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