rust-clippy/book/src/lint_configuration.md

Lint Configuration Options

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

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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: {} (rustc_data_structures::fx::FxHashSet<String>)

---

Affected lints:

• arithmetic_side_effects

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: [] (Vec<[String; 2]>)

---

Affected lints:

• arithmetic_side_effects

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: {} (rustc_data_structures::fx::FxHashSet<String>)

---

Affected lints:

• arithmetic_side_effects

avoid-breaking-exported-api

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

Default Value: true (bool)

---

Affected lints:

• enum_variant_names
• large_types_passed_by_value
• trivially_copy_pass_by_ref
• unnecessary_wraps
• unused_self
• upper_case_acronyms
• wrong_self_convention
• box_collection
• redundant_allocation
• rc_buffer
• vec_box
• option_option
• linkedlist
• rc_mutex
• unnecessary_box_returns
• single_call_fn

msrv

The minimum rust version that the project supports

Default Value: None (Option<String>)

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Affected lints:

• manual_split_once
• manual_str_repeat
• cloned_instead_of_copied
• redundant_field_names
• option_map_unwrap_or
• redundant_static_lifetimes
• filter_map_next
• checked_conversions
• manual_range_contains
• use_self
• mem_replace_with_default
• manual_non_exhaustive
• option_as_ref_deref
• map_unwrap_or
• match_like_matches_macro
• manual_strip
• missing_const_for_fn
• unnested_or_patterns
• from_over_into
• ptr_as_ptr
• if_then_some_else_none
• approx_constant
• deprecated_cfg_attr
• index_refutable_slice
• map_clone
• borrow_as_ptr
• manual_bits
• err_expect
• cast_abs_to_unsigned
• uninlined_format_args
• manual_clamp
• manual_let_else
• unchecked_duration_subtraction
• collapsible_str_replace
• seek_from_current
• seek_rewind
• unnecessary_lazy_evaluations
• transmute_ptr_to_ref
• almost_complete_range
• needless_borrow
• derivable_impls
• manual_is_ascii_check
• manual_rem_euclid
• manual_retain
• type_repetition_in_bounds
• tuple_array_conversions

cognitive-complexity-threshold

The maximum cognitive complexity a function can have

Default Value: 25 (u64)

---

Affected lints:

• cognitive_complexity

excessive-nesting-threshold

The maximum amount of nesting a block can reside in

Default Value: 0 (u64)

---

Affected lints:

• excessive_nesting

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"] (Vec<String>)

---

Affected lints:

• disallowed_names

semicolon-inside-block-ignore-singleline

Whether to lint only if it's multiline.

Default Value: false (bool)

---

Affected lints:

• semicolon_inside_block

semicolon-outside-block-ignore-multiline

Whether to lint only if it's singleline.

Default Value: false (bool)

---

Affected lints:

• semicolon_outside_block

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 list:

Default Value: ["KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "DirectX", "ECMAScript", "GPLv2", "GPLv3", "GitHub", "GitLab", "IPv4", "IPv6", "ClojureScript", "CoffeeScript", "JavaScript", "PureScript", "TypeScript", "WebAssembly", "NaN", "NaNs", "OAuth", "GraphQL", "OCaml", "OpenGL", "OpenMP", "OpenSSH", "OpenSSL", "OpenStreetMap", "OpenDNS", "WebGL", "TensorFlow", "TrueType", "iOS", "macOS", "FreeBSD", "TeX", "LaTeX", "BibTeX", "BibLaTeX", "MinGW", "CamelCase"] (Vec<String>)

---

Affected lints:

• doc_markdown

too-many-arguments-threshold

The maximum number of argument a function or method can have

Default Value: 7 (u64)

---

Affected lints:

• too_many_arguments

type-complexity-threshold

The maximum complexity a type can have

Default Value: 250 (u64)

---

Affected lints:

• type_complexity

single-char-binding-names-threshold

The maximum number of single char bindings a scope may have

Default Value: 4 (u64)

---

Affected lints:

• many_single_char_names

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 (u64)

---

Affected lints:

• boxed_local
• useless_vec

enum-variant-name-threshold

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

Default Value: 3 (u64)

---

Affected lints:

• enum_variant_names

enum-variant-size-threshold

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

Default Value: 200 (u64)

---

Affected lints:

• large_enum_variant

verbose-bit-mask-threshold

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

Default Value: 1 (u64)

---

Affected lints:

• verbose_bit_mask

literal-representation-threshold

The lower bound for linting decimal literals

Default Value: 16384 (u64)

---

Affected lints:

• decimal_literal_representation

trivial-copy-size-limit

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

Default Value: None (Option<u64>)

---

Affected lints:

• trivially_copy_pass_by_ref

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 (u64)

---

Affected lints:

• large_types_passed_by_value

too-many-lines-threshold

The maximum number of lines a function or method can have

Default Value: 100 (u64)

---

Affected lints:

• too_many_lines

array-size-threshold

The maximum allowed size for arrays on the stack

Default Value: 512000 (u64)

---

Affected lints:

• large_stack_arrays
• large_const_arrays

stack-size-threshold

The maximum allowed stack size for functions in bytes

Default Value: 512000 (u64)

---

Affected lints:

• large_stack_frames

vec-box-size-threshold

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

Default Value: 4096 (u64)

---

Affected lints:

• vec_box

max-trait-bounds

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

Default Value: 3 (u64)

---

Affected lints:

• type_repetition_in_bounds

max-struct-bools

The maximum number of bool fields a struct can have

Default Value: 3 (u64)

---

Affected lints:

• struct_excessive_bools

max-fn-params-bools

The maximum number of bool parameters a function can have

Default Value: 3 (u64)

---

Affected lints:

• fn_params_excessive_bools

warn-on-all-wildcard-imports

Whether to allow certain wildcard imports (prelude, super in tests).

Default Value: false (bool)

---

Affected lints:

• wildcard_imports

disallowed-macros

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

Default Value: [] (Vec<crate::utils::conf::DisallowedPath>)

---

Affected lints:

• disallowed_macros

disallowed-methods

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

Default Value: [] (Vec<crate::utils::conf::DisallowedPath>)

---

Affected lints:

• disallowed_methods

disallowed-types

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

Default Value: [] (Vec<crate::utils::conf::DisallowedPath>)

---

Affected lints:

• disallowed_types

unreadable-literal-lint-fractions

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

Default Value: true (bool)

---

Affected lints:

• unreadable_literal

upper-case-acronyms-aggressive

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

Default Value: false (bool)

---

Affected lints:

• upper_case_acronyms

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 (crate::manual_let_else::MatchLintBehaviour)

---

Affected lints:

• manual_let_else

cargo-ignore-publish

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

Default Value: false (bool)

---

Affected lints:

• _cargo_common_metadata

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: [] (Vec<crate::nonstandard_macro_braces::MacroMatcher>)

---

Affected lints:

• nonstandard_macro_braces

enforced-import-renames

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

Default Value: [] (Vec<crate::utils::conf::Rename>)

---

Affected lints:

• missing_enforced_import_renames

allowed-scripts

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

Default Value: ["Latin"] (Vec<String>)

---

Affected lints:

• disallowed_script_idents

enable-raw-pointer-heuristic-for-send

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

Default Value: true (bool)

---

Affected lints:

• non_send_fields_in_send_ty

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 (u64)

---

Affected lints:

• index_refutable_slice

await-holding-invalid-types

Default Value: [] (Vec<crate::utils::conf::DisallowedPath>)

---

Affected lints:

• await_holding_invalid_type

max-include-file-size

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

Default Value: 1000000 (u64)

---

Affected lints:

• large_include_file

allow-expect-in-tests

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

Default Value: false (bool)

---

Affected lints:

• expect_used

allow-unwrap-in-tests

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

Default Value: false (bool)

---

Affected lints:

• unwrap_used

allow-dbg-in-tests

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

Default Value: false (bool)

---

Affected lints:

• dbg_macro

allow-print-in-tests

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

Default Value: false (bool)

---

Affected lints:

• print_stdout
• print_stderr

large-error-threshold

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

Default Value: 128 (u64)

---

Affected lints:

• result_large_err

ignore-interior-mutability

A list of paths to types that should be treated like Arc, i.e. ignored but for the generic parameters for determining interior mutability

Default Value: ["bytes::Bytes"] (Vec<String>)

---

Affected lints:

• mutable_key_type
• ifs_same_cond

allow-mixed-uninlined-format-args

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

Default Value: true (bool)

---

Affected lints:

• uninlined_format_args

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 (bool)

---

Affected lints:

• indexing_slicing

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 (bool)

---

Affected lints:

• missing_docs_in_private_items

future-size-threshold

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

Default Value: 16384 (u64)

---

Affected lints:

• large_futures

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 (u64)

---

Affected lints:

• unnecessary_box_returns

allow-private-module-inception

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

Default Value: false (bool)

---

Affected lints:

• module_inception

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: {"j", "z", "i", "y", "n", "x", "w"} (rustc_data_structures::fx::FxHashSet<String>)

---

Affected lints:

• min_ident_chars

min-ident-chars-threshold

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

Default Value: 1 (u64)

---

Affected lints:

• min_ident_chars

accept-comment-above-statement

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

Default Value: false (bool)

---

Affected lints:

• undocumented_unsafe_blocks

accept-comment-above-attributes

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

Default Value: false (bool)

---

Affected lints:

• undocumented_unsafe_blocks

allow-one-hash-in-raw-strings

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

Default Value: false (bool)

---

Affected lints:

• unnecessary_raw_string_hashes