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 #![feature(half_open_range_patterns)]
  39 #![feature(exclusive_range_pattern)]
  40 #![feature(control_flow_enum)]
  41 #![recursion_limit = "256"]
  42
  43 #[macro_use]
  44 extern crate rustc_middle;
  45 #[macro_use]
  46 extern crate rustc_session;
  47
  48 mod array_into_iter;
  49 pub mod builtin;
  50 mod context;
  51 mod early;
  52 mod internal;
  53 mod late;
  54 mod levels;
  55 mod methods;
  56 mod non_ascii_idents;
  57 mod nonstandard_style;
  58 mod panic_fmt;
  59 mod passes;
  60 mod redundant_semicolon;
  61 mod traits;
  62 mod types;
  63 mod unused;
  64
  65 use rustc_ast as ast;
  66 use rustc_hir as hir;
  67 use rustc_hir::def_id::LocalDefId;
  68 use rustc_middle::ty::query::Providers;
  69 use rustc_middle::ty::TyCtxt;
  70 use rustc_session::lint::builtin::{
  71     BARE_TRAIT_OBJECTS, BROKEN_INTRA_DOC_LINKS, ELIDED_LIFETIMES_IN_PATHS,
  72     EXPLICIT_OUTLIVES_REQUIREMENTS, INVALID_CODEBLOCK_ATTRIBUTES, INVALID_HTML_TAGS,
  73     MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
  74 };
  75 use rustc_span::symbol::{Ident, Symbol};
  76 use rustc_span::Span;
  77
  78 use array_into_iter::ArrayIntoIter;
  79 use builtin::*;
  80 use internal::*;
  81 use methods::*;
  82 use non_ascii_idents::*;
  83 use nonstandard_style::*;
  84 use panic_fmt::PanicFmt;
  85 use redundant_semicolon::*;
  86 use traits::*;
  87 use types::*;
  88 use unused::*;
  89
  90 /// Useful for other parts of the compiler / Clippy.
  91 pub use builtin::SoftLints;
  92 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
  93 pub use early::check_ast_crate;
  94 pub use late::check_crate;
  95 pub use passes::{EarlyLintPass, LateLintPass};
  96 pub use rustc_session::lint::Level::{self, *};
  97 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
  98 pub use rustc_session::lint::{LintArray, LintPass};
  99
 100 pub fn provide(providers: &mut Providers) {
 101     levels::provide(providers);
 102     *providers = Providers { lint_mod, ..*providers };
 103 }
 104
 105 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
 106     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
 107 }
 108
 109 macro_rules! pre_expansion_lint_passes {
 110     ($macro:path, $args:tt) => {
 111         $macro!($args, [KeywordIdents: KeywordIdents,]);
 112     };
 113 }
 114
 115 macro_rules! early_lint_passes {
 116     ($macro:path, $args:tt) => {
 117         $macro!(
 118             $args,
 119             [
 120                 UnusedParens: UnusedParens,
 121                 UnusedBraces: UnusedBraces,
 122                 UnusedImportBraces: UnusedImportBraces,
 123                 UnsafeCode: UnsafeCode,
 124                 AnonymousParameters: AnonymousParameters,
 125                 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 126                 NonCamelCaseTypes: NonCamelCaseTypes,
 127                 DeprecatedAttr: DeprecatedAttr::new(),
 128                 WhileTrue: WhileTrue,
 129                 NonAsciiIdents: NonAsciiIdents,
 130                 IncompleteFeatures: IncompleteFeatures,
 131                 RedundantSemicolons: RedundantSemicolons,
 132                 UnusedDocComment: UnusedDocComment,
 133             ]
 134         );
 135     };
 136 }
 137
 138 macro_rules! declare_combined_early_pass {
 139     ([$name:ident], $passes:tt) => (
 140         early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
 141     )
 142 }
 143
 144 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
 145 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
 146
 147 macro_rules! late_lint_passes {
 148     ($macro:path, $args:tt) => {
 149         $macro!(
 150             $args,
 151             [
 152                 // FIXME: Look into regression when this is used as a module lint
 153                 // May Depend on constants elsewhere
 154                 UnusedBrokenConst: UnusedBrokenConst,
 155                 // Uses attr::is_used which is untracked, can't be an incremental module pass.
 156                 UnusedAttributes: UnusedAttributes::new(),
 157                 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
 158                 UnstableFeatures: UnstableFeatures,
 159                 // Tracks state across modules
 160                 UnnameableTestItems: UnnameableTestItems::new(),
 161                 // Tracks attributes of parents
 162                 MissingDoc: MissingDoc::new(),
 163                 // Depends on access levels
 164                 // FIXME: Turn the computation of types which implement Debug into a query
 165                 // and change this to a module lint pass
 166                 MissingDebugImplementations: MissingDebugImplementations::default(),
 167                 ArrayIntoIter: ArrayIntoIter,
 168                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
 169                 DropTraitConstraints: DropTraitConstraints,
 170                 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
 171                 PanicFmt: PanicFmt,
 172             ]
 173         );
 174     };
 175 }
 176
 177 macro_rules! late_lint_mod_passes {
 178     ($macro:path, $args:tt) => {
 179         $macro!(
 180             $args,
 181             [
 182                 HardwiredLints: HardwiredLints,
 183                 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 184                 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 185                 VariantSizeDifferences: VariantSizeDifferences,
 186                 BoxPointers: BoxPointers,
 187                 PathStatements: PathStatements,
 188                 // Depends on referenced function signatures in expressions
 189                 UnusedResults: UnusedResults,
 190                 NonUpperCaseGlobals: NonUpperCaseGlobals,
 191                 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 192                 UnusedAllocation: UnusedAllocation,
 193                 // Depends on types used in type definitions
 194                 MissingCopyImplementations: MissingCopyImplementations,
 195                 // Depends on referenced function signatures in expressions
 196                 MutableTransmutes: MutableTransmutes,
 197                 TypeAliasBounds: TypeAliasBounds,
 198                 TrivialConstraints: TrivialConstraints,
 199                 TypeLimits: TypeLimits::new(),
 200                 NonSnakeCase: NonSnakeCase,
 201                 InvalidNoMangleItems: InvalidNoMangleItems,
 202                 // Depends on access levels
 203                 UnreachablePub: UnreachablePub,
 204                 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 205                 InvalidValue: InvalidValue,
 206             ]
 207         );
 208     };
 209 }
 210
 211 macro_rules! declare_combined_late_pass {
 212     ([$v:vis $name:ident], $passes:tt) => (
 213         late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
 214     )
 215 }
 216
 217 // FIXME: Make a separate lint type which do not require typeck tables
 218 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
 219
 220 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
 221
 222 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
 223     let mut lint_store = LintStore::new();
 224
 225     register_builtins(&mut lint_store, no_interleave_lints);
 226     if internal_lints {
 227         register_internals(&mut lint_store);
 228     }
 229
 230     lint_store
 231 }
 232
 233 /// Tell the `LintStore` about all the built-in lints (the ones
 234 /// defined in this crate and the ones defined in
 235 /// `rustc_session::lint::builtin`).
 236 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
 237     macro_rules! add_lint_group {
 238         ($name:expr, $($lint:ident),*) => (
 239             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 240         )
 241     }
 242
 243     macro_rules! register_pass {
 244         ($method:ident, $ty:ident, $constructor:expr) => {
 245             store.register_lints(&$ty::get_lints());
 246             store.$method(|| box $constructor);
 247         };
 248     }
 249
 250     macro_rules! register_passes {
 251         ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
 252             $(
 253                 register_pass!($method, $passes, $constructor);
 254             )*
 255         )
 256     }
 257
 258     if no_interleave_lints {
 259         pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
 260         early_lint_passes!(register_passes, register_early_pass);
 261         late_lint_passes!(register_passes, register_late_pass);
 262         late_lint_mod_passes!(register_passes, register_late_mod_pass);
 263     } else {
 264         store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 265         store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 266         store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 267         store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 268     }
 269
 270     add_lint_group!(
 271         "nonstandard_style",
 272         NON_CAMEL_CASE_TYPES,
 273         NON_SNAKE_CASE,
 274         NON_UPPER_CASE_GLOBALS
 275     );
 276
 277     add_lint_group!(
 278         "unused",
 279         UNUSED_IMPORTS,
 280         UNUSED_VARIABLES,
 281         UNUSED_ASSIGNMENTS,
 282         DEAD_CODE,
 283         UNUSED_MUT,
 284         UNREACHABLE_CODE,
 285         UNREACHABLE_PATTERNS,
 286         UNUSED_MUST_USE,
 287         UNUSED_UNSAFE,
 288         PATH_STATEMENTS,
 289         UNUSED_ATTRIBUTES,
 290         UNUSED_MACROS,
 291         UNUSED_ALLOCATION,
 292         UNUSED_DOC_COMMENTS,
 293         UNUSED_EXTERN_CRATES,
 294         UNUSED_FEATURES,
 295         UNUSED_LABELS,
 296         UNUSED_PARENS,
 297         UNUSED_BRACES,
 298         REDUNDANT_SEMICOLONS
 299     );
 300
 301     add_lint_group!(
 302         "rust_2018_idioms",
 303         BARE_TRAIT_OBJECTS,
 304         UNUSED_EXTERN_CRATES,
 305         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 306         ELIDED_LIFETIMES_IN_PATHS,
 307         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 308                                        // macros are ready for this yet.
 309                                        // UNREACHABLE_PUB,
 310
 311                                        // FIXME macro crates are not up for this yet, too much
 312                                        // breakage is seen if we try to encourage this lint.
 313                                        // MACRO_USE_EXTERN_CRATE
 314     );
 315
 316     add_lint_group!(
 317         "rustdoc",
 318         NON_AUTOLINKS,
 319         BROKEN_INTRA_DOC_LINKS,
 320         PRIVATE_INTRA_DOC_LINKS,
 321         INVALID_CODEBLOCK_ATTRIBUTES,
 322         MISSING_DOC_CODE_EXAMPLES,
 323         PRIVATE_DOC_TESTS,
 324         INVALID_HTML_TAGS
 325     );
 326
 327     // Register renamed and removed lints.
 328     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 329     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 330     store.register_renamed("bare_trait_object", "bare_trait_objects");
 331     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 332     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 333     store.register_renamed("async_idents", "keyword_idents");
 334     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 335     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 336     store.register_renamed("intra_doc_link_resolution_failure", "broken_intra_doc_links");
 337     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
 338     store.register_removed("unknown_features", "replaced by an error");
 339     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 340     store.register_removed("negate_unsigned", "cast a signed value instead");
 341     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 342     // Register lint group aliases.
 343     store.register_group_alias("nonstandard_style", "bad_style");
 344     // This was renamed to `raw_pointer_derive`, which was then removed,
 345     // so it is also considered removed.
 346     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 347     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 348     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 349     store.register_removed("deprecated_attr", "use `deprecated` instead");
 350     store.register_removed(
 351         "transmute_from_fn_item_types",
 352         "always cast functions before transmuting them",
 353     );
 354     store.register_removed(
 355         "hr_lifetime_in_assoc_type",
 356         "converted into hard error, see issue #33685 \
 357          <https://github.com/rust-lang/rust/issues/33685> for more information",
 358     );
 359     store.register_removed(
 360         "inaccessible_extern_crate",
 361         "converted into hard error, see issue #36886 \
 362          <https://github.com/rust-lang/rust/issues/36886> for more information",
 363     );
 364     store.register_removed(
 365         "super_or_self_in_global_path",
 366         "converted into hard error, see issue #36888 \
 367          <https://github.com/rust-lang/rust/issues/36888> for more information",
 368     );
 369     store.register_removed(
 370         "overlapping_inherent_impls",
 371         "converted into hard error, see issue #36889 \
 372          <https://github.com/rust-lang/rust/issues/36889> for more information",
 373     );
 374     store.register_removed(
 375         "illegal_floating_point_constant_pattern",
 376         "converted into hard error, see issue #36890 \
 377          <https://github.com/rust-lang/rust/issues/36890> for more information",
 378     );
 379     store.register_removed(
 380         "illegal_struct_or_enum_constant_pattern",
 381         "converted into hard error, see issue #36891 \
 382          <https://github.com/rust-lang/rust/issues/36891> for more information",
 383     );
 384     store.register_removed(
 385         "lifetime_underscore",
 386         "converted into hard error, see issue #36892 \
 387          <https://github.com/rust-lang/rust/issues/36892> for more information",
 388     );
 389     store.register_removed(
 390         "extra_requirement_in_impl",
 391         "converted into hard error, see issue #37166 \
 392          <https://github.com/rust-lang/rust/issues/37166> for more information",
 393     );
 394     store.register_removed(
 395         "legacy_imports",
 396         "converted into hard error, see issue #38260 \
 397          <https://github.com/rust-lang/rust/issues/38260> for more information",
 398     );
 399     store.register_removed(
 400         "coerce_never",
 401         "converted into hard error, see issue #48950 \
 402          <https://github.com/rust-lang/rust/issues/48950> for more information",
 403     );
 404     store.register_removed(
 405         "resolve_trait_on_defaulted_unit",
 406         "converted into hard error, see issue #48950 \
 407          <https://github.com/rust-lang/rust/issues/48950> for more information",
 408     );
 409     store.register_removed(
 410         "private_no_mangle_fns",
 411         "no longer a warning, `#[no_mangle]` functions always exported",
 412     );
 413     store.register_removed(
 414         "private_no_mangle_statics",
 415         "no longer a warning, `#[no_mangle]` statics always exported",
 416     );
 417     store.register_removed("bad_repr", "replaced with a generic attribute input check");
 418     store.register_removed(
 419         "duplicate_matcher_binding_name",
 420         "converted into hard error, see issue #57742 \
 421          <https://github.com/rust-lang/rust/issues/57742> for more information",
 422     );
 423     store.register_removed(
 424         "incoherent_fundamental_impls",
 425         "converted into hard error, see issue #46205 \
 426          <https://github.com/rust-lang/rust/issues/46205> for more information",
 427     );
 428     store.register_removed(
 429         "legacy_constructor_visibility",
 430         "converted into hard error, see issue #39207 \
 431          <https://github.com/rust-lang/rust/issues/39207> for more information",
 432     );
 433     store.register_removed(
 434         "legacy_directory_ownership",
 435         "converted into hard error, see issue #37872 \
 436          <https://github.com/rust-lang/rust/issues/37872> for more information",
 437     );
 438     store.register_removed(
 439         "safe_extern_statics",
 440         "converted into hard error, see issue #36247 \
 441          <https://github.com/rust-lang/rust/issues/36247> for more information",
 442     );
 443     store.register_removed(
 444         "parenthesized_params_in_types_and_modules",
 445         "converted into hard error, see issue #42238 \
 446          <https://github.com/rust-lang/rust/issues/42238> for more information",
 447     );
 448     store.register_removed(
 449         "duplicate_macro_exports",
 450         "converted into hard error, see issue #35896 \
 451          <https://github.com/rust-lang/rust/issues/35896> for more information",
 452     );
 453     store.register_removed(
 454         "nested_impl_trait",
 455         "converted into hard error, see issue #59014 \
 456          <https://github.com/rust-lang/rust/issues/59014> for more information",
 457     );
 458     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 459 }
 460
 461 fn register_internals(store: &mut LintStore) {
 462     store.register_lints(&DefaultHashTypes::get_lints());
 463     store.register_early_pass(|| box DefaultHashTypes::new());
 464     store.register_lints(&LintPassImpl::get_lints());
 465     store.register_early_pass(|| box LintPassImpl);
 466     store.register_lints(&ExistingDocKeyword::get_lints());
 467     store.register_late_pass(|| box ExistingDocKeyword);
 468     store.register_lints(&TyTyKind::get_lints());
 469     store.register_late_pass(|| box TyTyKind);
 470     store.register_group(
 471         false,
 472         "rustc::internal",
 473         None,
 474         vec![
 475             LintId::of(DEFAULT_HASH_TYPES),
 476             LintId::of(USAGE_OF_TY_TYKIND),
 477             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 478             LintId::of(TY_PASS_BY_REFERENCE),
 479             LintId::of(USAGE_OF_QUALIFIED_TY),
 480             LintId::of(EXISTING_DOC_KEYWORD),
 481         ],
 482     );
 483 }