README.md

   1 # rust-clippy
   2
   3 [![Build Status](https://travis-ci.org/Manishearth/rust-clippy.svg?branch=master)](https://travis-ci.org/Manishearth/rust-clippy)
   4 [![Clippy Linting Result](http://clippy.bashy.io/github/Manishearth/rust-clippy/master/badge.svg)](http://clippy.bashy.io/github/Manishearth/rust-clippy/master/log)
   5 [![Current Version](http://meritbadge.herokuapp.com/clippy)](https://crates.io/crates/clippy)
   6 [![License: MPL-2.0](https://img.shields.io/crates/l/clippy.svg)](#License)
   7
   8 A collection of lints to catch common mistakes and improve your Rust code.
   9
  10 Table of contents:
  11
  12 *   [Lint list](#lints)
  13 *   [Usage instructions](#usage)
  14 *   [Configuration](#configuration)
  15 *   [*clippy-service*](#link-with-clippy-service)
  16 *   [License](#license)
  17
  18 ## Usage
  19
  20 Since this is a tool for helping the developer of a library or application
  21 write better code, it is recommended to include clippy as an optional
  22 dependency.
  23
  24 As a general rule clippy will only work with the *latest* Rust nightly for now.
  25
  26 ### Optional dependency
  27
  28 If you want to make clippy an optional dependency, you can do the following:
  29
  30 In your `Cargo.toml`:
  31
  32 ```toml
  33 [dependencies]
  34 clippy = {version = "*", optional = true}
  35
  36 [features]
  37 default = []
  38 ```
  39
  40 And, in your `main.rs` or `lib.rs`:
  41
  42 ```rust
  43 #![cfg_attr(feature="clippy", feature(plugin))]
  44
  45 #![cfg_attr(feature="clippy", plugin(clippy))]
  46 ```
  47
  48 Then build by enabling the feature: `cargo build --features "clippy"`
  49
  50 Instead of adding the `cfg_attr` attributes you can also run clippy on demand:
  51 `cargo rustc --features clippy -- -Z no-trans -Z extra-plugins=clippy`
  52 (the `-Z no trans`, while not neccessary, will stop the compilation process after
  53 typechecking (and lints) have completed, which can significantly reduce the runtime).
  54
  55 ### As a Compiler Plugin
  56
  57 Since stable Rust is backwards compatible, you should be able to
  58 compile your stable programs with nightly Rust with clippy plugged in to
  59 circumvent this.
  60
  61 Add in your `Cargo.toml`:
  62
  63 ```toml
  64 [dependencies]
  65 clippy = "*"
  66 ```
  67
  68 You then need to add `#![feature(plugin)]` and `#![plugin(clippy)]` to the top
  69 of your crate entry point (`main.rs` or `lib.rs`).
  70
  71 Sample `main.rs`:
  72
  73 ```rust
  74 #![feature(plugin)]
  75
  76 #![plugin(clippy)]
  77
  78
  79 fn main(){
  80     let x = Some(1u8);
  81     match x {
  82         Some(y) => println!("{:?}", y),
  83         _ => ()
  84     }
  85 }
  86 ```
  87
  88 Produces this warning:
  89
  90 ```terminal
  91 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
  92 src/main.rs:8     match x {
  93 src/main.rs:9         Some(y) => println!("{:?}", y),
  94 src/main.rs:10         _ => ()
  95 src/main.rs:11     }
  96 src/main.rs:8:5: 11:6 help: Try
  97 if let Some(y) = x { println!("{:?}", y) }
  98 ```
  99
 100 ### As a cargo subcommand (`cargo clippy`)
 101
 102 An alternate way to use clippy is by installing clippy through cargo as a cargo
 103 subcommand.
 104
 105 ```terminal
 106 cargo install clippy
 107 ```
 108
 109 Now you can run clippy by invoking `cargo clippy`, or
 110 `rustup run nightly cargo clippy` directly from a directory that is usually
 111 compiled with stable.
 112
 113 In case you are not using rustup, you need to set the environment flag
 114 `SYSROOT` during installation so clippy knows where to find `librustc` and
 115 similar crates.
 116
 117 ```terminal
 118 SYSROOT=/path/to/rustc/sysroot cargo install clippy
 119 ```
 120
 121 ### Running clippy from the command line without installing
 122
 123 To have cargo compile your crate with clippy without needing `#![plugin(clippy)]`
 124 in your code, you can use:
 125
 126 ```terminal
 127 cargo rustc -- -L /path/to/clippy_so -Z extra-plugins=clippy
 128 ```
 129
 130 *[Note](https://github.com/Manishearth/rust-clippy/wiki#a-word-of-warning):*
 131 Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
 132
 133
 134 ## Configuration
 135
 136 Some lints can be configured in a `clippy.toml` file. It contains basic `variable = value` mapping eg.
 137
 138 ```toml
 139 blacklisted-names = ["toto", "tata", "titi"]
 140 cyclomatic-complexity-threshold = 30
 141 ```
 142
 143 See the wiki for more information about which lints can be configured and the
 144 meaning of the variables.
 145
 146 You can also specify the path to the configuration file with:
 147
 148 ```rust
 149 #![plugin(clippy(conf_file="path/to/clippy's/configuration"))]
 150 ```
 151
 152 To deactivate the “for further information visit *wiki-link*” message you can
 153 define the `CLIPPY_DISABLE_WIKI_LINKS` environment variable.
 154
 155 ### Allowing/denying lints
 156
 157 You can add options  to `allow`/`warn`/`deny`:
 158
 159 *   the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy)]`)
 160
 161 *   all lints using both the `clippy` and `clippy_pedantic` lint groups (`#![deny(clippy)]`,
 162     `#![deny(clippy_pedantic)]`). Note that `clippy_pedantic` contains some very aggressive
 163     lints prone to false positives.
 164
 165 *   only some lints (`#![deny(single_match, box_vec)]`, etc)
 166
 167 *   `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
 168
 169 Note: `deny` produces errors instead of warnings.
 170
 171 For convenience, `cargo clippy` automatically defines a `cargo-clippy`
 172 features. This lets you set lints level and compile with or without clippy
 173 transparently:
 174
 175 ```rust
 176 #[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
 177 ```
 178
 179 ## Link with clippy service
 180
 181 `clippy-service` is a rust web initiative providing `rust-clippy` as a web service.
 182
 183 Both projects are independent and maintained by different people
 184 (even if some `clippy-service`'s contributions are authored by some `rust-clippy` members).
 185
 186 You can check out this great service at [clippy.bashy.io](https://clippy.bashy.io/).
 187
 188 ## Lints
 189
 190 There are 177 lints included in this crate:
 191
 192 name                                                                                                                   | default | triggers on
 193 -----------------------------------------------------------------------------------------------------------------------|---------|----------------------------------------------------------------------------------------------------------------------------------
 194 [absurd_extreme_comparisons](https://github.com/Manishearth/rust-clippy/wiki#absurd_extreme_comparisons)               | warn    | a comparison with a maximum or minimum value that is always true or false
 195 [almost_swapped](https://github.com/Manishearth/rust-clippy/wiki#almost_swapped)                                       | warn    | `foo = bar; bar = foo` sequence
 196 [approx_constant](https://github.com/Manishearth/rust-clippy/wiki#approx_constant)                                     | warn    | the approximate of a known float constant (in `std::fXX::consts`)
 197 [assign_op_pattern](https://github.com/Manishearth/rust-clippy/wiki#assign_op_pattern)                                 | warn    | assigning the result of an operation on a variable to that same variable
 198 [assign_ops](https://github.com/Manishearth/rust-clippy/wiki#assign_ops)                                               | allow   | any compound assignment operation
 199 [bad_bit_mask](https://github.com/Manishearth/rust-clippy/wiki#bad_bit_mask)                                           | warn    | expressions of the form `_ & mask == select` that will only ever return `true` or `false`
 200 [blacklisted_name](https://github.com/Manishearth/rust-clippy/wiki#blacklisted_name)                                   | warn    | usage of a blacklisted/placeholder name
 201 [block_in_if_condition_expr](https://github.com/Manishearth/rust-clippy/wiki#block_in_if_condition_expr)               | warn    | braces that can be eliminated in conditions, e.g `if { true } ...`
 202 [block_in_if_condition_stmt](https://github.com/Manishearth/rust-clippy/wiki#block_in_if_condition_stmt)               | warn    | complex blocks in conditions, e.g. `if { let x = true; x } ...`
 203 [bool_comparison](https://github.com/Manishearth/rust-clippy/wiki#bool_comparison)                                     | warn    | comparing a variable to a boolean, e.g. `if x == true`
 204 [box_vec](https://github.com/Manishearth/rust-clippy/wiki#box_vec)                                                     | warn    | usage of `Box<Vec<T>>`, vector elements are already on the heap
 205 [boxed_local](https://github.com/Manishearth/rust-clippy/wiki#boxed_local)                                             | warn    | using `Box<T>` where unnecessary
 206 [builtin_type_shadow](https://github.com/Manishearth/rust-clippy/wiki#builtin_type_shadow)                             | warn    | shadowing a builtin type
 207 [cast_possible_truncation](https://github.com/Manishearth/rust-clippy/wiki#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`
 208 [cast_possible_wrap](https://github.com/Manishearth/rust-clippy/wiki#cast_possible_wrap)                               | allow   | casts that may cause wrapping around the value, e.g `x as i32` where `x: u32` and `x > i32::MAX`
 209 [cast_precision_loss](https://github.com/Manishearth/rust-clippy/wiki#cast_precision_loss)                             | allow   | casts that cause loss of precision, e.g `x as f32` where `x: u64`
 210 [cast_sign_loss](https://github.com/Manishearth/rust-clippy/wiki#cast_sign_loss)                                       | allow   | casts from signed types to unsigned types, e.g `x as u32` where `x: i32`
 211 [char_lit_as_u8](https://github.com/Manishearth/rust-clippy/wiki#char_lit_as_u8)                                       | warn    | casting a character literal to u8
 212 [chars_next_cmp](https://github.com/Manishearth/rust-clippy/wiki#chars_next_cmp)                                       | warn    | using `.chars().next()` to check if a string starts with a char
 213 [clone_double_ref](https://github.com/Manishearth/rust-clippy/wiki#clone_double_ref)                                   | warn    | using `clone` on `&&T`
 214 [clone_on_copy](https://github.com/Manishearth/rust-clippy/wiki#clone_on_copy)                                         | warn    | using `clone` on a `Copy` type
 215 [cmp_nan](https://github.com/Manishearth/rust-clippy/wiki#cmp_nan)                                                     | deny    | comparisons to NAN, which will always return false, probably not intended
 216 [cmp_null](https://github.com/Manishearth/rust-clippy/wiki#cmp_null)                                                   | warn    | comparing a pointer to a null pointer, suggesting to use `.is_null()` instead.
 217 [cmp_owned](https://github.com/Manishearth/rust-clippy/wiki#cmp_owned)                                                 | warn    | creating owned instances for comparing with others, e.g. `x == "foo".to_string()`
 218 [collapsible_if](https://github.com/Manishearth/rust-clippy/wiki#collapsible_if)                                       | warn    | `if`s that can be collapsed (e.g. `if x { if y { ... } }` and `else { if x { ... } }`)
 219 [crosspointer_transmute](https://github.com/Manishearth/rust-clippy/wiki#crosspointer_transmute)                       | warn    | transmutes that have to or from types that are a pointer to the other
 220 [cyclomatic_complexity](https://github.com/Manishearth/rust-clippy/wiki#cyclomatic_complexity)                         | warn    | functions that should be split up into multiple functions
 221 [deprecated_semver](https://github.com/Manishearth/rust-clippy/wiki#deprecated_semver)                                 | warn    | use of `#[deprecated(since = "x")]` where x is not semver
 222 [derive_hash_xor_eq](https://github.com/Manishearth/rust-clippy/wiki#derive_hash_xor_eq)                               | warn    | deriving `Hash` but implementing `PartialEq` explicitly
 223 [diverging_sub_expression](https://github.com/Manishearth/rust-clippy/wiki#diverging_sub_expression)                   | warn    | whether an expression contains a diverging sub expression
 224 [doc_markdown](https://github.com/Manishearth/rust-clippy/wiki#doc_markdown)                                           | warn    | presence of `_`, `::` or camel-case outside backticks in documentation
 225 [double_neg](https://github.com/Manishearth/rust-clippy/wiki#double_neg)                                               | warn    | `--x`, which is a double negation of `x` and not a pre-decrement as in C/C++
 226 [drop_ref](https://github.com/Manishearth/rust-clippy/wiki#drop_ref)                                                   | warn    | calls to `std::mem::drop` with a reference instead of an owned value
 227 [duplicate_underscore_argument](https://github.com/Manishearth/rust-clippy/wiki#duplicate_underscore_argument)         | warn    | function arguments having names which only differ by an underscore
 228 [empty_loop](https://github.com/Manishearth/rust-clippy/wiki#empty_loop)                                               | warn    | empty `loop {}`, which should block or sleep
 229 [enum_clike_unportable_variant](https://github.com/Manishearth/rust-clippy/wiki#enum_clike_unportable_variant)         | warn    | C-like enums that are `repr(isize/usize)` and have values that don't fit into an `i32`
 230 [enum_glob_use](https://github.com/Manishearth/rust-clippy/wiki#enum_glob_use)                                         | allow   | use items that import all variants of an enum
 231 [enum_variant_names](https://github.com/Manishearth/rust-clippy/wiki#enum_variant_names)                               | warn    | enums where all variants share a prefix/postfix
 232 [eq_op](https://github.com/Manishearth/rust-clippy/wiki#eq_op)                                                         | warn    | equal operands on both sides of a comparison or bitwise combination (e.g. `x == x`)
 233 [eval_order_dependence](https://github.com/Manishearth/rust-clippy/wiki#eval_order_dependence)                         | warn    | whether a variable read occurs before a write depends on sub-expression evaluation order
 234 [expl_impl_clone_on_copy](https://github.com/Manishearth/rust-clippy/wiki#expl_impl_clone_on_copy)                     | warn    | implementing `Clone` explicitly on `Copy` types
 235 [explicit_counter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_counter_loop)                         | warn    | for-looping with an explicit counter when `_.enumerate()` would do
 236 [explicit_into_iter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_into_iter_loop)                     | warn    | for-looping over `_.into_iter()` when `_` would do
 237 [explicit_iter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_iter_loop)                               | warn    | for-looping over `_.iter()` or `_.iter_mut()` when `&_` or `&mut _` would do
 238 [extend_from_slice](https://github.com/Manishearth/rust-clippy/wiki#extend_from_slice)                                 | warn    | `.extend_from_slice(_)` is a faster way to extend a Vec by a slice
 239 [filter_map](https://github.com/Manishearth/rust-clippy/wiki#filter_map)                                               | allow   | using combinations of `filter`, `map`, `filter_map` and `flat_map` which can usually be written as a single method call
 240 [filter_next](https://github.com/Manishearth/rust-clippy/wiki#filter_next)                                             | warn    | using `filter(p).next()`, which is more succinctly expressed as `.find(p)`
 241 [float_arithmetic](https://github.com/Manishearth/rust-clippy/wiki#float_arithmetic)                                   | allow   | any floating-point arithmetic statement
 242 [float_cmp](https://github.com/Manishearth/rust-clippy/wiki#float_cmp)                                                 | warn    | using `==` or `!=` on float values instead of comparing difference with an epsilon
 243 [for_kv_map](https://github.com/Manishearth/rust-clippy/wiki#for_kv_map)                                               | warn    | looping on a map using `iter` when `keys` or `values` would do
 244 [for_loop_over_option](https://github.com/Manishearth/rust-clippy/wiki#for_loop_over_option)                           | warn    | for-looping over an `Option`, which is more clearly expressed as an `if let`
 245 [for_loop_over_result](https://github.com/Manishearth/rust-clippy/wiki#for_loop_over_result)                           | warn    | for-looping over a `Result`, which is more clearly expressed as an `if let`
 246 [get_unwrap](https://github.com/Manishearth/rust-clippy/wiki#get_unwrap)                                               | warn    | using `.get().unwrap()` or `.get_mut().unwrap()` when using `[]` would work instead
 247 [identity_op](https://github.com/Manishearth/rust-clippy/wiki#identity_op)                                             | warn    | using identity operations, e.g. `x + 0` or `y / 1`
 248 [if_let_redundant_pattern_matching](https://github.com/Manishearth/rust-clippy/wiki#if_let_redundant_pattern_matching) | warn    | use the proper utility function avoiding an `if let`
 249 [if_let_some_result](https://github.com/Manishearth/rust-clippy/wiki#if_let_some_result)                               | warn    | usage of `ok()` in `if let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead
 250 [if_not_else](https://github.com/Manishearth/rust-clippy/wiki#if_not_else)                                             | allow   | `if` branches that could be swapped so no negation operation is necessary on the condition
 251 [if_same_then_else](https://github.com/Manishearth/rust-clippy/wiki#if_same_then_else)                                 | warn    | if with the same *then* and *else* blocks
 252 [ifs_same_cond](https://github.com/Manishearth/rust-clippy/wiki#ifs_same_cond)                                         | warn    | consecutive `ifs` with the same condition
 253 [indexing_slicing](https://github.com/Manishearth/rust-clippy/wiki#indexing_slicing)                                   | allow   | indexing/slicing usage
 254 [ineffective_bit_mask](https://github.com/Manishearth/rust-clippy/wiki#ineffective_bit_mask)                           | warn    | expressions where a bit mask will be rendered useless by a comparison, e.g. `(x | 1) > 2`
 255 [inline_always](https://github.com/Manishearth/rust-clippy/wiki#inline_always)                                         | warn    | use of `#[inline(always)]`
 256 [integer_arithmetic](https://github.com/Manishearth/rust-clippy/wiki#integer_arithmetic)                               | allow   | any integer arithmetic statement
 257 [invalid_regex](https://github.com/Manishearth/rust-clippy/wiki#invalid_regex)                                         | deny    | invalid regular expressions
 258 [invalid_upcast_comparisons](https://github.com/Manishearth/rust-clippy/wiki#invalid_upcast_comparisons)               | allow   | a comparison involving an upcast which is always true or false
 259 [items_after_statements](https://github.com/Manishearth/rust-clippy/wiki#items_after_statements)                       | allow   | blocks where an item comes after a statement
 260 [iter_next_loop](https://github.com/Manishearth/rust-clippy/wiki#iter_next_loop)                                       | warn    | for-looping over `_.next()` which is probably not intended
 261 [iter_nth](https://github.com/Manishearth/rust-clippy/wiki#iter_nth)                                                   | warn    | using `.iter().nth()` on a standard library type with O(1) element access
 262 [iter_skip_next](https://github.com/Manishearth/rust-clippy/wiki#iter_skip_next)                                       | warn    | using `.skip(x).next()` on an iterator
 263 [len_without_is_empty](https://github.com/Manishearth/rust-clippy/wiki#len_without_is_empty)                           | warn    | traits or impls with a public `len` method but no corresponding `is_empty` method
 264 [len_zero](https://github.com/Manishearth/rust-clippy/wiki#len_zero)                                                   | warn    | checking `.len() == 0` or `.len() > 0` (or similar) when `.is_empty()` could be used instead
 265 [let_and_return](https://github.com/Manishearth/rust-clippy/wiki#let_and_return)                                       | warn    | creating a let-binding and then immediately returning it like `let x = expr; x` at the end of a block
 266 [let_unit_value](https://github.com/Manishearth/rust-clippy/wiki#let_unit_value)                                       | warn    | creating a let binding to a value of unit type, which usually can't be used afterwards
 267 [linkedlist](https://github.com/Manishearth/rust-clippy/wiki#linkedlist)                                               | warn    | usage of LinkedList, usually a vector is faster, or a more specialized data structure like a VecDeque
 268 [logic_bug](https://github.com/Manishearth/rust-clippy/wiki#logic_bug)                                                 | warn    | boolean expressions that contain terminals which can be eliminated
 269 [manual_swap](https://github.com/Manishearth/rust-clippy/wiki#manual_swap)                                             | warn    | manual swap of two variables
 270 [many_single_char_names](https://github.com/Manishearth/rust-clippy/wiki#many_single_char_names)                       | warn    | too many single character bindings
 271 [map_clone](https://github.com/Manishearth/rust-clippy/wiki#map_clone)                                                 | warn    | using `.map(|x| x.clone())` to clone an iterator or option's contents
 272 [map_entry](https://github.com/Manishearth/rust-clippy/wiki#map_entry)                                                 | warn    | use of `contains_key` followed by `insert` on a `HashMap` or `BTreeMap`
 273 [match_bool](https://github.com/Manishearth/rust-clippy/wiki#match_bool)                                               | warn    | a match on a boolean expression instead of an `if..else` block
 274 [match_overlapping_arm](https://github.com/Manishearth/rust-clippy/wiki#match_overlapping_arm)                         | warn    | a match with overlapping arms
 275 [match_ref_pats](https://github.com/Manishearth/rust-clippy/wiki#match_ref_pats)                                       | warn    | a match or `if let` with all arms prefixed with `&` instead of deref-ing the match expression
 276 [match_same_arms](https://github.com/Manishearth/rust-clippy/wiki#match_same_arms)                                     | warn    | `match` with identical arm bodies
 277 [mem_forget](https://github.com/Manishearth/rust-clippy/wiki#mem_forget)                                               | allow   | `mem::forget` usage on `Drop` types, likely to cause memory leaks
 278 [min_max](https://github.com/Manishearth/rust-clippy/wiki#min_max)                                                     | warn    | `min(_, max(_, _))` (or vice versa) with bounds clamping the result to a constant
 279 [misrefactored_assign_op](https://github.com/Manishearth/rust-clippy/wiki#misrefactored_assign_op)                     | warn    | having a variable on both sides of an assign op
 280 [missing_docs_in_private_items](https://github.com/Manishearth/rust-clippy/wiki#missing_docs_in_private_items)         | allow   | detects missing documentation for public and private members
 281 [mixed_case_hex_literals](https://github.com/Manishearth/rust-clippy/wiki#mixed_case_hex_literals)                     | warn    | hex literals whose letter digits are not consistently upper- or lowercased
 282 [module_inception](https://github.com/Manishearth/rust-clippy/wiki#module_inception)                                   | warn    | modules that have the same name as their parent module
 283 [modulo_one](https://github.com/Manishearth/rust-clippy/wiki#modulo_one)                                               | warn    | taking a number modulo 1, which always returns 0
 284 [mut_mut](https://github.com/Manishearth/rust-clippy/wiki#mut_mut)                                                     | allow   | usage of double-mut refs, e.g. `&mut &mut ...`
 285 [mutex_atomic](https://github.com/Manishearth/rust-clippy/wiki#mutex_atomic)                                           | warn    | using a mutex where an atomic value could be used instead
 286 [mutex_integer](https://github.com/Manishearth/rust-clippy/wiki#mutex_integer)                                         | allow   | using a mutex for an integer type
 287 [needless_bool](https://github.com/Manishearth/rust-clippy/wiki#needless_bool)                                         | warn    | if-statements with plain booleans in the then- and else-clause, e.g. `if p { true } else { false }`
 288 [needless_borrow](https://github.com/Manishearth/rust-clippy/wiki#needless_borrow)                                     | warn    | taking a reference that is going to be automatically dereferenced
 289 [needless_lifetimes](https://github.com/Manishearth/rust-clippy/wiki#needless_lifetimes)                               | warn    | using explicit lifetimes for references in function arguments when elision rules would allow omitting them
 290 [needless_range_loop](https://github.com/Manishearth/rust-clippy/wiki#needless_range_loop)                             | warn    | for-looping over a range of indices where an iterator over items would do
 291 [needless_return](https://github.com/Manishearth/rust-clippy/wiki#needless_return)                                     | warn    | using a return statement like `return expr;` where an expression would suffice
 292 [needless_update](https://github.com/Manishearth/rust-clippy/wiki#needless_update)                                     | warn    | using `Foo { ..base }` when there are no missing fields
 293 [neg_multiply](https://github.com/Manishearth/rust-clippy/wiki#neg_multiply)                                           | warn    | multiplying integers with -1
 294 [new_ret_no_self](https://github.com/Manishearth/rust-clippy/wiki#new_ret_no_self)                                     | warn    | not returning `Self` in a `new` method
 295 [new_without_default](https://github.com/Manishearth/rust-clippy/wiki#new_without_default)                             | warn    | `fn new() -> Self` method without `Default` implementation
 296 [new_without_default_derive](https://github.com/Manishearth/rust-clippy/wiki#new_without_default_derive)               | warn    | `fn new() -> Self` without `#[derive]`able `Default` implementation
 297 [no_effect](https://github.com/Manishearth/rust-clippy/wiki#no_effect)                                                 | warn    | statements with no effect
 298 [non_ascii_literal](https://github.com/Manishearth/rust-clippy/wiki#non_ascii_literal)                                 | allow   | using any literal non-ASCII chars in a string literal instead of using the `\\u` escape
 299 [nonminimal_bool](https://github.com/Manishearth/rust-clippy/wiki#nonminimal_bool)                                     | allow   | boolean expressions that can be written more concisely
 300 [nonsensical_open_options](https://github.com/Manishearth/rust-clippy/wiki#nonsensical_open_options)                   | warn    | nonsensical combination of options for opening a file
 301 [not_unsafe_ptr_arg_deref](https://github.com/Manishearth/rust-clippy/wiki#not_unsafe_ptr_arg_deref)                   | warn    | public functions dereferencing raw pointer arguments but not marked `unsafe`
 302 [ok_expect](https://github.com/Manishearth/rust-clippy/wiki#ok_expect)                                                 | warn    | using `ok().expect()`, which gives worse error messages than calling `expect` directly on the Result
 303 [option_map_unwrap_or](https://github.com/Manishearth/rust-clippy/wiki#option_map_unwrap_or)                           | allow   | using `Option.map(f).unwrap_or(a)`, which is more succinctly expressed as `map_or(a, f)`
 304 [option_map_unwrap_or_else](https://github.com/Manishearth/rust-clippy/wiki#option_map_unwrap_or_else)                 | allow   | using `Option.map(f).unwrap_or_else(g)`, which is more succinctly expressed as `map_or_else(g, f)`
 305 [option_unwrap_used](https://github.com/Manishearth/rust-clippy/wiki#option_unwrap_used)                               | allow   | using `Option.unwrap()`, which should at least get a better message using `expect()`
 306 [or_fun_call](https://github.com/Manishearth/rust-clippy/wiki#or_fun_call)                                             | warn    | using any `*or` method with a function call, which suggests `*or_else`
 307 [out_of_bounds_indexing](https://github.com/Manishearth/rust-clippy/wiki#out_of_bounds_indexing)                       | deny    | out of bounds constant indexing
 308 [overflow_check_conditional](https://github.com/Manishearth/rust-clippy/wiki#overflow_check_conditional)               | warn    | overflow checks inspired by C which are likely to panic
 309 [panic_params](https://github.com/Manishearth/rust-clippy/wiki#panic_params)                                           | warn    | missing parameters in `panic!` calls
 310 [partialeq_ne_impl](https://github.com/Manishearth/rust-clippy/wiki#partialeq_ne_impl)                                 | warn    | re-implementing `PartialEq::ne`
 311 [precedence](https://github.com/Manishearth/rust-clippy/wiki#precedence)                                               | warn    | operations where precedence may be unclear
 312 [print_stdout](https://github.com/Manishearth/rust-clippy/wiki#print_stdout)                                           | allow   | printing on stdout
 313 [print_with_newline](https://github.com/Manishearth/rust-clippy/wiki#print_with_newline)                               | warn    | using `print!()` with a format string that ends in a newline
 314 [ptr_arg](https://github.com/Manishearth/rust-clippy/wiki#ptr_arg)                                                     | warn    | fn arguments of the type `&Vec<...>` or `&String`, suggesting to use `&[...]` or `&str` instead, respectively
 315 [range_step_by_zero](https://github.com/Manishearth/rust-clippy/wiki#range_step_by_zero)                               | warn    | using `Range::step_by(0)`, which produces an infinite iterator
 316 [range_zip_with_len](https://github.com/Manishearth/rust-clippy/wiki#range_zip_with_len)                               | warn    | zipping iterator with a range when `enumerate()` would do
 317 [redundant_closure](https://github.com/Manishearth/rust-clippy/wiki#redundant_closure)                                 | warn    | redundant closures, i.e. `|a| foo(a)` (which can be written as just `foo`)
 318 [redundant_closure_call](https://github.com/Manishearth/rust-clippy/wiki#redundant_closure_call)                       | warn    | throwaway closures called in the expression they are defined
 319 [redundant_pattern](https://github.com/Manishearth/rust-clippy/wiki#redundant_pattern)                                 | warn    | using `name @ _` in a pattern
 320 [regex_macro](https://github.com/Manishearth/rust-clippy/wiki#regex_macro)                                             | warn    | use of `regex!(_)` instead of `Regex::new(_)`
 321 [result_unwrap_used](https://github.com/Manishearth/rust-clippy/wiki#result_unwrap_used)                               | allow   | using `Result.unwrap()`, which might be better handled
 322 [reverse_range_loop](https://github.com/Manishearth/rust-clippy/wiki#reverse_range_loop)                               | warn    | iteration over an empty range, such as `10..0` or `5..5`
 323 [search_is_some](https://github.com/Manishearth/rust-clippy/wiki#search_is_some)                                       | warn    | using an iterator search followed by `is_some()`, which is more succinctly expressed as a call to `any()`
 324 [serde_api_misuse](https://github.com/Manishearth/rust-clippy/wiki#serde_api_misuse)                                   | warn    | various things that will negatively affect your serde experience
 325 [shadow_reuse](https://github.com/Manishearth/rust-clippy/wiki#shadow_reuse)                                           | allow   | rebinding a name to an expression that re-uses the original value, e.g. `let x = x + 1`
 326 [shadow_same](https://github.com/Manishearth/rust-clippy/wiki#shadow_same)                                             | allow   | rebinding a name to itself, e.g. `let mut x = &mut x`
 327 [shadow_unrelated](https://github.com/Manishearth/rust-clippy/wiki#shadow_unrelated)                                   | allow   | rebinding a name without even using the original value
 328 [should_implement_trait](https://github.com/Manishearth/rust-clippy/wiki#should_implement_trait)                       | warn    | defining a method that should be implementing a std trait
 329 [similar_names](https://github.com/Manishearth/rust-clippy/wiki#similar_names)                                         | allow   | similarly named items and bindings
 330 [single_char_pattern](https://github.com/Manishearth/rust-clippy/wiki#single_char_pattern)                             | warn    | using a single-character str where a char could be used, e.g. `_.split("x")`
 331 [single_match](https://github.com/Manishearth/rust-clippy/wiki#single_match)                                           | warn    | a match statement with a single nontrivial arm (i.e, where the other arm is `_ => {}`) instead of `if let`
 332 [single_match_else](https://github.com/Manishearth/rust-clippy/wiki#single_match_else)                                 | allow   | a match statement with a two arms where the second arm's pattern is a wildcard instead of `if let`
 333 [string_add](https://github.com/Manishearth/rust-clippy/wiki#string_add)                                               | allow   | using `x + ..` where x is a `String` instead of `push_str()`
 334 [string_add_assign](https://github.com/Manishearth/rust-clippy/wiki#string_add_assign)                                 | allow   | using `x = x + ..` where x is a `String` instead of `push_str()`
 335 [string_lit_as_bytes](https://github.com/Manishearth/rust-clippy/wiki#string_lit_as_bytes)                             | warn    | calling `as_bytes` on a string literal instead of using a byte string literal
 336 [stutter](https://github.com/Manishearth/rust-clippy/wiki#stutter)                                                     | allow   | type names prefixed/postfixed with their containing module's name
 337 [suspicious_assignment_formatting](https://github.com/Manishearth/rust-clippy/wiki#suspicious_assignment_formatting)   | warn    | suspicious formatting of `*=`, `-=` or `!=`
 338 [suspicious_else_formatting](https://github.com/Manishearth/rust-clippy/wiki#suspicious_else_formatting)               | warn    | suspicious formatting of `else if`
 339 [temporary_assignment](https://github.com/Manishearth/rust-clippy/wiki#temporary_assignment)                           | warn    | assignments to temporaries
 340 [temporary_cstring_as_ptr](https://github.com/Manishearth/rust-clippy/wiki#temporary_cstring_as_ptr)                   | warn    | getting the inner pointer of a temporary `CString`
 341 [too_many_arguments](https://github.com/Manishearth/rust-clippy/wiki#too_many_arguments)                               | warn    | functions with too many arguments
 342 [toplevel_ref_arg](https://github.com/Manishearth/rust-clippy/wiki#toplevel_ref_arg)                                   | warn    | an entire binding declared as `ref`, in a function argument or a `let` statement
 343 [transmute_ptr_to_ref](https://github.com/Manishearth/rust-clippy/wiki#transmute_ptr_to_ref)                           | warn    | transmutes from a pointer to a reference type
 344 [trivial_regex](https://github.com/Manishearth/rust-clippy/wiki#trivial_regex)                                         | warn    | trivial regular expressions
 345 [type_complexity](https://github.com/Manishearth/rust-clippy/wiki#type_complexity)                                     | warn    | usage of very complex types that might be better factored into `type` definitions
 346 [unicode_not_nfc](https://github.com/Manishearth/rust-clippy/wiki#unicode_not_nfc)                                     | allow   | using a unicode literal not in NFC normal form (see [unicode tr15](http://www.unicode.org/reports/tr15/) for further information)
 347 [unit_cmp](https://github.com/Manishearth/rust-clippy/wiki#unit_cmp)                                                   | warn    | comparing unit values
 348 [unnecessary_mut_passed](https://github.com/Manishearth/rust-clippy/wiki#unnecessary_mut_passed)                       | warn    | an argument passed as a mutable reference although the callee only demands an immutable reference
 349 [unnecessary_operation](https://github.com/Manishearth/rust-clippy/wiki#unnecessary_operation)                         | warn    | outer expressions with no effect
 350 [unneeded_field_pattern](https://github.com/Manishearth/rust-clippy/wiki#unneeded_field_pattern)                       | warn    | struct fields bound to a wildcard instead of using `..`
 351 [unsafe_removed_from_name](https://github.com/Manishearth/rust-clippy/wiki#unsafe_removed_from_name)                   | warn    | `unsafe` removed from API names on import
 352 [unseparated_literal_suffix](https://github.com/Manishearth/rust-clippy/wiki#unseparated_literal_suffix)               | allow   | literals whose suffix is not separated by an underscore
 353 [unused_collect](https://github.com/Manishearth/rust-clippy/wiki#unused_collect)                                       | warn    | `collect()`ing an iterator without using the result; this is usually better written as a for loop
 354 [unused_label](https://github.com/Manishearth/rust-clippy/wiki#unused_label)                                           | warn    | unused labels
 355 [unused_lifetimes](https://github.com/Manishearth/rust-clippy/wiki#unused_lifetimes)                                   | warn    | unused lifetimes in function definitions
 356 [use_debug](https://github.com/Manishearth/rust-clippy/wiki#use_debug)                                                 | allow   | use of `Debug`-based formatting
 357 [used_underscore_binding](https://github.com/Manishearth/rust-clippy/wiki#used_underscore_binding)                     | allow   | using a binding which is prefixed with an underscore
 358 [useless_attribute](https://github.com/Manishearth/rust-clippy/wiki#useless_attribute)                                 | warn    | use of lint attributes on `extern crate` items
 359 [useless_format](https://github.com/Manishearth/rust-clippy/wiki#useless_format)                                       | warn    | useless use of `format!`
 360 [useless_let_if_seq](https://github.com/Manishearth/rust-clippy/wiki#useless_let_if_seq)                               | warn    | unidiomatic `let mut` declaration followed by initialization in `if`
 361 [useless_transmute](https://github.com/Manishearth/rust-clippy/wiki#useless_transmute)                                 | warn    | transmutes that have the same to and from types or could be a cast/coercion
 362 [useless_vec](https://github.com/Manishearth/rust-clippy/wiki#useless_vec)                                             | warn    | useless `vec!`
 363 [while_let_loop](https://github.com/Manishearth/rust-clippy/wiki#while_let_loop)                                       | warn    | `loop { if let { ... } else break }`, which can be written as a `while let` loop
 364 [while_let_on_iterator](https://github.com/Manishearth/rust-clippy/wiki#while_let_on_iterator)                         | warn    | using a while-let loop instead of a for loop on an iterator
 365 [wrong_pub_self_convention](https://github.com/Manishearth/rust-clippy/wiki#wrong_pub_self_convention)                 | allow   | defining a public method named with an established prefix (like "into_") that takes `self` with the wrong convention
 366 [wrong_self_convention](https://github.com/Manishearth/rust-clippy/wiki#wrong_self_convention)                         | warn    | defining a method named with an established prefix (like "into_") that takes `self` with the wrong convention
 367 [wrong_transmute](https://github.com/Manishearth/rust-clippy/wiki#wrong_transmute)                                     | warn    | transmutes that are confusing at best, undefined behaviour at worst and always useless
 368 [zero_divided_by_zero](https://github.com/Manishearth/rust-clippy/wiki#zero_divided_by_zero)                           | warn    | usage of `0.0 / 0.0` to obtain NaN instead of std::f32::NaN or std::f64::NaN
 369 [zero_prefixed_literal](https://github.com/Manishearth/rust-clippy/wiki#zero_prefixed_literal)                         | warn    | integer literals starting with `0`
 370 [zero_width_space](https://github.com/Manishearth/rust-clippy/wiki#zero_width_space)                                   | deny    | using a zero-width space in a string literal, which is confusing
 371
 372 More to come, please [file an issue](https://github.com/Manishearth/rust-clippy/issues) if you have ideas!
 373
 374 ## License
 375
 376 Licensed under [MPL](https://www.mozilla.org/MPL/2.0/).
 377 If you're having issues with the license, let me know and I'll try to change it to something more permissive.