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 #![recursion_limit = "256"]
  39
  40 #[macro_use]
  41 extern crate rustc_middle;
  42 #[macro_use]
  43 extern crate rustc_session;
  44
  45 mod array_into_iter;
  46 pub mod builtin;
  47 mod context;
  48 mod early;
  49 mod internal;
  50 mod late;
  51 mod levels;
  52 mod non_ascii_idents;
  53 mod nonstandard_style;
  54 mod passes;
  55 mod redundant_semicolon;
  56 mod types;
  57 mod unused;
  58
  59 use rustc_ast as ast;
  60 use rustc_hir as hir;
  61 use rustc_hir::def_id::LocalDefId;
  62 use rustc_middle::ty::query::Providers;
  63 use rustc_middle::ty::TyCtxt;
  64 use rustc_session::lint::builtin::{
  65     BARE_TRAIT_OBJECTS, BROKEN_INTRA_DOC_LINKS, ELIDED_LIFETIMES_IN_PATHS,
  66     EXPLICIT_OUTLIVES_REQUIREMENTS, INVALID_CODEBLOCK_ATTRIBUTES, MISSING_DOC_CODE_EXAMPLES,
  67     PRIVATE_DOC_TESTS,
  68 };
  69 use rustc_span::symbol::{Ident, Symbol};
  70 use rustc_span::Span;
  71
  72 use array_into_iter::ArrayIntoIter;
  73 use builtin::*;
  74 use internal::*;
  75 use non_ascii_idents::*;
  76 use nonstandard_style::*;
  77 use redundant_semicolon::*;
  78 use types::*;
  79 use unused::*;
  80
  81 /// Useful for other parts of the compiler / Clippy.
  82 pub use builtin::SoftLints;
  83 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
  84 pub use early::check_ast_crate;
  85 pub use late::check_crate;
  86 pub use passes::{EarlyLintPass, LateLintPass};
  87 pub use rustc_session::lint::Level::{self, *};
  88 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
  89 pub use rustc_session::lint::{LintArray, LintPass};
  90
  91 pub fn provide(providers: &mut Providers) {
  92     levels::provide(providers);
  93     *providers = Providers { lint_mod, ..*providers };
  94 }
  95
  96 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
  97     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
  98 }
  99
 100 macro_rules! pre_expansion_lint_passes {
 101     ($macro:path, $args:tt) => {
 102         $macro!($args, [KeywordIdents: KeywordIdents,]);
 103     };
 104 }
 105
 106 macro_rules! early_lint_passes {
 107     ($macro:path, $args:tt) => {
 108         $macro!(
 109             $args,
 110             [
 111                 UnusedParens: UnusedParens,
 112                 UnusedBraces: UnusedBraces,
 113                 UnusedImportBraces: UnusedImportBraces,
 114                 UnsafeCode: UnsafeCode,
 115                 AnonymousParameters: AnonymousParameters,
 116                 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 117                 NonCamelCaseTypes: NonCamelCaseTypes,
 118                 DeprecatedAttr: DeprecatedAttr::new(),
 119                 WhileTrue: WhileTrue,
 120                 NonAsciiIdents: NonAsciiIdents,
 121                 IncompleteFeatures: IncompleteFeatures,
 122                 RedundantSemicolons: RedundantSemicolons,
 123                 UnusedDocComment: UnusedDocComment,
 124             ]
 125         );
 126     };
 127 }
 128
 129 macro_rules! declare_combined_early_pass {
 130     ([$name:ident], $passes:tt) => (
 131         early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
 132     )
 133 }
 134
 135 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
 136 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
 137
 138 macro_rules! late_lint_passes {
 139     ($macro:path, $args:tt) => {
 140         $macro!(
 141             $args,
 142             [
 143                 // FIXME: Look into regression when this is used as a module lint
 144                 // May Depend on constants elsewhere
 145                 UnusedBrokenConst: UnusedBrokenConst,
 146                 // Uses attr::is_used which is untracked, can't be an incremental module pass.
 147                 UnusedAttributes: UnusedAttributes::new(),
 148                 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
 149                 UnstableFeatures: UnstableFeatures,
 150                 // Tracks state across modules
 151                 UnnameableTestItems: UnnameableTestItems::new(),
 152                 // Tracks attributes of parents
 153                 MissingDoc: MissingDoc::new(),
 154                 // Depends on access levels
 155                 // FIXME: Turn the computation of types which implement Debug into a query
 156                 // and change this to a module lint pass
 157                 MissingDebugImplementations: MissingDebugImplementations::default(),
 158                 ArrayIntoIter: ArrayIntoIter,
 159                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
 160             ]
 161         );
 162     };
 163 }
 164
 165 macro_rules! late_lint_mod_passes {
 166     ($macro:path, $args:tt) => {
 167         $macro!(
 168             $args,
 169             [
 170                 HardwiredLints: HardwiredLints,
 171                 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 172                 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 173                 VariantSizeDifferences: VariantSizeDifferences,
 174                 BoxPointers: BoxPointers,
 175                 PathStatements: PathStatements,
 176                 // Depends on referenced function signatures in expressions
 177                 UnusedResults: UnusedResults,
 178                 NonUpperCaseGlobals: NonUpperCaseGlobals,
 179                 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 180                 UnusedAllocation: UnusedAllocation,
 181                 // Depends on types used in type definitions
 182                 MissingCopyImplementations: MissingCopyImplementations,
 183                 // Depends on referenced function signatures in expressions
 184                 MutableTransmutes: MutableTransmutes,
 185                 TypeAliasBounds: TypeAliasBounds,
 186                 TrivialConstraints: TrivialConstraints,
 187                 TypeLimits: TypeLimits::new(),
 188                 NonSnakeCase: NonSnakeCase,
 189                 InvalidNoMangleItems: InvalidNoMangleItems,
 190                 // Depends on access levels
 191                 UnreachablePub: UnreachablePub,
 192                 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 193                 InvalidValue: InvalidValue,
 194             ]
 195         );
 196     };
 197 }
 198
 199 macro_rules! declare_combined_late_pass {
 200     ([$v:vis $name:ident], $passes:tt) => (
 201         late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
 202     )
 203 }
 204
 205 // FIXME: Make a separate lint type which do not require typeck tables
 206 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
 207
 208 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
 209
 210 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
 211     let mut lint_store = LintStore::new();
 212
 213     register_builtins(&mut lint_store, no_interleave_lints);
 214     if internal_lints {
 215         register_internals(&mut lint_store);
 216     }
 217
 218     lint_store
 219 }
 220
 221 /// Tell the `LintStore` about all the built-in lints (the ones
 222 /// defined in this crate and the ones defined in
 223 /// `rustc_session::lint::builtin`).
 224 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
 225     macro_rules! add_lint_group {
 226         ($name:expr, $($lint:ident),*) => (
 227             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 228         )
 229     }
 230
 231     macro_rules! register_pass {
 232         ($method:ident, $ty:ident, $constructor:expr) => {
 233             store.register_lints(&$ty::get_lints());
 234             store.$method(|| box $constructor);
 235         };
 236     }
 237
 238     macro_rules! register_passes {
 239         ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
 240             $(
 241                 register_pass!($method, $passes, $constructor);
 242             )*
 243         )
 244     }
 245
 246     if no_interleave_lints {
 247         pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
 248         early_lint_passes!(register_passes, register_early_pass);
 249         late_lint_passes!(register_passes, register_late_pass);
 250         late_lint_mod_passes!(register_passes, register_late_mod_pass);
 251     } else {
 252         store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 253         store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 254         store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 255         store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 256     }
 257
 258     add_lint_group!(
 259         "nonstandard_style",
 260         NON_CAMEL_CASE_TYPES,
 261         NON_SNAKE_CASE,
 262         NON_UPPER_CASE_GLOBALS
 263     );
 264
 265     add_lint_group!(
 266         "unused",
 267         UNUSED_IMPORTS,
 268         UNUSED_VARIABLES,
 269         UNUSED_ASSIGNMENTS,
 270         DEAD_CODE,
 271         UNUSED_MUT,
 272         UNREACHABLE_CODE,
 273         UNREACHABLE_PATTERNS,
 274         OVERLAPPING_PATTERNS,
 275         UNUSED_MUST_USE,
 276         UNUSED_UNSAFE,
 277         PATH_STATEMENTS,
 278         UNUSED_ATTRIBUTES,
 279         UNUSED_MACROS,
 280         UNUSED_ALLOCATION,
 281         UNUSED_DOC_COMMENTS,
 282         UNUSED_EXTERN_CRATES,
 283         UNUSED_FEATURES,
 284         UNUSED_LABELS,
 285         UNUSED_PARENS,
 286         UNUSED_BRACES,
 287         REDUNDANT_SEMICOLONS
 288     );
 289
 290     add_lint_group!(
 291         "rust_2018_idioms",
 292         BARE_TRAIT_OBJECTS,
 293         UNUSED_EXTERN_CRATES,
 294         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 295         ELIDED_LIFETIMES_IN_PATHS,
 296         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 297                                        // macros are ready for this yet.
 298                                        // UNREACHABLE_PUB,
 299
 300                                        // FIXME macro crates are not up for this yet, too much
 301                                        // breakage is seen if we try to encourage this lint.
 302                                        // MACRO_USE_EXTERN_CRATE
 303     );
 304
 305     add_lint_group!(
 306         "rustdoc",
 307         BROKEN_INTRA_DOC_LINKS,
 308         PRIVATE_INTRA_DOC_LINKS,
 309         INVALID_CODEBLOCK_ATTRIBUTES,
 310         MISSING_DOC_CODE_EXAMPLES,
 311         PRIVATE_DOC_TESTS
 312     );
 313
 314     // Register renamed and removed lints.
 315     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 316     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 317     store.register_renamed("bare_trait_object", "bare_trait_objects");
 318     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 319     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 320     store.register_renamed("async_idents", "keyword_idents");
 321     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 322     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 323     store.register_renamed("intra_doc_link_resolution_failure", "broken_intra_doc_links");
 324     store.register_removed("unknown_features", "replaced by an error");
 325     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 326     store.register_removed("negate_unsigned", "cast a signed value instead");
 327     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 328     // Register lint group aliases.
 329     store.register_group_alias("nonstandard_style", "bad_style");
 330     // This was renamed to `raw_pointer_derive`, which was then removed,
 331     // so it is also considered removed.
 332     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 333     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 334     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 335     store.register_removed("deprecated_attr", "use `deprecated` instead");
 336     store.register_removed(
 337         "transmute_from_fn_item_types",
 338         "always cast functions before transmuting them",
 339     );
 340     store.register_removed(
 341         "hr_lifetime_in_assoc_type",
 342         "converted into hard error, see issue #33685 \
 343          <https://github.com/rust-lang/rust/issues/33685> for more information",
 344     );
 345     store.register_removed(
 346         "inaccessible_extern_crate",
 347         "converted into hard error, see issue #36886 \
 348          <https://github.com/rust-lang/rust/issues/36886> for more information",
 349     );
 350     store.register_removed(
 351         "super_or_self_in_global_path",
 352         "converted into hard error, see issue #36888 \
 353          <https://github.com/rust-lang/rust/issues/36888> for more information",
 354     );
 355     store.register_removed(
 356         "overlapping_inherent_impls",
 357         "converted into hard error, see issue #36889 \
 358          <https://github.com/rust-lang/rust/issues/36889> for more information",
 359     );
 360     store.register_removed(
 361         "illegal_floating_point_constant_pattern",
 362         "converted into hard error, see issue #36890 \
 363          <https://github.com/rust-lang/rust/issues/36890> for more information",
 364     );
 365     store.register_removed(
 366         "illegal_struct_or_enum_constant_pattern",
 367         "converted into hard error, see issue #36891 \
 368          <https://github.com/rust-lang/rust/issues/36891> for more information",
 369     );
 370     store.register_removed(
 371         "lifetime_underscore",
 372         "converted into hard error, see issue #36892 \
 373          <https://github.com/rust-lang/rust/issues/36892> for more information",
 374     );
 375     store.register_removed(
 376         "extra_requirement_in_impl",
 377         "converted into hard error, see issue #37166 \
 378          <https://github.com/rust-lang/rust/issues/37166> for more information",
 379     );
 380     store.register_removed(
 381         "legacy_imports",
 382         "converted into hard error, see issue #38260 \
 383          <https://github.com/rust-lang/rust/issues/38260> for more information",
 384     );
 385     store.register_removed(
 386         "coerce_never",
 387         "converted into hard error, see issue #48950 \
 388          <https://github.com/rust-lang/rust/issues/48950> for more information",
 389     );
 390     store.register_removed(
 391         "resolve_trait_on_defaulted_unit",
 392         "converted into hard error, see issue #48950 \
 393          <https://github.com/rust-lang/rust/issues/48950> for more information",
 394     );
 395     store.register_removed(
 396         "private_no_mangle_fns",
 397         "no longer a warning, `#[no_mangle]` functions always exported",
 398     );
 399     store.register_removed(
 400         "private_no_mangle_statics",
 401         "no longer a warning, `#[no_mangle]` statics always exported",
 402     );
 403     store.register_removed("bad_repr", "replaced with a generic attribute input check");
 404     store.register_removed(
 405         "duplicate_matcher_binding_name",
 406         "converted into hard error, see issue #57742 \
 407          <https://github.com/rust-lang/rust/issues/57742> for more information",
 408     );
 409     store.register_removed(
 410         "incoherent_fundamental_impls",
 411         "converted into hard error, see issue #46205 \
 412          <https://github.com/rust-lang/rust/issues/46205> for more information",
 413     );
 414     store.register_removed(
 415         "legacy_constructor_visibility",
 416         "converted into hard error, see issue #39207 \
 417          <https://github.com/rust-lang/rust/issues/39207> for more information",
 418     );
 419     store.register_removed(
 420         "legacy_directory_ownership",
 421         "converted into hard error, see issue #37872 \
 422          <https://github.com/rust-lang/rust/issues/37872> for more information",
 423     );
 424     store.register_removed(
 425         "safe_extern_statics",
 426         "converted into hard error, see issue #36247 \
 427          <https://github.com/rust-lang/rust/issues/36247> for more information",
 428     );
 429     store.register_removed(
 430         "parenthesized_params_in_types_and_modules",
 431         "converted into hard error, see issue #42238 \
 432          <https://github.com/rust-lang/rust/issues/42238> for more information",
 433     );
 434     store.register_removed(
 435         "duplicate_macro_exports",
 436         "converted into hard error, see issue #35896 \
 437          <https://github.com/rust-lang/rust/issues/35896> for more information",
 438     );
 439     store.register_removed(
 440         "nested_impl_trait",
 441         "converted into hard error, see issue #59014 \
 442          <https://github.com/rust-lang/rust/issues/59014> for more information",
 443     );
 444     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 445 }
 446
 447 fn register_internals(store: &mut LintStore) {
 448     store.register_lints(&DefaultHashTypes::get_lints());
 449     store.register_early_pass(|| box DefaultHashTypes::new());
 450     store.register_lints(&LintPassImpl::get_lints());
 451     store.register_early_pass(|| box LintPassImpl);
 452     store.register_lints(&TyTyKind::get_lints());
 453     store.register_late_pass(|| box TyTyKind);
 454     store.register_group(
 455         false,
 456         "rustc::internal",
 457         None,
 458         vec![
 459             LintId::of(DEFAULT_HASH_TYPES),
 460             LintId::of(USAGE_OF_TY_TYKIND),
 461             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 462             LintId::of(TY_PASS_BY_REFERENCE),
 463             LintId::of(USAGE_OF_QUALIFIED_TY),
 464         ],
 465     );
 466 }