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