1 //! Lints, aka compiler warnings.
3 //! A 'lint' check is a kind of miscellaneous constraint that a user _might_
4 //! want to enforce, but might reasonably want to permit as well, on a
5 //! module-by-module basis. They contrast with static constraints enforced by
6 //! other phases of the compiler, which are generally required to hold in order
7 //! to compile the program at all.
9 //! Most lints can be written as [LintPass] instances. These run after
10 //! all other analyses. The `LintPass`es built into rustc are defined
11 //! within [rustc_session::lint::builtin],
12 //! which has further comments on how to add such a lint.
13 //! rustc can also load user-defined lint plugins via the plugin mechanism.
15 //! Some of rustc's lints are defined elsewhere in the compiler and work by
16 //! calling `add_lint()` on the overall `Session` object. This works when
17 //! it happens before the main lint pass, which emits the lints stored by
18 //! `add_lint()`. To emit lints after the main lint pass (from codegen, for
19 //! example) requires more effort. See `emit_lint` and `GatherNodeLevels`
22 //! Some code also exists in [rustc_session::lint], [rustc_middle::lint].
26 //! This API is completely unstable and subject to change.
28 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
29 #![feature(array_windows)]
30 #![feature(bool_to_option)]
31 #![feature(box_patterns)]
32 #![feature(crate_visibility_modifier)]
33 #![feature(if_let_guard)]
34 #![feature(iter_order_by)]
36 #![feature(never_type)]
38 #![feature(control_flow_enum)]
39 #![recursion_limit = "256"]
40 #![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
43 extern crate rustc_middle;
45 extern crate rustc_session;
51 mod enum_intrinsics_non_enums;
52 pub mod hidden_unicode_codepoints;
59 mod nonstandard_style;
63 mod redundant_semicolon;
68 pub use array_into_iter::ARRAY_INTO_ITER;
72 use rustc_hir::def_id::LocalDefId;
73 use rustc_middle::ty::query::Providers;
74 use rustc_middle::ty::TyCtxt;
75 use rustc_session::lint::builtin::{
76 BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
78 use rustc_span::symbol::{Ident, Symbol};
81 use array_into_iter::ArrayIntoIter;
83 use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
84 use hidden_unicode_codepoints::*;
87 use non_ascii_idents::*;
88 use non_fmt_panic::NonPanicFmt;
89 use nonstandard_style::*;
90 use noop_method_call::*;
92 use redundant_semicolon::*;
97 /// Useful for other parts of the compiler / Clippy.
98 pub use builtin::SoftLints;
99 pub use context::{CheckLintNameResult, FindLintError, LintStore};
100 pub use context::{EarlyContext, LateContext, LintContext};
101 pub use early::{check_ast_node, EarlyCheckNode};
102 pub use late::check_crate;
103 pub use passes::{EarlyLintPass, LateLintPass};
104 pub use rustc_session::lint::Level::{self, *};
105 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
106 pub use rustc_session::lint::{LintArray, LintPass};
108 pub fn provide(providers: &mut Providers) {
109 levels::provide(providers);
110 *providers = Providers { lint_mod, ..*providers };
113 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
114 late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
117 macro_rules! pre_expansion_lint_passes {
118 ($macro:path, $args:tt) => {
119 $macro!($args, [KeywordIdents: KeywordIdents,]);
123 macro_rules! early_lint_passes {
124 ($macro:path, $args:tt) => {
128 UnusedParens: UnusedParens,
129 UnusedBraces: UnusedBraces,
130 UnusedImportBraces: UnusedImportBraces,
131 UnsafeCode: UnsafeCode,
132 AnonymousParameters: AnonymousParameters,
133 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
134 NonCamelCaseTypes: NonCamelCaseTypes,
135 DeprecatedAttr: DeprecatedAttr::new(),
136 WhileTrue: WhileTrue,
137 NonAsciiIdents: NonAsciiIdents,
138 HiddenUnicodeCodepoints: HiddenUnicodeCodepoints,
139 IncompleteFeatures: IncompleteFeatures,
140 RedundantSemicolons: RedundantSemicolons,
141 UnusedDocComment: UnusedDocComment,
147 macro_rules! declare_combined_early_pass {
148 ([$name:ident], $passes:tt) => (
149 early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
153 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
154 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
156 macro_rules! late_lint_passes {
157 ($macro:path, $args:tt) => {
161 // FIXME: Look into regression when this is used as a module lint
162 // May Depend on constants elsewhere
163 UnusedBrokenConst: UnusedBrokenConst,
164 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
165 UnstableFeatures: UnstableFeatures,
166 // Tracks state across modules
167 UnnameableTestItems: UnnameableTestItems::new(),
168 // Tracks attributes of parents
169 MissingDoc: MissingDoc::new(),
170 // Depends on access levels
171 // FIXME: Turn the computation of types which implement Debug into a query
172 // and change this to a module lint pass
173 MissingDebugImplementations: MissingDebugImplementations::default(),
174 ArrayIntoIter: ArrayIntoIter::default(),
175 ClashingExternDeclarations: ClashingExternDeclarations::new(),
176 DropTraitConstraints: DropTraitConstraints,
177 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
178 NonPanicFmt: NonPanicFmt,
179 NoopMethodCall: NoopMethodCall,
180 EnumIntrinsicsNonEnums: EnumIntrinsicsNonEnums,
181 InvalidAtomicOrdering: InvalidAtomicOrdering,
182 NamedAsmLabels: NamedAsmLabels,
188 macro_rules! late_lint_mod_passes {
189 ($macro:path, $args:tt) => {
193 HardwiredLints: HardwiredLints,
194 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
195 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
196 VariantSizeDifferences: VariantSizeDifferences,
197 BoxPointers: BoxPointers,
198 PathStatements: PathStatements,
199 // Depends on referenced function signatures in expressions
200 UnusedResults: UnusedResults,
201 NonUpperCaseGlobals: NonUpperCaseGlobals,
202 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
203 UnusedAllocation: UnusedAllocation,
204 // Depends on types used in type definitions
205 MissingCopyImplementations: MissingCopyImplementations,
206 // Depends on referenced function signatures in expressions
207 MutableTransmutes: MutableTransmutes,
208 TypeAliasBounds: TypeAliasBounds,
209 TrivialConstraints: TrivialConstraints,
210 TypeLimits: TypeLimits::new(),
211 NonSnakeCase: NonSnakeCase,
212 InvalidNoMangleItems: InvalidNoMangleItems,
213 // Depends on access levels
214 UnreachablePub: UnreachablePub,
215 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
216 InvalidValue: InvalidValue,
217 DerefNullPtr: DerefNullPtr,
223 macro_rules! declare_combined_late_pass {
224 ([$v:vis $name:ident], $passes:tt) => (
225 late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
229 // FIXME: Make a separate lint type which do not require typeck tables
230 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
232 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
234 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
235 let mut lint_store = LintStore::new();
237 register_builtins(&mut lint_store, no_interleave_lints);
239 register_internals(&mut lint_store);
245 /// Tell the `LintStore` about all the built-in lints (the ones
246 /// defined in this crate and the ones defined in
247 /// `rustc_session::lint::builtin`).
248 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
249 macro_rules! add_lint_group {
250 ($name:expr, $($lint:ident),*) => (
251 store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
255 macro_rules! register_pass {
256 ($method:ident, $ty:ident, $constructor:expr) => {
257 store.register_lints(&$ty::get_lints());
258 store.$method(|| Box::new($constructor));
262 macro_rules! register_passes {
263 ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
265 register_pass!($method, $passes, $constructor);
270 if no_interleave_lints {
271 pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
272 early_lint_passes!(register_passes, register_early_pass);
273 late_lint_passes!(register_passes, register_late_pass);
274 late_lint_mod_passes!(register_passes, register_late_mod_pass);
276 store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
277 store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
278 store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
279 store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
284 NON_CAMEL_CASE_TYPES,
286 NON_UPPER_CASE_GLOBALS
297 UNREACHABLE_PATTERNS,
305 UNUSED_EXTERN_CRATES,
316 UNUSED_EXTERN_CRATES,
317 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
318 ELIDED_LIFETIMES_IN_PATHS,
319 EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
320 // macros are ready for this yet.
323 // FIXME macro crates are not up for this yet, too much
324 // breakage is seen if we try to encourage this lint.
325 // MACRO_USE_EXTERN_CRATE
328 // Register renamed and removed lints.
329 store.register_renamed("single_use_lifetime", "single_use_lifetimes");
330 store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
331 store.register_renamed("bare_trait_object", "bare_trait_objects");
332 store.register_renamed("unstable_name_collision", "unstable_name_collisions");
333 store.register_renamed("unused_doc_comment", "unused_doc_comments");
334 store.register_renamed("async_idents", "keyword_idents");
335 store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
336 store.register_renamed("redundant_semicolon", "redundant_semicolons");
337 store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
338 store.register_renamed("safe_packed_borrows", "unaligned_references");
339 store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
340 store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
341 store.register_renamed("non_fmt_panic", "non_fmt_panics");
343 // These were moved to tool lints, but rustc still sees them when compiling normally, before
344 // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
345 // `register_removed` explicitly.
346 const RUSTDOC_LINTS: &[&str] = &[
347 "broken_intra_doc_links",
348 "private_intra_doc_links",
349 "missing_crate_level_docs",
350 "missing_doc_code_examples",
352 "invalid_codeblock_attributes",
356 for rustdoc_lint in RUSTDOC_LINTS {
357 store.register_ignored(rustdoc_lint);
359 store.register_removed(
360 "intra_doc_link_resolution_failure",
361 "use `rustdoc::broken_intra_doc_links` instead",
363 store.register_removed("rustdoc", "use `rustdoc::all` instead");
365 store.register_removed("unknown_features", "replaced by an error");
366 store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
367 store.register_removed("negate_unsigned", "cast a signed value instead");
368 store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
369 // Register lint group aliases.
370 store.register_group_alias("nonstandard_style", "bad_style");
371 // This was renamed to `raw_pointer_derive`, which was then removed,
372 // so it is also considered removed.
373 store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
374 store.register_removed("drop_with_repr_extern", "drop flags have been removed");
375 store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
376 store.register_removed("deprecated_attr", "use `deprecated` instead");
377 store.register_removed(
378 "transmute_from_fn_item_types",
379 "always cast functions before transmuting them",
381 store.register_removed(
382 "hr_lifetime_in_assoc_type",
383 "converted into hard error, see issue #33685 \
384 <https://github.com/rust-lang/rust/issues/33685> for more information",
386 store.register_removed(
387 "inaccessible_extern_crate",
388 "converted into hard error, see issue #36886 \
389 <https://github.com/rust-lang/rust/issues/36886> for more information",
391 store.register_removed(
392 "super_or_self_in_global_path",
393 "converted into hard error, see issue #36888 \
394 <https://github.com/rust-lang/rust/issues/36888> for more information",
396 store.register_removed(
397 "overlapping_inherent_impls",
398 "converted into hard error, see issue #36889 \
399 <https://github.com/rust-lang/rust/issues/36889> for more information",
401 store.register_removed(
402 "illegal_floating_point_constant_pattern",
403 "converted into hard error, see issue #36890 \
404 <https://github.com/rust-lang/rust/issues/36890> for more information",
406 store.register_removed(
407 "illegal_struct_or_enum_constant_pattern",
408 "converted into hard error, see issue #36891 \
409 <https://github.com/rust-lang/rust/issues/36891> for more information",
411 store.register_removed(
412 "lifetime_underscore",
413 "converted into hard error, see issue #36892 \
414 <https://github.com/rust-lang/rust/issues/36892> for more information",
416 store.register_removed(
417 "extra_requirement_in_impl",
418 "converted into hard error, see issue #37166 \
419 <https://github.com/rust-lang/rust/issues/37166> for more information",
421 store.register_removed(
423 "converted into hard error, see issue #38260 \
424 <https://github.com/rust-lang/rust/issues/38260> for more information",
426 store.register_removed(
428 "converted into hard error, see issue #48950 \
429 <https://github.com/rust-lang/rust/issues/48950> for more information",
431 store.register_removed(
432 "resolve_trait_on_defaulted_unit",
433 "converted into hard error, see issue #48950 \
434 <https://github.com/rust-lang/rust/issues/48950> for more information",
436 store.register_removed(
437 "private_no_mangle_fns",
438 "no longer a warning, `#[no_mangle]` functions always exported",
440 store.register_removed(
441 "private_no_mangle_statics",
442 "no longer a warning, `#[no_mangle]` statics always exported",
444 store.register_removed("bad_repr", "replaced with a generic attribute input check");
445 store.register_removed(
446 "duplicate_matcher_binding_name",
447 "converted into hard error, see issue #57742 \
448 <https://github.com/rust-lang/rust/issues/57742> for more information",
450 store.register_removed(
451 "incoherent_fundamental_impls",
452 "converted into hard error, see issue #46205 \
453 <https://github.com/rust-lang/rust/issues/46205> for more information",
455 store.register_removed(
456 "legacy_constructor_visibility",
457 "converted into hard error, see issue #39207 \
458 <https://github.com/rust-lang/rust/issues/39207> for more information",
460 store.register_removed(
461 "legacy_directory_ownership",
462 "converted into hard error, see issue #37872 \
463 <https://github.com/rust-lang/rust/issues/37872> for more information",
465 store.register_removed(
466 "safe_extern_statics",
467 "converted into hard error, see issue #36247 \
468 <https://github.com/rust-lang/rust/issues/36247> for more information",
470 store.register_removed(
471 "parenthesized_params_in_types_and_modules",
472 "converted into hard error, see issue #42238 \
473 <https://github.com/rust-lang/rust/issues/42238> for more information",
475 store.register_removed(
476 "duplicate_macro_exports",
477 "converted into hard error, see issue #35896 \
478 <https://github.com/rust-lang/rust/issues/35896> for more information",
480 store.register_removed(
482 "converted into hard error, see issue #59014 \
483 <https://github.com/rust-lang/rust/issues/59014> for more information",
485 store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
486 store.register_removed(
487 "unsupported_naked_functions",
488 "converted into hard error, see RFC 2972 \
489 <https://github.com/rust-lang/rfcs/blob/master/text/2972-constrained-naked.md> for more information",
493 fn register_internals(store: &mut LintStore) {
494 store.register_lints(&LintPassImpl::get_lints());
495 store.register_early_pass(|| Box::new(LintPassImpl));
496 store.register_lints(&DefaultHashTypes::get_lints());
497 store.register_late_pass(|| Box::new(DefaultHashTypes));
498 store.register_lints(&QueryStability::get_lints());
499 store.register_late_pass(|| Box::new(QueryStability));
500 store.register_lints(&ExistingDocKeyword::get_lints());
501 store.register_late_pass(|| Box::new(ExistingDocKeyword));
502 store.register_lints(&TyTyKind::get_lints());
503 store.register_late_pass(|| Box::new(TyTyKind));
504 store.register_lints(&PassByValue::get_lints());
505 store.register_late_pass(|| Box::new(PassByValue));
506 store.register_group(
511 LintId::of(DEFAULT_HASH_TYPES),
512 LintId::of(POTENTIAL_QUERY_INSTABILITY),
513 LintId::of(USAGE_OF_TY_TYKIND),
514 LintId::of(PASS_BY_VALUE),
515 LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
516 LintId::of(USAGE_OF_QUALIFIED_TY),
517 LintId::of(EXISTING_DOC_KEYWORD),