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