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