src/librustc_lint/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/")]
  29 #![cfg_attr(test, feature(test))]
  30 #![feature(bool_to_option)]
  31 #![feature(box_syntax)]
  32 #![feature(crate_visibility_modifier)]
  33 #![feature(iter_order_by)]
  34 #![feature(never_type)]
  35 #![feature(nll)]
  36 #![feature(or_patterns)]
  37 #![recursion_limit = "256"]
  38
  39 #[macro_use]
  40 extern crate rustc_middle;
  41 #[macro_use]
  42 extern crate rustc_session;
  43
  44 mod array_into_iter;
  45 pub mod builtin;
  46 mod context;
  47 mod early;
  48 mod internal;
  49 mod late;
  50 mod levels;
  51 mod non_ascii_idents;
  52 mod nonstandard_style;
  53 mod passes;
  54 mod redundant_semicolon;
  55 mod types;
  56 mod unused;
  57
  58 use rustc_ast::ast;
  59 use rustc_hir as hir;
  60 use rustc_hir::def_id::LocalDefId;
  61 use rustc_middle::ty::query::Providers;
  62 use rustc_middle::ty::TyCtxt;
  63 use rustc_session::lint::builtin::{
  64     BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
  65     INTRA_DOC_LINK_RESOLUTION_FAILURE, INVALID_CODEBLOCK_ATTRIBUTES, MISSING_DOC_CODE_EXAMPLES,
  66     PRIVATE_DOC_TESTS,
  67 };
  68 use rustc_span::symbol::{Ident, Symbol};
  69 use rustc_span::Span;
  70
  71 use array_into_iter::ArrayIntoIter;
  72 use builtin::*;
  73 use internal::*;
  74 use non_ascii_idents::*;
  75 use nonstandard_style::*;
  76 use redundant_semicolon::*;
  77 use types::*;
  78 use unused::*;
  79
  80 /// Useful for other parts of the compiler / Clippy.
  81 pub use builtin::SoftLints;
  82 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
  83 pub use early::check_ast_crate;
  84 pub use late::check_crate;
  85 pub use passes::{EarlyLintPass, LateLintPass};
  86 pub use rustc_session::lint::Level::{self, *};
  87 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
  88 pub use rustc_session::lint::{LintArray, LintPass};
  89
  90 pub fn provide(providers: &mut Providers) {
  91     levels::provide(providers);
  92     *providers = Providers { lint_mod, ..*providers };
  93 }
  94
  95 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
  96     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
  97 }
  98
  99 macro_rules! pre_expansion_lint_passes {
 100     ($macro:path, $args:tt) => {
 101         $macro!($args, [KeywordIdents: KeywordIdents,]);
 102     };
 103 }
 104
 105 macro_rules! early_lint_passes {
 106     ($macro:path, $args:tt) => {
 107         $macro!(
 108             $args,
 109             [
 110                 UnusedParens: UnusedParens,
 111                 UnusedBraces: UnusedBraces,
 112                 UnusedImportBraces: UnusedImportBraces,
 113                 UnsafeCode: UnsafeCode,
 114                 AnonymousParameters: AnonymousParameters,
 115                 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 116                 NonCamelCaseTypes: NonCamelCaseTypes,
 117                 DeprecatedAttr: DeprecatedAttr::new(),
 118                 WhileTrue: WhileTrue,
 119                 NonAsciiIdents: NonAsciiIdents,
 120                 IncompleteFeatures: IncompleteFeatures,
 121                 RedundantSemicolons: RedundantSemicolons,
 122                 UnusedDocComment: UnusedDocComment,
 123             ]
 124         );
 125     };
 126 }
 127
 128 macro_rules! declare_combined_early_pass {
 129     ([$name:ident], $passes:tt) => (
 130         early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
 131     )
 132 }
 133
 134 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
 135 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
 136
 137 macro_rules! late_lint_passes {
 138     ($macro:path, $args:tt) => {
 139         $macro!(
 140             $args,
 141             [
 142                 // FIXME: Look into regression when this is used as a module lint
 143                 // May Depend on constants elsewhere
 144                 UnusedBrokenConst: UnusedBrokenConst,
 145                 // Uses attr::is_used which is untracked, can't be an incremental module pass.
 146                 UnusedAttributes: UnusedAttributes::new(),
 147                 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
 148                 UnstableFeatures: UnstableFeatures,
 149                 // Tracks state across modules
 150                 UnnameableTestItems: UnnameableTestItems::new(),
 151                 // Tracks attributes of parents
 152                 MissingDoc: MissingDoc::new(),
 153                 // Depends on access levels
 154                 // FIXME: Turn the computation of types which implement Debug into a query
 155                 // and change this to a module lint pass
 156                 MissingDebugImplementations: MissingDebugImplementations::default(),
 157                 ArrayIntoIter: ArrayIntoIter,
 158                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
 159             ]
 160         );
 161     };
 162 }
 163
 164 macro_rules! late_lint_mod_passes {
 165     ($macro:path, $args:tt) => {
 166         $macro!(
 167             $args,
 168             [
 169                 HardwiredLints: HardwiredLints,
 170                 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 171                 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 172                 VariantSizeDifferences: VariantSizeDifferences,
 173                 BoxPointers: BoxPointers,
 174                 PathStatements: PathStatements,
 175                 // Depends on referenced function signatures in expressions
 176                 UnusedResults: UnusedResults,
 177                 NonUpperCaseGlobals: NonUpperCaseGlobals,
 178                 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 179                 UnusedAllocation: UnusedAllocation,
 180                 // Depends on types used in type definitions
 181                 MissingCopyImplementations: MissingCopyImplementations,
 182                 // Depends on referenced function signatures in expressions
 183                 MutableTransmutes: MutableTransmutes,
 184                 TypeAliasBounds: TypeAliasBounds,
 185                 TrivialConstraints: TrivialConstraints,
 186                 TypeLimits: TypeLimits::new(),
 187                 NonSnakeCase: NonSnakeCase,
 188                 InvalidNoMangleItems: InvalidNoMangleItems,
 189                 // Depends on access levels
 190                 UnreachablePub: UnreachablePub,
 191                 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 192                 InvalidValue: InvalidValue,
 193             ]
 194         );
 195     };
 196 }
 197
 198 macro_rules! declare_combined_late_pass {
 199     ([$v:vis $name:ident], $passes:tt) => (
 200         late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
 201     )
 202 }
 203
 204 // FIXME: Make a separate lint type which do not require typeck tables
 205 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
 206
 207 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
 208
 209 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
 210     let mut lint_store = LintStore::new();
 211
 212     register_builtins(&mut lint_store, no_interleave_lints);
 213     if internal_lints {
 214         register_internals(&mut lint_store);
 215     }
 216
 217     lint_store
 218 }
 219
 220 /// Tell the `LintStore` about all the built-in lints (the ones
 221 /// defined in this crate and the ones defined in
 222 /// `rustc::lint::builtin`).
 223 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
 224     macro_rules! add_lint_group {
 225         ($name:expr, $($lint:ident),*) => (
 226             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 227         )
 228     }
 229
 230     macro_rules! register_pass {
 231         ($method:ident, $ty:ident, $constructor:expr) => {
 232             store.register_lints(&$ty::get_lints());
 233             store.$method(|| box $constructor);
 234         };
 235     }
 236
 237     macro_rules! register_passes {
 238         ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
 239             $(
 240                 register_pass!($method, $passes, $constructor);
 241             )*
 242         )
 243     }
 244
 245     if no_interleave_lints {
 246         pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
 247         early_lint_passes!(register_passes, register_early_pass);
 248         late_lint_passes!(register_passes, register_late_pass);
 249         late_lint_mod_passes!(register_passes, register_late_mod_pass);
 250     } else {
 251         store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 252         store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 253         store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 254         store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 255     }
 256
 257     add_lint_group!(
 258         "nonstandard_style",
 259         NON_CAMEL_CASE_TYPES,
 260         NON_SNAKE_CASE,
 261         NON_UPPER_CASE_GLOBALS
 262     );
 263
 264     add_lint_group!(
 265         "unused",
 266         UNUSED_IMPORTS,
 267         UNUSED_VARIABLES,
 268         UNUSED_ASSIGNMENTS,
 269         DEAD_CODE,
 270         UNUSED_MUT,
 271         UNREACHABLE_CODE,
 272         UNREACHABLE_PATTERNS,
 273         OVERLAPPING_PATTERNS,
 274         UNUSED_MUST_USE,
 275         UNUSED_UNSAFE,
 276         PATH_STATEMENTS,
 277         UNUSED_ATTRIBUTES,
 278         UNUSED_MACROS,
 279         UNUSED_ALLOCATION,
 280         UNUSED_DOC_COMMENTS,
 281         UNUSED_EXTERN_CRATES,
 282         UNUSED_FEATURES,
 283         UNUSED_LABELS,
 284         UNUSED_PARENS,
 285         UNUSED_BRACES,
 286         REDUNDANT_SEMICOLONS
 287     );
 288
 289     add_lint_group!(
 290         "rust_2018_idioms",
 291         BARE_TRAIT_OBJECTS,
 292         UNUSED_EXTERN_CRATES,
 293         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 294         ELIDED_LIFETIMES_IN_PATHS,
 295         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 296                                        // macros are ready for this yet.
 297                                        // UNREACHABLE_PUB,
 298
 299                                        // FIXME macro crates are not up for this yet, too much
 300                                        // breakage is seen if we try to encourage this lint.
 301                                        // MACRO_USE_EXTERN_CRATE
 302     );
 303
 304     add_lint_group!(
 305         "rustdoc",
 306         INTRA_DOC_LINK_RESOLUTION_FAILURE,
 307         INVALID_CODEBLOCK_ATTRIBUTES,
 308         MISSING_DOC_CODE_EXAMPLES,
 309         PRIVATE_DOC_TESTS
 310     );
 311
 312     // Register renamed and removed lints.
 313     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 314     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 315     store.register_renamed("bare_trait_object", "bare_trait_objects");
 316     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 317     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 318     store.register_renamed("async_idents", "keyword_idents");
 319     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 320     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 321     store.register_removed("unknown_features", "replaced by an error");
 322     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 323     store.register_removed("negate_unsigned", "cast a signed value instead");
 324     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 325     // Register lint group aliases.
 326     store.register_group_alias("nonstandard_style", "bad_style");
 327     // This was renamed to `raw_pointer_derive`, which was then removed,
 328     // so it is also considered removed.
 329     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 330     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 331     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 332     store.register_removed("deprecated_attr", "use `deprecated` instead");
 333     store.register_removed(
 334         "transmute_from_fn_item_types",
 335         "always cast functions before transmuting them",
 336     );
 337     store.register_removed(
 338         "hr_lifetime_in_assoc_type",
 339         "converted into hard error, see issue #33685 \
 340          <https://github.com/rust-lang/rust/issues/33685> for more information",
 341     );
 342     store.register_removed(
 343         "inaccessible_extern_crate",
 344         "converted into hard error, see issue #36886 \
 345          <https://github.com/rust-lang/rust/issues/36886> for more information",
 346     );
 347     store.register_removed(
 348         "super_or_self_in_global_path",
 349         "converted into hard error, see issue #36888 \
 350          <https://github.com/rust-lang/rust/issues/36888> for more information",
 351     );
 352     store.register_removed(
 353         "overlapping_inherent_impls",
 354         "converted into hard error, see issue #36889 \
 355          <https://github.com/rust-lang/rust/issues/36889> for more information",
 356     );
 357     store.register_removed(
 358         "illegal_floating_point_constant_pattern",
 359         "converted into hard error, see issue #36890 \
 360          <https://github.com/rust-lang/rust/issues/36890> for more information",
 361     );
 362     store.register_removed(
 363         "illegal_struct_or_enum_constant_pattern",
 364         "converted into hard error, see issue #36891 \
 365          <https://github.com/rust-lang/rust/issues/36891> for more information",
 366     );
 367     store.register_removed(
 368         "lifetime_underscore",
 369         "converted into hard error, see issue #36892 \
 370          <https://github.com/rust-lang/rust/issues/36892> for more information",
 371     );
 372     store.register_removed(
 373         "extra_requirement_in_impl",
 374         "converted into hard error, see issue #37166 \
 375          <https://github.com/rust-lang/rust/issues/37166> for more information",
 376     );
 377     store.register_removed(
 378         "legacy_imports",
 379         "converted into hard error, see issue #38260 \
 380          <https://github.com/rust-lang/rust/issues/38260> for more information",
 381     );
 382     store.register_removed(
 383         "coerce_never",
 384         "converted into hard error, see issue #48950 \
 385          <https://github.com/rust-lang/rust/issues/48950> for more information",
 386     );
 387     store.register_removed(
 388         "resolve_trait_on_defaulted_unit",
 389         "converted into hard error, see issue #48950 \
 390          <https://github.com/rust-lang/rust/issues/48950> for more information",
 391     );
 392     store.register_removed(
 393         "private_no_mangle_fns",
 394         "no longer a warning, `#[no_mangle]` functions always exported",
 395     );
 396     store.register_removed(
 397         "private_no_mangle_statics",
 398         "no longer a warning, `#[no_mangle]` statics always exported",
 399     );
 400     store.register_removed("bad_repr", "replaced with a generic attribute input check");
 401     store.register_removed(
 402         "duplicate_matcher_binding_name",
 403         "converted into hard error, see issue #57742 \
 404          <https://github.com/rust-lang/rust/issues/57742> for more information",
 405     );
 406     store.register_removed(
 407         "incoherent_fundamental_impls",
 408         "converted into hard error, see issue #46205 \
 409          <https://github.com/rust-lang/rust/issues/46205> for more information",
 410     );
 411     store.register_removed(
 412         "legacy_constructor_visibility",
 413         "converted into hard error, see issue #39207 \
 414          <https://github.com/rust-lang/rust/issues/39207> for more information",
 415     );
 416     store.register_removed(
 417         "legacy_directory_ownership",
 418         "converted into hard error, see issue #37872 \
 419          <https://github.com/rust-lang/rust/issues/37872> for more information",
 420     );
 421     store.register_removed(
 422         "safe_extern_statics",
 423         "converted into hard error, see issue #36247 \
 424          <https://github.com/rust-lang/rust/issues/36247> for more information",
 425     );
 426     store.register_removed(
 427         "parenthesized_params_in_types_and_modules",
 428         "converted into hard error, see issue #42238 \
 429          <https://github.com/rust-lang/rust/issues/42238> for more information",
 430     );
 431     store.register_removed(
 432         "duplicate_macro_exports",
 433         "converted into hard error, see issue #35896 \
 434          <https://github.com/rust-lang/rust/issues/35896> for more information",
 435     );
 436     store.register_removed(
 437         "nested_impl_trait",
 438         "converted into hard error, see issue #59014 \
 439          <https://github.com/rust-lang/rust/issues/59014> for more information",
 440     );
 441     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 442 }
 443
 444 fn register_internals(store: &mut LintStore) {
 445     store.register_lints(&DefaultHashTypes::get_lints());
 446     store.register_early_pass(|| box DefaultHashTypes::new());
 447     store.register_lints(&LintPassImpl::get_lints());
 448     store.register_early_pass(|| box LintPassImpl);
 449     store.register_lints(&TyTyKind::get_lints());
 450     store.register_late_pass(|| box TyTyKind);
 451     store.register_group(
 452         false,
 453         "rustc::internal",
 454         None,
 455         vec![
 456             LintId::of(DEFAULT_HASH_TYPES),
 457             LintId::of(USAGE_OF_TY_TYKIND),
 458             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 459             LintId::of(TY_PASS_BY_REFERENCE),
 460             LintId::of(USAGE_OF_QUALIFIED_TY),
 461         ],
 462     );
 463 }