Available lint options: -W Warn about -A Allow -D Deny -F Forbid (deny and all attempts to override) Lint checks provided by rustc: name default meaning ---- ------- ------- absolute-paths-not-starting-with-crate allow fully qualified paths that start with a module name instead of `crate`, `self`, or an extern crate name anonymous-parameters allow detects anonymous parameters box-pointers allow use of owned (Box type) heap memory deprecated-in-future allow detects use of items that will be deprecated in a future version elided-lifetimes-in-paths allow hidden lifetime parameters in types are deprecated explicit-outlives-requirements allow outlives requirements can be inferred invalid-html-tags allow detects invalid HTML tags in doc comments keyword-idents allow detects edition keywords being used as an identifier macro-use-extern-crate allow the `#[macro_use]` attribute is now deprecated in favor of using macros via the module system meta-variable-misuse allow possible meta-variable misuse at macro definition missing-copy-implementations allow detects potentially-forgotten implementations of `Copy` missing-crate-level-docs allow detects crates with no crate-level documentation missing-debug-implementations allow detects missing implementations of Debug missing-docs allow detects missing documentation for public members missing-doc-code-examples allow detects publicly-exported items without code samples in their documentation non-ascii-idents allow detects non-ASCII identifiers pointer-structural-match allow pointers are not structural-match private-doc-tests allow detects code samples in docs of private items not documented by rustdoc single-use-lifetimes allow detects lifetime parameters that are only used once trivial-casts allow detects trivial casts which could be removed trivial-numeric-casts allow detects trivial casts of numeric types which could be removed unaligned-references allow detects unaligned references to fields of packed structs unreachable-pub allow `pub` items not reachable from crate root unsafe-code allow usage of `unsafe` code unsafe-op-in-unsafe-fn allow unsafe operations in unsafe functions without an explicit unsafe block are deprecated unstable-features allow enabling unstable features (deprecated. do not use) unused-crate-dependencies allow crate dependencies that are never used unused-extern-crates allow extern crates that are never used unused-import-braces allow unnecessary braces around an imported item unused-lifetimes allow detects lifetime parameters that are never used unused-qualifications allow detects unnecessarily qualified names unused-results allow unused result of an expression in a statement variant-size-differences allow detects enums with widely varying variant sizes array-into-iter warn detects calling `into_iter` on arrays asm-sub-register warn using only a subset of a register for inline asm inputs bare-trait-objects warn suggest using `dyn Trait` for trait objects bindings-with-variant-name warn detects pattern bindings with the same name as one of the matched variants broken-intra-doc-links warn failures in resolving intra-doc link targets cenum-impl-drop-cast warn a C-like enum implementing Drop is cast clashing-extern-declarations warn detects when an extern fn has been declared with the same name but different types coherence-leak-check warn distinct impls distinguished only by the leak-check code confusable-idents warn detects visually confusable pairs between identifiers const-evaluatable-unchecked warn detects a generic constant is used in a type without a emitting a warning const-item-mutation warn detects attempts to mutate a `const` item dead-code warn detect unused, unexported items deprecated warn detects use of deprecated items drop-bounds warn bounds of the form `T: Drop` are useless ellipsis-inclusive-range-patterns warn `...` range patterns are deprecated exported-private-dependencies warn public interface leaks type from a private dependency illegal-floating-point-literal-pattern warn floating-point literals cannot be used in patterns improper-ctypes warn proper use of libc types in foreign modules improper-ctypes-definitions warn proper use of libc types in foreign item definitions incomplete-features warn incomplete features that may function improperly in some or all cases indirect-structural-match warn constant used in pattern contains value of non-structural-match type in a field or a variant inline-no-sanitize warn detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]` invalid-codeblock-attributes warn codeblock attribute looks a lot like a known one invalid-value warn an invalid value is being created (such as a NULL reference) irrefutable-let-patterns warn detects irrefutable patterns in if-let and while-let statements late-bound-lifetime-arguments warn detects generic lifetime arguments in path segments with late bound lifetime parameters mixed-script-confusables warn detects Unicode scripts whose mixed script confusables codepoints are solely used mutable-borrow-reservation-conflict warn reservation of a two-phased borrow conflicts with other shared borrows nontrivial-structural-match warn constant used in pattern of non-structural-match type and the constant's initializer expression contains values of non-structural-match types non-camel-case-types warn types, variants, traits and type parameters should have camel case names non-shorthand-field-patterns warn using `Struct { x: x }` instead of `Struct { x }` in a pattern non-snake-case warn variables, methods, functions, lifetime parameters and modules should have snake case names non-upper-case-globals warn static constants should have uppercase identifiers no-mangle-generic-items warn generic items must be mangled overlapping-patterns warn detects overlapping patterns path-statements warn path statements with no effect private-in-public warn detect private items in public interfaces not caught by the old implementation proc-macro-derive-resolution-fallback warn detects proc macro derives using inaccessible names from parent modules redundant-semicolons warn detects unnecessary trailing semicolons renamed-and-removed-lints warn lints that have been renamed or removed safe-packed-borrows warn safe borrows of fields of packed structs were erroneously allowed stable-features warn stable features found in `#[feature]` directive trivial-bounds warn these bounds don't depend on an type parameters type-alias-bounds warn bounds in type aliases are not enforced tyvar-behind-raw-pointer warn raw pointer to an inference variable uncommon-codepoints warn detects uncommon Unicode codepoints in identifiers unconditional-recursion warn functions that cannot return without calling themselves unknown-lints warn unrecognized lint attribute unnameable-test-items warn detects an item that cannot be named being marked as `#[test_case]` unreachable-code warn detects unreachable code paths unreachable-patterns warn detects unreachable patterns unstable-name-collisions warn detects name collision with an existing but unstable method unused-allocation warn detects unnecessary allocations that can be eliminated unused-assignments warn detect assignments that will never be read unused-attributes warn detects attributes that were not used by the compiler unused-braces warn unnecessary braces around an expression unused-comparisons warn comparisons made useless by limits of the types involved unused-doc-comments warn detects doc comments that aren't used by rustdoc unused-features warn unused features found in crate-level `#[feature]` directives unused-imports warn imports that are never used unused-labels warn detects labels that are never used unused-macros warn detects macros that were not used unused-must-use warn unused result of a type flagged as `#[must_use]` unused-mut warn detect mut variables which don't need to be mutable unused-parens warn `if`, `match`, `while` and `return` do not need parentheses unused-unsafe warn unnecessary use of an `unsafe` block unused-variables warn detect variables which are not used in any way warnings warn mass-change the level for lints which produce warnings where-clauses-object-safety warn checks the object safety of where clauses while-true warn suggest using `loop { }` instead of `while true { }` ambiguous-associated-items deny ambiguous associated items arithmetic-overflow deny arithmetic operation overflows conflicting-repr-hints deny conflicts between `#[repr(..)]` hints that were previously accepted and used in practice const-err deny constant evaluation detected erroneous expression ill-formed-attribute-input deny ill-formed attribute inputs that were previously accepted and used in practice incomplete-include deny trailing content in included file invalid-type-param-default deny type parameter default erroneously allowed in invalid location macro-expanded-macro-exports-accessed-by-absolute-paths deny macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths mutable-transmutes deny mutating transmuted &mut T from &T may cause undefined behavior no-mangle-const-items deny const items will not have their symbols exported order-dependent-trait-objects deny trait-object types were treated as different depending on marker-trait order overflowing-literals deny literal out of range for its type patterns-in-fns-without-body deny patterns in functions without body were erroneously allowed pub-use-of-private-extern-crate deny detect public re-exports of private extern crates soft-unstable deny a feature gate that doesn't break dependent crates unconditional-panic deny operation will cause a panic at runtime unknown-crate-types deny unknown crate type found in `#[crate_type]` directive Lint groups provided by rustc: name sub-lints ---- --------- warnings all lints that are set to issue warnings future-incompatible keyword-idents, anonymous-parameters, illegal-floating-point-literal-pattern, private-in-public, pub-use-of-private-extern-crate, invalid-type-param-default, safe-packed-borrows, patterns-in-fns-without-body, late-bound-lifetime-arguments, order-dependent-trait-objects, coherence-leak-check, tyvar-behind-raw-pointer, absolute-paths-not-starting-with-crate, unstable-name-collisions, where-clauses-object-safety, proc-macro-derive-resolution-fallback, macro-expanded-macro-exports-accessed-by-absolute-paths, ill-formed-attribute-input, conflicting-repr-hints, ambiguous-associated-items, mutable-borrow-reservation-conflict, indirect-structural-match, pointer-structural-match, nontrivial-structural-match, soft-unstable, cenum-impl-drop-cast, const-evaluatable-unchecked, array-into-iter nonstandard-style non-camel-case-types, non-snake-case, non-upper-case-globals rust-2018-compatibility keyword-idents, anonymous-parameters, tyvar-behind-raw-pointer, absolute-paths-not-starting-with-crate rust-2018-idioms bare-trait-objects, unused-extern-crates, ellipsis-inclusive-range-patterns, elided-lifetimes-in-paths, explicit-outlives-requirements rustdoc broken-intra-doc-links, private-intra-doc-links, invalid-codeblock-attributes, missing-doc-code-examples, private-doc-tests, invalid-html-tags unused unused-imports, unused-variables, unused-assignments, dead-code, unused-mut, unreachable-code, unreachable-patterns, overlapping-patterns, unused-must-use, unused-unsafe, path-statements, unused-attributes, unused-macros, unused-allocation, unused-doc-comments, unused-extern-crates, unused-features, unused-labels, unused-parens, unused-braces, redundant-semicolons Compiler plugins can provide additional lints and lint groups. To see a listing of these, re-run `rustc -W help` with a crate filename.