# rust-clippy
[![Build Status](https://travis-ci.org/Manishearth/rust-clippy.svg?branch=master)](https://travis-ci.org/Manishearth/rust-clippy)
+[![Windows build status](https://ci.appveyor.com/api/projects/status/github/Manishearth/rust-clippy?svg=true)](https://ci.appveyor.com/project/Manishearth/rust-clippy)
[![Clippy Linting Result](http://clippy.bashy.io/github/Manishearth/rust-clippy/master/badge.svg)](http://clippy.bashy.io/github/Manishearth/rust-clippy/master/log)
[![Current Version](http://meritbadge.herokuapp.com/clippy)](https://crates.io/crates/clippy)
[![License: MPL-2.0](https://img.shields.io/crates/l/clippy.svg)](#License)
* [Lint list](#lints)
* [Usage instructions](#usage)
* [Configuration](#configuration)
-* [*clippy-service*](#link-with-clippy-service)
* [License](#license)
## Usage
+Since this is a tool for helping the developer of a library or application
+write better code, it is recommended not to include clippy as a hard dependency.
+Options include using it as an optional dependency, as a cargo subcommand, or
+as an included feature during build. All of these options are detailed below.
+
As a general rule clippy will only work with the *latest* Rust nightly for now.
-### As a Compiler Plugin
+### Optional dependency
-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.
+If you want to make clippy an optional dependency, you can do the following:
-Add in your `Cargo.toml`:
+In your `Cargo.toml`:
```toml
[dependencies]
-clippy = "*"
-```
+clippy = {version = "*", optional = true}
-You then need to add `#![feature(plugin)]` and `#![plugin(clippy)]` to the top
-of your crate entry point (`main.rs` or `lib.rs`).
+[features]
+default = []
+```
-Sample `main.rs`:
+And, in your `main.rs` or `lib.rs`:
```rust
-#![feature(plugin)]
-
-#![plugin(clippy)]
-
+#![cfg_attr(feature="clippy", feature(plugin))]
-fn main(){
- let x = Some(1u8);
- match x {
- Some(y) => println!("{:?}", y),
- _ => ()
- }
-}
+#![cfg_attr(feature="clippy", plugin(clippy))]
```
-Produces this warning:
+Then build by enabling the feature: `cargo build --features "clippy"`
-```terminal
-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) }
-```
+Instead of adding the `cfg_attr` attributes you can also run clippy on demand:
+`cargo rustc --features clippy -- -Z no-trans -Z extra-plugins=clippy`
+(the `-Z no trans`, while not necessary, will stop the compilation process after
+typechecking (and lints) have completed, which can significantly reduce the runtime).
### As a cargo subcommand (`cargo clippy`)
in your code, you can use:
```terminal
-cargo rustc -- -L /path/to/clippy_so -Z extra-plugins=clippy
+cargo rustc -- -L /path/to/clippy_so/dir/ -Z extra-plugins=clippy
```
*[Note](https://github.com/Manishearth/rust-clippy/wiki#a-word-of-warning):*
Be sure that clippy was compiled with the same version of rustc that cargo invokes here!
-### Optional dependency
+### As a Compiler Plugin
-If you want to make clippy an optional dependency, you can do the following:
+*Note:* This is not a recommended installation method.
-In your `Cargo.toml`:
+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`:
```toml
[dependencies]
-clippy = {version = "*", optional = true}
-
-[features]
-default = []
+clippy = "*"
```
-And, in your `main.rs` or `lib.rs`:
+You then need to add `#![feature(plugin)]` and `#![plugin(clippy)]` to the top
+of your crate entry point (`main.rs` or `lib.rs`).
+
+Sample `main.rs`:
```rust
-#![cfg_attr(feature="clippy", feature(plugin))]
+#![feature(plugin)]
-#![cfg_attr(feature="clippy", plugin(clippy))]
+#![plugin(clippy)]
+
+
+fn main(){
+ let x = Some(1u8);
+ match x {
+ Some(y) => println!("{:?}", y),
+ _ => ()
+ }
+}
```
-Then build by enabling the feature: `cargo build --features "clippy"`
+Produces this warning:
-Instead of adding the `cfg_attr` attributes you can also run clippy on demand:
-`cargo rustc --features clippy -- -Z no-trans -Z extra-plugins=clippy`
-(the `-Z no trans`, while not neccessary, will stop the compilation process after
-typechecking (and lints) have completed, which can significantly reduce the runtime).
+```terminal
+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) }
+```
## Configuration
#[cfg_attr(feature = "cargo-clippy", allow(needless_lifetimes))]
```
-## Link with clippy service
-
-`clippy-service` is a rust web initiative providing `rust-clippy` as a web service.
-
-Both projects are independent and maintained by different people
-(even if some `clippy-service`'s contributions are authored by some `rust-clippy` members).
-
-You can check out this great service at [clippy.bashy.io](https://clippy.bashy.io/).
-
## Lints
-There are 177 lints included in this crate:
+There are 198 lints included in this crate:
name | default | triggers on
-----------------------------------------------------------------------------------------------------------------------|---------|----------------------------------------------------------------------------------------------------------------------------------
[assign_ops](https://github.com/Manishearth/rust-clippy/wiki#assign_ops) | allow | any compound assignment operation
[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`
[blacklisted_name](https://github.com/Manishearth/rust-clippy/wiki#blacklisted_name) | warn | usage of a blacklisted/placeholder name
-[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 } ...`
+[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 } ...`
[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 } ...`
[bool_comparison](https://github.com/Manishearth/rust-clippy/wiki#bool_comparison) | warn | comparing a variable to a boolean, e.g. `if x == true`
[box_vec](https://github.com/Manishearth/rust-clippy/wiki#box_vec) | warn | usage of `Box<Vec<T>>`, vector elements are already on the heap
[boxed_local](https://github.com/Manishearth/rust-clippy/wiki#boxed_local) | warn | using `Box<T>` where unnecessary
[builtin_type_shadow](https://github.com/Manishearth/rust-clippy/wiki#builtin_type_shadow) | warn | shadowing a builtin type
-[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`
-[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`
-[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`
-[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`
+[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`
+[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`
+[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`
+[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`
[char_lit_as_u8](https://github.com/Manishearth/rust-clippy/wiki#char_lit_as_u8) | warn | casting a character literal to u8
[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
[clone_double_ref](https://github.com/Manishearth/rust-clippy/wiki#clone_double_ref) | warn | using `clone` on `&&T`
[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
[cyclomatic_complexity](https://github.com/Manishearth/rust-clippy/wiki#cyclomatic_complexity) | warn | functions that should be split up into multiple functions
[deprecated_semver](https://github.com/Manishearth/rust-clippy/wiki#deprecated_semver) | warn | use of `#[deprecated(since = "x")]` where x is not semver
+[deref_addrof](https://github.com/Manishearth/rust-clippy/wiki#deref_addrof) | warn | use of `*&` or `*&mut` in an expression
[derive_hash_xor_eq](https://github.com/Manishearth/rust-clippy/wiki#derive_hash_xor_eq) | warn | deriving `Hash` but implementing `PartialEq` explicitly
[diverging_sub_expression](https://github.com/Manishearth/rust-clippy/wiki#diverging_sub_expression) | warn | whether an expression contains a diverging sub expression
[doc_markdown](https://github.com/Manishearth/rust-clippy/wiki#doc_markdown) | warn | presence of `_`, `::` or camel-case outside backticks in documentation
[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++
+[double_parens](https://github.com/Manishearth/rust-clippy/wiki#double_parens) | warn | Warn on unnecessary double parentheses
+[drop_copy](https://github.com/Manishearth/rust-clippy/wiki#drop_copy) | warn | calls to `std::mem::drop` with a value that implements Copy
[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
[duplicate_underscore_argument](https://github.com/Manishearth/rust-clippy/wiki#duplicate_underscore_argument) | warn | function arguments having names which only differ by an underscore
+[empty_enum](https://github.com/Manishearth/rust-clippy/wiki#empty_enum) | allow | enum with no variants
[empty_loop](https://github.com/Manishearth/rust-clippy/wiki#empty_loop) | warn | empty `loop {}`, which should block or sleep
[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`
[enum_glob_use](https://github.com/Manishearth/rust-clippy/wiki#enum_glob_use) | allow | use items that import all variants of an enum
[explicit_counter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_counter_loop) | warn | for-looping with an explicit counter when `_.enumerate()` would do
[explicit_into_iter_loop](https://github.com/Manishearth/rust-clippy/wiki#explicit_into_iter_loop) | warn | for-looping over `_.into_iter()` when `_` would do
[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
-[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
[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
[filter_next](https://github.com/Manishearth/rust-clippy/wiki#filter_next) | warn | using `filter(p).next()`, which is more succinctly expressed as `.find(p)`
[float_arithmetic](https://github.com/Manishearth/rust-clippy/wiki#float_arithmetic) | allow | any floating-point arithmetic statement
[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
[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`
[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`
+[forget_copy](https://github.com/Manishearth/rust-clippy/wiki#forget_copy) | warn | calls to `std::mem::forget` with a value that implements Copy
+[forget_ref](https://github.com/Manishearth/rust-clippy/wiki#forget_ref) | warn | calls to `std::mem::forget` with a reference instead of an owned value
[get_unwrap](https://github.com/Manishearth/rust-clippy/wiki#get_unwrap) | warn | using `.get().unwrap()` or `.get_mut().unwrap()` when using `[]` would work instead
[identity_op](https://github.com/Manishearth/rust-clippy/wiki#identity_op) | warn | using identity operations, e.g. `x + 0` or `y / 1`
[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`
[invalid_regex](https://github.com/Manishearth/rust-clippy/wiki#invalid_regex) | deny | invalid regular expressions
[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
[items_after_statements](https://github.com/Manishearth/rust-clippy/wiki#items_after_statements) | allow | blocks where an item comes after a statement
+[iter_cloned_collect](https://github.com/Manishearth/rust-clippy/wiki#iter_cloned_collect) | warn | using `.cloned().collect()` on slice to create a `Vec`
[iter_next_loop](https://github.com/Manishearth/rust-clippy/wiki#iter_next_loop) | warn | for-looping over `_.next()` which is probably not intended
[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
[iter_skip_next](https://github.com/Manishearth/rust-clippy/wiki#iter_skip_next) | warn | using `.skip(x).next()` on an iterator
+[large_enum_variant](https://github.com/Manishearth/rust-clippy/wiki#large_enum_variant) | warn | large size difference between variants on an enum
[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
[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
[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
[match_overlapping_arm](https://github.com/Manishearth/rust-clippy/wiki#match_overlapping_arm) | warn | a match with overlapping arms
[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
[match_same_arms](https://github.com/Manishearth/rust-clippy/wiki#match_same_arms) | warn | `match` with identical arm bodies
+[match_wild_err_arm](https://github.com/Manishearth/rust-clippy/wiki#match_wild_err_arm) | warn | a match with `Err(_)` arm and take drastic actions
[mem_forget](https://github.com/Manishearth/rust-clippy/wiki#mem_forget) | allow | `mem::forget` usage on `Drop` types, likely to cause memory leaks
[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
[misrefactored_assign_op](https://github.com/Manishearth/rust-clippy/wiki#misrefactored_assign_op) | warn | having a variable on both sides of an assign op
[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
[module_inception](https://github.com/Manishearth/rust-clippy/wiki#module_inception) | warn | modules that have the same name as their parent module
[modulo_one](https://github.com/Manishearth/rust-clippy/wiki#modulo_one) | warn | taking a number modulo 1, which always returns 0
+[mut_from_ref](https://github.com/Manishearth/rust-clippy/wiki#mut_from_ref) | warn | fns that create mutable refs from immutable ref args
[mut_mut](https://github.com/Manishearth/rust-clippy/wiki#mut_mut) | allow | usage of double-mut refs, e.g. `&mut &mut ...`
[mutex_atomic](https://github.com/Manishearth/rust-clippy/wiki#mutex_atomic) | warn | using a mutex where an atomic value could be used instead
[mutex_integer](https://github.com/Manishearth/rust-clippy/wiki#mutex_integer) | allow | using a mutex for an integer type
[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 }`
[needless_borrow](https://github.com/Manishearth/rust-clippy/wiki#needless_borrow) | warn | taking a reference that is going to be automatically dereferenced
+[needless_continue](https://github.com/Manishearth/rust-clippy/wiki#needless_continue) | warn | `continue` statements that can be replaced by a rearrangement of code
[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
+[needless_pass_by_value](https://github.com/Manishearth/rust-clippy/wiki#needless_pass_by_value) | warn | functions taking arguments by value, but not consuming them in its body
[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
[needless_return](https://github.com/Manishearth/rust-clippy/wiki#needless_return) | warn | using a return statement like `return expr;` where an expression would suffice
[needless_update](https://github.com/Manishearth/rust-clippy/wiki#needless_update) | warn | using `Foo { ..base }` when there are no missing fields
[neg_multiply](https://github.com/Manishearth/rust-clippy/wiki#neg_multiply) | warn | multiplying integers with -1
+[never_loop](https://github.com/Manishearth/rust-clippy/wiki#never_loop) | allow | any loop with an unconditional `break` or `return` statement
[new_ret_no_self](https://github.com/Manishearth/rust-clippy/wiki#new_ret_no_self) | warn | not returning `Self` in a `new` method
[new_without_default](https://github.com/Manishearth/rust-clippy/wiki#new_without_default) | warn | `fn new() -> Self` method without `Default` implementation
[new_without_default_derive](https://github.com/Manishearth/rust-clippy/wiki#new_without_default_derive) | warn | `fn new() -> Self` without `#[derive]`able `Default` implementation
[nonsensical_open_options](https://github.com/Manishearth/rust-clippy/wiki#nonsensical_open_options) | warn | nonsensical combination of options for opening a file
[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`
[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
+[op_ref](https://github.com/Manishearth/rust-clippy/wiki#op_ref) | warn | taking a reference to satisfy the type constraints on `==`
[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)`
[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)`
[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()`
[overflow_check_conditional](https://github.com/Manishearth/rust-clippy/wiki#overflow_check_conditional) | warn | overflow checks inspired by C which are likely to panic
[panic_params](https://github.com/Manishearth/rust-clippy/wiki#panic_params) | warn | missing parameters in `panic!` calls
[partialeq_ne_impl](https://github.com/Manishearth/rust-clippy/wiki#partialeq_ne_impl) | warn | re-implementing `PartialEq::ne`
+[possible_missing_comma](https://github.com/Manishearth/rust-clippy/wiki#possible_missing_comma) | warn | possible missing comma in array
[precedence](https://github.com/Manishearth/rust-clippy/wiki#precedence) | warn | operations where precedence may be unclear
[print_stdout](https://github.com/Manishearth/rust-clippy/wiki#print_stdout) | allow | printing on stdout
[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
[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
+[pub_enum_variant_names](https://github.com/Manishearth/rust-clippy/wiki#pub_enum_variant_names) | allow | enums where all variants share a prefix/postfix
[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
[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
[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`)
[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`
[shadow_same](https://github.com/Manishearth/rust-clippy/wiki#shadow_same) | allow | rebinding a name to itself, e.g. `let mut x = &mut x`
[shadow_unrelated](https://github.com/Manishearth/rust-clippy/wiki#shadow_unrelated) | allow | rebinding a name without even using the original value
+[short_circuit_statement](https://github.com/Manishearth/rust-clippy/wiki#short_circuit_statement) | warn | using a short circuit boolean condition as a statement
+[should_assert_eq](https://github.com/Manishearth/rust-clippy/wiki#should_assert_eq) | warn | using `assert` macro for asserting equality
[should_implement_trait](https://github.com/Manishearth/rust-clippy/wiki#should_implement_trait) | warn | defining a method that should be implementing a std trait
[similar_names](https://github.com/Manishearth/rust-clippy/wiki#similar_names) | allow | similarly named items and bindings
[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")`
-[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`
+[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`
[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`
[string_add](https://github.com/Manishearth/rust-clippy/wiki#string_add) | allow | using `x + ..` where x is a `String` instead of `push_str()`
[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()`
+[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`
[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
[stutter](https://github.com/Manishearth/rust-clippy/wiki#stutter) | allow | type names prefixed/postfixed with their containing module's name
[suspicious_assignment_formatting](https://github.com/Manishearth/rust-clippy/wiki#suspicious_assignment_formatting) | warn | suspicious formatting of `*=`, `-=` or `!=`
[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
[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)
[unit_cmp](https://github.com/Manishearth/rust-clippy/wiki#unit_cmp) | warn | comparing unit values
+[unnecessary_cast](https://github.com/Manishearth/rust-clippy/wiki#unnecessary_cast) | warn | cast to the same type, e.g. `x as i32` where `x: i32`
[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
[unnecessary_operation](https://github.com/Manishearth/rust-clippy/wiki#unnecessary_operation) | warn | outer expressions with no effect
[unneeded_field_pattern](https://github.com/Manishearth/rust-clippy/wiki#unneeded_field_pattern) | warn | struct fields bound to a wildcard instead of using `..`
[unsafe_removed_from_name](https://github.com/Manishearth/rust-clippy/wiki#unsafe_removed_from_name) | warn | `unsafe` removed from API names on import
[unseparated_literal_suffix](https://github.com/Manishearth/rust-clippy/wiki#unseparated_literal_suffix) | allow | literals whose suffix is not separated by an underscore
[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
+[unused_io_amount](https://github.com/Manishearth/rust-clippy/wiki#unused_io_amount) | deny | unused written/read amount
[unused_label](https://github.com/Manishearth/rust-clippy/wiki#unused_label) | warn | unused labels
[unused_lifetimes](https://github.com/Manishearth/rust-clippy/wiki#unused_lifetimes) | warn | unused lifetimes in function definitions
[use_debug](https://github.com/Manishearth/rust-clippy/wiki#use_debug) | allow | use of `Debug`-based formatting
[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
[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
[zero_prefixed_literal](https://github.com/Manishearth/rust-clippy/wiki#zero_prefixed_literal) | warn | integer literals starting with `0`
+[zero_ptr](https://github.com/Manishearth/rust-clippy/wiki#zero_ptr) | warn | using 0 as *{const, mut} T
[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
More to come, please [file an issue](https://github.com/Manishearth/rust-clippy/issues) if you have ideas!