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
  42 #[macro_use]
  43 extern crate rustc_middle;
  44 #[macro_use]
  45 extern crate rustc_session;
  46 #[macro_use]
  47 extern crate tracing;
  48
  49 mod array_into_iter;
  50 pub mod builtin;
  51 mod context;
  52 mod deref_into_dyn_supertrait;
  53 mod early;
  54 mod enum_intrinsics_non_enums;
  55 mod errors;
  56 mod expect;
  57 mod for_loops_over_fallibles;
  58 pub mod hidden_unicode_codepoints;
  59 mod internal;
  60 mod late;
  61 mod let_underscore;
  62 mod levels;
  63 mod methods;
  64 mod non_ascii_idents;
  65 mod non_fmt_panic;
  66 mod nonstandard_style;
  67 mod noop_method_call;
  68 mod opaque_hidden_inferred_bound;
  69 mod pass_by_value;
  70 mod passes;
  71 mod redundant_semicolon;
  72 mod traits;
  73 mod types;
  74 mod unused;
  75
  76 pub use array_into_iter::ARRAY_INTO_ITER;
  77
  78 use rustc_ast as ast;
  79 use rustc_hir as hir;
  80 use rustc_hir::def_id::LocalDefId;
  81 use rustc_middle::ty::query::Providers;
  82 use rustc_middle::ty::TyCtxt;
  83 use rustc_session::lint::builtin::{
  84     BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
  85 };
  86 use rustc_span::symbol::Ident;
  87 use rustc_span::Span;
  88
  89 use array_into_iter::ArrayIntoIter;
  90 use builtin::*;
  91 use deref_into_dyn_supertrait::*;
  92 use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
  93 use for_loops_over_fallibles::*;
  94 use hidden_unicode_codepoints::*;
  95 use internal::*;
  96 use let_underscore::*;
  97 use methods::*;
  98 use non_ascii_idents::*;
  99 use non_fmt_panic::NonPanicFmt;
 100 use nonstandard_style::*;
 101 use noop_method_call::*;
 102 use opaque_hidden_inferred_bound::*;
 103 use pass_by_value::*;
 104 use redundant_semicolon::*;
 105 use traits::*;
 106 use types::*;
 107 use unused::*;
 108
 109 /// Useful for other parts of the compiler / Clippy.
 110 pub use builtin::SoftLints;
 111 pub use context::{CheckLintNameResult, FindLintError, LintStore};
 112 pub use context::{EarlyContext, LateContext, LintContext};
 113 pub use early::{check_ast_node, EarlyCheckNode};
 114 pub use late::{check_crate, unerased_lint_store};
 115 pub use passes::{EarlyLintPass, LateLintPass};
 116 pub use rustc_session::lint::Level::{self, *};
 117 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
 118 pub use rustc_session::lint::{LintArray, LintPass};
 119
 120 pub fn provide(providers: &mut Providers) {
 121     levels::provide(providers);
 122     expect::provide(providers);
 123     *providers = Providers { lint_mod, ..*providers };
 124 }
 125
 126 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
 127     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
 128 }
 129
 130 early_lint_methods!(
 131     declare_combined_early_lint_pass,
 132     [
 133         pub BuiltinCombinedPreExpansionLintPass,
 134         [
 135             KeywordIdents: KeywordIdents,
 136         ]
 137     ]
 138 );
 139
 140 early_lint_methods!(
 141     declare_combined_early_lint_pass,
 142     [
 143         pub BuiltinCombinedEarlyLintPass,
 144         [
 145             UnusedParens: UnusedParens,
 146             UnusedBraces: UnusedBraces,
 147             UnusedImportBraces: UnusedImportBraces,
 148             UnsafeCode: UnsafeCode,
 149             SpecialModuleName: SpecialModuleName,
 150             AnonymousParameters: AnonymousParameters,
 151             EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 152             NonCamelCaseTypes: NonCamelCaseTypes,
 153             DeprecatedAttr: DeprecatedAttr::new(),
 154             WhileTrue: WhileTrue,
 155             NonAsciiIdents: NonAsciiIdents,
 156             HiddenUnicodeCodepoints: HiddenUnicodeCodepoints,
 157             IncompleteFeatures: IncompleteFeatures,
 158             RedundantSemicolons: RedundantSemicolons,
 159             UnusedDocComment: UnusedDocComment,
 160             UnexpectedCfgs: UnexpectedCfgs,
 161         ]
 162     ]
 163 );
 164
 165 // FIXME: Make a separate lint type which does not require typeck tables.
 166
 167 late_lint_methods!(
 168     declare_combined_late_lint_pass,
 169     [
 170         pub BuiltinCombinedLateLintPass,
 171         [
 172             // Tracks state across modules
 173             UnnameableTestItems: UnnameableTestItems::new(),
 174             // Tracks attributes of parents
 175             MissingDoc: MissingDoc::new(),
 176             // Builds a global list of all impls of `Debug`.
 177             // FIXME: Turn the computation of types which implement Debug into a query
 178             // and change this to a module lint pass
 179             MissingDebugImplementations: MissingDebugImplementations::default(),
 180             // Keeps a global list of foreign declarations.
 181             ClashingExternDeclarations: ClashingExternDeclarations::new(),
 182         ]
 183     ]
 184 );
 185
 186 late_lint_methods!(
 187     declare_combined_late_lint_pass,
 188     [
 189         BuiltinCombinedModuleLateLintPass,
 190         [
 191             ForLoopsOverFallibles: ForLoopsOverFallibles,
 192             DerefIntoDynSupertrait: DerefIntoDynSupertrait,
 193             HardwiredLints: HardwiredLints,
 194             ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 195             ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 196             VariantSizeDifferences: VariantSizeDifferences,
 197             BoxPointers: BoxPointers,
 198             PathStatements: PathStatements,
 199             LetUnderscore: LetUnderscore,
 200             // Depends on referenced function signatures in expressions
 201             UnusedResults: UnusedResults,
 202             NonUpperCaseGlobals: NonUpperCaseGlobals,
 203             NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 204             UnusedAllocation: UnusedAllocation,
 205             // Depends on types used in type definitions
 206             MissingCopyImplementations: MissingCopyImplementations,
 207             // Depends on referenced function signatures in expressions
 208             MutableTransmutes: MutableTransmutes,
 209             TypeAliasBounds: TypeAliasBounds,
 210             TrivialConstraints: TrivialConstraints,
 211             TypeLimits: TypeLimits::new(),
 212             NonSnakeCase: NonSnakeCase,
 213             InvalidNoMangleItems: InvalidNoMangleItems,
 214             // Depends on effective visibilities
 215             UnreachablePub: UnreachablePub,
 216             ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 217             InvalidValue: InvalidValue,
 218             DerefNullPtr: DerefNullPtr,
 219             // May Depend on constants elsewhere
 220             UnusedBrokenConst: UnusedBrokenConst,
 221             UnstableFeatures: UnstableFeatures,
 222             ArrayIntoIter: ArrayIntoIter::default(),
 223             DropTraitConstraints: DropTraitConstraints,
 224             TemporaryCStringAsPtr: TemporaryCStringAsPtr,
 225             NonPanicFmt: NonPanicFmt,
 226             NoopMethodCall: NoopMethodCall,
 227             EnumIntrinsicsNonEnums: EnumIntrinsicsNonEnums,
 228             InvalidAtomicOrdering: InvalidAtomicOrdering,
 229             NamedAsmLabels: NamedAsmLabels,
 230             OpaqueHiddenInferredBound: OpaqueHiddenInferredBound,
 231         ]
 232     ]
 233 );
 234
 235 pub fn new_lint_store(internal_lints: bool) -> LintStore {
 236     let mut lint_store = LintStore::new();
 237
 238     register_builtins(&mut lint_store);
 239     if internal_lints {
 240         register_internals(&mut lint_store);
 241     }
 242
 243     lint_store
 244 }
 245
 246 /// Tell the `LintStore` about all the built-in lints (the ones
 247 /// defined in this crate and the ones defined in
 248 /// `rustc_session::lint::builtin`).
 249 fn register_builtins(store: &mut LintStore) {
 250     macro_rules! add_lint_group {
 251         ($name:expr, $($lint:ident),*) => (
 252             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 253         )
 254     }
 255
 256     store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 257     store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 258     store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 259     store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 260
 261     add_lint_group!(
 262         "nonstandard_style",
 263         NON_CAMEL_CASE_TYPES,
 264         NON_SNAKE_CASE,
 265         NON_UPPER_CASE_GLOBALS
 266     );
 267
 268     add_lint_group!(
 269         "unused",
 270         UNUSED_IMPORTS,
 271         UNUSED_VARIABLES,
 272         UNUSED_ASSIGNMENTS,
 273         DEAD_CODE,
 274         UNUSED_MUT,
 275         UNREACHABLE_CODE,
 276         UNREACHABLE_PATTERNS,
 277         UNUSED_MUST_USE,
 278         UNUSED_UNSAFE,
 279         PATH_STATEMENTS,
 280         UNUSED_ATTRIBUTES,
 281         UNUSED_MACROS,
 282         UNUSED_MACRO_RULES,
 283         UNUSED_ALLOCATION,
 284         UNUSED_DOC_COMMENTS,
 285         UNUSED_EXTERN_CRATES,
 286         UNUSED_FEATURES,
 287         UNUSED_LABELS,
 288         UNUSED_PARENS,
 289         UNUSED_BRACES,
 290         REDUNDANT_SEMICOLONS
 291     );
 292
 293     add_lint_group!("let_underscore", LET_UNDERSCORE_DROP, LET_UNDERSCORE_LOCK);
 294
 295     add_lint_group!(
 296         "rust_2018_idioms",
 297         BARE_TRAIT_OBJECTS,
 298         UNUSED_EXTERN_CRATES,
 299         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 300         ELIDED_LIFETIMES_IN_PATHS,
 301         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 302                                        // macros are ready for this yet.
 303                                        // UNREACHABLE_PUB,
 304
 305                                        // FIXME macro crates are not up for this yet, too much
 306                                        // breakage is seen if we try to encourage this lint.
 307                                        // MACRO_USE_EXTERN_CRATE
 308     );
 309
 310     // Register renamed and removed lints.
 311     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 312     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 313     store.register_renamed("bare_trait_object", "bare_trait_objects");
 314     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 315     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 316     store.register_renamed("async_idents", "keyword_idents");
 317     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 318     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 319     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
 320     store.register_renamed("safe_packed_borrows", "unaligned_references");
 321     store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
 322     store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
 323     store.register_renamed("non_fmt_panic", "non_fmt_panics");
 324
 325     // These were moved to tool lints, but rustc still sees them when compiling normally, before
 326     // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
 327     // `register_removed` explicitly.
 328     const RUSTDOC_LINTS: &[&str] = &[
 329         "broken_intra_doc_links",
 330         "private_intra_doc_links",
 331         "missing_crate_level_docs",
 332         "missing_doc_code_examples",
 333         "private_doc_tests",
 334         "invalid_codeblock_attributes",
 335         "invalid_html_tags",
 336         "non_autolinks",
 337     ];
 338     for rustdoc_lint in RUSTDOC_LINTS {
 339         store.register_ignored(rustdoc_lint);
 340     }
 341     store.register_removed(
 342         "intra_doc_link_resolution_failure",
 343         "use `rustdoc::broken_intra_doc_links` instead",
 344     );
 345     store.register_removed("rustdoc", "use `rustdoc::all` instead");
 346
 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",
 362     );
 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",
 367     );
 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",
 372     );
 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",
 377     );
 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",
 382     );
 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",
 387     );
 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",
 392     );
 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",
 397     );
 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",
 402     );
 403     store.register_removed(
 404         "legacy_imports",
 405         "converted into hard error, see issue #38260 \
 406          <https://github.com/rust-lang/rust/issues/38260> for more information",
 407     );
 408     store.register_removed(
 409         "coerce_never",
 410         "converted into hard error, see issue #48950 \
 411          <https://github.com/rust-lang/rust/issues/48950> for more information",
 412     );
 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",
 417     );
 418     store.register_removed(
 419         "private_no_mangle_fns",
 420         "no longer a warning, `#[no_mangle]` functions always exported",
 421     );
 422     store.register_removed(
 423         "private_no_mangle_statics",
 424         "no longer a warning, `#[no_mangle]` statics always exported",
 425     );
 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",
 431     );
 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",
 436     );
 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",
 441     );
 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",
 446     );
 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",
 451     );
 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",
 456     );
 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",
 461     );
 462     store.register_removed(
 463         "nested_impl_trait",
 464         "converted into hard error, see issue #59014 \
 465          <https://github.com/rust-lang/rust/issues/59014> for more information",
 466     );
 467     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 468     store.register_removed(
 469         "unsupported_naked_functions",
 470         "converted into hard error, see RFC 2972 \
 471          <https://github.com/rust-lang/rfcs/blob/master/text/2972-constrained-naked.md> for more information",
 472     );
 473     store.register_removed(
 474         "mutable_borrow_reservation_conflict",
 475         "now allowed, see issue #59159 \
 476          <https://github.com/rust-lang/rust/issues/59159> for more information",
 477     );
 478     store.register_removed(
 479         "const_err",
 480         "converted into hard error, see issue #71800 \
 481          <https://github.com/rust-lang/rust/issues/71800> for more information",
 482     );
 483 }
 484
 485 fn register_internals(store: &mut LintStore) {
 486     store.register_lints(&LintPassImpl::get_lints());
 487     store.register_early_pass(|| Box::new(LintPassImpl));
 488     store.register_lints(&DefaultHashTypes::get_lints());
 489     store.register_late_pass(|_| Box::new(DefaultHashTypes));
 490     store.register_lints(&QueryStability::get_lints());
 491     store.register_late_pass(|_| Box::new(QueryStability));
 492     store.register_lints(&ExistingDocKeyword::get_lints());
 493     store.register_late_pass(|_| Box::new(ExistingDocKeyword));
 494     store.register_lints(&TyTyKind::get_lints());
 495     store.register_late_pass(|_| Box::new(TyTyKind));
 496     store.register_lints(&Diagnostics::get_lints());
 497     store.register_late_pass(|_| Box::new(Diagnostics));
 498     store.register_lints(&BadOptAccess::get_lints());
 499     store.register_late_pass(|_| Box::new(BadOptAccess));
 500     store.register_lints(&PassByValue::get_lints());
 501     store.register_late_pass(|_| Box::new(PassByValue));
 502     // FIXME(davidtwco): deliberately do not include `UNTRANSLATABLE_DIAGNOSTIC` and
 503     // `DIAGNOSTIC_OUTSIDE_OF_IMPL` here because `-Wrustc::internal` is provided to every crate and
 504     // these lints will trigger all of the time - change this once migration to diagnostic structs
 505     // and translation is completed
 506     store.register_group(
 507         false,
 508         "rustc::internal",
 509         None,
 510         vec![
 511             LintId::of(DEFAULT_HASH_TYPES),
 512             LintId::of(POTENTIAL_QUERY_INSTABILITY),
 513             LintId::of(USAGE_OF_TY_TYKIND),
 514             LintId::of(PASS_BY_VALUE),
 515             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 516             LintId::of(USAGE_OF_QUALIFIED_TY),
 517             LintId::of(EXISTING_DOC_KEYWORD),
 518             LintId::of(BAD_OPT_ACCESS),
 519         ],
 520     );
 521 }
 522
 523 #[cfg(test)]
 524 mod tests;