Lint Configuration Options

The following list shows each configuration option, along with a description, its default value, an example and lints affected.

absolute-paths-allowed-crates

Which crates to allow absolute paths from

Default Value: []

Affected lints:

absolute-paths-max-segments

The maximum number of segments a path can have before being linted, anything above this will be linted.

Default Value: 2

Affected lints:

accept-comment-above-attributes

Whether to accept a safety comment to be placed above the attributes for the unsafe block

Default Value: true

Affected lints:

accept-comment-above-statement

Whether to accept a safety comment to be placed above the statement containing the unsafe block

Default Value: true

Affected lints:

allow-comparison-to-zero

Don't lint when comparing the result of a modulo operation to zero.

Default Value: true

Affected lints:

allow-dbg-in-tests

Whether dbg! should be allowed in test functions or #[cfg(test)]

Default Value: false

Affected lints:

allow-exact-repetitions

Whether an item should be allowed to have the same name as its containing module

Default Value: true

Affected lints:

allow-expect-in-consts

Whether expect should be allowed in code always evaluated at compile time

Default Value: true

Affected lints:

allow-expect-in-tests

Whether expect should be allowed in test functions or #[cfg(test)]

Default Value: false

Affected lints:

allow-indexing-slicing-in-tests

Whether indexing_slicing should be allowed in test functions or #[cfg(test)]

Default Value: false

Affected lints:

allow-mixed-uninlined-format-args

Whether to allow mixed uninlined format args, e.g. format!("{} {}", a, foo.bar)

Default Value: true

Affected lints:

allow-one-hash-in-raw-strings

Whether to allow r#""# when r"" can be used

Default Value: false

Affected lints:

allow-panic-in-tests

Whether panic should be allowed in test functions or #[cfg(test)]

Default Value: false

Affected lints:

allow-print-in-tests

Whether print macros (ex. println!) should be allowed in test functions or #[cfg(test)]

Default Value: false

Affected lints:

allow-private-module-inception

Whether to allow module inception if it's not public.

Default Value: false

Affected lints:

allow-renamed-params-for

List of trait paths to ignore when checking renamed function parameters.

Example

allow-renamed-params-for = [ "std::convert::From" ]

Noteworthy

  • By default, the following traits are ignored: From, TryFrom, FromStr
  • ".." can be used as part of the list to indicate that the configured values should be appended to the default configuration of Clippy. By default, any configuration will replace the default value.

Default Value: ["core::convert::From", "core::convert::TryFrom", "core::str::FromStr"]

Affected lints:

allow-unwrap-in-consts

Whether unwrap should be allowed in code always evaluated at compile time

Default Value: true

Affected lints:

allow-unwrap-in-tests

Whether unwrap should be allowed in test functions or #[cfg(test)]

Default Value: false

Affected lints:

allow-useless-vec-in-tests

Whether useless_vec should ignore test functions or #[cfg(test)]

Default Value: false

Affected lints:

allowed-dotfiles

Additional dotfiles (files or directories starting with a dot) to allow

Default Value: []

Affected lints:

allowed-duplicate-crates

A list of crate names to allow duplicates of

Default Value: []

Affected lints:

allowed-idents-below-min-chars

Allowed names below the minimum allowed characters. The value ".." can be used as part of the list to indicate, that the configured values should be appended to the default configuration of Clippy. By default, any configuration will replace the default value.

Default Value: ["i", "j", "x", "y", "z", "w", "n"]

Affected lints:

allowed-prefixes

List of prefixes to allow when determining whether an item‘s name ends with the module’s name. If the rest of an item‘s name is an allowed prefix (e.g. item ToFoo or to_foo in module foo), then don’t emit a warning.

Example

allowed-prefixes = [ "to", "from" ]

Noteworthy

  • By default, the following prefixes are allowed: to, as, into, from, try_into and try_from
  • PascalCase variant is included automatically for each snake_case variant (e.g. if try_into is included, TryInto will also be included)
  • Use ".." as part of the list to indicate that the configured values should be appended to the default configuration of Clippy. By default, any configuration will replace the default value

Default Value: ["to", "as", "into", "from", "try_into", "try_from"]

Affected lints:

allowed-scripts

The list of unicode scripts allowed to be used in the scope.

Default Value: ["Latin"]

Affected lints:

allowed-wildcard-imports

List of path segments allowed to have wildcard imports.

Example

allowed-wildcard-imports = [ "utils", "common" ]

Noteworthy

  1. This configuration has no effects if used with warn_on_all_wildcard_imports = true.
  2. Paths with any segment that containing the word ‘prelude’ are already allowed by default.

Default Value: []

Affected lints:

arithmetic-side-effects-allowed

Suppress checking of the passed type names in all types of operations.

If a specific operation is desired, consider using arithmetic_side_effects_allowed_binary or arithmetic_side_effects_allowed_unary instead.

Example

arithmetic-side-effects-allowed = ["SomeType", "AnotherType"]

Noteworthy

A type, say SomeType, listed in this configuration has the same behavior of ["SomeType" , "*"], ["*", "SomeType"] in arithmetic_side_effects_allowed_binary.

Default Value: []

Affected lints:

arithmetic-side-effects-allowed-binary

Suppress checking of the passed type pair names in binary operations like addition or multiplication.

Supports the “*” wildcard to indicate that a certain type won't trigger the lint regardless of the involved counterpart. For example, ["SomeType", "*"] or ["*", "AnotherType"].

Pairs are asymmetric, which means that ["SomeType", "AnotherType"] is not the same as ["AnotherType", "SomeType"].

Example

arithmetic-side-effects-allowed-binary = [["SomeType" , "f32"], ["AnotherType", "*"]]

Default Value: []

Affected lints:

arithmetic-side-effects-allowed-unary

Suppress checking of the passed type names in unary operations like “negation” (-).

Example

arithmetic-side-effects-allowed-unary = ["SomeType", "AnotherType"]

Default Value: []

Affected lints:

array-size-threshold

The maximum allowed size for arrays on the stack

Default Value: 16384

Affected lints:

avoid-breaking-exported-api

Suppress lints whenever the suggested change would cause breakage for other crates.

Default Value: true

Affected lints:

await-holding-invalid-types

The list of types which may not be held across an await point.

Default Value: []

Affected lints:

cargo-ignore-publish

For internal testing only, ignores the current publish settings in the Cargo manifest.

Default Value: false

Affected lints:

check-incompatible-msrv-in-tests

Whether to check MSRV compatibility in #[test] and #[cfg(test)] code.

Default Value: false

Affected lints:

check-inconsistent-struct-field-initializers

Whether to suggest reordering constructor fields when initializers are present.

Warnings produced by this configuration aren't necessarily fixed by just reordering the fields. Even if the suggested code would compile, it can change semantics if the initializer expressions have side effects. The following example from rust-clippy#11846 shows how the suggestion can run into borrow check errors:

struct MyStruct {
    vector: Vec<u32>,
    length: usize
}
fn main() {
    let vector = vec![1,2,3];
    MyStruct { length: vector.len(), vector};
}

Default Value: false

Affected lints:

check-private-items

Whether to also run the listed lints on private items.

Default Value: false

Affected lints:

cognitive-complexity-threshold

The maximum cognitive complexity a function can have

Default Value: 25

Affected lints:

const-literal-digits-threshold

The minimum digits a const float literal must have to supress the excessive_precicion lint

Default Value: 30

Affected lints:

disallowed-macros

The list of disallowed macros, written as fully qualified paths.

Fields:

  • path (required): the fully qualified path to the macro that should be disallowed
  • reason (optional): explanation why this macro is disallowed
  • replacement (optional): suggested alternative macro
  • allow-invalid (optional, false by default): when set to true, it will ignore this entry if the path doesn't exist, instead of emitting an error

Default Value: []

Affected lints:

disallowed-methods

The list of disallowed methods, written as fully qualified paths.

Fields:

  • path (required): the fully qualified path to the method that should be disallowed
  • reason (optional): explanation why this method is disallowed
  • replacement (optional): suggested alternative method
  • allow-invalid (optional, false by default): when set to true, it will ignore this entry if the path doesn't exist, instead of emitting an error

Default Value: []

Affected lints:

disallowed-names

The list of disallowed names to lint about. NB: bar is not here since it has legitimate uses. The value ".." can be used as part of the list to indicate that the configured values should be appended to the default configuration of Clippy. By default, any configuration will replace the default value.

Default Value: ["foo", "baz", "quux"]

Affected lints:

disallowed-types

The list of disallowed types, written as fully qualified paths.

Fields:

  • path (required): the fully qualified path to the type that should be disallowed
  • reason (optional): explanation why this type is disallowed
  • replacement (optional): suggested alternative type
  • allow-invalid (optional, false by default): when set to true, it will ignore this entry if the path doesn't exist, instead of emitting an error

Default Value: []

Affected lints:

doc-valid-idents

The list of words this lint should not consider as identifiers needing ticks. The value ".." can be used as part of the list to indicate, that the configured values should be appended to the default configuration of Clippy. By default, any configuration will replace the default value. For example:

  • doc-valid-idents = ["ClipPy"] would replace the default list with ["ClipPy"].
  • doc-valid-idents = ["ClipPy", ".."] would append ClipPy to the default list.

Default Value: ["KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "MHz", "GHz", "THz", "AccessKit", "CoAP", "CoreFoundation", "CoreGraphics", "CoreText", "DevOps", "Direct2D", "Direct3D", "DirectWrite", "DirectX", "ECMAScript", "GPLv2", "GPLv3", "GitHub", "GitLab", "IPv4", "IPv6", "InfiniBand", "RoCE", "ClojureScript", "CoffeeScript", "JavaScript", "PostScript", "PureScript", "TypeScript", "PowerPC", "WebAssembly", "NaN", "NaNs", "OAuth", "GraphQL", "OCaml", "OpenAL", "OpenDNS", "OpenGL", "OpenMP", "OpenSSH", "OpenSSL", "OpenStreetMap", "OpenTelemetry", "OpenType", "WebGL", "WebGL2", "WebGPU", "WebRTC", "WebSocket", "WebTransport", "WebP", "OpenExr", "YCbCr", "sRGB", "TensorFlow", "TrueType", "iOS", "macOS", "FreeBSD", "NetBSD", "OpenBSD", "NixOS", "TeX", "LaTeX", "BibTeX", "BibLaTeX", "MinGW", "CamelCase"]

Affected lints:

enable-raw-pointer-heuristic-for-send

Whether to apply the raw pointer heuristic to determine if a type is Send.

Default Value: true

Affected lints:

enforce-iter-loop-reborrow

Whether to recommend using implicit into iter for reborrowed values.

Example

let mut vec = vec![1, 2, 3];
let rmvec = &mut vec;
for _ in rmvec.iter() {}
for _ in rmvec.iter_mut() {}

Use instead:

let mut vec = vec![1, 2, 3];
let rmvec = &mut vec;
for _ in &*rmvec {}
for _ in &mut *rmvec {}

Default Value: false

Affected lints:

enforced-import-renames

The list of imports to always rename, a fully qualified path followed by the rename.

Default Value: []

Affected lints:

enum-variant-name-threshold

The minimum number of enum variants for the lints about variant names to trigger

Default Value: 3

Affected lints:

enum-variant-size-threshold

The maximum size of an enum's variant to avoid box suggestion

Default Value: 200

Affected lints:

excessive-nesting-threshold

The maximum amount of nesting a block can reside in

Default Value: 0

Affected lints:

future-size-threshold

The maximum byte size a Future can have, before it triggers the clippy::large_futures lint

Default Value: 16384

Affected lints:

ignore-interior-mutability

A list of paths to types that should be treated as if they do not contain interior mutability

Default Value: ["bytes::Bytes"]

Affected lints:

inherent-impl-lint-scope

Sets the scope (“crate”, “file”, or “module”) in which duplicate inherent impl blocks for the same type are linted.

Default Value: "crate"

Affected lints:

large-error-ignored

A list of paths to types that should be ignored as overly large Err-variants in a Result returned from a function

Default Value: []

Affected lints:

large-error-threshold

The maximum size of the Err-variant in a Result returned from a function

Default Value: 128

Affected lints:

lint-commented-code

Whether collapsible if and else if chains are linted if they contain comments inside the parts that would be collapsed.

Default Value: false

Affected lints:

literal-representation-threshold

The lower bound for linting decimal literals

Default Value: 16384

Affected lints:

matches-for-let-else

Whether the matches should be considered by the lint, and whether there should be filtering for common types.

Default Value: "WellKnownTypes"

Affected lints:

max-fn-params-bools

The maximum number of bool parameters a function can have

Default Value: 3

Affected lints:

max-include-file-size

The maximum size of a file included via include_bytes!() or include_str!(), in bytes

Default Value: 1000000

Affected lints:

max-struct-bools

The maximum number of bool fields a struct can have

Default Value: 3

Affected lints:

max-suggested-slice-pattern-length

When Clippy suggests using a slice pattern, this is the maximum number of elements allowed in the slice pattern that is suggested. If more elements are necessary, the lint is suppressed. For example, [_, _, _, e, ..] is a slice pattern with 4 elements.

Default Value: 3

Affected lints:

max-trait-bounds

The maximum number of bounds a trait can have to be linted

Default Value: 3

Affected lints:

min-ident-chars-threshold

Minimum chars an ident can have, anything below or equal to this will be linted.

Default Value: 1

Affected lints:

missing-docs-allow-unused

Whether to allow fields starting with an underscore to skip documentation requirements

Default Value: false

Affected lints:

missing-docs-in-crate-items

Whether to only check for missing documentation in items visible within the current crate. For example, pub(crate) items.

Default Value: false

Affected lints:

module-item-order-groupings

The named groupings of different source item kinds within modules.

Default Value: [["modules", ["extern_crate", "mod", "foreign_mod"]], ["use", ["use"]], ["macros", ["macro"]], ["global_asm", ["global_asm"]], ["UPPER_SNAKE_CASE", ["static", "const"]], ["PascalCase", ["ty_alias", "enum", "struct", "union", "trait", "trait_alias", "impl"]], ["lower_snake_case", ["fn"]]]

Affected lints:

module-items-ordered-within-groupings

Whether the items within module groups should be ordered alphabetically or not.

This option can be configured to “all”, “none”, or a list of specific grouping names that should be checked (e.g. only “enums”).

Default Value: "none"

Affected lints:

msrv

The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

Default Value: current version

Affected lints:

pass-by-value-size-limit

The minimum size (in bytes) to consider a type for passing by reference instead of by value.

Default Value: 256

Affected lints:

pub-underscore-fields-behavior

Lint “public” fields in a struct that are prefixed with an underscore based on their exported visibility, or whether they are marked as “pub”.

Default Value: "PubliclyExported"

Affected lints:

recursive-self-in-type-definitions

Whether the type itself in a struct or enum should be replaced with Self when encountering recursive types.

Default Value: true

Affected lints:

semicolon-inside-block-ignore-singleline

Whether to lint only if it's multiline.

Default Value: false

Affected lints:

semicolon-outside-block-ignore-multiline

Whether to lint only if it's singleline.

Default Value: false

Affected lints:

single-char-binding-names-threshold

The maximum number of single char bindings a scope may have

Default Value: 4

Affected lints:

source-item-ordering

Which kind of elements should be ordered internally, possible values being enum, impl, module, struct, trait.

Default Value: ["enum", "impl", "module", "struct", "trait"]

Affected lints:

stack-size-threshold

The maximum allowed stack size for functions in bytes

Default Value: 512000

Affected lints:

standard-macro-braces

Enforce the named macros always use the braces specified.

A MacroMatcher can be added like so { name = "macro_name", brace = "(" }. If the macro could be used with a full path two MacroMatchers have to be added one with the full path crate_name::macro_name and one with just the macro name.

Default Value: []

Affected lints:

struct-field-name-threshold

The minimum number of struct fields for the lints about field names to trigger

Default Value: 3

Affected lints:

suppress-restriction-lint-in-const

Whether to suppress a restriction lint in constant code. In same cases the restructured operation might not be unavoidable, as the suggested counterparts are unavailable in constant code. This configuration will cause restriction lints to trigger even if no suggestion can be made.

Default Value: false

Affected lints:

too-large-for-stack

The maximum size of objects (in bytes) that will be linted. Larger objects are ok on the heap

Default Value: 200

Affected lints:

too-many-arguments-threshold

The maximum number of argument a function or method can have

Default Value: 7

Affected lints:

too-many-lines-threshold

The maximum number of lines a function or method can have

Default Value: 100

Affected lints:

trait-assoc-item-kinds-order

The order of associated items in traits.

Default Value: ["const", "type", "fn"]

Affected lints:

trivial-copy-size-limit

The maximum size (in bytes) to consider a Copy type for passing by value instead of by reference.

Default Value: target_pointer_width

Affected lints:

type-complexity-threshold

The maximum complexity a type can have

Default Value: 250

Affected lints:

unnecessary-box-size

The byte size a T in Box<T> can have, below which it triggers the clippy::unnecessary_box lint

Default Value: 128

Affected lints:

unreadable-literal-lint-fractions

Should the fraction of a decimal be linted to include separators.

Default Value: true

Affected lints:

upper-case-acronyms-aggressive

Enables verbose mode. Triggers if there is more than one uppercase char next to each other

Default Value: false

Affected lints:

vec-box-size-threshold

The size of the boxed type in bytes, where boxing in a Vec is allowed

Default Value: 4096

Affected lints:

verbose-bit-mask-threshold

The maximum allowed size of a bit mask before suggesting to use ‘trailing_zeros’

Default Value: 1

Affected lints:

warn-on-all-wildcard-imports

Whether to emit warnings on all wildcard imports, including those from prelude, from super in tests, or for pub use reexports.

Default Value: false

Affected lints:

warn-unsafe-macro-metavars-in-private-macros

Whether to also emit warnings for unsafe blocks with metavariable expansions in private macros.

Default Value: false

Affected lints: