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
;
62 mod redundant_semicolon
;
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
;
82 use non_ascii_idents
::*;
83 use non_fmt_panic
::NonPanicFmt
;
84 use nonstandard_style
::*;
85 use noop_method_call
::*;
86 use redundant_semicolon
::*;
91 /// Useful for other parts of the compiler / Clippy.
92 pub use builtin
::SoftLints
;
93 pub use context
::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore}
;
94 pub use early
::check_ast_crate
;
95 pub use late
::check_crate
;
96 pub use passes
::{EarlyLintPass, LateLintPass}
;
97 pub use rustc_session
::lint
::Level
::{self, *}
;
98 pub use rustc_session
::lint
::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId}
;
99 pub use rustc_session
::lint
::{LintArray, LintPass}
;
101 pub fn provide(providers
: &mut Providers
) {
102 levels
::provide(providers
);
103 *providers
= Providers { lint_mod, ..*providers }
;
106 fn lint_mod(tcx
: TyCtxt
<'_
>, module_def_id
: LocalDefId
) {
107 late
::late_lint_mod(tcx
, module_def_id
, BuiltinCombinedModuleLateLintPass
::new());
110 macro_rules
! pre_expansion_lint_passes
{
111 ($
macro:path
, $args
:tt
) => {
112 $
macro!($args
, [KeywordIdents
: KeywordIdents
,]);
116 macro_rules
! early_lint_passes
{
117 ($
macro:path
, $args
:tt
) => {
121 UnusedParens
: UnusedParens
,
122 UnusedBraces
: UnusedBraces
,
123 UnusedImportBraces
: UnusedImportBraces
,
124 UnsafeCode
: UnsafeCode
,
125 AnonymousParameters
: AnonymousParameters
,
126 EllipsisInclusiveRangePatterns
: EllipsisInclusiveRangePatterns
::default(),
127 NonCamelCaseTypes
: NonCamelCaseTypes
,
128 DeprecatedAttr
: DeprecatedAttr
::new(),
129 WhileTrue
: WhileTrue
,
130 NonAsciiIdents
: NonAsciiIdents
,
131 IncompleteFeatures
: IncompleteFeatures
,
132 RedundantSemicolons
: RedundantSemicolons
,
133 UnusedDocComment
: UnusedDocComment
,
139 macro_rules
! declare_combined_early_pass
{
140 ([$name
:ident
], $passes
:tt
) => (
141 early_lint_methods
!(declare_combined_early_lint_pass
, [pub $name
, $passes
]);
145 pre_expansion_lint_passes
!(declare_combined_early_pass
, [BuiltinCombinedPreExpansionLintPass
]);
146 early_lint_passes
!(declare_combined_early_pass
, [BuiltinCombinedEarlyLintPass
]);
148 macro_rules
! late_lint_passes
{
149 ($
macro:path
, $args
:tt
) => {
153 // FIXME: Look into regression when this is used as a module lint
154 // May Depend on constants elsewhere
155 UnusedBrokenConst
: UnusedBrokenConst
,
156 // Uses attr::is_used which is untracked, can't be an incremental module pass.
157 UnusedAttributes
: UnusedAttributes
::new(),
158 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
159 UnstableFeatures
: UnstableFeatures
,
160 // Tracks state across modules
161 UnnameableTestItems
: UnnameableTestItems
::new(),
162 // Tracks attributes of parents
163 MissingDoc
: MissingDoc
::new(),
164 // Depends on access levels
165 // FIXME: Turn the computation of types which implement Debug into a query
166 // and change this to a module lint pass
167 MissingDebugImplementations
: MissingDebugImplementations
::default(),
168 ArrayIntoIter
: ArrayIntoIter
,
169 ClashingExternDeclarations
: ClashingExternDeclarations
::new(),
170 DropTraitConstraints
: DropTraitConstraints
,
171 TemporaryCStringAsPtr
: TemporaryCStringAsPtr
,
172 NonPanicFmt
: NonPanicFmt
,
173 NoopMethodCall
: NoopMethodCall
,
179 macro_rules
! late_lint_mod_passes
{
180 ($
macro:path
, $args
:tt
) => {
184 HardwiredLints
: HardwiredLints
,
185 ImproperCTypesDeclarations
: ImproperCTypesDeclarations
,
186 ImproperCTypesDefinitions
: ImproperCTypesDefinitions
,
187 VariantSizeDifferences
: VariantSizeDifferences
,
188 BoxPointers
: BoxPointers
,
189 PathStatements
: PathStatements
,
190 // Depends on referenced function signatures in expressions
191 UnusedResults
: UnusedResults
,
192 NonUpperCaseGlobals
: NonUpperCaseGlobals
,
193 NonShorthandFieldPatterns
: NonShorthandFieldPatterns
,
194 UnusedAllocation
: UnusedAllocation
,
195 // Depends on types used in type definitions
196 MissingCopyImplementations
: MissingCopyImplementations
,
197 // Depends on referenced function signatures in expressions
198 MutableTransmutes
: MutableTransmutes
,
199 TypeAliasBounds
: TypeAliasBounds
,
200 TrivialConstraints
: TrivialConstraints
,
201 TypeLimits
: TypeLimits
::new(),
202 NonSnakeCase
: NonSnakeCase
,
203 InvalidNoMangleItems
: InvalidNoMangleItems
,
204 // Depends on access levels
205 UnreachablePub
: UnreachablePub
,
206 ExplicitOutlivesRequirements
: ExplicitOutlivesRequirements
,
207 InvalidValue
: InvalidValue
,
213 macro_rules
! declare_combined_late_pass
{
214 ([$v
:vis $name
:ident
], $passes
:tt
) => (
215 late_lint_methods
!(declare_combined_late_lint_pass
, [$v $name
, $passes
], ['tcx
]);
219 // FIXME: Make a separate lint type which do not require typeck tables
220 late_lint_passes
!(declare_combined_late_pass
, [pub BuiltinCombinedLateLintPass
]);
222 late_lint_mod_passes
!(declare_combined_late_pass
, [BuiltinCombinedModuleLateLintPass
]);
224 pub fn new_lint_store(no_interleave_lints
: bool
, internal_lints
: bool
) -> LintStore
{
225 let mut lint_store
= LintStore
::new();
227 register_builtins(&mut lint_store
, no_interleave_lints
);
229 register_internals(&mut lint_store
);
235 /// Tell the `LintStore` about all the built-in lints (the ones
236 /// defined in this crate and the ones defined in
237 /// `rustc_session::lint::builtin`).
238 fn register_builtins(store
: &mut LintStore
, no_interleave_lints
: bool
) {
239 macro_rules
! add_lint_group
{
240 ($name
:expr
, $
($lint
:ident
),*) => (
241 store
.register_group(false, $name
, None
, vec
![$
(LintId
::of($lint
)),*]);
245 macro_rules
! register_pass
{
246 ($method
:ident
, $ty
:ident
, $constructor
:expr
) => {
247 store
.register_lints(&$ty
::get_lints());
248 store
.$
method(|| box $constructor
);
252 macro_rules
! register_passes
{
253 ($method
:ident
, [$
($passes
:ident
: $constructor
:expr
,)*]) => (
255 register_pass
!($method
, $passes
, $constructor
);
260 if no_interleave_lints
{
261 pre_expansion_lint_passes
!(register_passes
, register_pre_expansion_pass
);
262 early_lint_passes
!(register_passes
, register_early_pass
);
263 late_lint_passes
!(register_passes
, register_late_pass
);
264 late_lint_mod_passes
!(register_passes
, register_late_mod_pass
);
266 store
.register_lints(&BuiltinCombinedPreExpansionLintPass
::get_lints());
267 store
.register_lints(&BuiltinCombinedEarlyLintPass
::get_lints());
268 store
.register_lints(&BuiltinCombinedModuleLateLintPass
::get_lints());
269 store
.register_lints(&BuiltinCombinedLateLintPass
::get_lints());
274 NON_CAMEL_CASE_TYPES
,
276 NON_UPPER_CASE_GLOBALS
287 UNREACHABLE_PATTERNS
,
295 UNUSED_EXTERN_CRATES
,
306 UNUSED_EXTERN_CRATES
,
307 ELLIPSIS_INCLUSIVE_RANGE_PATTERNS
,
308 ELIDED_LIFETIMES_IN_PATHS
,
309 EXPLICIT_OUTLIVES_REQUIREMENTS
// FIXME(#52665, #47816) not always applicable and not all
310 // macros are ready for this yet.
313 // FIXME macro crates are not up for this yet, too much
314 // breakage is seen if we try to encourage this lint.
315 // MACRO_USE_EXTERN_CRATE
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("overlapping_patterns", "overlapping_range_endpoints");
329 // These were moved to tool lints, but rustc still sees them when compiling normally, before
330 // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
331 // `register_removed` explicitly.
332 const RUSTDOC_LINTS
: &[&str] = &[
333 "broken_intra_doc_links",
334 "private_intra_doc_links",
335 "missing_crate_level_docs",
336 "missing_doc_code_examples",
338 "invalid_codeblock_attributes",
342 for rustdoc_lint
in RUSTDOC_LINTS
{
343 store
.register_ignored(rustdoc_lint
);
345 store
.register_removed(
346 "intra_doc_link_resolution_failure",
347 "use `rustdoc::broken_intra_doc_links` instead",
349 store
.register_removed("rustdoc", "use `rustdoc::all` instead");
351 store
.register_removed("unknown_features", "replaced by an error");
352 store
.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
353 store
.register_removed("negate_unsigned", "cast a signed value instead");
354 store
.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
355 // Register lint group aliases.
356 store
.register_group_alias("nonstandard_style", "bad_style");
357 // This was renamed to `raw_pointer_derive`, which was then removed,
358 // so it is also considered removed.
359 store
.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
360 store
.register_removed("drop_with_repr_extern", "drop flags have been removed");
361 store
.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
362 store
.register_removed("deprecated_attr", "use `deprecated` instead");
363 store
.register_removed(
364 "transmute_from_fn_item_types",
365 "always cast functions before transmuting them",
367 store
.register_removed(
368 "hr_lifetime_in_assoc_type",
369 "converted into hard error, see issue #33685 \
370 <https://github.com/rust-lang/rust/issues/33685> for more information",
372 store
.register_removed(
373 "inaccessible_extern_crate",
374 "converted into hard error, see issue #36886 \
375 <https://github.com/rust-lang/rust/issues/36886> for more information",
377 store
.register_removed(
378 "super_or_self_in_global_path",
379 "converted into hard error, see issue #36888 \
380 <https://github.com/rust-lang/rust/issues/36888> for more information",
382 store
.register_removed(
383 "overlapping_inherent_impls",
384 "converted into hard error, see issue #36889 \
385 <https://github.com/rust-lang/rust/issues/36889> for more information",
387 store
.register_removed(
388 "illegal_floating_point_constant_pattern",
389 "converted into hard error, see issue #36890 \
390 <https://github.com/rust-lang/rust/issues/36890> for more information",
392 store
.register_removed(
393 "illegal_struct_or_enum_constant_pattern",
394 "converted into hard error, see issue #36891 \
395 <https://github.com/rust-lang/rust/issues/36891> for more information",
397 store
.register_removed(
398 "lifetime_underscore",
399 "converted into hard error, see issue #36892 \
400 <https://github.com/rust-lang/rust/issues/36892> for more information",
402 store
.register_removed(
403 "extra_requirement_in_impl",
404 "converted into hard error, see issue #37166 \
405 <https://github.com/rust-lang/rust/issues/37166> for more information",
407 store
.register_removed(
409 "converted into hard error, see issue #38260 \
410 <https://github.com/rust-lang/rust/issues/38260> for more information",
412 store
.register_removed(
414 "converted into hard error, see issue #48950 \
415 <https://github.com/rust-lang/rust/issues/48950> for more information",
417 store
.register_removed(
418 "resolve_trait_on_defaulted_unit",
419 "converted into hard error, see issue #48950 \
420 <https://github.com/rust-lang/rust/issues/48950> for more information",
422 store
.register_removed(
423 "private_no_mangle_fns",
424 "no longer a warning, `#[no_mangle]` functions always exported",
426 store
.register_removed(
427 "private_no_mangle_statics",
428 "no longer a warning, `#[no_mangle]` statics always exported",
430 store
.register_removed("bad_repr", "replaced with a generic attribute input check");
431 store
.register_removed(
432 "duplicate_matcher_binding_name",
433 "converted into hard error, see issue #57742 \
434 <https://github.com/rust-lang/rust/issues/57742> for more information",
436 store
.register_removed(
437 "incoherent_fundamental_impls",
438 "converted into hard error, see issue #46205 \
439 <https://github.com/rust-lang/rust/issues/46205> for more information",
441 store
.register_removed(
442 "legacy_constructor_visibility",
443 "converted into hard error, see issue #39207 \
444 <https://github.com/rust-lang/rust/issues/39207> for more information",
446 store
.register_removed(
447 "legacy_directory_ownership",
448 "converted into hard error, see issue #37872 \
449 <https://github.com/rust-lang/rust/issues/37872> for more information",
451 store
.register_removed(
452 "safe_extern_statics",
453 "converted into hard error, see issue #36247 \
454 <https://github.com/rust-lang/rust/issues/36247> for more information",
456 store
.register_removed(
457 "parenthesized_params_in_types_and_modules",
458 "converted into hard error, see issue #42238 \
459 <https://github.com/rust-lang/rust/issues/42238> for more information",
461 store
.register_removed(
462 "duplicate_macro_exports",
463 "converted into hard error, see issue #35896 \
464 <https://github.com/rust-lang/rust/issues/35896> for more information",
466 store
.register_removed(
468 "converted into hard error, see issue #59014 \
469 <https://github.com/rust-lang/rust/issues/59014> for more information",
471 store
.register_removed("plugin_as_library", "plugins have been deprecated and retired");
474 fn register_internals(store
: &mut LintStore
) {
475 store
.register_lints(&DefaultHashTypes
::get_lints());
476 store
.register_early_pass(|| box DefaultHashTypes
::new());
477 store
.register_lints(&LintPassImpl
::get_lints());
478 store
.register_early_pass(|| box LintPassImpl
);
479 store
.register_lints(&ExistingDocKeyword
::get_lints());
480 store
.register_late_pass(|| box ExistingDocKeyword
);
481 store
.register_lints(&TyTyKind
::get_lints());
482 store
.register_late_pass(|| box TyTyKind
);
483 store
.register_group(
488 LintId
::of(DEFAULT_HASH_TYPES
),
489 LintId
::of(USAGE_OF_TY_TYKIND
),
490 LintId
::of(LINT_PASS_IMPL_WITHOUT_MACRO
),
491 LintId
::of(TY_PASS_BY_REFERENCE
),
492 LintId
::of(USAGE_OF_QUALIFIED_TY
),
493 LintId
::of(EXISTING_DOC_KEYWORD
),