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 #![cfg_attr(bootstrap, feature(let_chains))]
38 #![feature(never_type)]
39 #![recursion_limit = "256"]
42 extern crate rustc_middle;
44 extern crate rustc_session;
50 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, unerased_lint_store};
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 expect::provide(providers);
111 *providers = Providers { lint_mod, ..*providers };
114 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
115 late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
118 macro_rules! pre_expansion_lint_passes {
119 ($macro:path, $args:tt) => {
120 $macro!($args, [KeywordIdents: KeywordIdents,]);
124 macro_rules! early_lint_passes {
125 ($macro:path, $args:tt) => {
129 UnusedParens: UnusedParens,
130 UnusedBraces: UnusedBraces,
131 UnusedImportBraces: UnusedImportBraces,
132 UnsafeCode: UnsafeCode,
133 AnonymousParameters: AnonymousParameters,
134 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
135 NonCamelCaseTypes: NonCamelCaseTypes,
136 DeprecatedAttr: DeprecatedAttr::new(),
137 WhileTrue: WhileTrue,
138 NonAsciiIdents: NonAsciiIdents,
139 HiddenUnicodeCodepoints: HiddenUnicodeCodepoints,
140 IncompleteFeatures: IncompleteFeatures,
141 RedundantSemicolons: RedundantSemicolons,
142 UnusedDocComment: UnusedDocComment,
148 macro_rules! declare_combined_early_pass {
149 ([$name:ident], $passes:tt) => (
150 early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
154 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
155 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
157 macro_rules! late_lint_passes {
158 ($macro:path, $args:tt) => {
162 // Tracks state across modules
163 UnnameableTestItems: UnnameableTestItems::new(),
164 // Tracks attributes of parents
165 MissingDoc: MissingDoc::new(),
166 // Builds a global list of all impls of `Debug`.
167 // FIXME: Turn the computation of types which implement Debug into a query
168 // and change this to a module lint pass
169 MissingDebugImplementations: MissingDebugImplementations::default(),
170 // Keeps a global list of foreign declarations.
171 ClashingExternDeclarations: ClashingExternDeclarations::new(),
177 macro_rules! late_lint_mod_passes {
178 ($macro:path, $args:tt) => {
182 HardwiredLints: HardwiredLints,
183 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
184 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
185 VariantSizeDifferences: VariantSizeDifferences,
186 BoxPointers: BoxPointers,
187 PathStatements: PathStatements,
188 // Depends on referenced function signatures in expressions
189 UnusedResults: UnusedResults,
190 NonUpperCaseGlobals: NonUpperCaseGlobals,
191 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
192 UnusedAllocation: UnusedAllocation,
193 // Depends on types used in type definitions
194 MissingCopyImplementations: MissingCopyImplementations,
195 // Depends on referenced function signatures in expressions
196 MutableTransmutes: MutableTransmutes,
197 TypeAliasBounds: TypeAliasBounds,
198 TrivialConstraints: TrivialConstraints,
199 TypeLimits: TypeLimits::new(),
200 NonSnakeCase: NonSnakeCase,
201 InvalidNoMangleItems: InvalidNoMangleItems,
202 // Depends on access levels
203 UnreachablePub: UnreachablePub,
204 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
205 InvalidValue: InvalidValue,
206 DerefNullPtr: DerefNullPtr,
207 // May Depend on constants elsewhere
208 UnusedBrokenConst: UnusedBrokenConst,
209 UnstableFeatures: UnstableFeatures,
210 ArrayIntoIter: ArrayIntoIter::default(),
211 DropTraitConstraints: DropTraitConstraints,
212 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
213 NonPanicFmt: NonPanicFmt,
214 NoopMethodCall: NoopMethodCall,
215 EnumIntrinsicsNonEnums: EnumIntrinsicsNonEnums,
216 InvalidAtomicOrdering: InvalidAtomicOrdering,
217 NamedAsmLabels: NamedAsmLabels,
223 macro_rules! declare_combined_late_pass {
224 ([$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,
306 UNUSED_EXTERN_CRATES,
317 UNUSED_EXTERN_CRATES,
318 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
319 ELIDED_LIFETIMES_IN_PATHS,
320 EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
321 // macros are ready for this yet.
324 // FIXME macro crates are not up for this yet, too much
325 // breakage is seen if we try to encourage this lint.
326 // MACRO_USE_EXTERN_CRATE
329 // Register renamed and removed lints.
330 store.register_renamed("single_use_lifetime", "single_use_lifetimes");
331 store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
332 store.register_renamed("bare_trait_object", "bare_trait_objects");
333 store.register_renamed("unstable_name_collision", "unstable_name_collisions");
334 store.register_renamed("unused_doc_comment", "unused_doc_comments");
335 store.register_renamed("async_idents", "keyword_idents");
336 store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
337 store.register_renamed("redundant_semicolon", "redundant_semicolons");
338 store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
339 store.register_renamed("safe_packed_borrows", "unaligned_references");
340 store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
341 store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
342 store.register_renamed("non_fmt_panic", "non_fmt_panics");
344 // These were moved to tool lints, but rustc still sees them when compiling normally, before
345 // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
346 // `register_removed` explicitly.
347 const RUSTDOC_LINTS: &[&str] = &[
348 "broken_intra_doc_links",
349 "private_intra_doc_links",
350 "missing_crate_level_docs",
351 "missing_doc_code_examples",
353 "invalid_codeblock_attributes",
357 for rustdoc_lint in RUSTDOC_LINTS {
358 store.register_ignored(rustdoc_lint);
360 store.register_removed(
361 "intra_doc_link_resolution_failure",
362 "use `rustdoc::broken_intra_doc_links` instead",
364 store.register_removed("rustdoc", "use `rustdoc::all` instead");
366 store.register_removed("unknown_features", "replaced by an error");
367 store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
368 store.register_removed("negate_unsigned", "cast a signed value instead");
369 store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
370 // Register lint group aliases.
371 store.register_group_alias("nonstandard_style", "bad_style");
372 // This was renamed to `raw_pointer_derive`, which was then removed,
373 // so it is also considered removed.
374 store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
375 store.register_removed("drop_with_repr_extern", "drop flags have been removed");
376 store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
377 store.register_removed("deprecated_attr", "use `deprecated` instead");
378 store.register_removed(
379 "transmute_from_fn_item_types",
380 "always cast functions before transmuting them",
382 store.register_removed(
383 "hr_lifetime_in_assoc_type",
384 "converted into hard error, see issue #33685 \
385 <https://github.com/rust-lang/rust/issues/33685> for more information",
387 store.register_removed(
388 "inaccessible_extern_crate",
389 "converted into hard error, see issue #36886 \
390 <https://github.com/rust-lang/rust/issues/36886> for more information",
392 store.register_removed(
393 "super_or_self_in_global_path",
394 "converted into hard error, see issue #36888 \
395 <https://github.com/rust-lang/rust/issues/36888> for more information",
397 store.register_removed(
398 "overlapping_inherent_impls",
399 "converted into hard error, see issue #36889 \
400 <https://github.com/rust-lang/rust/issues/36889> for more information",
402 store.register_removed(
403 "illegal_floating_point_constant_pattern",
404 "converted into hard error, see issue #36890 \
405 <https://github.com/rust-lang/rust/issues/36890> for more information",
407 store.register_removed(
408 "illegal_struct_or_enum_constant_pattern",
409 "converted into hard error, see issue #36891 \
410 <https://github.com/rust-lang/rust/issues/36891> for more information",
412 store.register_removed(
413 "lifetime_underscore",
414 "converted into hard error, see issue #36892 \
415 <https://github.com/rust-lang/rust/issues/36892> for more information",
417 store.register_removed(
418 "extra_requirement_in_impl",
419 "converted into hard error, see issue #37166 \
420 <https://github.com/rust-lang/rust/issues/37166> for more information",
422 store.register_removed(
424 "converted into hard error, see issue #38260 \
425 <https://github.com/rust-lang/rust/issues/38260> for more information",
427 store.register_removed(
429 "converted into hard error, see issue #48950 \
430 <https://github.com/rust-lang/rust/issues/48950> for more information",
432 store.register_removed(
433 "resolve_trait_on_defaulted_unit",
434 "converted into hard error, see issue #48950 \
435 <https://github.com/rust-lang/rust/issues/48950> for more information",
437 store.register_removed(
438 "private_no_mangle_fns",
439 "no longer a warning, `#[no_mangle]` functions always exported",
441 store.register_removed(
442 "private_no_mangle_statics",
443 "no longer a warning, `#[no_mangle]` statics always exported",
445 store.register_removed("bad_repr", "replaced with a generic attribute input check");
446 store.register_removed(
447 "duplicate_matcher_binding_name",
448 "converted into hard error, see issue #57742 \
449 <https://github.com/rust-lang/rust/issues/57742> for more information",
451 store.register_removed(
452 "incoherent_fundamental_impls",
453 "converted into hard error, see issue #46205 \
454 <https://github.com/rust-lang/rust/issues/46205> for more information",
456 store.register_removed(
457 "legacy_constructor_visibility",
458 "converted into hard error, see issue #39207 \
459 <https://github.com/rust-lang/rust/issues/39207> for more information",
461 store.register_removed(
462 "legacy_directory_ownership",
463 "converted into hard error, see issue #37872 \
464 <https://github.com/rust-lang/rust/issues/37872> for more information",
466 store.register_removed(
467 "safe_extern_statics",
468 "converted into hard error, see issue #36247 \
469 <https://github.com/rust-lang/rust/issues/36247> for more information",
471 store.register_removed(
472 "parenthesized_params_in_types_and_modules",
473 "converted into hard error, see issue #42238 \
474 <https://github.com/rust-lang/rust/issues/42238> for more information",
476 store.register_removed(
477 "duplicate_macro_exports",
478 "converted into hard error, see issue #35896 \
479 <https://github.com/rust-lang/rust/issues/35896> for more information",
481 store.register_removed(
483 "converted into hard error, see issue #59014 \
484 <https://github.com/rust-lang/rust/issues/59014> for more information",
486 store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
487 store.register_removed(
488 "unsupported_naked_functions",
489 "converted into hard error, see RFC 2972 \
490 <https://github.com/rust-lang/rfcs/blob/master/text/2972-constrained-naked.md> for more information",
492 store.register_removed(
493 "mutable_borrow_reservation_conflict",
494 "now allowed, see issue #59159 \
495 <https://github.com/rust-lang/rust/issues/59159> for more information",
499 fn register_internals(store: &mut LintStore) {
500 store.register_lints(&LintPassImpl::get_lints());
501 store.register_early_pass(|| Box::new(LintPassImpl));
502 store.register_lints(&DefaultHashTypes::get_lints());
503 store.register_late_pass(|| Box::new(DefaultHashTypes));
504 store.register_lints(&QueryStability::get_lints());
505 store.register_late_pass(|| Box::new(QueryStability));
506 store.register_lints(&ExistingDocKeyword::get_lints());
507 store.register_late_pass(|| Box::new(ExistingDocKeyword));
508 store.register_lints(&TyTyKind::get_lints());
509 store.register_late_pass(|| Box::new(TyTyKind));
510 store.register_lints(&Diagnostics::get_lints());
511 store.register_late_pass(|| Box::new(Diagnostics));
512 store.register_lints(&BadOptAccess::get_lints());
513 store.register_late_pass(|| Box::new(BadOptAccess));
514 store.register_lints(&PassByValue::get_lints());
515 store.register_late_pass(|| Box::new(PassByValue));
516 // FIXME(davidtwco): deliberately do not include `UNTRANSLATABLE_DIAGNOSTIC` and
517 // `DIAGNOSTIC_OUTSIDE_OF_IMPL` here because `-Wrustc::internal` is provided to every crate and
518 // these lints will trigger all of the time - change this once migration to diagnostic structs
519 // and translation is completed
520 store.register_group(
525 LintId::of(DEFAULT_HASH_TYPES),
526 LintId::of(POTENTIAL_QUERY_INSTABILITY),
527 LintId::of(USAGE_OF_TY_TYKIND),
528 LintId::of(PASS_BY_VALUE),
529 LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
530 LintId::of(USAGE_OF_QUALIFIED_TY),
531 LintId::of(EXISTING_DOC_KEYWORD),
532 LintId::of(BAD_OPT_ACCESS),