue was created:
- [x] `new_without_default` and `new_without_default_derive` → `new_without_default`
Need more discussion:
- `string_add` and `string_add_assign`: do we agree to merge them or not? Is there something more to do? → **not merge finally**
- `identity_op` and `modulo_one` → `useless_arithmetic`: seems outdated, since `modulo_arithmetic` has been created.
fixes#1078
changelog: Merging some lints together:
- `block_in_if_condition_expr` and `block_in_if_condition_stmt` → `blocks_in_if_conditions`
- `option_map_unwrap_or`, `option_map_unwrap_or_else` and `result_map_unwrap_or_else` → `map_unwrap_or`
- `option_unwrap_used` and `result_unwrap_used` → `unwrap_used`
- `option_expect_used` and `result_expect_used` → `expect_used`
- `for_loop_over_option` and `for_loop_over_result` → `for_loops_over_fallibles`
Implement the manual_non_exhaustive lint
Some implementation notes:
* Not providing automatic fixups because additional changes may be needed in other parts of the code, e.g. when constructing a struct.
* Even though the attribute is valid on enum variants, it's not possible to use the manual implementation of the pattern because the visibility is always public, so the lint ignores enum variants.
* Unit structs are also ignored, it's not possible to implement the pattern manually without fields.
* The attribute is not accepted in unions, so those are ignored too.
* Even though the original issue did not mention it, tuple structs are also linted because it's possible to apply the pattern manually.
changelog: Added the manual non-exhaustive implementation lint
Closes#2017
New lint `match_vec_item`
Added new lint to warn a match on index item which can panic. It's always better to use `get(..)` instead.
Closes#5500
changelog: New lint `match_on_vec_items`
Fixes#4226
This introduces the lint await_holding_lock. For async functions, we iterate
over all types in generator_interior_types and look for types named MutexGuard,
RwLockReadGuard, or RwLockWriteGuard. If we find one then we emit a lint.
If let else mutex
changelog: Adds lint to catch incorrect use of `Mutex::lock` in `if let` expressions with lock calls in any of the blocks.
closes: #5219
Add lint on large non scalar const
This PR adds the new lint `non_scalar_const` that aims to warn against `const` declaration of large arrays. For performance, because of inlining, large arrays should be preferably declared as `static`.
Note: i made this one to warn on all const arrays, whether they are in a body function or not. I don't know if this is really necessary, i could just reduce this lint to variables out of function scope.
Fixes: #400
changelog: add new lint for large non-scalar types declared as const
Downgrade implicit_hasher to pedantic
From the [documentation](https://rust-lang.github.io/rust-clippy/master/index.html#implicit_hasher), this lint is intended to suggest:
```diff
- pub fn foo(map: &mut HashMap<i32, i32>) { }
+ pub fn foo<S: BuildHasher>(map: &mut HashMap<i32, i32, S>) { }
```
I think this is pedantic. I get that this lint can benefit core libraries like serde, but that's exactly the use case for pedantic lints; a library like serde will [enable clippy_pedantic](fd6741f4b0/src/lib.rs (L304)) and take the time to go through everything possible. Similar for libraries doing a libz blitz style checkup before committing to a 1.0 release; it would make sense to run through all the available pedantic lints then.
But otherwise, for most codebases and certainly for industrial codebases, the above suggested change just makes the codebase more obtuse for questionable benefit.
changelog: Remove implicit_hasher from default set of enabled lints
Downgrade unreadable_literal to pedantic
As motivated by #5418. This is the top most commonly suppressed Clippy style lint, which indicates that the community has decided they don't share Clippy's opinion on the best style of this.
I've left the lint in as pedantic, though it could be that "restriction" would be better -- I can see this lint being useful as an opt-in restriction in some codebases.
changelog: Remove unreadable_literal from default set of enabled lints
Add new lint for `Result<T, E>.map_or(None, Some(T))`
Fixes#5414
PR Checklist
---
- [x] Followed lint naming conventions (the name is a bit awkward, but it seems to conform)
- [x] Added passing UI tests (including committed .stderr file)
- [x] cargo test passes locally
- [x] Executed cargo dev update_lints
- [x] Added lint documentation
- [x] Run cargo dev fmt
`Result<T, E>` has an [`ok()`](https://doc.rust-lang.org/std/result/enum.Result.html#method.ok) method that adapts a `Result<T,E>` into an `Option<T>`.
It's possible to get around this adapter by writing `Result<T,E>.map_or(None, Some)`.
This lint is implemented as a new variant of the existing [`option_map_none` lint](https://github.com/rust-lang/rust-clippy/pull/2128)
Downgrade inefficient_to_string to pedantic
From the [documentation](https://rust-lang.github.io/rust-clippy/master/index.html#inefficient_to_string):
> ```diff
> - ["foo", "bar"].iter().map(|s| s.to_string());
>
> + ["foo", "bar"].iter().map(|&s| s.to_string());
> ```
I feel like saving 10 nanoseconds from the formatting machinery isn't worth asking the programmer to insert extra `&` / `*` noise in the *vast* majority of cases. This is a pedantic lint.
changelog: Remove inefficient_to_string from default set of enabled lints
Downgrade trivially_copy_pass_by_ref to pedantic
The rationale for this lint is documented as:
> In many calling conventions instances of structs will be passed through registers if they fit into two or less general purpose registers.
I think the purported performance benefits of clippy's recommendation are overstated. This isn't worth asking people to sprinkle code with more `*``*``&``*``&` to chase the alleged performance.
This should be a pedantic lint that is disabled by default and opted in if some specific performance sensitive codebase determines that it is worthwhile.
As a reminder, a typical place that a reference to a primitive would come up is if the function is used as a filter. Triggering a performance-oriented lint on this type of code is the definition of pedantic.
```rust
fn filter(_n: &i32) -> bool {
true
}
fn main() {
let v = vec![1, 2, 3];
v.iter().copied().filter(filter).for_each(drop);
}
```
```console
warning: this argument (4 byte) is passed by reference, but would be more efficient if passed by value (limit: 8 byte)
--> src/main.rs:1:15
|
1 | fn filter(_n: &i32) -> bool {
| ^^^^ help: consider passing by value instead: `i32`
```
changelog: Remove trivially_copy_pass_by_ref from default set of enabled lints
Downgrade let_unit_value to pedantic
Given that the false positive in #1502 is marked E-hard and I don't have much hope of it getting fixed, I think it would be wise to disable this lint by default. I have had to suppress this lint in every substantial codebase (\>100k line) I have worked in. Any time this lint is being triggered, it's always the false positive case.
The motivation for this lint is documented as:
> A unit value cannot usefully be used anywhere. So binding one is kind of pointless.
with this example:
> ```rust
> let x = {
> 1;
> };
> ```
Sure, but the author would find this out via an unused_variable warning or from `x` not being the type that they need further down. If there ends up being a type error on `x`, clippy's advice isn't going to help get the code compiling because it can only run if the code already compiles.
changelog: Remove let_unit_value from default set of enabled lints
Result<T, E> has an `ok()` method that adapts a Result<T,E> into an Option<T>.
It's possible to get around this adapter by writing Result<T,E>.map_or(None, Some).
This lint is implemented as a new variant of the existing
[`option_map_none` lint](https://github.com/rust-lang/rust-clippy/pull/2128)
Move verbose_file_reads to restriction
cc #5368
Using `File::read` instead of `fs::read_to_end` does make sense in multiple cases, so this lint is rather restriction, than complexity
changelog: Move [`verbose_file_reads`] to restriction
Lint for `pub(crate)` items that are not crate visible due to the visibility of the module that contains them
changelog: Add `redundant_pub_crate` lint
Closes#5274.
Add lint to detect floating point operations that can be computed more
accurately at the cost of performance. `cbrt`, `ln_1p` and `exp_m1`
library functions call their equivalent cmath implementations which is
slower but more accurate so moving checks for these under this new lint.
Merge the accuracy and efficiency lints into a single lint that
checks for improvements to accuracy, efficiency and readability
of floating-point expressions.
Move check for lossy whole-number floats out of `excessive_precision`
changelog: Add new lint `lossy_float_literal` to detect lossy whole number float literals and move it out of `excessive_precision` again.
Fixes#5201
New lint: pats_with_wild_match_arm
Wildcard use with other pattern in same match arm.
The wildcard covers other(s) pattern(s) as it will match anyway.
changelog: add new lint when multiple patterns (including wildcard) are used in a match arm.
Fixes#4640.
Detect usage of invalid atomic ordering modes such as
`Ordering::{Release, AcqRel}` in atomic loads and
`Ordering::{Acquire, AcqRel}` in atomic stores.
new lint: mutable_key_type
This fixes#732 - well, partly, it doesn't adress `Hash` impls, but the use of mutable types as map keys or set members
changelog: add `mutable_key_type` lint
r? @flip1995
The Rust Book recommends that functions that return a `Result` type have
a doc comment with an `# Errors` section describing the kind of errors
that can be returned
(https://doc.rust-lang.org/book/ch14-02-publishing-to-crates-io.html#commonly-used-sections).
This change adds a lint to enforce this. The lint is allow by default;
it can be enabled with `#![warn(clippy::missing_errors_doc)]`.
Closes#4854.
This utilizes https://github.com/rust-lang/rust/pull/60584 by setting
our own `panic_hook` and pointing to our own issue tracker instead of
the rustc issue tracker.
This also adds a new internal lint to test the ICE message.
**Potential downsides**
* This essentially copies rustc's `report_ice` function as
`report_clippy_ice`. I think that's how it's meant to be implemented, but
maybe @jonas-schievink could have a look as well =)
The downside of more-or-less copying this function is that we have to
maintain it as well now.
The original function can be found [here][original].
* `driver` now depends directly on `rustc` and `rustc_errors`
Closes#2734
[original]: 59367b074f/src/librustc_driver/lib.rs (L1185)
