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use visitor for contains_self |
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util | ||
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Cargo.toml | ||
CONTRIBUTING.md | ||
README.md |
A collection of lints to catch common mistakes and improve your Rust code.
##Lints There are 73 lints included in this crate:
name | default | meaning |
---|---|---|
approx_constant | warn | the approximate of a known float constant (in std::f64::consts or std::f32::consts ) is found; suggests to use the constant |
bad_bit_mask | warn | expressions of the form _ & mask == select that will only ever return true or false (because in the example select containing bits that mask doesn't have) |
box_vec | warn | usage of Box<Vec<T>> , vector elements are already on the heap |
cast_possible_truncation | allow | casts that may cause truncation of the value, e.g x as u8 where x: u32 , or x as i32 where x: f32 |
cast_possible_wrap | allow | casts that may cause wrapping around the value, e.g x as i32 where x: u32 and x > i32::MAX |
cast_precision_loss | allow | casts that cause loss of precision, e.g x as f32 where x: u64 |
cast_sign_loss | allow | casts from signed types to unsigned types, e.g x as u32 where x: i32 |
cmp_nan | deny | comparisons to NAN (which will always return false, which is probably not intended) |
cmp_owned | warn | creating owned instances for comparing with others, e.g. x == "foo".to_string() |
collapsible_if | warn | two nested if -expressions can be collapsed into one, e.g. if x { if y { foo() } } can be written as if x && y { foo() } |
empty_loop | warn | empty loop {} detected |
eq_op | warn | equal operands on both sides of a comparison or bitwise combination (e.g. x == x ) |
explicit_counter_loop | warn | for-looping with an explicit counter when _.enumerate() would do |
explicit_iter_loop | warn | for-looping over _.iter() or _.iter_mut() when &_ or &mut _ would do |
float_cmp | warn | using == or != on float values (as floating-point operations usually involve rounding errors, it is always better to check for approximate equality within small bounds) |
identity_op | warn | using identity operations, e.g. x + 0 or y / 1 |
ineffective_bit_mask | warn | expressions where a bit mask will be rendered useless by a comparison, e.g. `(x |
inline_always | warn | #[inline(always)] is a bad idea in most cases |
iter_next_loop | warn | for-looping over _.next() which is probably not intended |
len_without_is_empty | warn | traits and impls that have .len() but not .is_empty() |
len_zero | warn | checking .len() == 0 or .len() > 0 (or similar) when .is_empty() could be used instead |
let_and_return | warn | creating a let-binding and then immediately returning it like let x = expr; x at the end of a block |
let_unit_value | warn | creating a let binding to a value of unit type, which usually can't be used afterwards |
linkedlist | warn | usage of LinkedList, usually a vector is faster, or a more specialized data structure like a VecDeque |
map_clone | warn | using `.map( |
match_bool | warn | a match on boolean expression; recommends if..else block instead |
match_ref_pats | warn | a match has all arms prefixed with & ; the match expression can be dereferenced instead |
min_max | warn | min(_, max(_, _)) (or vice versa) with bounds clamping the result to a constant |
modulo_one | warn | taking a number modulo 1, which always returns 0 |
mut_mut | allow | usage of double-mut refs, e.g. &mut &mut ... (either copy'n'paste error, or shows a fundamental misunderstanding of references) |
mutex_atomic | warn | using a Mutex where an atomic value could be used instead |
mutex_integer | allow | using a Mutex for an integer type |
needless_bool | warn | if-statements with plain booleans in the then- and else-clause, e.g. if p { true } else { false } |
needless_lifetimes | warn | using explicit lifetimes for references in function arguments when elision rules would allow omitting them |
needless_range_loop | warn | for-looping over a range of indices where an iterator over items would do |
needless_return | warn | using a return statement like return expr; where an expression would suffice |
needless_update | warn | using { ..base } when there are no missing fields |
no_effect | warn | statements with no effect |
non_ascii_literal | allow | using any literal non-ASCII chars in a string literal; suggests using the \u escape instead |
nonsensical_open_options | warn | nonsensical combination of options for opening a file |
option_unwrap_used | allow | using Option.unwrap() , which should at least get a better message using expect() |
precedence | warn | catches operations where precedence may be unclear. See the wiki for a list of cases caught |
ptr_arg | warn | fn arguments of the type &Vec<...> or &String , suggesting to use &[...] or &str instead, respectively |
range_step_by_zero | warn | using Range::step_by(0), which produces an infinite iterator |
range_zip_with_len | warn | zipping iterator with a range when enumerate() would do |
redundant_closure | warn | using redundant closures, i.e. ` |
redundant_pattern | warn | using name @ _ in a pattern |
result_unwrap_used | allow | using Result.unwrap() , which might be better handled |
reverse_range_loop | warn | Iterating over an empty range, such as 10..0 or 5..5 |
shadow_reuse | allow | rebinding a name to an expression that re-uses the original value, e.g. let x = x + 1 |
shadow_same | allow | rebinding a name to itself, e.g. let mut x = &mut x |
shadow_unrelated | allow | The name is re-bound without even using the original value |
should_implement_trait | warn | defining a method that should be implementing a std trait |
single_match | warn | a match statement with a single nontrivial arm (i.e, where the other arm is _ => {} ) is used; recommends if let instead |
str_to_string | warn | using to_string() on a str, which should be to_owned() |
string_add | allow | using x + .. where x is a String ; suggests using push_str() instead |
string_add_assign | allow | using x = x + .. where x is a String ; suggests using push_str() instead |
string_to_string | warn | calling String.to_string() which is a no-op |
temporary_assignment | warn | assignments to temporaries |
toplevel_ref_arg | warn | An entire binding was declared as ref , in a function argument (fn foo(ref x: Bar) ), or a let statement (let ref x = foo() ). In such cases, it is preferred to take references with & . |
type_complexity | warn | usage of very complex types; recommends factoring out parts into type definitions |
unicode_not_nfc | allow | using a unicode literal not in NFC normal form (see http://www.unicode.org/reports/tr15/ for further information) |
unit_cmp | warn | comparing unit values (which is always true or false , respectively) |
unnecessary_mut_passed | warn | an argument is passed as a mutable reference although the function/method only demands an immutable reference |
unstable_as_mut_slice | warn | as_mut_slice is not stable and can be replaced by &mut v[..]see https://github.com/rust-lang/rust/issues/27729 |
unstable_as_slice | warn | as_slice is not stable and can be replaced by & v[..]see https://github.com/rust-lang/rust/issues/27729 |
unused_collect | warn | collect() ing an iterator without using the result; this is usually better written as a for loop |
while_let_loop | warn | loop { if let { ... } else break } can be written as a while let loop |
while_let_on_iterator | warn | using a while-let loop instead of a for loop on an iterator |
wrong_pub_self_convention | allow | defining a public method named with an established prefix (like "into_") that takes self with the wrong convention |
wrong_self_convention | warn | defining a method named with an established prefix (like "into_") that takes self with the wrong convention |
zero_divided_by_zero | warn | usage of 0.0 / 0.0 to obtain NaN instead of std::f32::NaN or std::f64::NaN |
zero_width_space | deny | using a zero-width space in a string literal, which is confusing |
More to come, please file an issue if you have ideas!
##Usage
Compiler plugins are highly unstable and will only work with a nightly Rust for now. Since stable Rust is backwards compatible, you should be able to compile your stable programs with nightly Rust with clippy plugged in to circumvent this.
Add in your Cargo.toml
:
[dependencies]
clippy = "*"
You may also use cargo clippy
, a custom cargo subcommand that runs clippy on a given project.
Sample main.rs
:
#![feature(plugin)]
#![plugin(clippy)]
fn main(){
let x = Some(1u8);
match x {
Some(y) => println!("{:?}", y),
_ => ()
}
}
Produces this warning:
src/main.rs:8:5: 11:6 warning: you seem to be trying to use match for destructuring a single type. Consider using `if let`, #[warn(single_match)] on by default
src/main.rs:8 match x {
src/main.rs:9 Some(y) => println!("{:?}", y),
src/main.rs:10 _ => ()
src/main.rs:11 }
src/main.rs:8:5: 11:6 help: Try
if let Some(y) = x { println!("{:?}", y) }
You can add options to allow
/warn
/deny
:
- the whole set of
Warn
lints using theclippy
lint group (#![deny(clippy)]
) - all lints using both the
clippy
andclippy_pedantic
lint groups (#![deny(clippy)]
,#![deny(clippy_pedantic)]
). Note thatclippy_pedantic
contains some very aggressive lints prone to false positives. - only some lints (
#![deny(single_match, box_vec)]
, etc) allow
/warn
/deny
can be limited to a single function or module using#[allow(...)]
, etc
Note: deny
produces errors instead of warnings
To have cargo compile your crate with clippy without needing #![plugin(clippy)]
in your code, you can use:
cargo rustc -- -L /path/to/clippy_so -Z extra-plugins=clippy
Note: Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
If you want to make clippy an optional dependency, you can do the following:
In your Cargo.toml
:
[dependencies]
clippy = {version = "*", optional = true}
[features]
default=[]
And, in your main.rs
or lib.rs
:
#![cfg_attr(feature="clippy", feature(plugin))]
#![cfg_attr(feature="clippy", plugin(clippy))]
##License Licensed under MPL. If you're having issues with the license, let me know and I'll try to change it to something more permissive.