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