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