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_patterns)]
  33 #![feature(crate_visibility_modifier)]
  34 #![feature(format_args_capture)]
  35 #![feature(iter_order_by)]
  36 #![feature(iter_zip)]
  37 #![feature(never_type)]
  38 #![feature(nll)]
  39 #![feature(control_flow_enum)]
  40 #![recursion_limit = "256"]
  41
  42 #[macro_use]
  43 extern crate rustc_middle;
  44 #[macro_use]
  45 extern crate rustc_session;
  46
  47 mod array_into_iter;
  48 pub mod builtin;
  49 mod context;
  50 mod early;
  51 mod internal;
  52 mod late;
  53 mod levels;
  54 mod methods;
  55 mod non_ascii_idents;
  56 mod non_fmt_panic;
  57 mod nonstandard_style;
  58 mod noop_method_call;
  59 mod passes;
  60 mod redundant_semicolon;
  61 mod traits;
  62 mod types;
  63 mod unused;
  64
  65 pub use array_into_iter::ARRAY_INTO_ITER;
  66
  67 use rustc_ast as ast;
  68 use rustc_hir as hir;
  69 use rustc_hir::def_id::LocalDefId;
  70 use rustc_middle::ty::query::Providers;
  71 use rustc_middle::ty::TyCtxt;
  72 use rustc_session::lint::builtin::{
  73     BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
  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 non_fmt_panic::NonPanicFmt;
  84 use nonstandard_style::*;
  85 use noop_method_call::*;
  86 use redundant_semicolon::*;
  87 use traits::*;
  88 use types::*;
  89 use unused::*;
  90
  91 /// Useful for other parts of the compiler / Clippy.
  92 pub use builtin::SoftLints;
  93 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
  94 pub use early::check_ast_crate;
  95 pub use late::check_crate;
  96 pub use passes::{EarlyLintPass, LateLintPass};
  97 pub use rustc_session::lint::Level::{self, *};
  98 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
  99 pub use rustc_session::lint::{LintArray, LintPass};
 100
 101 pub fn provide(providers: &mut Providers) {
 102     levels::provide(providers);
 103     *providers = Providers { lint_mod, ..*providers };
 104 }
 105
 106 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
 107     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
 108 }
 109
 110 macro_rules! pre_expansion_lint_passes {
 111     ($macro:path, $args:tt) => {
 112         $macro!($args, [KeywordIdents: KeywordIdents,]);
 113     };
 114 }
 115
 116 macro_rules! early_lint_passes {
 117     ($macro:path, $args:tt) => {
 118         $macro!(
 119             $args,
 120             [
 121                 UnusedParens: UnusedParens,
 122                 UnusedBraces: UnusedBraces,
 123                 UnusedImportBraces: UnusedImportBraces,
 124                 UnsafeCode: UnsafeCode,
 125                 AnonymousParameters: AnonymousParameters,
 126                 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 127                 NonCamelCaseTypes: NonCamelCaseTypes,
 128                 DeprecatedAttr: DeprecatedAttr::new(),
 129                 WhileTrue: WhileTrue,
 130                 NonAsciiIdents: NonAsciiIdents,
 131                 IncompleteFeatures: IncompleteFeatures,
 132                 RedundantSemicolons: RedundantSemicolons,
 133                 UnusedDocComment: UnusedDocComment,
 134             ]
 135         );
 136     };
 137 }
 138
 139 macro_rules! declare_combined_early_pass {
 140     ([$name:ident], $passes:tt) => (
 141         early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
 142     )
 143 }
 144
 145 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
 146 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
 147
 148 macro_rules! late_lint_passes {
 149     ($macro:path, $args:tt) => {
 150         $macro!(
 151             $args,
 152             [
 153                 // FIXME: Look into regression when this is used as a module lint
 154                 // May Depend on constants elsewhere
 155                 UnusedBrokenConst: UnusedBrokenConst,
 156                 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
 157                 UnstableFeatures: UnstableFeatures,
 158                 // Tracks state across modules
 159                 UnnameableTestItems: UnnameableTestItems::new(),
 160                 // Tracks attributes of parents
 161                 MissingDoc: MissingDoc::new(),
 162                 // Depends on access levels
 163                 // FIXME: Turn the computation of types which implement Debug into a query
 164                 // and change this to a module lint pass
 165                 MissingDebugImplementations: MissingDebugImplementations::default(),
 166                 ArrayIntoIter: ArrayIntoIter::default(),
 167                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
 168                 DropTraitConstraints: DropTraitConstraints,
 169                 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
 170                 NonPanicFmt: NonPanicFmt,
 171                 NoopMethodCall: NoopMethodCall,
 172                 InvalidAtomicOrdering: InvalidAtomicOrdering,
 173                 NamedAsmLabels: NamedAsmLabels,
 174             ]
 175         );
 176     };
 177 }
 178
 179 macro_rules! late_lint_mod_passes {
 180     ($macro:path, $args:tt) => {
 181         $macro!(
 182             $args,
 183             [
 184                 HardwiredLints: HardwiredLints,
 185                 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 186                 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 187                 VariantSizeDifferences: VariantSizeDifferences,
 188                 BoxPointers: BoxPointers,
 189                 PathStatements: PathStatements,
 190                 // Depends on referenced function signatures in expressions
 191                 UnusedResults: UnusedResults,
 192                 NonUpperCaseGlobals: NonUpperCaseGlobals,
 193                 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 194                 UnusedAllocation: UnusedAllocation,
 195                 // Depends on types used in type definitions
 196                 MissingCopyImplementations: MissingCopyImplementations,
 197                 // Depends on referenced function signatures in expressions
 198                 MutableTransmutes: MutableTransmutes,
 199                 TypeAliasBounds: TypeAliasBounds,
 200                 TrivialConstraints: TrivialConstraints,
 201                 TypeLimits: TypeLimits::new(),
 202                 NonSnakeCase: NonSnakeCase,
 203                 InvalidNoMangleItems: InvalidNoMangleItems,
 204                 // Depends on access levels
 205                 UnreachablePub: UnreachablePub,
 206                 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 207                 InvalidValue: InvalidValue,
 208                 DerefNullPtr: DerefNullPtr,
 209             ]
 210         );
 211     };
 212 }
 213
 214 macro_rules! declare_combined_late_pass {
 215     ([$v:vis $name:ident], $passes:tt) => (
 216         late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
 217     )
 218 }
 219
 220 // FIXME: Make a separate lint type which do not require typeck tables
 221 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
 222
 223 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
 224
 225 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
 226     let mut lint_store = LintStore::new();
 227
 228     register_builtins(&mut lint_store, no_interleave_lints);
 229     if internal_lints {
 230         register_internals(&mut lint_store);
 231     }
 232
 233     lint_store
 234 }
 235
 236 /// Tell the `LintStore` about all the built-in lints (the ones
 237 /// defined in this crate and the ones defined in
 238 /// `rustc_session::lint::builtin`).
 239 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
 240     macro_rules! add_lint_group {
 241         ($name:expr, $($lint:ident),*) => (
 242             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 243         )
 244     }
 245
 246     macro_rules! register_pass {
 247         ($method:ident, $ty:ident, $constructor:expr) => {
 248             store.register_lints(&$ty::get_lints());
 249             store.$method(|| Box::new($constructor));
 250         };
 251     }
 252
 253     macro_rules! register_passes {
 254         ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
 255             $(
 256                 register_pass!($method, $passes, $constructor);
 257             )*
 258         )
 259     }
 260
 261     if no_interleave_lints {
 262         pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
 263         early_lint_passes!(register_passes, register_early_pass);
 264         late_lint_passes!(register_passes, register_late_pass);
 265         late_lint_mod_passes!(register_passes, register_late_mod_pass);
 266     } else {
 267         store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 268         store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 269         store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 270         store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 271     }
 272
 273     add_lint_group!(
 274         "nonstandard_style",
 275         NON_CAMEL_CASE_TYPES,
 276         NON_SNAKE_CASE,
 277         NON_UPPER_CASE_GLOBALS
 278     );
 279
 280     add_lint_group!(
 281         "unused",
 282         UNUSED_IMPORTS,
 283         UNUSED_VARIABLES,
 284         UNUSED_ASSIGNMENTS,
 285         DEAD_CODE,
 286         UNUSED_MUT,
 287         UNREACHABLE_CODE,
 288         UNREACHABLE_PATTERNS,
 289         UNUSED_MUST_USE,
 290         UNUSED_UNSAFE,
 291         PATH_STATEMENTS,
 292         UNUSED_ATTRIBUTES,
 293         UNUSED_MACROS,
 294         UNUSED_ALLOCATION,
 295         UNUSED_DOC_COMMENTS,
 296         UNUSED_EXTERN_CRATES,
 297         UNUSED_FEATURES,
 298         UNUSED_LABELS,
 299         UNUSED_PARENS,
 300         UNUSED_BRACES,
 301         MUST_NOT_SUSPEND,
 302         REDUNDANT_SEMICOLONS
 303     );
 304
 305     add_lint_group!(
 306         "rust_2018_idioms",
 307         BARE_TRAIT_OBJECTS,
 308         UNUSED_EXTERN_CRATES,
 309         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 310         ELIDED_LIFETIMES_IN_PATHS,
 311         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 312                                        // macros are ready for this yet.
 313                                        // UNREACHABLE_PUB,
 314
 315                                        // FIXME macro crates are not up for this yet, too much
 316                                        // breakage is seen if we try to encourage this lint.
 317                                        // MACRO_USE_EXTERN_CRATE
 318     );
 319
 320     // Register renamed and removed lints.
 321     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 322     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 323     store.register_renamed("bare_trait_object", "bare_trait_objects");
 324     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 325     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 326     store.register_renamed("async_idents", "keyword_idents");
 327     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 328     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 329     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
 330     store.register_renamed("safe_packed_borrows", "unaligned_references");
 331     store.register_renamed("disjoint_capture_migration", "rust_2021_incompatible_closure_captures");
 332     store.register_renamed("or_patterns_back_compat", "rust_2021_incompatible_or_patterns");
 333     store.register_renamed("non_fmt_panic", "non_fmt_panics");
 334
 335     // These were moved to tool lints, but rustc still sees them when compiling normally, before
 336     // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
 337     // `register_removed` explicitly.
 338     const RUSTDOC_LINTS: &[&str] = &[
 339         "broken_intra_doc_links",
 340         "private_intra_doc_links",
 341         "missing_crate_level_docs",
 342         "missing_doc_code_examples",
 343         "private_doc_tests",
 344         "invalid_codeblock_attributes",
 345         "invalid_html_tags",
 346         "non_autolinks",
 347     ];
 348     for rustdoc_lint in RUSTDOC_LINTS {
 349         store.register_ignored(rustdoc_lint);
 350     }
 351     store.register_removed(
 352         "intra_doc_link_resolution_failure",
 353         "use `rustdoc::broken_intra_doc_links` instead",
 354     );
 355     store.register_removed("rustdoc", "use `rustdoc::all` instead");
 356
 357     store.register_removed("unknown_features", "replaced by an error");
 358     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 359     store.register_removed("negate_unsigned", "cast a signed value instead");
 360     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 361     // Register lint group aliases.
 362     store.register_group_alias("nonstandard_style", "bad_style");
 363     // This was renamed to `raw_pointer_derive`, which was then removed,
 364     // so it is also considered removed.
 365     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 366     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 367     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 368     store.register_removed("deprecated_attr", "use `deprecated` instead");
 369     store.register_removed(
 370         "transmute_from_fn_item_types",
 371         "always cast functions before transmuting them",
 372     );
 373     store.register_removed(
 374         "hr_lifetime_in_assoc_type",
 375         "converted into hard error, see issue #33685 \
 376          <https://github.com/rust-lang/rust/issues/33685> for more information",
 377     );
 378     store.register_removed(
 379         "inaccessible_extern_crate",
 380         "converted into hard error, see issue #36886 \
 381          <https://github.com/rust-lang/rust/issues/36886> for more information",
 382     );
 383     store.register_removed(
 384         "super_or_self_in_global_path",
 385         "converted into hard error, see issue #36888 \
 386          <https://github.com/rust-lang/rust/issues/36888> for more information",
 387     );
 388     store.register_removed(
 389         "overlapping_inherent_impls",
 390         "converted into hard error, see issue #36889 \
 391          <https://github.com/rust-lang/rust/issues/36889> for more information",
 392     );
 393     store.register_removed(
 394         "illegal_floating_point_constant_pattern",
 395         "converted into hard error, see issue #36890 \
 396          <https://github.com/rust-lang/rust/issues/36890> for more information",
 397     );
 398     store.register_removed(
 399         "illegal_struct_or_enum_constant_pattern",
 400         "converted into hard error, see issue #36891 \
 401          <https://github.com/rust-lang/rust/issues/36891> for more information",
 402     );
 403     store.register_removed(
 404         "lifetime_underscore",
 405         "converted into hard error, see issue #36892 \
 406          <https://github.com/rust-lang/rust/issues/36892> for more information",
 407     );
 408     store.register_removed(
 409         "extra_requirement_in_impl",
 410         "converted into hard error, see issue #37166 \
 411          <https://github.com/rust-lang/rust/issues/37166> for more information",
 412     );
 413     store.register_removed(
 414         "legacy_imports",
 415         "converted into hard error, see issue #38260 \
 416          <https://github.com/rust-lang/rust/issues/38260> for more information",
 417     );
 418     store.register_removed(
 419         "coerce_never",
 420         "converted into hard error, see issue #48950 \
 421          <https://github.com/rust-lang/rust/issues/48950> for more information",
 422     );
 423     store.register_removed(
 424         "resolve_trait_on_defaulted_unit",
 425         "converted into hard error, see issue #48950 \
 426          <https://github.com/rust-lang/rust/issues/48950> for more information",
 427     );
 428     store.register_removed(
 429         "private_no_mangle_fns",
 430         "no longer a warning, `#[no_mangle]` functions always exported",
 431     );
 432     store.register_removed(
 433         "private_no_mangle_statics",
 434         "no longer a warning, `#[no_mangle]` statics always exported",
 435     );
 436     store.register_removed("bad_repr", "replaced with a generic attribute input check");
 437     store.register_removed(
 438         "duplicate_matcher_binding_name",
 439         "converted into hard error, see issue #57742 \
 440          <https://github.com/rust-lang/rust/issues/57742> for more information",
 441     );
 442     store.register_removed(
 443         "incoherent_fundamental_impls",
 444         "converted into hard error, see issue #46205 \
 445          <https://github.com/rust-lang/rust/issues/46205> for more information",
 446     );
 447     store.register_removed(
 448         "legacy_constructor_visibility",
 449         "converted into hard error, see issue #39207 \
 450          <https://github.com/rust-lang/rust/issues/39207> for more information",
 451     );
 452     store.register_removed(
 453         "legacy_directory_ownership",
 454         "converted into hard error, see issue #37872 \
 455          <https://github.com/rust-lang/rust/issues/37872> for more information",
 456     );
 457     store.register_removed(
 458         "safe_extern_statics",
 459         "converted into hard error, see issue #36247 \
 460          <https://github.com/rust-lang/rust/issues/36247> for more information",
 461     );
 462     store.register_removed(
 463         "parenthesized_params_in_types_and_modules",
 464         "converted into hard error, see issue #42238 \
 465          <https://github.com/rust-lang/rust/issues/42238> for more information",
 466     );
 467     store.register_removed(
 468         "duplicate_macro_exports",
 469         "converted into hard error, see issue #35896 \
 470          <https://github.com/rust-lang/rust/issues/35896> for more information",
 471     );
 472     store.register_removed(
 473         "nested_impl_trait",
 474         "converted into hard error, see issue #59014 \
 475          <https://github.com/rust-lang/rust/issues/59014> for more information",
 476     );
 477     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 478 }
 479
 480 fn register_internals(store: &mut LintStore) {
 481     store.register_lints(&LintPassImpl::get_lints());
 482     store.register_early_pass(|| Box::new(LintPassImpl));
 483     store.register_lints(&DefaultHashTypes::get_lints());
 484     store.register_late_pass(|| Box::new(DefaultHashTypes));
 485     store.register_lints(&ExistingDocKeyword::get_lints());
 486     store.register_late_pass(|| Box::new(ExistingDocKeyword));
 487     store.register_lints(&TyTyKind::get_lints());
 488     store.register_late_pass(|| Box::new(TyTyKind));
 489     store.register_group(
 490         false,
 491         "rustc::internal",
 492         None,
 493         vec![
 494             LintId::of(DEFAULT_HASH_TYPES),
 495             LintId::of(USAGE_OF_TY_TYKIND),
 496             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 497             LintId::of(TY_PASS_BY_REFERENCE),
 498             LintId::of(USAGE_OF_QUALIFIED_TY),
 499             LintId::of(EXISTING_DOC_KEYWORD),
 500         ],
 501     );
 502 }
 503
 504 #[cfg(test)]
 505 mod tests;