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