compiler/rustc_lint/src/lib.rs

   1 //! Lints, aka compiler warnings.
   2 //!
   3 //! A 'lint' check is a kind of miscellaneous constraint that a user _might_
   4 //! want to enforce, but might reasonably want to permit as well, on a
   5 //! module-by-module basis. They contrast with static constraints enforced by
   6 //! other phases of the compiler, which are generally required to hold in order
   7 //! to compile the program at all.
   8 //!
   9 //! Most lints can be written as [LintPass] instances. These run after
  10 //! all other analyses. The `LintPass`es built into rustc are defined
  11 //! within [rustc_session::lint::builtin],
  12 //! which has further comments on how to add such a lint.
  13 //! rustc can also load user-defined lint plugins via the plugin mechanism.
  14 //!
  15 //! Some of rustc's lints are defined elsewhere in the compiler and work by
  16 //! calling `add_lint()` on the overall `Session` object. This works when
  17 //! it happens before the main lint pass, which emits the lints stored by
  18 //! `add_lint()`. To emit lints after the main lint pass (from codegen, for
  19 //! example) requires more effort. See `emit_lint` and `GatherNodeLevels`
  20 //! in `context.rs`.
  21 //!
  22 //! Some code also exists in [rustc_session::lint], [rustc_middle::lint].
  23 //!
  24 //! ## Note
  25 //!
  26 //! This API is completely unstable and subject to change.
  27
  28 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
  29 #![feature(array_windows)]
  30 #![feature(bool_to_option)]
  31 #![feature(box_patterns)]
  32 #![feature(crate_visibility_modifier)]
  33 #![feature(format_args_capture)]
  34 #![feature(iter_order_by)]
  35 #![feature(iter_zip)]
  36 #![feature(never_type)]
  37 #![feature(nll)]
  38 #![feature(control_flow_enum)]
  39 #![recursion_limit = "256"]
  40
  41 #[macro_use]
  42 extern crate rustc_middle;
  43 #[macro_use]
  44 extern crate rustc_session;
  45
  46 mod array_into_iter;
  47 pub mod builtin;
  48 mod context;
  49 mod early;
  50 mod internal;
  51 mod late;
  52 mod levels;
  53 mod methods;
  54 mod non_ascii_idents;
  55 mod non_fmt_panic;
  56 mod nonstandard_style;
  57 mod noop_method_call;
  58 mod passes;
  59 mod redundant_semicolon;
  60 mod traits;
  61 mod types;
  62 mod unused;
  63
  64 pub use array_into_iter::ARRAY_INTO_ITER;
  65
  66 use rustc_ast as ast;
  67 use rustc_hir as hir;
  68 use rustc_hir::def_id::LocalDefId;
  69 use rustc_middle::ty::query::Providers;
  70 use rustc_middle::ty::TyCtxt;
  71 use rustc_session::lint::builtin::{
  72     BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
  73 };
  74 use rustc_span::symbol::{Ident, Symbol};
  75 use rustc_span::Span;
  76
  77 use array_into_iter::ArrayIntoIter;
  78 use builtin::*;
  79 use internal::*;
  80 use methods::*;
  81 use non_ascii_idents::*;
  82 use non_fmt_panic::NonPanicFmt;
  83 use nonstandard_style::*;
  84 use noop_method_call::*;
  85 use redundant_semicolon::*;
  86 use traits::*;
  87 use types::*;
  88 use unused::*;
  89
  90 /// Useful for other parts of the compiler / Clippy.
  91 pub use builtin::SoftLints;
  92 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
  93 pub use early::check_ast_crate;
  94 pub use late::check_crate;
  95 pub use passes::{EarlyLintPass, LateLintPass};
  96 pub use rustc_session::lint::Level::{self, *};
  97 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
  98 pub use rustc_session::lint::{LintArray, LintPass};
  99
 100 pub fn provide(providers: &mut Providers) {
 101     levels::provide(providers);
 102     *providers = Providers { lint_mod, ..*providers };
 103 }
 104
 105 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
 106     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
 107 }
 108
 109 macro_rules! pre_expansion_lint_passes {
 110     ($macro:path, $args:tt) => {
 111         $macro!($args, [KeywordIdents: KeywordIdents,]);
 112     };
 113 }
 114
 115 macro_rules! early_lint_passes {
 116     ($macro:path, $args:tt) => {
 117         $macro!(
 118             $args,
 119             [
 120                 UnusedParens: UnusedParens,
 121                 UnusedBraces: UnusedBraces,
 122                 UnusedImportBraces: UnusedImportBraces,
 123                 UnsafeCode: UnsafeCode,
 124                 AnonymousParameters: AnonymousParameters,
 125                 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 126                 NonCamelCaseTypes: NonCamelCaseTypes,
 127                 DeprecatedAttr: DeprecatedAttr::new(),
 128                 WhileTrue: WhileTrue,
 129                 NonAsciiIdents: NonAsciiIdents,
 130                 IncompleteFeatures: IncompleteFeatures,
 131                 RedundantSemicolons: RedundantSemicolons,
 132                 UnusedDocComment: UnusedDocComment,
 133             ]
 134         );
 135     };
 136 }
 137
 138 macro_rules! declare_combined_early_pass {
 139     ([$name:ident], $passes:tt) => (
 140         early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
 141     )
 142 }
 143
 144 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
 145 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
 146
 147 macro_rules! late_lint_passes {
 148     ($macro:path, $args:tt) => {
 149         $macro!(
 150             $args,
 151             [
 152                 // FIXME: Look into regression when this is used as a module lint
 153                 // May Depend on constants elsewhere
 154                 UnusedBrokenConst: UnusedBrokenConst,
 155                 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
 156                 UnstableFeatures: UnstableFeatures,
 157                 // Tracks state across modules
 158                 UnnameableTestItems: UnnameableTestItems::new(),
 159                 // Tracks attributes of parents
 160                 MissingDoc: MissingDoc::new(),
 161                 // Depends on access levels
 162                 // FIXME: Turn the computation of types which implement Debug into a query
 163                 // and change this to a module lint pass
 164                 MissingDebugImplementations: MissingDebugImplementations::default(),
 165                 ArrayIntoIter: ArrayIntoIter::default(),
 166                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
 167                 DropTraitConstraints: DropTraitConstraints,
 168                 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
 169                 NonPanicFmt: NonPanicFmt,
 170                 NoopMethodCall: NoopMethodCall,
 171                 InvalidAtomicOrdering: InvalidAtomicOrdering,
 172                 NamedAsmLabels: NamedAsmLabels,
 173             ]
 174         );
 175     };
 176 }
 177
 178 macro_rules! late_lint_mod_passes {
 179     ($macro:path, $args:tt) => {
 180         $macro!(
 181             $args,
 182             [
 183                 HardwiredLints: HardwiredLints,
 184                 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 185                 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 186                 VariantSizeDifferences: VariantSizeDifferences,
 187                 BoxPointers: BoxPointers,
 188                 PathStatements: PathStatements,
 189                 // Depends on referenced function signatures in expressions
 190                 UnusedResults: UnusedResults,
 191                 NonUpperCaseGlobals: NonUpperCaseGlobals,
 192                 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 193                 UnusedAllocation: UnusedAllocation,
 194                 // Depends on types used in type definitions
 195                 MissingCopyImplementations: MissingCopyImplementations,
 196                 // Depends on referenced function signatures in expressions
 197                 MutableTransmutes: MutableTransmutes,
 198                 TypeAliasBounds: TypeAliasBounds,
 199                 TrivialConstraints: TrivialConstraints,
 200                 TypeLimits: TypeLimits::new(),
 201                 NonSnakeCase: NonSnakeCase,
 202                 InvalidNoMangleItems: InvalidNoMangleItems,
 203                 // Depends on access levels
 204                 UnreachablePub: UnreachablePub,
 205                 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 206                 InvalidValue: InvalidValue,
 207                 DerefNullPtr: DerefNullPtr,
 208             ]
 209         );
 210     };
 211 }
 212
 213 macro_rules! declare_combined_late_pass {
 214     ([$v:vis $name:ident], $passes:tt) => (
 215         late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
 216     )
 217 }
 218
 219 // FIXME: Make a separate lint type which do not require typeck tables
 220 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
 221
 222 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
 223
 224 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
 225     let mut lint_store = LintStore::new();
 226
 227     register_builtins(&mut lint_store, no_interleave_lints);
 228     if internal_lints {
 229         register_internals(&mut lint_store);
 230     }
 231
 232     lint_store
 233 }
 234
 235 /// Tell the `LintStore` about all the built-in lints (the ones
 236 /// defined in this crate and the ones defined in
 237 /// `rustc_session::lint::builtin`).
 238 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
 239     macro_rules! add_lint_group {
 240         ($name:expr, $($lint:ident),*) => (
 241             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 242         )
 243     }
 244
 245     macro_rules! register_pass {
 246         ($method:ident, $ty:ident, $constructor:expr) => {
 247             store.register_lints(&$ty::get_lints());
 248             store.$method(|| Box::new($constructor));
 249         };
 250     }
 251
 252     macro_rules! register_passes {
 253         ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
 254             $(
 255                 register_pass!($method, $passes, $constructor);
 256             )*
 257         )
 258     }
 259
 260     if no_interleave_lints {
 261         pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
 262         early_lint_passes!(register_passes, register_early_pass);
 263         late_lint_passes!(register_passes, register_late_pass);
 264         late_lint_mod_passes!(register_passes, register_late_mod_pass);
 265     } else {
 266         store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 267         store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 268         store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 269         store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 270     }
 271
 272     add_lint_group!(
 273         "nonstandard_style",
 274         NON_CAMEL_CASE_TYPES,
 275         NON_SNAKE_CASE,
 276         NON_UPPER_CASE_GLOBALS
 277     );
 278
 279     add_lint_group!(
 280         "unused",
 281         UNUSED_IMPORTS,
 282         UNUSED_VARIABLES,
 283         UNUSED_ASSIGNMENTS,
 284         DEAD_CODE,
 285         UNUSED_MUT,
 286         UNREACHABLE_CODE,
 287         UNREACHABLE_PATTERNS,
 288         UNUSED_MUST_USE,
 289         UNUSED_UNSAFE,
 290         PATH_STATEMENTS,
 291         UNUSED_ATTRIBUTES,
 292         UNUSED_MACROS,
 293         UNUSED_ALLOCATION,
 294         UNUSED_DOC_COMMENTS,
 295         UNUSED_EXTERN_CRATES,
 296         UNUSED_FEATURES,
 297         UNUSED_LABELS,
 298         UNUSED_PARENS,
 299         UNUSED_BRACES,
 300         MUST_NOT_SUSPEND,
 301         REDUNDANT_SEMICOLONS
 302     );
 303
 304     add_lint_group!(
 305         "rust_2018_idioms",
 306         BARE_TRAIT_OBJECTS,
 307         UNUSED_EXTERN_CRATES,
 308         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 309         ELIDED_LIFETIMES_IN_PATHS,
 310         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 311                                        // macros are ready for this yet.
 312                                        // UNREACHABLE_PUB,
 313
 314                                        // FIXME macro crates are not up for this yet, too much
 315                                        // breakage is seen if we try to encourage this lint.
 316                                        // MACRO_USE_EXTERN_CRATE
 317     );
 318
 319     // Register renamed and removed lints.
 320     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 321     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 322     store.register_renamed("bare_trait_object", "bare_trait_objects");
 323     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 324     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 325     store.register_renamed("async_idents", "keyword_idents");
 326     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 327     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 328     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
 329     store.register_renamed("safe_packed_borrows", "unaligned_references");
 330     store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
 331     store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
 332     store.register_renamed("non_fmt_panic", "non_fmt_panics");
 333
 334     // These were moved to tool lints, but rustc still sees them when compiling normally, before
 335     // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
 336     // `register_removed` explicitly.
 337     const RUSTDOC_LINTS: &[&str] = &[
 338         "broken_intra_doc_links",
 339         "private_intra_doc_links",
 340         "missing_crate_level_docs",
 341         "missing_doc_code_examples",
 342         "private_doc_tests",
 343         "invalid_codeblock_attributes",
 344         "invalid_html_tags",
 345         "non_autolinks",
 346     ];
 347     for rustdoc_lint in RUSTDOC_LINTS {
 348         store.register_ignored(rustdoc_lint);
 349     }
 350     store.register_removed(
 351         "intra_doc_link_resolution_failure",
 352         "use `rustdoc::broken_intra_doc_links` instead",
 353     );
 354     store.register_removed("rustdoc", "use `rustdoc::all` instead");
 355
 356     store.register_removed("unknown_features", "replaced by an error");
 357     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 358     store.register_removed("negate_unsigned", "cast a signed value instead");
 359     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 360     // Register lint group aliases.
 361     store.register_group_alias("nonstandard_style", "bad_style");
 362     // This was renamed to `raw_pointer_derive`, which was then removed,
 363     // so it is also considered removed.
 364     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 365     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 366     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 367     store.register_removed("deprecated_attr", "use `deprecated` instead");
 368     store.register_removed(
 369         "transmute_from_fn_item_types",
 370         "always cast functions before transmuting them",
 371     );
 372     store.register_removed(
 373         "hr_lifetime_in_assoc_type",
 374         "converted into hard error, see issue #33685 \
 375          <https://github.com/rust-lang/rust/issues/33685> for more information",
 376     );
 377     store.register_removed(
 378         "inaccessible_extern_crate",
 379         "converted into hard error, see issue #36886 \
 380          <https://github.com/rust-lang/rust/issues/36886> for more information",
 381     );
 382     store.register_removed(
 383         "super_or_self_in_global_path",
 384         "converted into hard error, see issue #36888 \
 385          <https://github.com/rust-lang/rust/issues/36888> for more information",
 386     );
 387     store.register_removed(
 388         "overlapping_inherent_impls",
 389         "converted into hard error, see issue #36889 \
 390          <https://github.com/rust-lang/rust/issues/36889> for more information",
 391     );
 392     store.register_removed(
 393         "illegal_floating_point_constant_pattern",
 394         "converted into hard error, see issue #36890 \
 395          <https://github.com/rust-lang/rust/issues/36890> for more information",
 396     );
 397     store.register_removed(
 398         "illegal_struct_or_enum_constant_pattern",
 399         "converted into hard error, see issue #36891 \
 400          <https://github.com/rust-lang/rust/issues/36891> for more information",
 401     );
 402     store.register_removed(
 403         "lifetime_underscore",
 404         "converted into hard error, see issue #36892 \
 405          <https://github.com/rust-lang/rust/issues/36892> for more information",
 406     );
 407     store.register_removed(
 408         "extra_requirement_in_impl",
 409         "converted into hard error, see issue #37166 \
 410          <https://github.com/rust-lang/rust/issues/37166> for more information",
 411     );
 412     store.register_removed(
 413         "legacy_imports",
 414         "converted into hard error, see issue #38260 \
 415          <https://github.com/rust-lang/rust/issues/38260> for more information",
 416     );
 417     store.register_removed(
 418         "coerce_never",
 419         "converted into hard error, see issue #48950 \
 420          <https://github.com/rust-lang/rust/issues/48950> for more information",
 421     );
 422     store.register_removed(
 423         "resolve_trait_on_defaulted_unit",
 424         "converted into hard error, see issue #48950 \
 425          <https://github.com/rust-lang/rust/issues/48950> for more information",
 426     );
 427     store.register_removed(
 428         "private_no_mangle_fns",
 429         "no longer a warning, `#[no_mangle]` functions always exported",
 430     );
 431     store.register_removed(
 432         "private_no_mangle_statics",
 433         "no longer a warning, `#[no_mangle]` statics always exported",
 434     );
 435     store.register_removed("bad_repr", "replaced with a generic attribute input check");
 436     store.register_removed(
 437         "duplicate_matcher_binding_name",
 438         "converted into hard error, see issue #57742 \
 439          <https://github.com/rust-lang/rust/issues/57742> for more information",
 440     );
 441     store.register_removed(
 442         "incoherent_fundamental_impls",
 443         "converted into hard error, see issue #46205 \
 444          <https://github.com/rust-lang/rust/issues/46205> for more information",
 445     );
 446     store.register_removed(
 447         "legacy_constructor_visibility",
 448         "converted into hard error, see issue #39207 \
 449          <https://github.com/rust-lang/rust/issues/39207> for more information",
 450     );
 451     store.register_removed(
 452         "legacy_directory_ownership",
 453         "converted into hard error, see issue #37872 \
 454          <https://github.com/rust-lang/rust/issues/37872> for more information",
 455     );
 456     store.register_removed(
 457         "safe_extern_statics",
 458         "converted into hard error, see issue #36247 \
 459          <https://github.com/rust-lang/rust/issues/36247> for more information",
 460     );
 461     store.register_removed(
 462         "parenthesized_params_in_types_and_modules",
 463         "converted into hard error, see issue #42238 \
 464          <https://github.com/rust-lang/rust/issues/42238> for more information",
 465     );
 466     store.register_removed(
 467         "duplicate_macro_exports",
 468         "converted into hard error, see issue #35896 \
 469          <https://github.com/rust-lang/rust/issues/35896> for more information",
 470     );
 471     store.register_removed(
 472         "nested_impl_trait",
 473         "converted into hard error, see issue #59014 \
 474          <https://github.com/rust-lang/rust/issues/59014> for more information",
 475     );
 476     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 477 }
 478
 479 fn register_internals(store: &mut LintStore) {
 480     store.register_lints(&LintPassImpl::get_lints());
 481     store.register_early_pass(|| Box::new(LintPassImpl));
 482     store.register_lints(&DefaultHashTypes::get_lints());
 483     store.register_late_pass(|| Box::new(DefaultHashTypes));
 484     store.register_lints(&ExistingDocKeyword::get_lints());
 485     store.register_late_pass(|| Box::new(ExistingDocKeyword));
 486     store.register_lints(&TyTyKind::get_lints());
 487     store.register_late_pass(|| Box::new(TyTyKind));
 488     store.register_group(
 489         false,
 490         "rustc::internal",
 491         None,
 492         vec![
 493             LintId::of(DEFAULT_HASH_TYPES),
 494             LintId::of(USAGE_OF_TY_TYKIND),
 495             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 496             LintId::of(TY_PASS_BY_REFERENCE),
 497             LintId::of(USAGE_OF_QUALIFIED_TY),
 498             LintId::of(EXISTING_DOC_KEYWORD),
 499         ],
 500     );
 501 }
 502
 503 #[cfg(test)]
 504 mod tests;