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