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