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 #![allow(rustc::potential_query_instability)]
29 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
30 #![feature(array_windows)]
31 #![feature(box_patterns)]
32 #![feature(control_flow_enum)]
33 #![feature(if_let_guard)]
34 #![feature(iter_intersperse)]
35 #![feature(iter_order_by)]
36 #![feature(let_chains)]
37 #![feature(min_specialization)]
38 #![feature(never_type)]
39 #![feature(rustc_attrs)]
40 #![recursion_limit = "256"]
41 #![deny(rustc::untranslatable_diagnostic)]
42 #![deny(rustc::diagnostic_outside_of_impl)]
45 extern crate rustc_middle;
47 extern crate rustc_session;
54 mod deref_into_dyn_supertrait;
56 mod enum_intrinsics_non_enums;
59 mod for_loops_over_fallibles;
60 pub mod hidden_unicode_codepoints;
67 mod multiple_supertrait_upcastable;
70 mod nonstandard_style;
72 mod opaque_hidden_inferred_bound;
75 mod redundant_semicolon;
80 pub use array_into_iter::ARRAY_INTO_ITER;
84 use rustc_hir::def_id::LocalDefId;
85 use rustc_middle::ty::query::Providers;
86 use rustc_middle::ty::TyCtxt;
87 use rustc_session::lint::builtin::{
88 BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
90 use rustc_span::symbol::Ident;
93 use array_into_iter::ArrayIntoIter;
95 use deref_into_dyn_supertrait::*;
96 use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
97 use for_loops_over_fallibles::*;
98 use hidden_unicode_codepoints::*;
100 use let_underscore::*;
102 use multiple_supertrait_upcastable::*;
103 use non_ascii_idents::*;
104 use non_fmt_panic::NonPanicFmt;
105 use nonstandard_style::*;
106 use noop_method_call::*;
107 use opaque_hidden_inferred_bound::*;
108 use pass_by_value::*;
109 use redundant_semicolon::*;
114 /// Useful for other parts of the compiler / Clippy.
115 pub use builtin::SoftLints;
116 pub use context::{CheckLintNameResult, FindLintError, LintStore};
117 pub use context::{EarlyContext, LateContext, LintContext};
118 pub use early::{check_ast_node, EarlyCheckNode};
119 pub use late::{check_crate, unerased_lint_store};
120 pub use passes::{EarlyLintPass, LateLintPass};
121 pub use rustc_session::lint::Level::{self, *};
122 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
123 pub use rustc_session::lint::{LintArray, LintPass};
125 pub fn provide(providers: &mut Providers) {
126 levels::provide(providers);
127 expect::provide(providers);
128 *providers = Providers { lint_mod, ..*providers };
131 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
132 late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
136 declare_combined_early_lint_pass,
138 pub BuiltinCombinedPreExpansionLintPass,
140 KeywordIdents: KeywordIdents,
146 declare_combined_early_lint_pass,
148 pub BuiltinCombinedEarlyLintPass,
150 UnusedParens: UnusedParens::new(),
151 UnusedBraces: UnusedBraces,
152 UnusedImportBraces: UnusedImportBraces,
153 UnsafeCode: UnsafeCode,
154 SpecialModuleName: SpecialModuleName,
155 AnonymousParameters: AnonymousParameters,
156 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
157 NonCamelCaseTypes: NonCamelCaseTypes,
158 DeprecatedAttr: DeprecatedAttr::new(),
159 WhileTrue: WhileTrue,
160 NonAsciiIdents: NonAsciiIdents,
161 HiddenUnicodeCodepoints: HiddenUnicodeCodepoints,
162 IncompleteFeatures: IncompleteFeatures,
163 RedundantSemicolons: RedundantSemicolons,
164 UnusedDocComment: UnusedDocComment,
165 UnexpectedCfgs: UnexpectedCfgs,
170 // FIXME: Make a separate lint type which does not require typeck tables.
173 declare_combined_late_lint_pass,
175 pub BuiltinCombinedLateLintPass,
177 // Tracks state across modules
178 UnnameableTestItems: UnnameableTestItems::new(),
179 // Tracks attributes of parents
180 MissingDoc: MissingDoc::new(),
181 // Builds a global list of all impls of `Debug`.
182 // FIXME: Turn the computation of types which implement Debug into a query
183 // and change this to a module lint pass
184 MissingDebugImplementations: MissingDebugImplementations::default(),
185 // Keeps a global list of foreign declarations.
186 ClashingExternDeclarations: ClashingExternDeclarations::new(),
192 declare_combined_late_lint_pass,
194 BuiltinCombinedModuleLateLintPass,
196 ForLoopsOverFallibles: ForLoopsOverFallibles,
197 DerefIntoDynSupertrait: DerefIntoDynSupertrait,
198 HardwiredLints: HardwiredLints,
199 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
200 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
201 VariantSizeDifferences: VariantSizeDifferences,
202 BoxPointers: BoxPointers,
203 PathStatements: PathStatements,
204 LetUnderscore: LetUnderscore,
205 // Depends on referenced function signatures in expressions
206 UnusedResults: UnusedResults,
207 NonUpperCaseGlobals: NonUpperCaseGlobals,
208 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
209 UnusedAllocation: UnusedAllocation,
210 // Depends on types used in type definitions
211 MissingCopyImplementations: MissingCopyImplementations,
212 // Depends on referenced function signatures in expressions
213 MutableTransmutes: MutableTransmutes,
214 TypeAliasBounds: TypeAliasBounds,
215 TrivialConstraints: TrivialConstraints,
216 TypeLimits: TypeLimits::new(),
217 NonSnakeCase: NonSnakeCase,
218 InvalidNoMangleItems: InvalidNoMangleItems,
219 // Depends on effective visibilities
220 UnreachablePub: UnreachablePub,
221 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
222 InvalidValue: InvalidValue,
223 DerefNullPtr: DerefNullPtr,
224 // May Depend on constants elsewhere
225 UnusedBrokenConst: UnusedBrokenConst,
226 UnstableFeatures: UnstableFeatures,
227 UngatedAsyncFnTrackCaller: UngatedAsyncFnTrackCaller,
228 ArrayIntoIter: ArrayIntoIter::default(),
229 DropTraitConstraints: DropTraitConstraints,
230 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
231 NonPanicFmt: NonPanicFmt,
232 NoopMethodCall: NoopMethodCall,
233 EnumIntrinsicsNonEnums: EnumIntrinsicsNonEnums,
234 InvalidAtomicOrdering: InvalidAtomicOrdering,
235 NamedAsmLabels: NamedAsmLabels,
236 OpaqueHiddenInferredBound: OpaqueHiddenInferredBound,
237 MultipleSupertraitUpcastable: MultipleSupertraitUpcastable,
242 pub fn new_lint_store(internal_lints: bool) -> LintStore {
243 let mut lint_store = LintStore::new();
245 register_builtins(&mut lint_store);
247 register_internals(&mut lint_store);
253 /// Tell the `LintStore` about all the built-in lints (the ones
254 /// defined in this crate and the ones defined in
255 /// `rustc_session::lint::builtin`).
256 fn register_builtins(store: &mut LintStore) {
257 macro_rules! add_lint_group {
258 ($name:expr, $($lint:ident),*) => (
259 store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
263 store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
264 store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
265 store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
266 store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
270 NON_CAMEL_CASE_TYPES,
272 NON_UPPER_CASE_GLOBALS
283 UNREACHABLE_PATTERNS,
292 UNUSED_EXTERN_CRATES,
300 add_lint_group!("let_underscore", LET_UNDERSCORE_DROP, LET_UNDERSCORE_LOCK);
305 UNUSED_EXTERN_CRATES,
306 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
307 ELIDED_LIFETIMES_IN_PATHS,
308 EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
309 // macros are ready for this yet.
312 // FIXME macro crates are not up for this yet, too much
313 // breakage is seen if we try to encourage this lint.
314 // MACRO_USE_EXTERN_CRATE
317 // Register renamed and removed lints.
318 store.register_renamed("single_use_lifetime", "single_use_lifetimes");
319 store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
320 store.register_renamed("bare_trait_object", "bare_trait_objects");
321 store.register_renamed("unstable_name_collision", "unstable_name_collisions");
322 store.register_renamed("unused_doc_comment", "unused_doc_comments");
323 store.register_renamed("async_idents", "keyword_idents");
324 store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
325 store.register_renamed("redundant_semicolon", "redundant_semicolons");
326 store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
327 store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
328 store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
329 store.register_renamed("non_fmt_panic", "non_fmt_panics");
331 // These were moved to tool lints, but rustc still sees them when compiling normally, before
332 // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
333 // `register_removed` explicitly.
334 const RUSTDOC_LINTS: &[&str] = &[
335 "broken_intra_doc_links",
336 "private_intra_doc_links",
337 "missing_crate_level_docs",
338 "missing_doc_code_examples",
340 "invalid_codeblock_attributes",
344 for rustdoc_lint in RUSTDOC_LINTS {
345 store.register_ignored(rustdoc_lint);
347 store.register_removed(
348 "intra_doc_link_resolution_failure",
349 "use `rustdoc::broken_intra_doc_links` instead",
351 store.register_removed("rustdoc", "use `rustdoc::all` instead");
353 store.register_removed("unknown_features", "replaced by an error");
354 store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
355 store.register_removed("negate_unsigned", "cast a signed value instead");
356 store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
357 // Register lint group aliases.
358 store.register_group_alias("nonstandard_style", "bad_style");
359 // This was renamed to `raw_pointer_derive`, which was then removed,
360 // so it is also considered removed.
361 store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
362 store.register_removed("drop_with_repr_extern", "drop flags have been removed");
363 store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
364 store.register_removed("deprecated_attr", "use `deprecated` instead");
365 store.register_removed(
366 "transmute_from_fn_item_types",
367 "always cast functions before transmuting them",
369 store.register_removed(
370 "hr_lifetime_in_assoc_type",
371 "converted into hard error, see issue #33685 \
372 <https://github.com/rust-lang/rust/issues/33685> for more information",
374 store.register_removed(
375 "inaccessible_extern_crate",
376 "converted into hard error, see issue #36886 \
377 <https://github.com/rust-lang/rust/issues/36886> for more information",
379 store.register_removed(
380 "super_or_self_in_global_path",
381 "converted into hard error, see issue #36888 \
382 <https://github.com/rust-lang/rust/issues/36888> for more information",
384 store.register_removed(
385 "overlapping_inherent_impls",
386 "converted into hard error, see issue #36889 \
387 <https://github.com/rust-lang/rust/issues/36889> for more information",
389 store.register_removed(
390 "illegal_floating_point_constant_pattern",
391 "converted into hard error, see issue #36890 \
392 <https://github.com/rust-lang/rust/issues/36890> for more information",
394 store.register_removed(
395 "illegal_struct_or_enum_constant_pattern",
396 "converted into hard error, see issue #36891 \
397 <https://github.com/rust-lang/rust/issues/36891> for more information",
399 store.register_removed(
400 "lifetime_underscore",
401 "converted into hard error, see issue #36892 \
402 <https://github.com/rust-lang/rust/issues/36892> for more information",
404 store.register_removed(
405 "extra_requirement_in_impl",
406 "converted into hard error, see issue #37166 \
407 <https://github.com/rust-lang/rust/issues/37166> for more information",
409 store.register_removed(
411 "converted into hard error, see issue #38260 \
412 <https://github.com/rust-lang/rust/issues/38260> for more information",
414 store.register_removed(
416 "converted into hard error, see issue #48950 \
417 <https://github.com/rust-lang/rust/issues/48950> for more information",
419 store.register_removed(
420 "resolve_trait_on_defaulted_unit",
421 "converted into hard error, see issue #48950 \
422 <https://github.com/rust-lang/rust/issues/48950> for more information",
424 store.register_removed(
425 "private_no_mangle_fns",
426 "no longer a warning, `#[no_mangle]` functions always exported",
428 store.register_removed(
429 "private_no_mangle_statics",
430 "no longer a warning, `#[no_mangle]` statics always exported",
432 store.register_removed("bad_repr", "replaced with a generic attribute input check");
433 store.register_removed(
434 "duplicate_matcher_binding_name",
435 "converted into hard error, see issue #57742 \
436 <https://github.com/rust-lang/rust/issues/57742> for more information",
438 store.register_removed(
439 "incoherent_fundamental_impls",
440 "converted into hard error, see issue #46205 \
441 <https://github.com/rust-lang/rust/issues/46205> for more information",
443 store.register_removed(
444 "legacy_constructor_visibility",
445 "converted into hard error, see issue #39207 \
446 <https://github.com/rust-lang/rust/issues/39207> for more information",
448 store.register_removed(
449 "legacy_directory_ownership",
450 "converted into hard error, see issue #37872 \
451 <https://github.com/rust-lang/rust/issues/37872> for more information",
453 store.register_removed(
454 "safe_extern_statics",
455 "converted into hard error, see issue #36247 \
456 <https://github.com/rust-lang/rust/issues/36247> for more information",
458 store.register_removed(
459 "parenthesized_params_in_types_and_modules",
460 "converted into hard error, see issue #42238 \
461 <https://github.com/rust-lang/rust/issues/42238> for more information",
463 store.register_removed(
464 "duplicate_macro_exports",
465 "converted into hard error, see issue #35896 \
466 <https://github.com/rust-lang/rust/issues/35896> for more information",
468 store.register_removed(
470 "converted into hard error, see issue #59014 \
471 <https://github.com/rust-lang/rust/issues/59014> for more information",
473 store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
474 store.register_removed(
475 "unsupported_naked_functions",
476 "converted into hard error, see RFC 2972 \
477 <https://github.com/rust-lang/rfcs/blob/master/text/2972-constrained-naked.md> for more information",
479 store.register_removed(
480 "mutable_borrow_reservation_conflict",
481 "now allowed, see issue #59159 \
482 <https://github.com/rust-lang/rust/issues/59159> for more information",
484 store.register_removed(
486 "converted into hard error, see issue #71800 \
487 <https://github.com/rust-lang/rust/issues/71800> for more information",
489 store.register_removed(
490 "safe_packed_borrows",
491 "converted into hard error, see issue #82523 \
492 <https://github.com/rust-lang/rust/issues/82523> for more information",
494 store.register_removed(
495 "unaligned_references",
496 "converted into hard error, see issue #82523 \
497 <https://github.com/rust-lang/rust/issues/82523> for more information",
501 fn register_internals(store: &mut LintStore) {
502 store.register_lints(&LintPassImpl::get_lints());
503 store.register_early_pass(|| Box::new(LintPassImpl));
504 store.register_lints(&DefaultHashTypes::get_lints());
505 store.register_late_pass(|_| Box::new(DefaultHashTypes));
506 store.register_lints(&QueryStability::get_lints());
507 store.register_late_pass(|_| Box::new(QueryStability));
508 store.register_lints(&ExistingDocKeyword::get_lints());
509 store.register_late_pass(|_| Box::new(ExistingDocKeyword));
510 store.register_lints(&TyTyKind::get_lints());
511 store.register_late_pass(|_| Box::new(TyTyKind));
512 store.register_lints(&Diagnostics::get_lints());
513 store.register_late_pass(|_| Box::new(Diagnostics));
514 store.register_lints(&BadOptAccess::get_lints());
515 store.register_late_pass(|_| Box::new(BadOptAccess));
516 store.register_lints(&PassByValue::get_lints());
517 store.register_late_pass(|_| Box::new(PassByValue));
518 // FIXME(davidtwco): deliberately do not include `UNTRANSLATABLE_DIAGNOSTIC` and
519 // `DIAGNOSTIC_OUTSIDE_OF_IMPL` here because `-Wrustc::internal` is provided to every crate and
520 // these lints will trigger all of the time - change this once migration to diagnostic structs
521 // and translation is completed
522 store.register_group(
527 LintId::of(DEFAULT_HASH_TYPES),
528 LintId::of(POTENTIAL_QUERY_INSTABILITY),
529 LintId::of(USAGE_OF_TY_TYKIND),
530 LintId::of(PASS_BY_VALUE),
531 LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
532 LintId::of(USAGE_OF_QUALIFIED_TY),
533 LintId::of(EXISTING_DOC_KEYWORD),
534 LintId::of(BAD_OPT_ACCESS),