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