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(format_args_capture)]
34 #![feature(iter_order_by)]
36 #![feature(never_type)]
38 #![feature(control_flow_enum)]
39 #![recursion_limit = "256"]
42 extern crate rustc_middle;
44 extern crate rustc_session;
50 mod enum_intrinsics_non_enums;
57 mod nonstandard_style;
60 mod redundant_semicolon;
65 pub use array_into_iter::ARRAY_INTO_ITER;
69 use rustc_hir::def_id::LocalDefId;
70 use rustc_middle::ty::query::Providers;
71 use rustc_middle::ty::TyCtxt;
72 use rustc_session::lint::builtin::{
73 BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
75 use rustc_span::symbol::{Ident, Symbol};
78 use array_into_iter::ArrayIntoIter;
80 use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
83 use non_ascii_idents::*;
84 use non_fmt_panic::NonPanicFmt;
85 use nonstandard_style::*;
86 use noop_method_call::*;
87 use redundant_semicolon::*;
92 /// Useful for other parts of the compiler / Clippy.
93 pub use builtin::SoftLints;
94 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
95 pub use early::check_ast_crate;
96 pub use late::check_crate;
97 pub use passes::{EarlyLintPass, LateLintPass};
98 pub use rustc_session::lint::Level::{self, *};
99 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
100 pub use rustc_session::lint::{LintArray, LintPass};
102 pub fn provide(providers: &mut Providers) {
103 levels::provide(providers);
104 *providers = Providers { lint_mod, ..*providers };
107 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
108 late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
111 macro_rules! pre_expansion_lint_passes {
112 ($macro:path, $args:tt) => {
113 $macro!($args, [KeywordIdents: KeywordIdents,]);
117 macro_rules! early_lint_passes {
118 ($macro:path, $args:tt) => {
122 UnusedParens: UnusedParens,
123 UnusedBraces: UnusedBraces,
124 UnusedImportBraces: UnusedImportBraces,
125 UnsafeCode: UnsafeCode,
126 AnonymousParameters: AnonymousParameters,
127 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
128 NonCamelCaseTypes: NonCamelCaseTypes,
129 DeprecatedAttr: DeprecatedAttr::new(),
130 WhileTrue: WhileTrue,
131 NonAsciiIdents: NonAsciiIdents,
132 IncompleteFeatures: IncompleteFeatures,
133 RedundantSemicolons: RedundantSemicolons,
134 UnusedDocComment: UnusedDocComment,
140 macro_rules! declare_combined_early_pass {
141 ([$name:ident], $passes:tt) => (
142 early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
146 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
147 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
149 macro_rules! late_lint_passes {
150 ($macro:path, $args:tt) => {
154 // FIXME: Look into regression when this is used as a module lint
155 // May Depend on constants elsewhere
156 UnusedBrokenConst: UnusedBrokenConst,
157 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
158 UnstableFeatures: UnstableFeatures,
159 // Tracks state across modules
160 UnnameableTestItems: UnnameableTestItems::new(),
161 // Tracks attributes of parents
162 MissingDoc: MissingDoc::new(),
163 // Depends on access levels
164 // FIXME: Turn the computation of types which implement Debug into a query
165 // and change this to a module lint pass
166 MissingDebugImplementations: MissingDebugImplementations::default(),
167 ArrayIntoIter: ArrayIntoIter::default(),
168 ClashingExternDeclarations: ClashingExternDeclarations::new(),
169 DropTraitConstraints: DropTraitConstraints,
170 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
171 NonPanicFmt: NonPanicFmt,
172 NoopMethodCall: NoopMethodCall,
173 EnumIntrinsicsNonEnums: EnumIntrinsicsNonEnums,
174 InvalidAtomicOrdering: InvalidAtomicOrdering,
175 NamedAsmLabels: NamedAsmLabels,
181 macro_rules! late_lint_mod_passes {
182 ($macro:path, $args:tt) => {
186 HardwiredLints: HardwiredLints,
187 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
188 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
189 VariantSizeDifferences: VariantSizeDifferences,
190 BoxPointers: BoxPointers,
191 PathStatements: PathStatements,
192 // Depends on referenced function signatures in expressions
193 UnusedResults: UnusedResults,
194 NonUpperCaseGlobals: NonUpperCaseGlobals,
195 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
196 UnusedAllocation: UnusedAllocation,
197 // Depends on types used in type definitions
198 MissingCopyImplementations: MissingCopyImplementations,
199 // Depends on referenced function signatures in expressions
200 MutableTransmutes: MutableTransmutes,
201 TypeAliasBounds: TypeAliasBounds,
202 TrivialConstraints: TrivialConstraints,
203 TypeLimits: TypeLimits::new(),
204 NonSnakeCase: NonSnakeCase,
205 InvalidNoMangleItems: InvalidNoMangleItems,
206 // Depends on access levels
207 UnreachablePub: UnreachablePub,
208 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
209 InvalidValue: InvalidValue,
210 DerefNullPtr: DerefNullPtr,
216 macro_rules! declare_combined_late_pass {
217 ([$v:vis $name:ident], $passes:tt) => (
218 late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
222 // FIXME: Make a separate lint type which do not require typeck tables
223 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
225 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
227 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
228 let mut lint_store = LintStore::new();
230 register_builtins(&mut lint_store, no_interleave_lints);
232 register_internals(&mut lint_store);
238 /// Tell the `LintStore` about all the built-in lints (the ones
239 /// defined in this crate and the ones defined in
240 /// `rustc_session::lint::builtin`).
241 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
242 macro_rules! add_lint_group {
243 ($name:expr, $($lint:ident),*) => (
244 store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
248 macro_rules! register_pass {
249 ($method:ident, $ty:ident, $constructor:expr) => {
250 store.register_lints(&$ty::get_lints());
251 store.$method(|| Box::new($constructor));
255 macro_rules! register_passes {
256 ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
258 register_pass!($method, $passes, $constructor);
263 if no_interleave_lints {
264 pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
265 early_lint_passes!(register_passes, register_early_pass);
266 late_lint_passes!(register_passes, register_late_pass);
267 late_lint_mod_passes!(register_passes, register_late_mod_pass);
269 store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
270 store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
271 store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
272 store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
277 NON_CAMEL_CASE_TYPES,
279 NON_UPPER_CASE_GLOBALS
290 UNREACHABLE_PATTERNS,
298 UNUSED_EXTERN_CRATES,
310 UNUSED_EXTERN_CRATES,
311 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
312 ELIDED_LIFETIMES_IN_PATHS,
313 EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
314 // macros are ready for this yet.
317 // FIXME macro crates are not up for this yet, too much
318 // breakage is seen if we try to encourage this lint.
319 // MACRO_USE_EXTERN_CRATE
322 // Register renamed and removed lints.
323 store.register_renamed("single_use_lifetime", "single_use_lifetimes");
324 store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
325 store.register_renamed("bare_trait_object", "bare_trait_objects");
326 store.register_renamed("unstable_name_collision", "unstable_name_collisions");
327 store.register_renamed("unused_doc_comment", "unused_doc_comments");
328 store.register_renamed("async_idents", "keyword_idents");
329 store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
330 store.register_renamed("redundant_semicolon", "redundant_semicolons");
331 store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
332 store.register_renamed("safe_packed_borrows", "unaligned_references");
333 store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
334 store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
335 store.register_renamed("non_fmt_panic", "non_fmt_panics");
337 // These were moved to tool lints, but rustc still sees them when compiling normally, before
338 // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
339 // `register_removed` explicitly.
340 const RUSTDOC_LINTS: &[&str] = &[
341 "broken_intra_doc_links",
342 "private_intra_doc_links",
343 "missing_crate_level_docs",
344 "missing_doc_code_examples",
346 "invalid_codeblock_attributes",
350 for rustdoc_lint in RUSTDOC_LINTS {
351 store.register_ignored(rustdoc_lint);
353 store.register_removed(
354 "intra_doc_link_resolution_failure",
355 "use `rustdoc::broken_intra_doc_links` instead",
357 store.register_removed("rustdoc", "use `rustdoc::all` instead");
359 store.register_removed("unknown_features", "replaced by an error");
360 store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
361 store.register_removed("negate_unsigned", "cast a signed value instead");
362 store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
363 // Register lint group aliases.
364 store.register_group_alias("nonstandard_style", "bad_style");
365 // This was renamed to `raw_pointer_derive`, which was then removed,
366 // so it is also considered removed.
367 store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
368 store.register_removed("drop_with_repr_extern", "drop flags have been removed");
369 store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
370 store.register_removed("deprecated_attr", "use `deprecated` instead");
371 store.register_removed(
372 "transmute_from_fn_item_types",
373 "always cast functions before transmuting them",
375 store.register_removed(
376 "hr_lifetime_in_assoc_type",
377 "converted into hard error, see issue #33685 \
378 <https://github.com/rust-lang/rust/issues/33685> for more information",
380 store.register_removed(
381 "inaccessible_extern_crate",
382 "converted into hard error, see issue #36886 \
383 <https://github.com/rust-lang/rust/issues/36886> for more information",
385 store.register_removed(
386 "super_or_self_in_global_path",
387 "converted into hard error, see issue #36888 \
388 <https://github.com/rust-lang/rust/issues/36888> for more information",
390 store.register_removed(
391 "overlapping_inherent_impls",
392 "converted into hard error, see issue #36889 \
393 <https://github.com/rust-lang/rust/issues/36889> for more information",
395 store.register_removed(
396 "illegal_floating_point_constant_pattern",
397 "converted into hard error, see issue #36890 \
398 <https://github.com/rust-lang/rust/issues/36890> for more information",
400 store.register_removed(
401 "illegal_struct_or_enum_constant_pattern",
402 "converted into hard error, see issue #36891 \
403 <https://github.com/rust-lang/rust/issues/36891> for more information",
405 store.register_removed(
406 "lifetime_underscore",
407 "converted into hard error, see issue #36892 \
408 <https://github.com/rust-lang/rust/issues/36892> for more information",
410 store.register_removed(
411 "extra_requirement_in_impl",
412 "converted into hard error, see issue #37166 \
413 <https://github.com/rust-lang/rust/issues/37166> for more information",
415 store.register_removed(
417 "converted into hard error, see issue #38260 \
418 <https://github.com/rust-lang/rust/issues/38260> for more information",
420 store.register_removed(
422 "converted into hard error, see issue #48950 \
423 <https://github.com/rust-lang/rust/issues/48950> for more information",
425 store.register_removed(
426 "resolve_trait_on_defaulted_unit",
427 "converted into hard error, see issue #48950 \
428 <https://github.com/rust-lang/rust/issues/48950> for more information",
430 store.register_removed(
431 "private_no_mangle_fns",
432 "no longer a warning, `#[no_mangle]` functions always exported",
434 store.register_removed(
435 "private_no_mangle_statics",
436 "no longer a warning, `#[no_mangle]` statics always exported",
438 store.register_removed("bad_repr", "replaced with a generic attribute input check");
439 store.register_removed(
440 "duplicate_matcher_binding_name",
441 "converted into hard error, see issue #57742 \
442 <https://github.com/rust-lang/rust/issues/57742> for more information",
444 store.register_removed(
445 "incoherent_fundamental_impls",
446 "converted into hard error, see issue #46205 \
447 <https://github.com/rust-lang/rust/issues/46205> for more information",
449 store.register_removed(
450 "legacy_constructor_visibility",
451 "converted into hard error, see issue #39207 \
452 <https://github.com/rust-lang/rust/issues/39207> for more information",
454 store.register_removed(
455 "legacy_directory_ownership",
456 "converted into hard error, see issue #37872 \
457 <https://github.com/rust-lang/rust/issues/37872> for more information",
459 store.register_removed(
460 "safe_extern_statics",
461 "converted into hard error, see issue #36247 \
462 <https://github.com/rust-lang/rust/issues/36247> for more information",
464 store.register_removed(
465 "parenthesized_params_in_types_and_modules",
466 "converted into hard error, see issue #42238 \
467 <https://github.com/rust-lang/rust/issues/42238> for more information",
469 store.register_removed(
470 "duplicate_macro_exports",
471 "converted into hard error, see issue #35896 \
472 <https://github.com/rust-lang/rust/issues/35896> for more information",
474 store.register_removed(
476 "converted into hard error, see issue #59014 \
477 <https://github.com/rust-lang/rust/issues/59014> for more information",
479 store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
482 fn register_internals(store: &mut LintStore) {
483 store.register_lints(&LintPassImpl::get_lints());
484 store.register_early_pass(|| Box::new(LintPassImpl));
485 store.register_lints(&DefaultHashTypes::get_lints());
486 store.register_late_pass(|| Box::new(DefaultHashTypes));
487 store.register_lints(&ExistingDocKeyword::get_lints());
488 store.register_late_pass(|| Box::new(ExistingDocKeyword));
489 store.register_lints(&TyTyKind::get_lints());
490 store.register_late_pass(|| Box::new(TyTyKind));
491 store.register_group(
496 LintId::of(DEFAULT_HASH_TYPES),
497 LintId::of(USAGE_OF_TY_TYKIND),
498 LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
499 LintId::of(TY_PASS_BY_REFERENCE),
500 LintId::of(USAGE_OF_QUALIFIED_TY),
501 LintId::of(EXISTING_DOC_KEYWORD),