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