compiler/rustc_lint/src/lib.rs

   1 //! Lints, aka compiler warnings.
   2 //!
   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.
   8 //!
   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.
  14 //!
  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`
  20 //! in `context.rs`.
  21 //!
  22 //! Some code also exists in [rustc_session::lint], [rustc_middle::lint].
  23 //!
  24 //! ## Note
  25 //!
  26 //! This API is completely unstable and subject to change.
  27
  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 #![feature(let_chains)]
  37 #![feature(min_specialization)]
  38 #![feature(never_type)]
  39 #![feature(rustc_attrs)]
  40 #![recursion_limit = "256"]
  41 #![deny(rustc::untranslatable_diagnostic)]
  42 #![deny(rustc::diagnostic_outside_of_impl)]
  43
  44 #[macro_use]
  45 extern crate rustc_middle;
  46 #[macro_use]
  47 extern crate rustc_session;
  48 #[macro_use]
  49 extern crate tracing;
  50
  51 mod array_into_iter;
  52 pub mod builtin;
  53 mod context;
  54 mod deref_into_dyn_supertrait;
  55 mod early;
  56 mod enum_intrinsics_non_enums;
  57 mod errors;
  58 mod expect;
  59 mod for_loops_over_fallibles;
  60 pub mod hidden_unicode_codepoints;
  61 mod internal;
  62 mod late;
  63 mod let_underscore;
  64 mod levels;
  65 mod lints;
  66 mod methods;
  67 mod non_ascii_idents;
  68 mod non_fmt_panic;
  69 mod nonstandard_style;
  70 mod noop_method_call;
  71 mod opaque_hidden_inferred_bound;
  72 mod pass_by_value;
  73 mod passes;
  74 mod redundant_semicolon;
  75 mod traits;
  76 mod types;
  77 mod unused;
  78
  79 pub use array_into_iter::ARRAY_INTO_ITER;
  80
  81 use rustc_ast as ast;
  82 use rustc_hir as hir;
  83 use rustc_hir::def_id::LocalDefId;
  84 use rustc_middle::ty::query::Providers;
  85 use rustc_middle::ty::TyCtxt;
  86 use rustc_session::lint::builtin::{
  87     BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
  88 };
  89 use rustc_span::symbol::Ident;
  90 use rustc_span::Span;
  91
  92 use array_into_iter::ArrayIntoIter;
  93 use builtin::*;
  94 use deref_into_dyn_supertrait::*;
  95 use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
  96 use for_loops_over_fallibles::*;
  97 use hidden_unicode_codepoints::*;
  98 use internal::*;
  99 use let_underscore::*;
 100 use methods::*;
 101 use non_ascii_idents::*;
 102 use non_fmt_panic::NonPanicFmt;
 103 use nonstandard_style::*;
 104 use noop_method_call::*;
 105 use opaque_hidden_inferred_bound::*;
 106 use pass_by_value::*;
 107 use redundant_semicolon::*;
 108 use traits::*;
 109 use types::*;
 110 use unused::*;
 111
 112 /// Useful for other parts of the compiler / Clippy.
 113 pub use builtin::SoftLints;
 114 pub use context::{CheckLintNameResult, FindLintError, LintStore};
 115 pub use context::{EarlyContext, LateContext, LintContext};
 116 pub use early::{check_ast_node, EarlyCheckNode};
 117 pub use late::{check_crate, unerased_lint_store};
 118 pub use passes::{EarlyLintPass, LateLintPass};
 119 pub use rustc_session::lint::Level::{self, *};
 120 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
 121 pub use rustc_session::lint::{LintArray, LintPass};
 122
 123 pub fn provide(providers: &mut Providers) {
 124     levels::provide(providers);
 125     expect::provide(providers);
 126     *providers = Providers { lint_mod, ..*providers };
 127 }
 128
 129 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
 130     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
 131 }
 132
 133 early_lint_methods!(
 134     declare_combined_early_lint_pass,
 135     [
 136         pub BuiltinCombinedPreExpansionLintPass,
 137         [
 138             KeywordIdents: KeywordIdents,
 139         ]
 140     ]
 141 );
 142
 143 early_lint_methods!(
 144     declare_combined_early_lint_pass,
 145     [
 146         pub BuiltinCombinedEarlyLintPass,
 147         [
 148             UnusedParens: UnusedParens::new(),
 149             UnusedBraces: UnusedBraces,
 150             UnusedImportBraces: UnusedImportBraces,
 151             UnsafeCode: UnsafeCode,
 152             SpecialModuleName: SpecialModuleName,
 153             AnonymousParameters: AnonymousParameters,
 154             EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 155             NonCamelCaseTypes: NonCamelCaseTypes,
 156             DeprecatedAttr: DeprecatedAttr::new(),
 157             WhileTrue: WhileTrue,
 158             NonAsciiIdents: NonAsciiIdents,
 159             HiddenUnicodeCodepoints: HiddenUnicodeCodepoints,
 160             IncompleteFeatures: IncompleteFeatures,
 161             RedundantSemicolons: RedundantSemicolons,
 162             UnusedDocComment: UnusedDocComment,
 163             UnexpectedCfgs: UnexpectedCfgs,
 164         ]
 165     ]
 166 );
 167
 168 // FIXME: Make a separate lint type which does not require typeck tables.
 169
 170 late_lint_methods!(
 171     declare_combined_late_lint_pass,
 172     [
 173         pub BuiltinCombinedLateLintPass,
 174         [
 175             // Tracks state across modules
 176             UnnameableTestItems: UnnameableTestItems::new(),
 177             // Tracks attributes of parents
 178             MissingDoc: MissingDoc::new(),
 179             // Builds a global list of all impls of `Debug`.
 180             // FIXME: Turn the computation of types which implement Debug into a query
 181             // and change this to a module lint pass
 182             MissingDebugImplementations: MissingDebugImplementations::default(),
 183             // Keeps a global list of foreign declarations.
 184             ClashingExternDeclarations: ClashingExternDeclarations::new(),
 185         ]
 186     ]
 187 );
 188
 189 late_lint_methods!(
 190     declare_combined_late_lint_pass,
 191     [
 192         BuiltinCombinedModuleLateLintPass,
 193         [
 194             ForLoopsOverFallibles: ForLoopsOverFallibles,
 195             DerefIntoDynSupertrait: DerefIntoDynSupertrait,
 196             HardwiredLints: HardwiredLints,
 197             ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 198             ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 199             VariantSizeDifferences: VariantSizeDifferences,
 200             BoxPointers: BoxPointers,
 201             PathStatements: PathStatements,
 202             LetUnderscore: LetUnderscore,
 203             // Depends on referenced function signatures in expressions
 204             UnusedResults: UnusedResults,
 205             NonUpperCaseGlobals: NonUpperCaseGlobals,
 206             NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 207             UnusedAllocation: UnusedAllocation,
 208             // Depends on types used in type definitions
 209             MissingCopyImplementations: MissingCopyImplementations,
 210             // Depends on referenced function signatures in expressions
 211             MutableTransmutes: MutableTransmutes,
 212             TypeAliasBounds: TypeAliasBounds,
 213             TrivialConstraints: TrivialConstraints,
 214             TypeLimits: TypeLimits::new(),
 215             NonSnakeCase: NonSnakeCase,
 216             InvalidNoMangleItems: InvalidNoMangleItems,
 217             // Depends on effective visibilities
 218             UnreachablePub: UnreachablePub,
 219             ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 220             InvalidValue: InvalidValue,
 221             DerefNullPtr: DerefNullPtr,
 222             // May Depend on constants elsewhere
 223             UnusedBrokenConst: UnusedBrokenConst,
 224             UnstableFeatures: UnstableFeatures,
 225             UngatedAsyncFnTrackCaller: UngatedAsyncFnTrackCaller,
 226             ArrayIntoIter: ArrayIntoIter::default(),
 227             DropTraitConstraints: DropTraitConstraints,
 228             TemporaryCStringAsPtr: TemporaryCStringAsPtr,
 229             NonPanicFmt: NonPanicFmt,
 230             NoopMethodCall: NoopMethodCall,
 231             EnumIntrinsicsNonEnums: EnumIntrinsicsNonEnums,
 232             InvalidAtomicOrdering: InvalidAtomicOrdering,
 233             NamedAsmLabels: NamedAsmLabels,
 234             OpaqueHiddenInferredBound: OpaqueHiddenInferredBound,
 235         ]
 236     ]
 237 );
 238
 239 pub fn new_lint_store(internal_lints: bool) -> LintStore {
 240     let mut lint_store = LintStore::new();
 241
 242     register_builtins(&mut lint_store);
 243     if internal_lints {
 244         register_internals(&mut lint_store);
 245     }
 246
 247     lint_store
 248 }
 249
 250 /// Tell the `LintStore` about all the built-in lints (the ones
 251 /// defined in this crate and the ones defined in
 252 /// `rustc_session::lint::builtin`).
 253 fn register_builtins(store: &mut LintStore) {
 254     macro_rules! add_lint_group {
 255         ($name:expr, $($lint:ident),*) => (
 256             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 257         )
 258     }
 259
 260     store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 261     store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 262     store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 263     store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 264
 265     add_lint_group!(
 266         "nonstandard_style",
 267         NON_CAMEL_CASE_TYPES,
 268         NON_SNAKE_CASE,
 269         NON_UPPER_CASE_GLOBALS
 270     );
 271
 272     add_lint_group!(
 273         "unused",
 274         UNUSED_IMPORTS,
 275         UNUSED_VARIABLES,
 276         UNUSED_ASSIGNMENTS,
 277         DEAD_CODE,
 278         UNUSED_MUT,
 279         UNREACHABLE_CODE,
 280         UNREACHABLE_PATTERNS,
 281         UNUSED_MUST_USE,
 282         UNUSED_UNSAFE,
 283         PATH_STATEMENTS,
 284         UNUSED_ATTRIBUTES,
 285         UNUSED_MACROS,
 286         UNUSED_MACRO_RULES,
 287         UNUSED_ALLOCATION,
 288         UNUSED_DOC_COMMENTS,
 289         UNUSED_EXTERN_CRATES,
 290         UNUSED_FEATURES,
 291         UNUSED_LABELS,
 292         UNUSED_PARENS,
 293         UNUSED_BRACES,
 294         REDUNDANT_SEMICOLONS
 295     );
 296
 297     add_lint_group!("let_underscore", LET_UNDERSCORE_DROP, LET_UNDERSCORE_LOCK);
 298
 299     add_lint_group!(
 300         "rust_2018_idioms",
 301         BARE_TRAIT_OBJECTS,
 302         UNUSED_EXTERN_CRATES,
 303         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 304         ELIDED_LIFETIMES_IN_PATHS,
 305         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 306                                        // macros are ready for this yet.
 307                                        // UNREACHABLE_PUB,
 308
 309                                        // FIXME macro crates are not up for this yet, too much
 310                                        // breakage is seen if we try to encourage this lint.
 311                                        // MACRO_USE_EXTERN_CRATE
 312     );
 313
 314     // Register renamed and removed lints.
 315     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 316     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 317     store.register_renamed("bare_trait_object", "bare_trait_objects");
 318     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 319     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 320     store.register_renamed("async_idents", "keyword_idents");
 321     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 322     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 323     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
 324     store.register_renamed("safe_packed_borrows", "unaligned_references");
 325     store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
 326     store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
 327     store.register_renamed("non_fmt_panic", "non_fmt_panics");
 328
 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",
 337         "private_doc_tests",
 338         "invalid_codeblock_attributes",
 339         "invalid_html_tags",
 340         "non_autolinks",
 341     ];
 342     for rustdoc_lint in RUSTDOC_LINTS {
 343         store.register_ignored(rustdoc_lint);
 344     }
 345     store.register_removed(
 346         "intra_doc_link_resolution_failure",
 347         "use `rustdoc::broken_intra_doc_links` instead",
 348     );
 349     store.register_removed("rustdoc", "use `rustdoc::all` instead");
 350
 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",
 366     );
 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",
 371     );
 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",
 376     );
 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",
 381     );
 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",
 386     );
 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",
 391     );
 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",
 396     );
 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",
 401     );
 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",
 406     );
 407     store.register_removed(
 408         "legacy_imports",
 409         "converted into hard error, see issue #38260 \
 410          <https://github.com/rust-lang/rust/issues/38260> for more information",
 411     );
 412     store.register_removed(
 413         "coerce_never",
 414         "converted into hard error, see issue #48950 \
 415          <https://github.com/rust-lang/rust/issues/48950> for more information",
 416     );
 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",
 421     );
 422     store.register_removed(
 423         "private_no_mangle_fns",
 424         "no longer a warning, `#[no_mangle]` functions always exported",
 425     );
 426     store.register_removed(
 427         "private_no_mangle_statics",
 428         "no longer a warning, `#[no_mangle]` statics always exported",
 429     );
 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",
 435     );
 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",
 440     );
 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",
 445     );
 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",
 450     );
 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",
 455     );
 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",
 460     );
 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",
 465     );
 466     store.register_removed(
 467         "nested_impl_trait",
 468         "converted into hard error, see issue #59014 \
 469          <https://github.com/rust-lang/rust/issues/59014> for more information",
 470     );
 471     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 472     store.register_removed(
 473         "unsupported_naked_functions",
 474         "converted into hard error, see RFC 2972 \
 475          <https://github.com/rust-lang/rfcs/blob/master/text/2972-constrained-naked.md> for more information",
 476     );
 477     store.register_removed(
 478         "mutable_borrow_reservation_conflict",
 479         "now allowed, see issue #59159 \
 480          <https://github.com/rust-lang/rust/issues/59159> for more information",
 481     );
 482     store.register_removed(
 483         "const_err",
 484         "converted into hard error, see issue #71800 \
 485          <https://github.com/rust-lang/rust/issues/71800> for more information",
 486     );
 487 }
 488
 489 fn register_internals(store: &mut LintStore) {
 490     store.register_lints(&LintPassImpl::get_lints());
 491     store.register_early_pass(|| Box::new(LintPassImpl));
 492     store.register_lints(&DefaultHashTypes::get_lints());
 493     store.register_late_pass(|_| Box::new(DefaultHashTypes));
 494     store.register_lints(&QueryStability::get_lints());
 495     store.register_late_pass(|_| Box::new(QueryStability));
 496     store.register_lints(&ExistingDocKeyword::get_lints());
 497     store.register_late_pass(|_| Box::new(ExistingDocKeyword));
 498     store.register_lints(&TyTyKind::get_lints());
 499     store.register_late_pass(|_| Box::new(TyTyKind));
 500     store.register_lints(&Diagnostics::get_lints());
 501     store.register_late_pass(|_| Box::new(Diagnostics));
 502     store.register_lints(&BadOptAccess::get_lints());
 503     store.register_late_pass(|_| Box::new(BadOptAccess));
 504     store.register_lints(&PassByValue::get_lints());
 505     store.register_late_pass(|_| Box::new(PassByValue));
 506     // FIXME(davidtwco): deliberately do not include `UNTRANSLATABLE_DIAGNOSTIC` and
 507     // `DIAGNOSTIC_OUTSIDE_OF_IMPL` here because `-Wrustc::internal` is provided to every crate and
 508     // these lints will trigger all of the time - change this once migration to diagnostic structs
 509     // and translation is completed
 510     store.register_group(
 511         false,
 512         "rustc::internal",
 513         None,
 514         vec![
 515             LintId::of(DEFAULT_HASH_TYPES),
 516             LintId::of(POTENTIAL_QUERY_INSTABILITY),
 517             LintId::of(USAGE_OF_TY_TYKIND),
 518             LintId::of(PASS_BY_VALUE),
 519             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 520             LintId::of(USAGE_OF_QUALIFIED_TY),
 521             LintId::of(EXISTING_DOC_KEYWORD),
 522             LintId::of(BAD_OPT_ACCESS),
 523         ],
 524     );
 525 }
 526
 527 #[cfg(test)]
 528 mod tests;