Fix the bugs of `manual_memcpy`, simplify the suggestion and refactor it
While I’m working on the long procrastinated work to expand `manual_memcpy`(#1670), I found a few minor bugs and probably unidiomatic or old coding style. There is a brief explanation of changes to the behaviour this PR will make below. And, I have a questoin: do I need to add tests for the first and second fixed bugs? I thought it might be too rare cases to include the tests for those. I added for the last one though.
* Bug fix
* It negates resulted offsets (`src/dst_offset`) when `offset` is subtraction by 0. This PR will remove any subtraction by 0 as a part of minification.
```rust
for i in 0..5 {
dst[i - 0] = src[i];
}
```
```diff
warning: it looks like you're manually copying between slices
--> src/main.rs:2:14
|
LL | for i in 0..5 {
- | ^^^^ help: try replacing the loop by: `dst[..-5].clone_from_slice(&src[..5])`
+ | ^^^^ help: try replacing the loop by: `dst[..5].clone_from_slice(&src[..5])`
|
```
* It prints `RangeTo` or `RangeFull` when both of `end` and `offset` are 0, which have different meaning. This PR will print 0. I could reject the cases `end` is 0, but I thought I won’t catch other cases `reverse_range_loop` will trigger, and it’s over to catch every such cases.
```rust
for i in 0..0 {
dst[i] = src[i];
}
```
```diff
warning: it looks like you're manually copying between slices
--> src/main.rs:2:14
|
LL | for i in 0..0 {
- | ^^^^ help: try replacing the loop by: `dst.clone_from_slice(&src[..])`
+ | ^^^^ help: try replacing the loop by: `dst[..0].clone_from_slice(&src[..0])`
|
```
* it prints four dots when `end` is `None`. This PR will ignore any `for` loops without `end` because a `for` loop that takes `RangeFrom` as its argument and contains indexing without the statements or the expressions that end loops such as `break` will definitely panic, and `manual_memcpy` should ignore the loops with such control flow.
```rust
fn manual_copy(src: &[u32], dst: &mut [u32]) {
for i in 0.. {
dst[i] = src[i];
}
}
```
```diff
-warning: it looks like you're manually copying between slices
- --> src/main.rs:2:14
- |
-LL | for i in 0.. {
- | ^^^ help: try replacing the loop by: `dst[....].clone_from_slice(&src[....])`
- |
```
* Simplification of the suggestion
* It prints 0 when `start` or `end` and `offset` are same (from #3323). This PR will use `RangeTo`
changelog: fixed the bugs of `manual_memcpy` and also simplify the suggestion.
Current example is incorrect (or pseudo-code) because a struct name is omitted. I have used the code from the tests instead. Perhaps this example can be made less verbose, but I think it is more convenient to see a "real" code as an example.
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`
- Show just one error message with multiple suggestions in case of
using multiple times an OS in target family position
- Only suggest #[cfg(unix)] when the OS is in the Unix family
- Test all the operating systems
Don't trigger while_let_on_iterator when the iterator is recreated every iteration
r? @phansch
Fixes#1654
changelog: Fix false positive in [`while_let_on_iterator`]
Downgrade match_bool to pedantic
I don't quite buy the justification in https://rust-lang.github.io/rust-clippy/. The justification is:
> It makes the code less readable.
In the Rust codebases I've worked in, I have found people were comfortable using `match bool` (selectively) to make code more readable. For example, initializing struct fields is a place where the indentation of `match` can work better than the indentation of `if`:
```rust
let _ = Struct {
v: {
...
},
w: match doing_w {
true => ...,
false => ...,
},
x: Nested {
c: ...,
b: ...,
a: ...,
},
y: if doing_y {
...
} else { // :(
...
},
z: ...,
};
```
Or sometimes people prefer something a bit less pithy than `if` when the meaning of the bool doesn't read off clearly from the condition:
```rust
if set.insert(...) {
... // ???
} else {
...
}
match set.insert(...) {
// set.insert returns false if already present
false => ...,
true => ...,
}
```
Or `match` can be a better fit when the bool is playing the role more of a value than a branch condition:
```rust
impl ErrorCodes {
pub fn from(b: bool) -> Self {
match b {
true => ErrorCodes::Yes,
false => ErrorCodes::No,
}
}
}
```
And then there's plain old it's-1-line-shorter, which means we get 25% more content on a screen when stacking a sequence of conditions:
```rust
let old_noun = match old_binding.is_import() {
true => "import",
false => "definition",
};
let new_participle = match new_binding.is_import() {
true => "imported",
false => "defined",
};
```
Bottom line is I think this lint fits the bill better as a pedantic lint; I don't think linting on this by default is justified.
changelog: Remove match_bool from default set of enabled lints
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
Fix issue #2907.
Update the "borrow box" lint to avoid recommending the following
conversion:
```
// Old
pub fn f(&mut Box<T>) {...}
// New
pub fn f(&mut T) {...}
```
Given a mutable reference to a box, functions may want to change
"which" object the Box is pointing at.
This change avoids recommending removing the "Box" parameter
for mutable references.
changelog: Don't trigger [`borrow_box`] lint on `&mut Box` references
Cleanup: `node_id` -> `hir_id`
This removes some more `node_id` terminology from Clippy and replaces one occurrence of `as_local_node_id` with `as_local_hir_id`, which should be doing the same for that particular case.
changelog: none
Update the "borrow box" lint to avoid recommending the following
conversion:
```
// Old
pub fn f(&mut Box<T>) {...}
// New
pub fn f(&mut T) {...}
```
Given a mutable reference to a box, functions may want to change
"which" object the Box is pointing at.
This change avoids recommending removing the "Box" parameter
for mutable references.
add lint futures_not_send
changelog: add lint futures_not_send
fixes#5379
~Remark: one thing that can (should?) still be improved is to directly include the error message from the `Send` check so that the programmer stays in the flow. Currently, getting the actual error message requires a restructuring of the code to make the `Send` constraint explicit.~
It now shows all unmet constraints for allowing the Future to be Send.
Fixes issue #4892.
First contribution here 😊 ! Do not hesitate to correct me.
This PR is related to issue #4892 .
# Summary
```rust
-literal.method_call(args)
```
The main idea is to not trigger `clippy::precedence` when the method call is an odd function.
# Example
```rust
// should trigger lint
let _ = -1.0_f64.abs() //precedence of method call abs() and neg ('-') is ambiguous
// should not trigger lint
let _ = -1.0_f64.sin() // sin is an odd function => -sin(x) = sin(-x)
```
# Theory
Rust allows following literals:
- char
- string
- integers
- floats
- byte
- bool
Only integers/floats implements the relevant `std::ops::Neg`.
Following odd functions are implemented on i[8-128] and/or f[32-64]:
- `asin`
- `asinh`
- `atan`
- `atanh`
- `cbrt`
- `fract`
- `round`
- `signum`
- `sin`
- `sinh`
- `tan`
- `tanh `
- `to_degrees`
- `to_radians`
# Implementation
As suggested by `flip1995` in [comment](https://github.com/rust-lang/rust-clippy/issues/4892#issuecomment-568249683), this PR add a whitelist of odd functions and compare method call to the the whitelist before triggering lint.
changelog: Don't trigger [`clippy::precedence`] on odd functions.
question_mark: don't add `as_ref()` for a call expression
If a call returns a `!Copy` value, it does so regardless of whether `as_ref()` is added. For example, `foo.into_option().as_ref()?` can be simplified to `foo.into_option()?`.
---
changelog: Improved `question_mark` lint suggestion so that it doesn't add redundant `as_ref()`
Do not lint in macros for match lints
Don't lint in macros for match lints, more precisely in `check_pat` and `check_local` where it was not the case.
changelog: none
fixes: #5362
large_enum_variant: Report sizes of variants
This reports the sizes of the largest and second-largest variants.
Closes#5459
changelog: `large_enum_variant`: Report the sizes of the largest and second-largest variants.
Disallow bit-shifting in integer_arithmetic
Make the `integer_arithmetic` lint detect all the operations that are defined as being capable of overflow in the [Rust Reference](https://doc.rust-lang.org/reference/expressions/operator-expr.html#overflow), by also linting for bit-shifting operations (`<<`, `>>`).
changelog: Disallow bit-shifting in `integer_arithmetic`
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
Add lint for explicit deref and deref_mut method calls
This PR adds the lint `explicit_deref_method` that suggests replacing `deref()` and `deref_mut()` with `&*a` and `&mut *a`.
It doesn't lint inside macros.
This PR is the continuation of #3258.
changelog: Add lint `explicit_deref_method`.
Fixes: #1566
Add lint for float in array comparison
Fixes#4277
changelog:
- Added new handler for expression of index kind (e.g. `arr[i]`). It returns a constant when both array and index are constant, or when the array is constant and all values are equal.
- Trigger float_cmp and float_cmp_const lint when comparing arrays. Allow for comparison when one of the arrays contains only zeros or infinities.
- Added appropriate tests for such cases.
Refactor: Use rustc's `match_def_path`
This replaces our match_def_path implementation with the rustc one.
Note that we can't just use it in all call sites because of the
`&[&str]` / `&[Symbol]` difference in Clippy/rustc.
changelog: none
This replaces our match_def_path implementation with the rustc one.
Note that we can't just use it in all call sites because of the
`&[&str]` / `&[Symbol]` difference in Clippy/rustc.
Make use of more diagnostic items
This makes use of some (not all) already existing diagnostic items. Specifically:
* 79982a2: `core::mem::uninitialized`, `core::mem::zeroed`, `alloc::sync::Arc`, `alloc::sync::Rc`
* 83874d0: `Option` and `Result`
cc #5393
changelog: none
Fixes#5405: redundant clone false positive with arrays
Check whether slice elements implement Copy before suggesting to drop
the clone method
changelog: add a check for slice indexing on redundant_clone lint
Update documentation for new_ret_no_self
changelog: Update documentation for lint new_ret_no_self to reflect that the return type must only contain `Self`, not be `Self`
The lint was changed to be more lenient than the documentation implies in PR #3338 (Related issue #3313)
Change the existing hex bit mask (`0x1111`) to a binary one (`0b1111`).
The former does not seem to have anything to do with trailing zeros and is
probably a typo.
This change adds a check to the `inconsistent_digit_grouping` to add a check for
NumericLiterals that follow the UUID format of 8-4-4-4-12.
If the NumericLiteral matches the UUID format, no further inconsistent grouping checks
will be performed.
Closes#5431
Check for clone-on-copy in argument positions
Earlier if arguments to method calls matched the above pattern they were
not reported. This patch ensures such arguments are checked as well.
Fixes#5436
changelog: apply clone_on_copy lint to func args as well
Earlier if arguments to method calls matched the above pattern they were
not reported. This patch ensures such arguments are checked as well.
Fixes#5436
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
Check fn header along with decl when suggesting to implement trait
When checking for functions that are potential candidates for trait
implementations check the function header to make sure modifiers like
asyncness, constness and safety match before triggering the lint.
Fixes#5413, #4290
changelog: check fn header along with decl for should_implement_trait
When checking for functions that are potential candidates for trait
implementations check the function header to make sure modifiers like
asyncness, constness and safety match before triggering the lint.
Fixes#5413, #4290
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
Fix update_lints
This fixes a bug in update_lints, where `internal` lints were not registered properly. This also cleans up some code. For example: The code generation functions no longer filter the lints the are given. This is now the task of the caller. This way, it is more obvious in the `replace_in_file` calls which lints will be included in which part of a file.
This also turns the lint modules private. There is no need for them to be public, since shared code should be in the utils module anyway.
And last but not least, this fixes the `register_lints` code generation, so also internal lints get registered.
changelog: none
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)
useless Rc<Rc<T>>, Rc<Box<T>>, Rc<&T>, Box<&T>
refers to #2394
changelog: Add lints for Rc<Rc<T>> and Rc<Box<T>> and Rc<&T>, Box<&T>
this is based on top of another change #5310 so probably should go after that one.
Downgrade option_option to pedantic
Based on a search of my work codebase (\>500k lines) for `Option<Option<`, it looks like a bunch of reasonable uses to me. The documented motivation for this lint is:
> an optional optional value is logically the same thing as an optional value but has an unneeded extra level of wrapping
which seems a bit bogus in practice. For example a typical usage would look like:
```rust
let mut host: Option<String> = None;
let mut port: Option<i32> = None;
let mut payload: Option<Option<String>> = None;
for each field {
match field.name {
"host" => host = Some(...),
"port" => port = Some(...),
"payload" => payload = Some(...), // can be null or string
_ => return error,
}
}
let host = host.ok_or(...)?;
let port = port.ok_or(...)?;
let payload = payload.ok_or(...)?;
do_thing(host, port, payload)
```
This lint seems to fit right in with the pedantic group; I don't think linting on occurrences of `Option<Option<T>>` by default is justified.
---
changelog: Remove option_option from default set of enabled lints
Lint unnamed address comparisons
Functions and vtables have an insignificant address. Attempts to compare such addresses will lead to very surprising behaviour. For example: addresses of different functions could compare equal; two trait object pointers representing the same object and the same type could be unequal.
Lint against unnamed address comparisons to avoid issues like those in rust-lang/rust#69757 and rust-lang/rust#54685.
changelog: New lints: [`fn_address_comparisons`] [#5294](https://github.com/rust-lang/rust-clippy/pull/5294), [`vtable_address_comparisons`] [#5294](https://github.com/rust-lang/rust-clippy/pull/5294)
`unused_self` false positive
fixes#5351
Remove the for loop in `unused_self` so that lint enabled for one method doesn't trigger on another method.
changelog: Fix false positive in `unused_self` around lint gates on impl items
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.
Fix single binding closure
Fix the `match_single_binding` lint when triggered inside a closure.
Fixes: #5347
changelog: Improve suggestion for [`match_single_binding`]
Improvement: Don't show function body in needless_lifetimes
Changes the span on which the lint is reported to point to only the
function return type instead of the entire function body.
Fixes#5284
changelog: none
Extend `redundant_clone` to the case that cloned value is not consumed
Fixes#5303.
---
changelog: Extend `redundant_clone` to the case that cloned value is not consumed
add lint on File::read_to_string and File::read_to_end
Adds lint `verbose_file_reads` which checks for use of File::read_to_end and File::read_to_string.
Closes https://github.com/rust-lang/rust-clippy/issues/4916
changelog: add lint on File::{read_to_end, read_to_string}
redundant_pattern: take binding (ref, ref mut) into account in suggestion
fixes#5271
changelog: redundant_pattern: take binding (ref, ref mut) into account in suggestion (#5271)
Fix match single binding when in a let stmt
Fix bad suggestion when `match_single_binding` lints when inside a local (let) statement.
Fixes#5267
changelog: none
Resolve false positives of unnecessary_cast for non-decimal integers
This PR resolves false positives of `unnecessary_cast` for hexadecimal integers to floats and adds a corresponding test case.
Fixes: #5220
changelog: none
Add lint for .. use in fully binded struct
This PR adds the lint `match-wild-in-fully-binded-struct` to prevent the use of the `..` pattern when all fields of the struct are already binded.
Fixes: #638
changelog: Add [`rest_pat_in_fully_bound_structs`] lint to warn against the use of `..` in fully binded struct
Detect usage of custom floating-point abs implementation
Closes#5224
changelog: Enhance [`suboptimal_flops`] lint to detect manual implementations of the `abs` method
Whitelist unused attribute for use items.
This PR whitelists the `unused` attribute with `use` items and adds a corresponding test case.
Fixes: #5229
changelog: none
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
Make it possible to correctly indent snippet_block snippets
This adds a `indent_relative_to` arg to the `{snippet,expr}_block` functions. This makes it possible to keep the correct indentation of block like suggestions.
In addition, this makes the `trim_multiline` function private and adds a `indent_of` function, to get the indentation of the first line of a span.
The suggestion of `needless_continue` cannot be made auto applicable, since it would be also necessary to remove code following the linted expression. (Well, maybe it is possible, but I don't know how to do it. Expanding the suggestion span to the last expression, that should be removed didn't work)
changelog: Improve suggestions, when blocks of code are involved
