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