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 *   [License](#license)
  16
  17 ## Usage
  18
  19 Since this is a tool for helping the developer of a library or application
  20 write better code, it is recommended not to include clippy as a hard dependency.
  21 Options include using it as an optional dependency, as a cargo subcommand, or
  22 as an included feature during build. All of these options are detailed below.
  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 cargo subcommand (`cargo clippy`)
  56
  57 An alternate way to use clippy is by installing clippy through cargo as a cargo
  58 subcommand.
  59
  60 ```terminal
  61 cargo install clippy
  62 ```
  63
  64 Now you can run clippy by invoking `cargo clippy`, or
  65 `rustup run nightly cargo clippy` directly from a directory that is usually
  66 compiled with stable.
  67
  68 In case you are not using rustup, you need to set the environment flag
  69 `SYSROOT` during installation so clippy knows where to find `librustc` and
  70 similar crates.
  71
  72 ```terminal
  73 SYSROOT=/path/to/rustc/sysroot cargo install clippy
  74 ```
  75
  76 ### Running clippy from the command line without installing
  77
  78 To have cargo compile your crate with clippy without needing `#![plugin(clippy)]`
  79 in your code, you can use:
  80
  81 ```terminal
  82 cargo rustc -- -L /path/to/clippy_so -Z extra-plugins=clippy
  83 ```
  84
  85 *[Note](https://github.com/Manishearth/rust-clippy/wiki#a-word-of-warning):*
  86 Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
  87
  88 ### As a Compiler Plugin
  89
  90 *Note:* This is not a recommended installation method.
  91
  92 Since stable Rust is backwards compatible, you should be able to
  93 compile your stable programs with nightly Rust with clippy plugged in to
  94 circumvent this.
  95
  96 Add in your `Cargo.toml`:
  97
  98 ```toml
  99 [dependencies]
 100 clippy = "*"
 101 ```
 102
 103 You then need to add `#![feature(plugin)]` and `#![plugin(clippy)]` to the top
 104 of your crate entry point (`main.rs` or `lib.rs`).
 105
 106 Sample `main.rs`:
 107
 108 ```rust
 109 #![feature(plugin)]
 110
 111 #![plugin(clippy)]
 112
 113
 114 fn main(){
 115     let x = Some(1u8);
 116     match x {
 117         Some(y) => println!("{:?}", y),
 118         _ => ()
 119     }
 120 }
 121 ```
 122
 123 Produces this warning:
 124
 125 ```terminal
 126 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
 127 src/main.rs:8     match x {
 128 src/main.rs:9         Some(y) => println!("{:?}", y),
 129 src/main.rs:10         _ => ()
 130 src/main.rs:11     }
 131 src/main.rs:8:5: 11:6 help: Try
 132 if let Some(y) = x { println!("{:?}", y) }
 133 ```
 134
 135 ## Configuration
 136
 137 Some lints can be configured in a `clippy.toml` file. It contains basic `variable = value` mapping eg.
 138
 139 ```toml
 140 blacklisted-names = ["toto", "tata", "titi"]
 141 cyclomatic-complexity-threshold = 30
 142 ```
 143
 144 See the wiki for more information about which lints can be configured and the
 145 meaning of the variables.
 146
 147 You can also specify the path to the configuration file with:
 148
 149 ```rust
 150 #![plugin(clippy(conf_file="path/to/clippy's/configuration"))]
 151 ```
 152
 153 To deactivate the “for further information visit *wiki-link*” message you can
 154 define the `CLIPPY_DISABLE_WIKI_LINKS` environment variable.
 155
 156 ### Allowing/denying lints
 157
 158 You can add options  to `allow`/`warn`/`deny`:
 159
 160 *   the whole set of `Warn` lints using the `clippy` lint group (`#![deny(clippy)]`)
 161
 162 *   all lints using both the `clippy` and `clippy_pedantic` lint groups (`#![deny(clippy)]`,
 163     `#![deny(clippy_pedantic)]`). Note that `clippy_pedantic` contains some very aggressive
 164     lints prone to false positives.
 165
 166 *   only some lints (`#![deny(single_match, box_vec)]`, etc)
 167
 168 *   `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc
 169
 170 Note: `deny` produces errors instead of warnings.
 171
 172 For convenience, `cargo clippy` automatically defines a `cargo-clippy`
 173 features. This lets you set lints level and compile with or without clippy
 174 transparently:
 175
 176 ```rust
 177 #[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
 178 ```
 179
 180 ## Lints
 181
 182 There are 179 lints included in this crate:
 183
 184 name                                                                                                                   | default | triggers on
 185 -----------------------------------------------------------------------------------------------------------------------|---------|----------------------------------------------------------------------------------------------------------------------------------
 186 [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
 187 [almost_swapped](https://github.com/Manishearth/rust-clippy/wiki#almost_swapped)                                       | warn    | `foo = bar; bar = foo` sequence
 188 [approx_constant](https://github.com/Manishearth/rust-clippy/wiki#approx_constant)                                     | warn    | the approximate of a known float constant (in `std::fXX::consts`)
 189 [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
 190 [assign_ops](https://github.com/Manishearth/rust-clippy/wiki#assign_ops)                                               | allow   | any compound assignment operation
 191 [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`
 192 [blacklisted_name](https://github.com/Manishearth/rust-clippy/wiki#blacklisted_name)                                   | warn    | usage of a blacklisted/placeholder name
 193 [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 } ...`
 194 [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 } ...`
 195 [bool_comparison](https://github.com/Manishearth/rust-clippy/wiki#bool_comparison)                                     | warn    | comparing a variable to a boolean, e.g. `if x == true`
 196 [box_vec](https://github.com/Manishearth/rust-clippy/wiki#box_vec)                                                     | warn    | usage of `Box<Vec<T>>`, vector elements are already on the heap
 197 [boxed_local](https://github.com/Manishearth/rust-clippy/wiki#boxed_local)                                             | warn    | using `Box<T>` where unnecessary
 198 [builtin_type_shadow](https://github.com/Manishearth/rust-clippy/wiki#builtin_type_shadow)                             | warn    | shadowing a builtin type
 199 [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`
 200 [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`
 201 [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`
 202 [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`
 203 [char_lit_as_u8](https://github.com/Manishearth/rust-clippy/wiki#char_lit_as_u8)                                       | warn    | casting a character literal to u8
 204 [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
 205 [clone_double_ref](https://github.com/Manishearth/rust-clippy/wiki#clone_double_ref)                                   | warn    | using `clone` on `&&T`
 206 [clone_on_copy](https://github.com/Manishearth/rust-clippy/wiki#clone_on_copy)                                         | warn    | using `clone` on a `Copy` type
 207 [cmp_nan](https://github.com/Manishearth/rust-clippy/wiki#cmp_nan)                                                     | deny    | comparisons to NAN, which will always return false, probably not intended
 208 [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.
 209 [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()`
 210 [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 { ... } }`)
 211 [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
 212 [cyclomatic_complexity](https://github.com/Manishearth/rust-clippy/wiki#cyclomatic_complexity)                         | warn    | functions that should be split up into multiple functions
 213 [deprecated_semver](https://github.com/Manishearth/rust-clippy/wiki#deprecated_semver)                                 | warn    | use of `#[deprecated(since = "x")]` where x is not semver
 214 [deref_addrof](https://github.com/Manishearth/rust-clippy/wiki#deref_addrof)                                           | warn    | use of `*&` or `*&mut` in an expression
 215 [derive_hash_xor_eq](https://github.com/Manishearth/rust-clippy/wiki#derive_hash_xor_eq)                               | warn    | deriving `Hash` but implementing `PartialEq` explicitly
 216 [diverging_sub_expression](https://github.com/Manishearth/rust-clippy/wiki#diverging_sub_expression)                   | warn    | whether an expression contains a diverging sub expression
 217 [doc_markdown](https://github.com/Manishearth/rust-clippy/wiki#doc_markdown)                                           | warn    | presence of `_`, `::` or camel-case outside backticks in documentation
 218 [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++
 219 [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
 220 [duplicate_underscore_argument](https://github.com/Manishearth/rust-clippy/wiki#duplicate_underscore_argument)         | warn    | function arguments having names which only differ by an underscore
 221 [empty_loop](https://github.com/Manishearth/rust-clippy/wiki#empty_loop)                                               | warn    | empty `loop {}`, which should block or sleep
 222 [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`
 223 [enum_glob_use](https://github.com/Manishearth/rust-clippy/wiki#enum_glob_use)                                         | allow   | use items that import all variants of an enum
 224 [enum_variant_names](https://github.com/Manishearth/rust-clippy/wiki#enum_variant_names)                               | warn    | enums where all variants share a prefix/postfix
 225 [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`)
 226 [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
 227 [expl_impl_clone_on_copy](https://github.com/Manishearth/rust-clippy/wiki#expl_impl_clone_on_copy)                     | warn    | implementing `Clone` explicitly on `Copy` types
 228 [explicit_counter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_counter_loop)                         | warn    | for-looping with an explicit counter when `_.enumerate()` would do
 229 [explicit_into_iter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_into_iter_loop)                     | warn    | for-looping over `_.into_iter()` when `_` would do
 230 [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
 231 [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
 232 [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
 233 [filter_next](https://github.com/Manishearth/rust-clippy/wiki#filter_next)                                             | warn    | using `filter(p).next()`, which is more succinctly expressed as `.find(p)`
 234 [float_arithmetic](https://github.com/Manishearth/rust-clippy/wiki#float_arithmetic)                                   | allow   | any floating-point arithmetic statement
 235 [float_cmp](https://github.com/Manishearth/rust-clippy/wiki#float_cmp)                                                 | warn    | using `==` or `!=` on float values instead of comparing difference with an epsilon
 236 [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
 237 [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`
 238 [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`
 239 [get_unwrap](https://github.com/Manishearth/rust-clippy/wiki#get_unwrap)                                               | warn    | using `.get().unwrap()` or `.get_mut().unwrap()` when using `[]` would work instead
 240 [identity_op](https://github.com/Manishearth/rust-clippy/wiki#identity_op)                                             | warn    | using identity operations, e.g. `x + 0` or `y / 1`
 241 [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`
 242 [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
 243 [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
 244 [if_same_then_else](https://github.com/Manishearth/rust-clippy/wiki#if_same_then_else)                                 | warn    | if with the same *then* and *else* blocks
 245 [ifs_same_cond](https://github.com/Manishearth/rust-clippy/wiki#ifs_same_cond)                                         | warn    | consecutive `ifs` with the same condition
 246 [indexing_slicing](https://github.com/Manishearth/rust-clippy/wiki#indexing_slicing)                                   | allow   | indexing/slicing usage
 247 [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`
 248 [inline_always](https://github.com/Manishearth/rust-clippy/wiki#inline_always)                                         | warn    | use of `#[inline(always)]`
 249 [integer_arithmetic](https://github.com/Manishearth/rust-clippy/wiki#integer_arithmetic)                               | allow   | any integer arithmetic statement
 250 [invalid_regex](https://github.com/Manishearth/rust-clippy/wiki#invalid_regex)                                         | deny    | invalid regular expressions
 251 [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
 252 [items_after_statements](https://github.com/Manishearth/rust-clippy/wiki#items_after_statements)                       | allow   | blocks where an item comes after a statement
 253 [iter_next_loop](https://github.com/Manishearth/rust-clippy/wiki#iter_next_loop)                                       | warn    | for-looping over `_.next()` which is probably not intended
 254 [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
 255 [iter_skip_next](https://github.com/Manishearth/rust-clippy/wiki#iter_skip_next)                                       | warn    | using `.skip(x).next()` on an iterator
 256 [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
 257 [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
 258 [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
 259 [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
 260 [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
 261 [logic_bug](https://github.com/Manishearth/rust-clippy/wiki#logic_bug)                                                 | warn    | boolean expressions that contain terminals which can be eliminated
 262 [manual_swap](https://github.com/Manishearth/rust-clippy/wiki#manual_swap)                                             | warn    | manual swap of two variables
 263 [many_single_char_names](https://github.com/Manishearth/rust-clippy/wiki#many_single_char_names)                       | warn    | too many single character bindings
 264 [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
 265 [map_entry](https://github.com/Manishearth/rust-clippy/wiki#map_entry)                                                 | warn    | use of `contains_key` followed by `insert` on a `HashMap` or `BTreeMap`
 266 [match_bool](https://github.com/Manishearth/rust-clippy/wiki#match_bool)                                               | warn    | a match on a boolean expression instead of an `if..else` block
 267 [match_overlapping_arm](https://github.com/Manishearth/rust-clippy/wiki#match_overlapping_arm)                         | warn    | a match with overlapping arms
 268 [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
 269 [match_same_arms](https://github.com/Manishearth/rust-clippy/wiki#match_same_arms)                                     | warn    | `match` with identical arm bodies
 270 [mem_forget](https://github.com/Manishearth/rust-clippy/wiki#mem_forget)                                               | allow   | `mem::forget` usage on `Drop` types, likely to cause memory leaks
 271 [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
 272 [misrefactored_assign_op](https://github.com/Manishearth/rust-clippy/wiki#misrefactored_assign_op)                     | warn    | having a variable on both sides of an assign op
 273 [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
 274 [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
 275 [module_inception](https://github.com/Manishearth/rust-clippy/wiki#module_inception)                                   | warn    | modules that have the same name as their parent module
 276 [modulo_one](https://github.com/Manishearth/rust-clippy/wiki#modulo_one)                                               | warn    | taking a number modulo 1, which always returns 0
 277 [mut_mut](https://github.com/Manishearth/rust-clippy/wiki#mut_mut)                                                     | allow   | usage of double-mut refs, e.g. `&mut &mut ...`
 278 [mutex_atomic](https://github.com/Manishearth/rust-clippy/wiki#mutex_atomic)                                           | warn    | using a mutex where an atomic value could be used instead
 279 [mutex_integer](https://github.com/Manishearth/rust-clippy/wiki#mutex_integer)                                         | allow   | using a mutex for an integer type
 280 [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 }`
 281 [needless_borrow](https://github.com/Manishearth/rust-clippy/wiki#needless_borrow)                                     | warn    | taking a reference that is going to be automatically dereferenced
 282 [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
 283 [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
 284 [needless_return](https://github.com/Manishearth/rust-clippy/wiki#needless_return)                                     | warn    | using a return statement like `return expr;` where an expression would suffice
 285 [needless_update](https://github.com/Manishearth/rust-clippy/wiki#needless_update)                                     | warn    | using `Foo { ..base }` when there are no missing fields
 286 [neg_multiply](https://github.com/Manishearth/rust-clippy/wiki#neg_multiply)                                           | warn    | multiplying integers with -1
 287 [new_ret_no_self](https://github.com/Manishearth/rust-clippy/wiki#new_ret_no_self)                                     | warn    | not returning `Self` in a `new` method
 288 [new_without_default](https://github.com/Manishearth/rust-clippy/wiki#new_without_default)                             | warn    | `fn new() -> Self` method without `Default` implementation
 289 [new_without_default_derive](https://github.com/Manishearth/rust-clippy/wiki#new_without_default_derive)               | warn    | `fn new() -> Self` without `#[derive]`able `Default` implementation
 290 [no_effect](https://github.com/Manishearth/rust-clippy/wiki#no_effect)                                                 | warn    | statements with no effect
 291 [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
 292 [nonminimal_bool](https://github.com/Manishearth/rust-clippy/wiki#nonminimal_bool)                                     | allow   | boolean expressions that can be written more concisely
 293 [nonsensical_open_options](https://github.com/Manishearth/rust-clippy/wiki#nonsensical_open_options)                   | warn    | nonsensical combination of options for opening a file
 294 [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`
 295 [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
 296 [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)`
 297 [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)`
 298 [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()`
 299 [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`
 300 [out_of_bounds_indexing](https://github.com/Manishearth/rust-clippy/wiki#out_of_bounds_indexing)                       | deny    | out of bounds constant indexing
 301 [overflow_check_conditional](https://github.com/Manishearth/rust-clippy/wiki#overflow_check_conditional)               | warn    | overflow checks inspired by C which are likely to panic
 302 [panic_params](https://github.com/Manishearth/rust-clippy/wiki#panic_params)                                           | warn    | missing parameters in `panic!` calls
 303 [partialeq_ne_impl](https://github.com/Manishearth/rust-clippy/wiki#partialeq_ne_impl)                                 | warn    | re-implementing `PartialEq::ne`
 304 [precedence](https://github.com/Manishearth/rust-clippy/wiki#precedence)                                               | warn    | operations where precedence may be unclear
 305 [print_stdout](https://github.com/Manishearth/rust-clippy/wiki#print_stdout)                                           | allow   | printing on stdout
 306 [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
 307 [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
 308 [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
 309 [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
 310 [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`)
 311 [redundant_closure_call](https://github.com/Manishearth/rust-clippy/wiki#redundant_closure_call)                       | warn    | throwaway closures called in the expression they are defined
 312 [redundant_pattern](https://github.com/Manishearth/rust-clippy/wiki#redundant_pattern)                                 | warn    | using `name @ _` in a pattern
 313 [regex_macro](https://github.com/Manishearth/rust-clippy/wiki#regex_macro)                                             | warn    | use of `regex!(_)` instead of `Regex::new(_)`
 314 [result_unwrap_used](https://github.com/Manishearth/rust-clippy/wiki#result_unwrap_used)                               | allow   | using `Result.unwrap()`, which might be better handled
 315 [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`
 316 [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()`
 317 [serde_api_misuse](https://github.com/Manishearth/rust-clippy/wiki#serde_api_misuse)                                   | warn    | various things that will negatively affect your serde experience
 318 [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`
 319 [shadow_same](https://github.com/Manishearth/rust-clippy/wiki#shadow_same)                                             | allow   | rebinding a name to itself, e.g. `let mut x = &mut x`
 320 [shadow_unrelated](https://github.com/Manishearth/rust-clippy/wiki#shadow_unrelated)                                   | allow   | rebinding a name without even using the original value
 321 [should_implement_trait](https://github.com/Manishearth/rust-clippy/wiki#should_implement_trait)                       | warn    | defining a method that should be implementing a std trait
 322 [similar_names](https://github.com/Manishearth/rust-clippy/wiki#similar_names)                                         | allow   | similarly named items and bindings
 323 [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")`
 324 [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`
 325 [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`
 326 [string_add](https://github.com/Manishearth/rust-clippy/wiki#string_add)                                               | allow   | using `x + ..` where x is a `String` instead of `push_str()`
 327 [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()`
 328 [string_extend_chars](https://github.com/Manishearth/rust-clippy/wiki#string_extend_chars)                             | warn    | using `x.extend(s.chars())` where s is a `&str` or `String`
 329 [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
 330 [stutter](https://github.com/Manishearth/rust-clippy/wiki#stutter)                                                     | allow   | type names prefixed/postfixed with their containing module's name
 331 [suspicious_assignment_formatting](https://github.com/Manishearth/rust-clippy/wiki#suspicious_assignment_formatting)   | warn    | suspicious formatting of `*=`, `-=` or `!=`
 332 [suspicious_else_formatting](https://github.com/Manishearth/rust-clippy/wiki#suspicious_else_formatting)               | warn    | suspicious formatting of `else if`
 333 [temporary_assignment](https://github.com/Manishearth/rust-clippy/wiki#temporary_assignment)                           | warn    | assignments to temporaries
 334 [temporary_cstring_as_ptr](https://github.com/Manishearth/rust-clippy/wiki#temporary_cstring_as_ptr)                   | warn    | getting the inner pointer of a temporary `CString`
 335 [too_many_arguments](https://github.com/Manishearth/rust-clippy/wiki#too_many_arguments)                               | warn    | functions with too many arguments
 336 [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
 337 [transmute_ptr_to_ref](https://github.com/Manishearth/rust-clippy/wiki#transmute_ptr_to_ref)                           | warn    | transmutes from a pointer to a reference type
 338 [trivial_regex](https://github.com/Manishearth/rust-clippy/wiki#trivial_regex)                                         | warn    | trivial regular expressions
 339 [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
 340 [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)
 341 [unit_cmp](https://github.com/Manishearth/rust-clippy/wiki#unit_cmp)                                                   | warn    | comparing unit values
 342 [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
 343 [unnecessary_operation](https://github.com/Manishearth/rust-clippy/wiki#unnecessary_operation)                         | warn    | outer expressions with no effect
 344 [unneeded_field_pattern](https://github.com/Manishearth/rust-clippy/wiki#unneeded_field_pattern)                       | warn    | struct fields bound to a wildcard instead of using `..`
 345 [unsafe_removed_from_name](https://github.com/Manishearth/rust-clippy/wiki#unsafe_removed_from_name)                   | warn    | `unsafe` removed from API names on import
 346 [unseparated_literal_suffix](https://github.com/Manishearth/rust-clippy/wiki#unseparated_literal_suffix)               | allow   | literals whose suffix is not separated by an underscore
 347 [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
 348 [unused_label](https://github.com/Manishearth/rust-clippy/wiki#unused_label)                                           | warn    | unused labels
 349 [unused_lifetimes](https://github.com/Manishearth/rust-clippy/wiki#unused_lifetimes)                                   | warn    | unused lifetimes in function definitions
 350 [use_debug](https://github.com/Manishearth/rust-clippy/wiki#use_debug)                                                 | allow   | use of `Debug`-based formatting
 351 [used_underscore_binding](https://github.com/Manishearth/rust-clippy/wiki#used_underscore_binding)                     | allow   | using a binding which is prefixed with an underscore
 352 [useless_attribute](https://github.com/Manishearth/rust-clippy/wiki#useless_attribute)                                 | warn    | use of lint attributes on `extern crate` items
 353 [useless_format](https://github.com/Manishearth/rust-clippy/wiki#useless_format)                                       | warn    | useless use of `format!`
 354 [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`
 355 [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
 356 [useless_vec](https://github.com/Manishearth/rust-clippy/wiki#useless_vec)                                             | warn    | useless `vec!`
 357 [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
 358 [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
 359 [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
 360 [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
 361 [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
 362 [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
 363 [zero_prefixed_literal](https://github.com/Manishearth/rust-clippy/wiki#zero_prefixed_literal)                         | warn    | integer literals starting with `0`
 364 [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
 365
 366 More to come, please [file an issue](https://github.com/Manishearth/rust-clippy/issues) if you have ideas!
 367
 368 ## License
 369
 370 Licensed under [MPL](https://www.mozilla.org/MPL/2.0/).
 371 If you're having issues with the license, let me know and I'll try to change it to something more permissive.