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 #![cfg_attr(test, feature(test))]
30 #![feature(array_windows)]
31 #![feature(bool_to_option)]
32 #![feature(box_syntax)]
33 #![feature(crate_visibility_modifier)]
34 #![feature(iter_order_by)]
35 #![feature(never_type)]
37 #![feature(or_patterns)]
38 #![recursion_limit = "256"]
41 extern crate rustc_middle;
43 extern crate rustc_session;
53 mod nonstandard_style;
55 mod redundant_semicolon;
62 use rustc_hir::def_id::LocalDefId;
63 use rustc_middle::ty::query::Providers;
64 use rustc_middle::ty::TyCtxt;
65 use rustc_session::lint::builtin::{
66 BARE_TRAIT_OBJECTS, BROKEN_INTRA_DOC_LINKS, ELIDED_LIFETIMES_IN_PATHS,
67 EXPLICIT_OUTLIVES_REQUIREMENTS, INVALID_CODEBLOCK_ATTRIBUTES, INVALID_HTML_TAGS,
68 MISSING_DOC_CODE_EXAMPLES, PRIVATE_DOC_TESTS,
70 use rustc_span::symbol::{Ident, Symbol};
73 use array_into_iter::ArrayIntoIter;
76 use non_ascii_idents::*;
77 use nonstandard_style::*;
78 use redundant_semicolon::*;
83 /// Useful for other parts of the compiler / Clippy.
84 pub use builtin::SoftLints;
85 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
86 pub use early::check_ast_crate;
87 pub use late::check_crate;
88 pub use passes::{EarlyLintPass, LateLintPass};
89 pub use rustc_session::lint::Level::{self, *};
90 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
91 pub use rustc_session::lint::{LintArray, LintPass};
93 pub fn provide(providers: &mut Providers) {
94 levels::provide(providers);
95 *providers = Providers { lint_mod, ..*providers };
98 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
99 late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
102 macro_rules! pre_expansion_lint_passes {
103 ($macro:path, $args:tt) => {
104 $macro!($args, [KeywordIdents: KeywordIdents,]);
108 macro_rules! early_lint_passes {
109 ($macro:path, $args:tt) => {
113 UnusedParens: UnusedParens,
114 UnusedBraces: UnusedBraces,
115 UnusedImportBraces: UnusedImportBraces,
116 UnsafeCode: UnsafeCode,
117 AnonymousParameters: AnonymousParameters,
118 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
119 NonCamelCaseTypes: NonCamelCaseTypes,
120 DeprecatedAttr: DeprecatedAttr::new(),
121 WhileTrue: WhileTrue,
122 NonAsciiIdents: NonAsciiIdents,
123 IncompleteFeatures: IncompleteFeatures,
124 RedundantSemicolons: RedundantSemicolons,
125 UnusedDocComment: UnusedDocComment,
131 macro_rules! declare_combined_early_pass {
132 ([$name:ident], $passes:tt) => (
133 early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
137 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
138 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
140 macro_rules! late_lint_passes {
141 ($macro:path, $args:tt) => {
145 // FIXME: Look into regression when this is used as a module lint
146 // May Depend on constants elsewhere
147 UnusedBrokenConst: UnusedBrokenConst,
148 // Uses attr::is_used which is untracked, can't be an incremental module pass.
149 UnusedAttributes: UnusedAttributes::new(),
150 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
151 UnstableFeatures: UnstableFeatures,
152 // Tracks state across modules
153 UnnameableTestItems: UnnameableTestItems::new(),
154 // Tracks attributes of parents
155 MissingDoc: MissingDoc::new(),
156 // Depends on access levels
157 // FIXME: Turn the computation of types which implement Debug into a query
158 // and change this to a module lint pass
159 MissingDebugImplementations: MissingDebugImplementations::default(),
160 ArrayIntoIter: ArrayIntoIter,
161 ClashingExternDeclarations: ClashingExternDeclarations::new(),
162 DropTraitConstraints: DropTraitConstraints,
168 macro_rules! late_lint_mod_passes {
169 ($macro:path, $args:tt) => {
173 HardwiredLints: HardwiredLints,
174 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
175 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
176 VariantSizeDifferences: VariantSizeDifferences,
177 BoxPointers: BoxPointers,
178 PathStatements: PathStatements,
179 // Depends on referenced function signatures in expressions
180 UnusedResults: UnusedResults,
181 NonUpperCaseGlobals: NonUpperCaseGlobals,
182 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
183 UnusedAllocation: UnusedAllocation,
184 // Depends on types used in type definitions
185 MissingCopyImplementations: MissingCopyImplementations,
186 // Depends on referenced function signatures in expressions
187 MutableTransmutes: MutableTransmutes,
188 TypeAliasBounds: TypeAliasBounds,
189 TrivialConstraints: TrivialConstraints,
190 TypeLimits: TypeLimits::new(),
191 NonSnakeCase: NonSnakeCase,
192 InvalidNoMangleItems: InvalidNoMangleItems,
193 // Depends on access levels
194 UnreachablePub: UnreachablePub,
195 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
196 InvalidValue: InvalidValue,
202 macro_rules! declare_combined_late_pass {
203 ([$v:vis $name:ident], $passes:tt) => (
204 late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
208 // FIXME: Make a separate lint type which do not require typeck tables
209 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
211 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
213 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
214 let mut lint_store = LintStore::new();
216 register_builtins(&mut lint_store, no_interleave_lints);
218 register_internals(&mut lint_store);
224 /// Tell the `LintStore` about all the built-in lints (the ones
225 /// defined in this crate and the ones defined in
226 /// `rustc_session::lint::builtin`).
227 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
228 macro_rules! add_lint_group {
229 ($name:expr, $($lint:ident),*) => (
230 store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
234 macro_rules! register_pass {
235 ($method:ident, $ty:ident, $constructor:expr) => {
236 store.register_lints(&$ty::get_lints());
237 store.$method(|| box $constructor);
241 macro_rules! register_passes {
242 ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
244 register_pass!($method, $passes, $constructor);
249 if no_interleave_lints {
250 pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
251 early_lint_passes!(register_passes, register_early_pass);
252 late_lint_passes!(register_passes, register_late_pass);
253 late_lint_mod_passes!(register_passes, register_late_mod_pass);
255 store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
256 store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
257 store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
258 store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
263 NON_CAMEL_CASE_TYPES,
265 NON_UPPER_CASE_GLOBALS
276 UNREACHABLE_PATTERNS,
277 OVERLAPPING_PATTERNS,
285 UNUSED_EXTERN_CRATES,
296 UNUSED_EXTERN_CRATES,
297 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
298 ELIDED_LIFETIMES_IN_PATHS,
299 EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
300 // macros are ready for this yet.
303 // FIXME macro crates are not up for this yet, too much
304 // breakage is seen if we try to encourage this lint.
305 // MACRO_USE_EXTERN_CRATE
310 BROKEN_INTRA_DOC_LINKS,
311 PRIVATE_INTRA_DOC_LINKS,
312 INVALID_CODEBLOCK_ATTRIBUTES,
313 MISSING_DOC_CODE_EXAMPLES,
318 // Register renamed and removed lints.
319 store.register_renamed("single_use_lifetime", "single_use_lifetimes");
320 store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
321 store.register_renamed("bare_trait_object", "bare_trait_objects");
322 store.register_renamed("unstable_name_collision", "unstable_name_collisions");
323 store.register_renamed("unused_doc_comment", "unused_doc_comments");
324 store.register_renamed("async_idents", "keyword_idents");
325 store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
326 store.register_renamed("redundant_semicolon", "redundant_semicolons");
327 store.register_renamed("intra_doc_link_resolution_failure", "broken_intra_doc_links");
328 store.register_removed("unknown_features", "replaced by an error");
329 store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
330 store.register_removed("negate_unsigned", "cast a signed value instead");
331 store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
332 // Register lint group aliases.
333 store.register_group_alias("nonstandard_style", "bad_style");
334 // This was renamed to `raw_pointer_derive`, which was then removed,
335 // so it is also considered removed.
336 store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
337 store.register_removed("drop_with_repr_extern", "drop flags have been removed");
338 store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
339 store.register_removed("deprecated_attr", "use `deprecated` instead");
340 store.register_removed(
341 "transmute_from_fn_item_types",
342 "always cast functions before transmuting them",
344 store.register_removed(
345 "hr_lifetime_in_assoc_type",
346 "converted into hard error, see issue #33685 \
347 <https://github.com/rust-lang/rust/issues/33685> for more information",
349 store.register_removed(
350 "inaccessible_extern_crate",
351 "converted into hard error, see issue #36886 \
352 <https://github.com/rust-lang/rust/issues/36886> for more information",
354 store.register_removed(
355 "super_or_self_in_global_path",
356 "converted into hard error, see issue #36888 \
357 <https://github.com/rust-lang/rust/issues/36888> for more information",
359 store.register_removed(
360 "overlapping_inherent_impls",
361 "converted into hard error, see issue #36889 \
362 <https://github.com/rust-lang/rust/issues/36889> for more information",
364 store.register_removed(
365 "illegal_floating_point_constant_pattern",
366 "converted into hard error, see issue #36890 \
367 <https://github.com/rust-lang/rust/issues/36890> for more information",
369 store.register_removed(
370 "illegal_struct_or_enum_constant_pattern",
371 "converted into hard error, see issue #36891 \
372 <https://github.com/rust-lang/rust/issues/36891> for more information",
374 store.register_removed(
375 "lifetime_underscore",
376 "converted into hard error, see issue #36892 \
377 <https://github.com/rust-lang/rust/issues/36892> for more information",
379 store.register_removed(
380 "extra_requirement_in_impl",
381 "converted into hard error, see issue #37166 \
382 <https://github.com/rust-lang/rust/issues/37166> for more information",
384 store.register_removed(
386 "converted into hard error, see issue #38260 \
387 <https://github.com/rust-lang/rust/issues/38260> for more information",
389 store.register_removed(
391 "converted into hard error, see issue #48950 \
392 <https://github.com/rust-lang/rust/issues/48950> for more information",
394 store.register_removed(
395 "resolve_trait_on_defaulted_unit",
396 "converted into hard error, see issue #48950 \
397 <https://github.com/rust-lang/rust/issues/48950> for more information",
399 store.register_removed(
400 "private_no_mangle_fns",
401 "no longer a warning, `#[no_mangle]` functions always exported",
403 store.register_removed(
404 "private_no_mangle_statics",
405 "no longer a warning, `#[no_mangle]` statics always exported",
407 store.register_removed("bad_repr", "replaced with a generic attribute input check");
408 store.register_removed(
409 "duplicate_matcher_binding_name",
410 "converted into hard error, see issue #57742 \
411 <https://github.com/rust-lang/rust/issues/57742> for more information",
413 store.register_removed(
414 "incoherent_fundamental_impls",
415 "converted into hard error, see issue #46205 \
416 <https://github.com/rust-lang/rust/issues/46205> for more information",
418 store.register_removed(
419 "legacy_constructor_visibility",
420 "converted into hard error, see issue #39207 \
421 <https://github.com/rust-lang/rust/issues/39207> for more information",
423 store.register_removed(
424 "legacy_directory_ownership",
425 "converted into hard error, see issue #37872 \
426 <https://github.com/rust-lang/rust/issues/37872> for more information",
428 store.register_removed(
429 "safe_extern_statics",
430 "converted into hard error, see issue #36247 \
431 <https://github.com/rust-lang/rust/issues/36247> for more information",
433 store.register_removed(
434 "parenthesized_params_in_types_and_modules",
435 "converted into hard error, see issue #42238 \
436 <https://github.com/rust-lang/rust/issues/42238> for more information",
438 store.register_removed(
439 "duplicate_macro_exports",
440 "converted into hard error, see issue #35896 \
441 <https://github.com/rust-lang/rust/issues/35896> for more information",
443 store.register_removed(
445 "converted into hard error, see issue #59014 \
446 <https://github.com/rust-lang/rust/issues/59014> for more information",
448 store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
451 fn register_internals(store: &mut LintStore) {
452 store.register_lints(&DefaultHashTypes::get_lints());
453 store.register_early_pass(|| box DefaultHashTypes::new());
454 store.register_lints(&LintPassImpl::get_lints());
455 store.register_early_pass(|| box LintPassImpl);
456 store.register_lints(&TyTyKind::get_lints());
457 store.register_late_pass(|| box TyTyKind);
458 store.register_group(
463 LintId::of(DEFAULT_HASH_TYPES),
464 LintId::of(USAGE_OF_TY_TYKIND),
465 LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
466 LintId::of(TY_PASS_BY_REFERENCE),
467 LintId::of(USAGE_OF_QUALIFIED_TY),