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 multiple_supertrait_upcastable;
  68 mod non_ascii_idents;
  69 mod non_fmt_panic;
  70 mod nonstandard_style;
  71 mod noop_method_call;
  72 mod opaque_hidden_inferred_bound;
  73 mod pass_by_value;
  74 mod passes;
  75 mod redundant_semicolon;
  76 mod traits;
  77 mod types;
  78 mod unused;
  79
  80 pub use array_into_iter::ARRAY_INTO_ITER;
  81
  82 use rustc_ast as ast;
  83 use rustc_hir as hir;
  84 use rustc_hir::def_id::LocalDefId;
  85 use rustc_middle::ty::query::Providers;
  86 use rustc_middle::ty::TyCtxt;
  87 use rustc_session::lint::builtin::{
  88     BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
  89 };
  90 use rustc_span::symbol::Ident;
  91 use rustc_span::Span;
  92
  93 use array_into_iter::ArrayIntoIter;
  94 use builtin::*;
  95 use deref_into_dyn_supertrait::*;
  96 use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
  97 use for_loops_over_fallibles::*;
  98 use hidden_unicode_codepoints::*;
  99 use internal::*;
 100 use let_underscore::*;
 101 use methods::*;
 102 use multiple_supertrait_upcastable::*;
 103 use non_ascii_idents::*;
 104 use non_fmt_panic::NonPanicFmt;
 105 use nonstandard_style::*;
 106 use noop_method_call::*;
 107 use opaque_hidden_inferred_bound::*;
 108 use pass_by_value::*;
 109 use redundant_semicolon::*;
 110 use traits::*;
 111 use types::*;
 112 use unused::*;
 113
 114 /// Useful for other parts of the compiler / Clippy.
 115 pub use builtin::SoftLints;
 116 pub use context::{CheckLintNameResult, FindLintError, LintStore};
 117 pub use context::{EarlyContext, LateContext, LintContext};
 118 pub use early::{check_ast_node, EarlyCheckNode};
 119 pub use late::{check_crate, unerased_lint_store};
 120 pub use passes::{EarlyLintPass, LateLintPass};
 121 pub use rustc_session::lint::Level::{self, *};
 122 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
 123 pub use rustc_session::lint::{LintArray, LintPass};
 124
 125 pub fn provide(providers: &mut Providers) {
 126     levels::provide(providers);
 127     expect::provide(providers);
 128     *providers = Providers { lint_mod, ..*providers };
 129 }
 130
 131 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
 132     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
 133 }
 134
 135 early_lint_methods!(
 136     declare_combined_early_lint_pass,
 137     [
 138         pub BuiltinCombinedPreExpansionLintPass,
 139         [
 140             KeywordIdents: KeywordIdents,
 141         ]
 142     ]
 143 );
 144
 145 early_lint_methods!(
 146     declare_combined_early_lint_pass,
 147     [
 148         pub BuiltinCombinedEarlyLintPass,
 149         [
 150             UnusedParens: UnusedParens::new(),
 151             UnusedBraces: UnusedBraces,
 152             UnusedImportBraces: UnusedImportBraces,
 153             UnsafeCode: UnsafeCode,
 154             SpecialModuleName: SpecialModuleName,
 155             AnonymousParameters: AnonymousParameters,
 156             EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 157             NonCamelCaseTypes: NonCamelCaseTypes,
 158             DeprecatedAttr: DeprecatedAttr::new(),
 159             WhileTrue: WhileTrue,
 160             NonAsciiIdents: NonAsciiIdents,
 161             HiddenUnicodeCodepoints: HiddenUnicodeCodepoints,
 162             IncompleteFeatures: IncompleteFeatures,
 163             RedundantSemicolons: RedundantSemicolons,
 164             UnusedDocComment: UnusedDocComment,
 165             UnexpectedCfgs: UnexpectedCfgs,
 166         ]
 167     ]
 168 );
 169
 170 // FIXME: Make a separate lint type which does not require typeck tables.
 171
 172 late_lint_methods!(
 173     declare_combined_late_lint_pass,
 174     [
 175         pub BuiltinCombinedLateLintPass,
 176         [
 177             // Tracks state across modules
 178             UnnameableTestItems: UnnameableTestItems::new(),
 179             // Tracks attributes of parents
 180             MissingDoc: MissingDoc::new(),
 181             // Builds a global list of all impls of `Debug`.
 182             // FIXME: Turn the computation of types which implement Debug into a query
 183             // and change this to a module lint pass
 184             MissingDebugImplementations: MissingDebugImplementations::default(),
 185             // Keeps a global list of foreign declarations.
 186             ClashingExternDeclarations: ClashingExternDeclarations::new(),
 187         ]
 188     ]
 189 );
 190
 191 late_lint_methods!(
 192     declare_combined_late_lint_pass,
 193     [
 194         BuiltinCombinedModuleLateLintPass,
 195         [
 196             ForLoopsOverFallibles: ForLoopsOverFallibles,
 197             DerefIntoDynSupertrait: DerefIntoDynSupertrait,
 198             HardwiredLints: HardwiredLints,
 199             ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 200             ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 201             VariantSizeDifferences: VariantSizeDifferences,
 202             BoxPointers: BoxPointers,
 203             PathStatements: PathStatements,
 204             LetUnderscore: LetUnderscore,
 205             // Depends on referenced function signatures in expressions
 206             UnusedResults: UnusedResults,
 207             NonUpperCaseGlobals: NonUpperCaseGlobals,
 208             NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 209             UnusedAllocation: UnusedAllocation,
 210             // Depends on types used in type definitions
 211             MissingCopyImplementations: MissingCopyImplementations,
 212             // Depends on referenced function signatures in expressions
 213             MutableTransmutes: MutableTransmutes,
 214             TypeAliasBounds: TypeAliasBounds,
 215             TrivialConstraints: TrivialConstraints,
 216             TypeLimits: TypeLimits::new(),
 217             NonSnakeCase: NonSnakeCase,
 218             InvalidNoMangleItems: InvalidNoMangleItems,
 219             // Depends on effective visibilities
 220             UnreachablePub: UnreachablePub,
 221             ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 222             InvalidValue: InvalidValue,
 223             DerefNullPtr: DerefNullPtr,
 224             // May Depend on constants elsewhere
 225             UnusedBrokenConst: UnusedBrokenConst,
 226             UnstableFeatures: UnstableFeatures,
 227             UngatedAsyncFnTrackCaller: UngatedAsyncFnTrackCaller,
 228             ArrayIntoIter: ArrayIntoIter::default(),
 229             DropTraitConstraints: DropTraitConstraints,
 230             TemporaryCStringAsPtr: TemporaryCStringAsPtr,
 231             NonPanicFmt: NonPanicFmt,
 232             NoopMethodCall: NoopMethodCall,
 233             EnumIntrinsicsNonEnums: EnumIntrinsicsNonEnums,
 234             InvalidAtomicOrdering: InvalidAtomicOrdering,
 235             NamedAsmLabels: NamedAsmLabels,
 236             OpaqueHiddenInferredBound: OpaqueHiddenInferredBound,
 237             MultipleSupertraitUpcastable: MultipleSupertraitUpcastable,
 238         ]
 239     ]
 240 );
 241
 242 pub fn new_lint_store(internal_lints: bool) -> LintStore {
 243     let mut lint_store = LintStore::new();
 244
 245     register_builtins(&mut lint_store);
 246     if internal_lints {
 247         register_internals(&mut lint_store);
 248     }
 249
 250     lint_store
 251 }
 252
 253 /// Tell the `LintStore` about all the built-in lints (the ones
 254 /// defined in this crate and the ones defined in
 255 /// `rustc_session::lint::builtin`).
 256 fn register_builtins(store: &mut LintStore) {
 257     macro_rules! add_lint_group {
 258         ($name:expr, $($lint:ident),*) => (
 259             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 260         )
 261     }
 262
 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());
 267
 268     add_lint_group!(
 269         "nonstandard_style",
 270         NON_CAMEL_CASE_TYPES,
 271         NON_SNAKE_CASE,
 272         NON_UPPER_CASE_GLOBALS
 273     );
 274
 275     add_lint_group!(
 276         "unused",
 277         UNUSED_IMPORTS,
 278         UNUSED_VARIABLES,
 279         UNUSED_ASSIGNMENTS,
 280         DEAD_CODE,
 281         UNUSED_MUT,
 282         UNREACHABLE_CODE,
 283         UNREACHABLE_PATTERNS,
 284         UNUSED_MUST_USE,
 285         UNUSED_UNSAFE,
 286         PATH_STATEMENTS,
 287         UNUSED_ATTRIBUTES,
 288         UNUSED_MACROS,
 289         UNUSED_MACRO_RULES,
 290         UNUSED_ALLOCATION,
 291         UNUSED_DOC_COMMENTS,
 292         UNUSED_EXTERN_CRATES,
 293         UNUSED_FEATURES,
 294         UNUSED_LABELS,
 295         UNUSED_PARENS,
 296         UNUSED_BRACES,
 297         REDUNDANT_SEMICOLONS
 298     );
 299
 300     add_lint_group!("let_underscore", LET_UNDERSCORE_DROP, LET_UNDERSCORE_LOCK);
 301
 302     add_lint_group!(
 303         "rust_2018_idioms",
 304         BARE_TRAIT_OBJECTS,
 305         UNUSED_EXTERN_CRATES,
 306         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 307         ELIDED_LIFETIMES_IN_PATHS,
 308         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 309                                        // macros are ready for this yet.
 310                                        // UNREACHABLE_PUB,
 311
 312                                        // FIXME macro crates are not up for this yet, too much
 313                                        // breakage is seen if we try to encourage this lint.
 314                                        // MACRO_USE_EXTERN_CRATE
 315     );
 316
 317     // Register renamed and removed lints.
 318     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 319     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 320     store.register_renamed("bare_trait_object", "bare_trait_objects");
 321     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 322     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 323     store.register_renamed("async_idents", "keyword_idents");
 324     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 325     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 326     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
 327     store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
 328     store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
 329     store.register_renamed("non_fmt_panic", "non_fmt_panics");
 330
 331     // These were moved to tool lints, but rustc still sees them when compiling normally, before
 332     // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
 333     // `register_removed` explicitly.
 334     const RUSTDOC_LINTS: &[&str] = &[
 335         "broken_intra_doc_links",
 336         "private_intra_doc_links",
 337         "missing_crate_level_docs",
 338         "missing_doc_code_examples",
 339         "private_doc_tests",
 340         "invalid_codeblock_attributes",
 341         "invalid_html_tags",
 342         "non_autolinks",
 343     ];
 344     for rustdoc_lint in RUSTDOC_LINTS {
 345         store.register_ignored(rustdoc_lint);
 346     }
 347     store.register_removed(
 348         "intra_doc_link_resolution_failure",
 349         "use `rustdoc::broken_intra_doc_links` instead",
 350     );
 351     store.register_removed("rustdoc", "use `rustdoc::all` instead");
 352
 353     store.register_removed("unknown_features", "replaced by an error");
 354     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 355     store.register_removed("negate_unsigned", "cast a signed value instead");
 356     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 357     // Register lint group aliases.
 358     store.register_group_alias("nonstandard_style", "bad_style");
 359     // This was renamed to `raw_pointer_derive`, which was then removed,
 360     // so it is also considered removed.
 361     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 362     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 363     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 364     store.register_removed("deprecated_attr", "use `deprecated` instead");
 365     store.register_removed(
 366         "transmute_from_fn_item_types",
 367         "always cast functions before transmuting them",
 368     );
 369     store.register_removed(
 370         "hr_lifetime_in_assoc_type",
 371         "converted into hard error, see issue #33685 \
 372          <https://github.com/rust-lang/rust/issues/33685> for more information",
 373     );
 374     store.register_removed(
 375         "inaccessible_extern_crate",
 376         "converted into hard error, see issue #36886 \
 377          <https://github.com/rust-lang/rust/issues/36886> for more information",
 378     );
 379     store.register_removed(
 380         "super_or_self_in_global_path",
 381         "converted into hard error, see issue #36888 \
 382          <https://github.com/rust-lang/rust/issues/36888> for more information",
 383     );
 384     store.register_removed(
 385         "overlapping_inherent_impls",
 386         "converted into hard error, see issue #36889 \
 387          <https://github.com/rust-lang/rust/issues/36889> for more information",
 388     );
 389     store.register_removed(
 390         "illegal_floating_point_constant_pattern",
 391         "converted into hard error, see issue #36890 \
 392          <https://github.com/rust-lang/rust/issues/36890> for more information",
 393     );
 394     store.register_removed(
 395         "illegal_struct_or_enum_constant_pattern",
 396         "converted into hard error, see issue #36891 \
 397          <https://github.com/rust-lang/rust/issues/36891> for more information",
 398     );
 399     store.register_removed(
 400         "lifetime_underscore",
 401         "converted into hard error, see issue #36892 \
 402          <https://github.com/rust-lang/rust/issues/36892> for more information",
 403     );
 404     store.register_removed(
 405         "extra_requirement_in_impl",
 406         "converted into hard error, see issue #37166 \
 407          <https://github.com/rust-lang/rust/issues/37166> for more information",
 408     );
 409     store.register_removed(
 410         "legacy_imports",
 411         "converted into hard error, see issue #38260 \
 412          <https://github.com/rust-lang/rust/issues/38260> for more information",
 413     );
 414     store.register_removed(
 415         "coerce_never",
 416         "converted into hard error, see issue #48950 \
 417          <https://github.com/rust-lang/rust/issues/48950> for more information",
 418     );
 419     store.register_removed(
 420         "resolve_trait_on_defaulted_unit",
 421         "converted into hard error, see issue #48950 \
 422          <https://github.com/rust-lang/rust/issues/48950> for more information",
 423     );
 424     store.register_removed(
 425         "private_no_mangle_fns",
 426         "no longer a warning, `#[no_mangle]` functions always exported",
 427     );
 428     store.register_removed(
 429         "private_no_mangle_statics",
 430         "no longer a warning, `#[no_mangle]` statics always exported",
 431     );
 432     store.register_removed("bad_repr", "replaced with a generic attribute input check");
 433     store.register_removed(
 434         "duplicate_matcher_binding_name",
 435         "converted into hard error, see issue #57742 \
 436          <https://github.com/rust-lang/rust/issues/57742> for more information",
 437     );
 438     store.register_removed(
 439         "incoherent_fundamental_impls",
 440         "converted into hard error, see issue #46205 \
 441          <https://github.com/rust-lang/rust/issues/46205> for more information",
 442     );
 443     store.register_removed(
 444         "legacy_constructor_visibility",
 445         "converted into hard error, see issue #39207 \
 446          <https://github.com/rust-lang/rust/issues/39207> for more information",
 447     );
 448     store.register_removed(
 449         "legacy_directory_ownership",
 450         "converted into hard error, see issue #37872 \
 451          <https://github.com/rust-lang/rust/issues/37872> for more information",
 452     );
 453     store.register_removed(
 454         "safe_extern_statics",
 455         "converted into hard error, see issue #36247 \
 456          <https://github.com/rust-lang/rust/issues/36247> for more information",
 457     );
 458     store.register_removed(
 459         "parenthesized_params_in_types_and_modules",
 460         "converted into hard error, see issue #42238 \
 461          <https://github.com/rust-lang/rust/issues/42238> for more information",
 462     );
 463     store.register_removed(
 464         "duplicate_macro_exports",
 465         "converted into hard error, see issue #35896 \
 466          <https://github.com/rust-lang/rust/issues/35896> for more information",
 467     );
 468     store.register_removed(
 469         "nested_impl_trait",
 470         "converted into hard error, see issue #59014 \
 471          <https://github.com/rust-lang/rust/issues/59014> for more information",
 472     );
 473     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 474     store.register_removed(
 475         "unsupported_naked_functions",
 476         "converted into hard error, see RFC 2972 \
 477          <https://github.com/rust-lang/rfcs/blob/master/text/2972-constrained-naked.md> for more information",
 478     );
 479     store.register_removed(
 480         "mutable_borrow_reservation_conflict",
 481         "now allowed, see issue #59159 \
 482          <https://github.com/rust-lang/rust/issues/59159> for more information",
 483     );
 484     store.register_removed(
 485         "const_err",
 486         "converted into hard error, see issue #71800 \
 487          <https://github.com/rust-lang/rust/issues/71800> for more information",
 488     );
 489     store.register_removed(
 490         "safe_packed_borrows",
 491         "converted into hard error, see issue #82523 \
 492          <https://github.com/rust-lang/rust/issues/82523> for more information",
 493     );
 494     store.register_removed(
 495         "unaligned_references",
 496         "converted into hard error, see issue #82523 \
 497          <https://github.com/rust-lang/rust/issues/82523> for more information",
 498     );
 499 }
 500
 501 fn register_internals(store: &mut LintStore) {
 502     store.register_lints(&LintPassImpl::get_lints());
 503     store.register_early_pass(|| Box::new(LintPassImpl));
 504     store.register_lints(&DefaultHashTypes::get_lints());
 505     store.register_late_pass(|_| Box::new(DefaultHashTypes));
 506     store.register_lints(&QueryStability::get_lints());
 507     store.register_late_pass(|_| Box::new(QueryStability));
 508     store.register_lints(&ExistingDocKeyword::get_lints());
 509     store.register_late_pass(|_| Box::new(ExistingDocKeyword));
 510     store.register_lints(&TyTyKind::get_lints());
 511     store.register_late_pass(|_| Box::new(TyTyKind));
 512     store.register_lints(&Diagnostics::get_lints());
 513     store.register_late_pass(|_| Box::new(Diagnostics));
 514     store.register_lints(&BadOptAccess::get_lints());
 515     store.register_late_pass(|_| Box::new(BadOptAccess));
 516     store.register_lints(&PassByValue::get_lints());
 517     store.register_late_pass(|_| Box::new(PassByValue));
 518     // FIXME(davidtwco): deliberately do not include `UNTRANSLATABLE_DIAGNOSTIC` and
 519     // `DIAGNOSTIC_OUTSIDE_OF_IMPL` here because `-Wrustc::internal` is provided to every crate and
 520     // these lints will trigger all of the time - change this once migration to diagnostic structs
 521     // and translation is completed
 522     store.register_group(
 523         false,
 524         "rustc::internal",
 525         None,
 526         vec![
 527             LintId::of(DEFAULT_HASH_TYPES),
 528             LintId::of(POTENTIAL_QUERY_INSTABILITY),
 529             LintId::of(USAGE_OF_TY_TYKIND),
 530             LintId::of(PASS_BY_VALUE),
 531             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 532             LintId::of(USAGE_OF_QUALIFIED_TY),
 533             LintId::of(EXISTING_DOC_KEYWORD),
 534             LintId::of(BAD_OPT_ACCESS),
 535         ],
 536     );
 537 }
 538
 539 #[cfg(test)]
 540 mod tests;