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(let_else)]
  38 #![feature(never_type)]
  39 #![recursion_limit = "256"]
  40
  41 #[macro_use]
  42 extern crate rustc_middle;
  43 #[macro_use]
  44 extern crate rustc_session;
  45 #[macro_use]
  46 extern crate tracing;
  47
  48 mod array_into_iter;
  49 pub mod builtin;
  50 mod context;
  51 mod early;
  52 mod enum_intrinsics_non_enums;
  53 mod errors;
  54 mod expect;
  55 pub mod hidden_unicode_codepoints;
  56 mod internal;
  57 mod late;
  58 mod let_underscore;
  59 mod levels;
  60 mod methods;
  61 mod non_ascii_idents;
  62 mod non_fmt_panic;
  63 mod nonstandard_style;
  64 mod noop_method_call;
  65 mod pass_by_value;
  66 mod passes;
  67 mod redundant_semicolon;
  68 mod traits;
  69 mod types;
  70 mod unused;
  71
  72 pub use array_into_iter::ARRAY_INTO_ITER;
  73
  74 use rustc_ast as ast;
  75 use rustc_hir as hir;
  76 use rustc_hir::def_id::LocalDefId;
  77 use rustc_middle::ty::query::Providers;
  78 use rustc_middle::ty::TyCtxt;
  79 use rustc_session::lint::builtin::{
  80     BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
  81 };
  82 use rustc_span::symbol::Ident;
  83 use rustc_span::Span;
  84
  85 use array_into_iter::ArrayIntoIter;
  86 use builtin::*;
  87 use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
  88 use hidden_unicode_codepoints::*;
  89 use internal::*;
  90 use let_underscore::*;
  91 use methods::*;
  92 use non_ascii_idents::*;
  93 use non_fmt_panic::NonPanicFmt;
  94 use nonstandard_style::*;
  95 use noop_method_call::*;
  96 use pass_by_value::*;
  97 use redundant_semicolon::*;
  98 use traits::*;
  99 use types::*;
 100 use unused::*;
 101
 102 /// Useful for other parts of the compiler / Clippy.
 103 pub use builtin::SoftLints;
 104 pub use context::{CheckLintNameResult, FindLintError, LintStore};
 105 pub use context::{EarlyContext, LateContext, LintContext};
 106 pub use early::{check_ast_node, EarlyCheckNode};
 107 pub use late::{check_crate, unerased_lint_store};
 108 pub use passes::{EarlyLintPass, LateLintPass};
 109 pub use rustc_session::lint::Level::{self, *};
 110 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
 111 pub use rustc_session::lint::{LintArray, LintPass};
 112
 113 pub fn provide(providers: &mut Providers) {
 114     levels::provide(providers);
 115     expect::provide(providers);
 116     *providers = Providers { lint_mod, ..*providers };
 117 }
 118
 119 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
 120     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
 121 }
 122
 123 macro_rules! pre_expansion_lint_passes {
 124     ($macro:path, $args:tt) => {
 125         $macro!($args, [KeywordIdents: KeywordIdents,]);
 126     };
 127 }
 128
 129 macro_rules! early_lint_passes {
 130     ($macro:path, $args:tt) => {
 131         $macro!(
 132             $args,
 133             [
 134                 UnusedParens: UnusedParens,
 135                 UnusedBraces: UnusedBraces,
 136                 UnusedImportBraces: UnusedImportBraces,
 137                 UnsafeCode: UnsafeCode,
 138                 SpecialModuleName: SpecialModuleName,
 139                 AnonymousParameters: AnonymousParameters,
 140                 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 141                 NonCamelCaseTypes: NonCamelCaseTypes,
 142                 DeprecatedAttr: DeprecatedAttr::new(),
 143                 WhileTrue: WhileTrue,
 144                 NonAsciiIdents: NonAsciiIdents,
 145                 HiddenUnicodeCodepoints: HiddenUnicodeCodepoints,
 146                 IncompleteFeatures: IncompleteFeatures,
 147                 RedundantSemicolons: RedundantSemicolons,
 148                 UnusedDocComment: UnusedDocComment,
 149             ]
 150         );
 151     };
 152 }
 153
 154 macro_rules! declare_combined_early_pass {
 155     ([$name:ident], $passes:tt) => (
 156         early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
 157     )
 158 }
 159
 160 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
 161 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
 162
 163 macro_rules! late_lint_passes {
 164     ($macro:path, $args:tt) => {
 165         $macro!(
 166             $args,
 167             [
 168                 // Tracks state across modules
 169                 UnnameableTestItems: UnnameableTestItems::new(),
 170                 // Tracks attributes of parents
 171                 MissingDoc: MissingDoc::new(),
 172                 // Builds a global list of all impls of `Debug`.
 173                 // FIXME: Turn the computation of types which implement Debug into a query
 174                 // and change this to a module lint pass
 175                 MissingDebugImplementations: MissingDebugImplementations::default(),
 176                 // Keeps a global list of foreign declarations.
 177                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
 178             ]
 179         );
 180     };
 181 }
 182
 183 macro_rules! late_lint_mod_passes {
 184     ($macro:path, $args:tt) => {
 185         $macro!(
 186             $args,
 187             [
 188                 HardwiredLints: HardwiredLints,
 189                 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 190                 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 191                 VariantSizeDifferences: VariantSizeDifferences,
 192                 BoxPointers: BoxPointers,
 193                 PathStatements: PathStatements,
 194                 LetUnderscore: LetUnderscore,
 195                 // Depends on referenced function signatures in expressions
 196                 UnusedResults: UnusedResults,
 197                 NonUpperCaseGlobals: NonUpperCaseGlobals,
 198                 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 199                 UnusedAllocation: UnusedAllocation,
 200                 // Depends on types used in type definitions
 201                 MissingCopyImplementations: MissingCopyImplementations,
 202                 // Depends on referenced function signatures in expressions
 203                 MutableTransmutes: MutableTransmutes,
 204                 TypeAliasBounds: TypeAliasBounds,
 205                 TrivialConstraints: TrivialConstraints,
 206                 TypeLimits: TypeLimits::new(),
 207                 NonSnakeCase: NonSnakeCase,
 208                 InvalidNoMangleItems: InvalidNoMangleItems,
 209                 // Depends on access levels
 210                 UnreachablePub: UnreachablePub,
 211                 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 212                 InvalidValue: InvalidValue,
 213                 DerefNullPtr: DerefNullPtr,
 214                 // May Depend on constants elsewhere
 215                 UnusedBrokenConst: UnusedBrokenConst,
 216                 UnstableFeatures: UnstableFeatures,
 217                 ArrayIntoIter: ArrayIntoIter::default(),
 218                 DropTraitConstraints: DropTraitConstraints,
 219                 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
 220                 NonPanicFmt: NonPanicFmt,
 221                 NoopMethodCall: NoopMethodCall,
 222                 EnumIntrinsicsNonEnums: EnumIntrinsicsNonEnums,
 223                 InvalidAtomicOrdering: InvalidAtomicOrdering,
 224                 NamedAsmLabels: NamedAsmLabels,
 225             ]
 226         );
 227     };
 228 }
 229
 230 macro_rules! declare_combined_late_pass {
 231     ([$v:vis $name:ident], $passes:tt) => (
 232         late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
 233     )
 234 }
 235
 236 // FIXME: Make a separate lint type which do not require typeck tables
 237 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
 238
 239 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
 240
 241 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
 242     let mut lint_store = LintStore::new();
 243
 244     register_builtins(&mut lint_store, no_interleave_lints);
 245     if internal_lints {
 246         register_internals(&mut lint_store);
 247     }
 248
 249     lint_store
 250 }
 251
 252 /// Tell the `LintStore` about all the built-in lints (the ones
 253 /// defined in this crate and the ones defined in
 254 /// `rustc_session::lint::builtin`).
 255 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
 256     macro_rules! add_lint_group {
 257         ($name:expr, $($lint:ident),*) => (
 258             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 259         )
 260     }
 261
 262     macro_rules! register_pass {
 263         ($method:ident, $ty:ident, $constructor:expr) => {
 264             store.register_lints(&$ty::get_lints());
 265             store.$method(|| Box::new($constructor));
 266         };
 267     }
 268
 269     macro_rules! register_passes {
 270         ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
 271             $(
 272                 register_pass!($method, $passes, $constructor);
 273             )*
 274         )
 275     }
 276
 277     if no_interleave_lints {
 278         pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
 279         early_lint_passes!(register_passes, register_early_pass);
 280         late_lint_passes!(register_passes, register_late_pass);
 281         late_lint_mod_passes!(register_passes, register_late_mod_pass);
 282     } else {
 283         store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 284         store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 285         store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 286         store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 287     }
 288
 289     add_lint_group!(
 290         "nonstandard_style",
 291         NON_CAMEL_CASE_TYPES,
 292         NON_SNAKE_CASE,
 293         NON_UPPER_CASE_GLOBALS
 294     );
 295
 296     add_lint_group!(
 297         "unused",
 298         UNUSED_IMPORTS,
 299         UNUSED_VARIABLES,
 300         UNUSED_ASSIGNMENTS,
 301         DEAD_CODE,
 302         UNUSED_MUT,
 303         UNREACHABLE_CODE,
 304         UNREACHABLE_PATTERNS,
 305         UNUSED_MUST_USE,
 306         UNUSED_UNSAFE,
 307         PATH_STATEMENTS,
 308         UNUSED_ATTRIBUTES,
 309         UNUSED_MACROS,
 310         UNUSED_MACRO_RULES,
 311         UNUSED_ALLOCATION,
 312         UNUSED_DOC_COMMENTS,
 313         UNUSED_EXTERN_CRATES,
 314         UNUSED_FEATURES,
 315         UNUSED_LABELS,
 316         UNUSED_PARENS,
 317         UNUSED_BRACES,
 318         REDUNDANT_SEMICOLONS
 319     );
 320
 321     add_lint_group!("let_underscore", LET_UNDERSCORE_DROP, LET_UNDERSCORE_LOCK);
 322
 323     add_lint_group!(
 324         "rust_2018_idioms",
 325         BARE_TRAIT_OBJECTS,
 326         UNUSED_EXTERN_CRATES,
 327         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 328         ELIDED_LIFETIMES_IN_PATHS,
 329         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 330                                        // macros are ready for this yet.
 331                                        // UNREACHABLE_PUB,
 332
 333                                        // FIXME macro crates are not up for this yet, too much
 334                                        // breakage is seen if we try to encourage this lint.
 335                                        // MACRO_USE_EXTERN_CRATE
 336     );
 337
 338     // Register renamed and removed lints.
 339     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 340     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 341     store.register_renamed("bare_trait_object", "bare_trait_objects");
 342     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 343     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 344     store.register_renamed("async_idents", "keyword_idents");
 345     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 346     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 347     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
 348     store.register_renamed("safe_packed_borrows", "unaligned_references");
 349     store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
 350     store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
 351     store.register_renamed("non_fmt_panic", "non_fmt_panics");
 352
 353     // These were moved to tool lints, but rustc still sees them when compiling normally, before
 354     // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
 355     // `register_removed` explicitly.
 356     const RUSTDOC_LINTS: &[&str] = &[
 357         "broken_intra_doc_links",
 358         "private_intra_doc_links",
 359         "missing_crate_level_docs",
 360         "missing_doc_code_examples",
 361         "private_doc_tests",
 362         "invalid_codeblock_attributes",
 363         "invalid_html_tags",
 364         "non_autolinks",
 365     ];
 366     for rustdoc_lint in RUSTDOC_LINTS {
 367         store.register_ignored(rustdoc_lint);
 368     }
 369     store.register_removed(
 370         "intra_doc_link_resolution_failure",
 371         "use `rustdoc::broken_intra_doc_links` instead",
 372     );
 373     store.register_removed("rustdoc", "use `rustdoc::all` instead");
 374
 375     store.register_removed("unknown_features", "replaced by an error");
 376     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 377     store.register_removed("negate_unsigned", "cast a signed value instead");
 378     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 379     // Register lint group aliases.
 380     store.register_group_alias("nonstandard_style", "bad_style");
 381     // This was renamed to `raw_pointer_derive`, which was then removed,
 382     // so it is also considered removed.
 383     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 384     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 385     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 386     store.register_removed("deprecated_attr", "use `deprecated` instead");
 387     store.register_removed(
 388         "transmute_from_fn_item_types",
 389         "always cast functions before transmuting them",
 390     );
 391     store.register_removed(
 392         "hr_lifetime_in_assoc_type",
 393         "converted into hard error, see issue #33685 \
 394          <https://github.com/rust-lang/rust/issues/33685> for more information",
 395     );
 396     store.register_removed(
 397         "inaccessible_extern_crate",
 398         "converted into hard error, see issue #36886 \
 399          <https://github.com/rust-lang/rust/issues/36886> for more information",
 400     );
 401     store.register_removed(
 402         "super_or_self_in_global_path",
 403         "converted into hard error, see issue #36888 \
 404          <https://github.com/rust-lang/rust/issues/36888> for more information",
 405     );
 406     store.register_removed(
 407         "overlapping_inherent_impls",
 408         "converted into hard error, see issue #36889 \
 409          <https://github.com/rust-lang/rust/issues/36889> for more information",
 410     );
 411     store.register_removed(
 412         "illegal_floating_point_constant_pattern",
 413         "converted into hard error, see issue #36890 \
 414          <https://github.com/rust-lang/rust/issues/36890> for more information",
 415     );
 416     store.register_removed(
 417         "illegal_struct_or_enum_constant_pattern",
 418         "converted into hard error, see issue #36891 \
 419          <https://github.com/rust-lang/rust/issues/36891> for more information",
 420     );
 421     store.register_removed(
 422         "lifetime_underscore",
 423         "converted into hard error, see issue #36892 \
 424          <https://github.com/rust-lang/rust/issues/36892> for more information",
 425     );
 426     store.register_removed(
 427         "extra_requirement_in_impl",
 428         "converted into hard error, see issue #37166 \
 429          <https://github.com/rust-lang/rust/issues/37166> for more information",
 430     );
 431     store.register_removed(
 432         "legacy_imports",
 433         "converted into hard error, see issue #38260 \
 434          <https://github.com/rust-lang/rust/issues/38260> for more information",
 435     );
 436     store.register_removed(
 437         "coerce_never",
 438         "converted into hard error, see issue #48950 \
 439          <https://github.com/rust-lang/rust/issues/48950> for more information",
 440     );
 441     store.register_removed(
 442         "resolve_trait_on_defaulted_unit",
 443         "converted into hard error, see issue #48950 \
 444          <https://github.com/rust-lang/rust/issues/48950> for more information",
 445     );
 446     store.register_removed(
 447         "private_no_mangle_fns",
 448         "no longer a warning, `#[no_mangle]` functions always exported",
 449     );
 450     store.register_removed(
 451         "private_no_mangle_statics",
 452         "no longer a warning, `#[no_mangle]` statics always exported",
 453     );
 454     store.register_removed("bad_repr", "replaced with a generic attribute input check");
 455     store.register_removed(
 456         "duplicate_matcher_binding_name",
 457         "converted into hard error, see issue #57742 \
 458          <https://github.com/rust-lang/rust/issues/57742> for more information",
 459     );
 460     store.register_removed(
 461         "incoherent_fundamental_impls",
 462         "converted into hard error, see issue #46205 \
 463          <https://github.com/rust-lang/rust/issues/46205> for more information",
 464     );
 465     store.register_removed(
 466         "legacy_constructor_visibility",
 467         "converted into hard error, see issue #39207 \
 468          <https://github.com/rust-lang/rust/issues/39207> for more information",
 469     );
 470     store.register_removed(
 471         "legacy_directory_ownership",
 472         "converted into hard error, see issue #37872 \
 473          <https://github.com/rust-lang/rust/issues/37872> for more information",
 474     );
 475     store.register_removed(
 476         "safe_extern_statics",
 477         "converted into hard error, see issue #36247 \
 478          <https://github.com/rust-lang/rust/issues/36247> for more information",
 479     );
 480     store.register_removed(
 481         "parenthesized_params_in_types_and_modules",
 482         "converted into hard error, see issue #42238 \
 483          <https://github.com/rust-lang/rust/issues/42238> for more information",
 484     );
 485     store.register_removed(
 486         "duplicate_macro_exports",
 487         "converted into hard error, see issue #35896 \
 488          <https://github.com/rust-lang/rust/issues/35896> for more information",
 489     );
 490     store.register_removed(
 491         "nested_impl_trait",
 492         "converted into hard error, see issue #59014 \
 493          <https://github.com/rust-lang/rust/issues/59014> for more information",
 494     );
 495     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 496     store.register_removed(
 497         "unsupported_naked_functions",
 498         "converted into hard error, see RFC 2972 \
 499          <https://github.com/rust-lang/rfcs/blob/master/text/2972-constrained-naked.md> for more information",
 500     );
 501     store.register_removed(
 502         "mutable_borrow_reservation_conflict",
 503         "now allowed, see issue #59159 \
 504          <https://github.com/rust-lang/rust/issues/59159> for more information",
 505     );
 506 }
 507
 508 fn register_internals(store: &mut LintStore) {
 509     store.register_lints(&LintPassImpl::get_lints());
 510     store.register_early_pass(|| Box::new(LintPassImpl));
 511     store.register_lints(&DefaultHashTypes::get_lints());
 512     store.register_late_pass(|| Box::new(DefaultHashTypes));
 513     store.register_lints(&QueryStability::get_lints());
 514     store.register_late_pass(|| Box::new(QueryStability));
 515     store.register_lints(&ExistingDocKeyword::get_lints());
 516     store.register_late_pass(|| Box::new(ExistingDocKeyword));
 517     store.register_lints(&TyTyKind::get_lints());
 518     store.register_late_pass(|| Box::new(TyTyKind));
 519     store.register_lints(&Diagnostics::get_lints());
 520     store.register_late_pass(|| Box::new(Diagnostics));
 521     store.register_lints(&BadOptAccess::get_lints());
 522     store.register_late_pass(|| Box::new(BadOptAccess));
 523     store.register_lints(&PassByValue::get_lints());
 524     store.register_late_pass(|| Box::new(PassByValue));
 525     // FIXME(davidtwco): deliberately do not include `UNTRANSLATABLE_DIAGNOSTIC` and
 526     // `DIAGNOSTIC_OUTSIDE_OF_IMPL` here because `-Wrustc::internal` is provided to every crate and
 527     // these lints will trigger all of the time - change this once migration to diagnostic structs
 528     // and translation is completed
 529     store.register_group(
 530         false,
 531         "rustc::internal",
 532         None,
 533         vec![
 534             LintId::of(DEFAULT_HASH_TYPES),
 535             LintId::of(POTENTIAL_QUERY_INSTABILITY),
 536             LintId::of(USAGE_OF_TY_TYKIND),
 537             LintId::of(PASS_BY_VALUE),
 538             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 539             LintId::of(USAGE_OF_QUALIFIED_TY),
 540             LintId::of(EXISTING_DOC_KEYWORD),
 541             LintId::of(BAD_OPT_ACCESS),
 542         ],
 543     );
 544 }
 545
 546 #[cfg(test)]
 547 mod tests;