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(box_patterns)]
34 #![feature(crate_visibility_modifier)]
35 #![feature(iter_order_by)]
36 #![feature(never_type)]
38 #![feature(or_patterns)]
39 #![feature(half_open_range_patterns)]
40 #![feature(exclusive_range_pattern)]
41 #![feature(control_flow_enum)]
42 #![recursion_limit = "256"]
45 extern crate rustc_middle;
47 extern crate rustc_session;
59 mod nonstandard_style;
61 mod redundant_semicolon;
68 use rustc_hir::def_id::LocalDefId;
69 use rustc_middle::ty::query::Providers;
70 use rustc_middle::ty::TyCtxt;
71 use rustc_session::lint::builtin::{
72 BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
74 use rustc_span::symbol::{Ident, Symbol};
77 use array_into_iter::ArrayIntoIter;
81 use non_ascii_idents::*;
82 use non_fmt_panic::NonPanicFmt;
83 use nonstandard_style::*;
84 use redundant_semicolon::*;
89 /// Useful for other parts of the compiler / Clippy.
90 pub use builtin::SoftLints;
91 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
92 pub use early::check_ast_crate;
93 pub use late::check_crate;
94 pub use passes::{EarlyLintPass, LateLintPass};
95 pub use rustc_session::lint::Level::{self, *};
96 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
97 pub use rustc_session::lint::{LintArray, LintPass};
99 pub fn provide(providers: &mut Providers) {
100 levels::provide(providers);
101 *providers = Providers { lint_mod, ..*providers };
104 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
105 late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
108 macro_rules! pre_expansion_lint_passes {
109 ($macro:path, $args:tt) => {
110 $macro!($args, [KeywordIdents: KeywordIdents,]);
114 macro_rules! early_lint_passes {
115 ($macro:path, $args:tt) => {
119 UnusedParens: UnusedParens,
120 UnusedBraces: UnusedBraces,
121 UnusedImportBraces: UnusedImportBraces,
122 UnsafeCode: UnsafeCode,
123 AnonymousParameters: AnonymousParameters,
124 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
125 NonCamelCaseTypes: NonCamelCaseTypes,
126 DeprecatedAttr: DeprecatedAttr::new(),
127 WhileTrue: WhileTrue,
128 NonAsciiIdents: NonAsciiIdents,
129 IncompleteFeatures: IncompleteFeatures,
130 RedundantSemicolons: RedundantSemicolons,
131 UnusedDocComment: UnusedDocComment,
137 macro_rules! declare_combined_early_pass {
138 ([$name:ident], $passes:tt) => (
139 early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
143 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
144 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
146 macro_rules! late_lint_passes {
147 ($macro:path, $args:tt) => {
151 // FIXME: Look into regression when this is used as a module lint
152 // May Depend on constants elsewhere
153 UnusedBrokenConst: UnusedBrokenConst,
154 // Uses attr::is_used which is untracked, can't be an incremental module pass.
155 UnusedAttributes: UnusedAttributes::new(),
156 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
157 UnstableFeatures: UnstableFeatures,
158 // Tracks state across modules
159 UnnameableTestItems: UnnameableTestItems::new(),
160 // Tracks attributes of parents
161 MissingDoc: MissingDoc::new(),
162 // Depends on access levels
163 // FIXME: Turn the computation of types which implement Debug into a query
164 // and change this to a module lint pass
165 MissingDebugImplementations: MissingDebugImplementations::default(),
166 ArrayIntoIter: ArrayIntoIter,
167 ClashingExternDeclarations: ClashingExternDeclarations::new(),
168 DropTraitConstraints: DropTraitConstraints,
169 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
170 NonPanicFmt: NonPanicFmt,
176 macro_rules! late_lint_mod_passes {
177 ($macro:path, $args:tt) => {
181 HardwiredLints: HardwiredLints,
182 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
183 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
184 VariantSizeDifferences: VariantSizeDifferences,
185 BoxPointers: BoxPointers,
186 PathStatements: PathStatements,
187 // Depends on referenced function signatures in expressions
188 UnusedResults: UnusedResults,
189 NonUpperCaseGlobals: NonUpperCaseGlobals,
190 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
191 UnusedAllocation: UnusedAllocation,
192 // Depends on types used in type definitions
193 MissingCopyImplementations: MissingCopyImplementations,
194 // Depends on referenced function signatures in expressions
195 MutableTransmutes: MutableTransmutes,
196 TypeAliasBounds: TypeAliasBounds,
197 TrivialConstraints: TrivialConstraints,
198 TypeLimits: TypeLimits::new(),
199 NonSnakeCase: NonSnakeCase,
200 InvalidNoMangleItems: InvalidNoMangleItems,
201 // Depends on access levels
202 UnreachablePub: UnreachablePub,
203 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
204 InvalidValue: InvalidValue,
210 macro_rules! declare_combined_late_pass {
211 ([$v:vis $name:ident], $passes:tt) => (
212 late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
216 // FIXME: Make a separate lint type which do not require typeck tables
217 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
219 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
221 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
222 let mut lint_store = LintStore::new();
224 register_builtins(&mut lint_store, no_interleave_lints);
226 register_internals(&mut lint_store);
232 /// Tell the `LintStore` about all the built-in lints (the ones
233 /// defined in this crate and the ones defined in
234 /// `rustc_session::lint::builtin`).
235 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
236 macro_rules! add_lint_group {
237 ($name:expr, $($lint:ident),*) => (
238 store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
242 macro_rules! register_pass {
243 ($method:ident, $ty:ident, $constructor:expr) => {
244 store.register_lints(&$ty::get_lints());
245 store.$method(|| box $constructor);
249 macro_rules! register_passes {
250 ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
252 register_pass!($method, $passes, $constructor);
257 if no_interleave_lints {
258 pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
259 early_lint_passes!(register_passes, register_early_pass);
260 late_lint_passes!(register_passes, register_late_pass);
261 late_lint_mod_passes!(register_passes, register_late_mod_pass);
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());
271 NON_CAMEL_CASE_TYPES,
273 NON_UPPER_CASE_GLOBALS
284 UNREACHABLE_PATTERNS,
292 UNUSED_EXTERN_CRATES,
303 UNUSED_EXTERN_CRATES,
304 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
305 ELIDED_LIFETIMES_IN_PATHS,
306 EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
307 // macros are ready for this yet.
310 // FIXME macro crates are not up for this yet, too much
311 // breakage is seen if we try to encourage this lint.
312 // MACRO_USE_EXTERN_CRATE
315 // Register renamed and removed lints.
316 store.register_renamed("single_use_lifetime", "single_use_lifetimes");
317 store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
318 store.register_renamed("bare_trait_object", "bare_trait_objects");
319 store.register_renamed("unstable_name_collision", "unstable_name_collisions");
320 store.register_renamed("unused_doc_comment", "unused_doc_comments");
321 store.register_renamed("async_idents", "keyword_idents");
322 store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
323 store.register_renamed("redundant_semicolon", "redundant_semicolons");
324 store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
326 // These were moved to tool lints, but rustc still sees them when compiling normally, before
327 // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
328 // `register_removed` explicitly.
329 const RUSTDOC_LINTS: &[&str] = &[
330 "broken_intra_doc_links",
331 "private_intra_doc_links",
332 "missing_crate_level_docs",
333 "missing_doc_code_examples",
335 "invalid_codeblock_attributes",
339 for rustdoc_lint in RUSTDOC_LINTS {
340 store.register_removed(rustdoc_lint, &format!("use `rustdoc::{}` instead", rustdoc_lint));
342 store.register_removed(
343 "intra_doc_link_resolution_failure",
344 "use `rustdoc::broken_intra_doc_links` instead",
347 store.register_removed("unknown_features", "replaced by an error");
348 store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
349 store.register_removed("negate_unsigned", "cast a signed value instead");
350 store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
351 // Register lint group aliases.
352 store.register_group_alias("nonstandard_style", "bad_style");
353 // This was renamed to `raw_pointer_derive`, which was then removed,
354 // so it is also considered removed.
355 store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
356 store.register_removed("drop_with_repr_extern", "drop flags have been removed");
357 store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
358 store.register_removed("deprecated_attr", "use `deprecated` instead");
359 store.register_removed(
360 "transmute_from_fn_item_types",
361 "always cast functions before transmuting them",
363 store.register_removed(
364 "hr_lifetime_in_assoc_type",
365 "converted into hard error, see issue #33685 \
366 <https://github.com/rust-lang/rust/issues/33685> for more information",
368 store.register_removed(
369 "inaccessible_extern_crate",
370 "converted into hard error, see issue #36886 \
371 <https://github.com/rust-lang/rust/issues/36886> for more information",
373 store.register_removed(
374 "super_or_self_in_global_path",
375 "converted into hard error, see issue #36888 \
376 <https://github.com/rust-lang/rust/issues/36888> for more information",
378 store.register_removed(
379 "overlapping_inherent_impls",
380 "converted into hard error, see issue #36889 \
381 <https://github.com/rust-lang/rust/issues/36889> for more information",
383 store.register_removed(
384 "illegal_floating_point_constant_pattern",
385 "converted into hard error, see issue #36890 \
386 <https://github.com/rust-lang/rust/issues/36890> for more information",
388 store.register_removed(
389 "illegal_struct_or_enum_constant_pattern",
390 "converted into hard error, see issue #36891 \
391 <https://github.com/rust-lang/rust/issues/36891> for more information",
393 store.register_removed(
394 "lifetime_underscore",
395 "converted into hard error, see issue #36892 \
396 <https://github.com/rust-lang/rust/issues/36892> for more information",
398 store.register_removed(
399 "extra_requirement_in_impl",
400 "converted into hard error, see issue #37166 \
401 <https://github.com/rust-lang/rust/issues/37166> for more information",
403 store.register_removed(
405 "converted into hard error, see issue #38260 \
406 <https://github.com/rust-lang/rust/issues/38260> for more information",
408 store.register_removed(
410 "converted into hard error, see issue #48950 \
411 <https://github.com/rust-lang/rust/issues/48950> for more information",
413 store.register_removed(
414 "resolve_trait_on_defaulted_unit",
415 "converted into hard error, see issue #48950 \
416 <https://github.com/rust-lang/rust/issues/48950> for more information",
418 store.register_removed(
419 "private_no_mangle_fns",
420 "no longer a warning, `#[no_mangle]` functions always exported",
422 store.register_removed(
423 "private_no_mangle_statics",
424 "no longer a warning, `#[no_mangle]` statics always exported",
426 store.register_removed("bad_repr", "replaced with a generic attribute input check");
427 store.register_removed(
428 "duplicate_matcher_binding_name",
429 "converted into hard error, see issue #57742 \
430 <https://github.com/rust-lang/rust/issues/57742> for more information",
432 store.register_removed(
433 "incoherent_fundamental_impls",
434 "converted into hard error, see issue #46205 \
435 <https://github.com/rust-lang/rust/issues/46205> for more information",
437 store.register_removed(
438 "legacy_constructor_visibility",
439 "converted into hard error, see issue #39207 \
440 <https://github.com/rust-lang/rust/issues/39207> for more information",
442 store.register_removed(
443 "legacy_directory_ownership",
444 "converted into hard error, see issue #37872 \
445 <https://github.com/rust-lang/rust/issues/37872> for more information",
447 store.register_removed(
448 "safe_extern_statics",
449 "converted into hard error, see issue #36247 \
450 <https://github.com/rust-lang/rust/issues/36247> for more information",
452 store.register_removed(
453 "parenthesized_params_in_types_and_modules",
454 "converted into hard error, see issue #42238 \
455 <https://github.com/rust-lang/rust/issues/42238> for more information",
457 store.register_removed(
458 "duplicate_macro_exports",
459 "converted into hard error, see issue #35896 \
460 <https://github.com/rust-lang/rust/issues/35896> for more information",
462 store.register_removed(
464 "converted into hard error, see issue #59014 \
465 <https://github.com/rust-lang/rust/issues/59014> for more information",
467 store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
470 fn register_internals(store: &mut LintStore) {
471 store.register_lints(&DefaultHashTypes::get_lints());
472 store.register_early_pass(|| box DefaultHashTypes::new());
473 store.register_lints(&LintPassImpl::get_lints());
474 store.register_early_pass(|| box LintPassImpl);
475 store.register_lints(&ExistingDocKeyword::get_lints());
476 store.register_late_pass(|| box ExistingDocKeyword);
477 store.register_lints(&TyTyKind::get_lints());
478 store.register_late_pass(|| box TyTyKind);
479 store.register_group(
484 LintId::of(DEFAULT_HASH_TYPES),
485 LintId::of(USAGE_OF_TY_TYKIND),
486 LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
487 LintId::of(TY_PASS_BY_REFERENCE),
488 LintId::of(USAGE_OF_QUALIFIED_TY),
489 LintId::of(EXISTING_DOC_KEYWORD),