src/librustc_lint/lib.rs

   1 //! # Lints in the Rust compiler
   2 //!
   3 //! This currently only contains the definitions and implementations
   4 //! of most of the lints that `rustc` supports directly, it does not
   5 //! contain the infrastructure for defining/registering lints. That is
   6 //! available in `rustc::lint` and `rustc_plugin` respectively.
   7 //!
   8 //! ## Note
   9 //!
  10 //! This API is completely unstable and subject to change.
  11
  12 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
  13
  14 #![cfg_attr(test, feature(test))]
  15 #![feature(box_patterns)]
  16 #![feature(box_syntax)]
  17 #![feature(nll)]
  18 #![feature(rustc_diagnostic_macros)]
  19
  20 #![recursion_limit="256"]
  21
  22 #![deny(rust_2018_idioms)]
  23 #![deny(internal)]
  24
  25 #[macro_use]
  26 extern crate rustc;
  27
  28 mod diagnostics;
  29 mod nonstandard_style;
  30 pub mod builtin;
  31 mod types;
  32 mod unused;
  33
  34 use rustc::lint;
  35 use rustc::lint::{EarlyContext, LateContext, LateLintPass, EarlyLintPass, LintPass, LintArray};
  36 use rustc::lint::builtin::{
  37     BARE_TRAIT_OBJECTS,
  38     ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
  39     ELIDED_LIFETIMES_IN_PATHS,
  40     EXPLICIT_OUTLIVES_REQUIREMENTS,
  41     INTRA_DOC_LINK_RESOLUTION_FAILURE,
  42     MISSING_DOC_CODE_EXAMPLES,
  43     PRIVATE_DOC_TESTS,
  44     parser::QUESTION_MARK_MACRO_SEP,
  45     parser::ILL_FORMED_ATTRIBUTE_INPUT,
  46 };
  47 use rustc::session;
  48 use rustc::hir;
  49 use rustc::hir::def_id::DefId;
  50 use rustc::ty::query::Providers;
  51 use rustc::ty::TyCtxt;
  52
  53 use syntax::ast;
  54 use syntax::edition::Edition;
  55 use syntax_pos::Span;
  56
  57 use session::Session;
  58 use lint::LintId;
  59 use lint::FutureIncompatibleInfo;
  60
  61 use nonstandard_style::*;
  62 use builtin::*;
  63 use types::*;
  64 use unused::*;
  65 use rustc::lint::internal::*;
  66
  67 /// Useful for other parts of the compiler.
  68 pub use builtin::SoftLints;
  69
  70 pub fn provide(providers: &mut Providers<'_>) {
  71     *providers = Providers {
  72         lint_mod,
  73         ..*providers
  74     };
  75 }
  76
  77 fn lint_mod<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
  78     lint::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
  79 }
  80
  81 macro_rules! pre_expansion_lint_passes {
  82     ($macro:path, $args:tt) => (
  83         $macro!($args, [
  84             KeywordIdents: KeywordIdents,
  85             UnusedDocComment: UnusedDocComment,
  86         ]);
  87     )
  88 }
  89
  90 macro_rules! early_lint_passes {
  91     ($macro:path, $args:tt) => (
  92         $macro!($args, [
  93             UnusedParens: UnusedParens,
  94             UnusedImportBraces: UnusedImportBraces,
  95             UnsafeCode: UnsafeCode,
  96             AnonymousParameters: AnonymousParameters,
  97             EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns,
  98             NonCamelCaseTypes: NonCamelCaseTypes,
  99             DeprecatedAttr: DeprecatedAttr::new(),
 100         ]);
 101     )
 102 }
 103
 104 macro_rules! declare_combined_early_pass {
 105     ([$name:ident], $passes:tt) => (
 106         early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
 107     )
 108 }
 109
 110 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
 111 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
 112
 113 macro_rules! late_lint_passes {
 114     ($macro:path, $args:tt) => (
 115         $macro!($args, [
 116             // FIXME: Look into regression when this is used as a module lint
 117             // May Depend on constants elsewhere
 118             UnusedBrokenConst: UnusedBrokenConst,
 119
 120             // Uses attr::is_used which is untracked, can't be an incremental module pass.
 121             UnusedAttributes: UnusedAttributes::new(),
 122
 123             // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
 124             UnstableFeatures: UnstableFeatures,
 125
 126             // Tracks state across modules
 127             UnnameableTestItems: UnnameableTestItems::new(),
 128
 129             // Tracks attributes of parents
 130             MissingDoc: MissingDoc::new(),
 131
 132             // Depends on access levels
 133             // FIXME: Turn the computation of types which implement Debug into a query
 134             // and change this to a module lint pass
 135             MissingDebugImplementations: MissingDebugImplementations::new(),
 136         ]);
 137     )
 138 }
 139
 140 macro_rules! late_lint_mod_passes {
 141     ($macro:path, $args:tt) => (
 142         $macro!($args, [
 143             HardwiredLints: HardwiredLints,
 144             WhileTrue: WhileTrue,
 145             ImproperCTypes: ImproperCTypes,
 146             VariantSizeDifferences: VariantSizeDifferences,
 147             BoxPointers: BoxPointers,
 148             PathStatements: PathStatements,
 149
 150             // Depends on referenced function signatures in expressions
 151             UnusedResults: UnusedResults,
 152
 153             NonUpperCaseGlobals: NonUpperCaseGlobals,
 154             NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 155             UnusedAllocation: UnusedAllocation,
 156
 157             // Depends on types used in type definitions
 158             MissingCopyImplementations: MissingCopyImplementations,
 159
 160             PluginAsLibrary: PluginAsLibrary,
 161
 162             // Depends on referenced function signatures in expressions
 163             MutableTransmutes: MutableTransmutes,
 164
 165             // Depends on types of fields, checks if they implement Drop
 166             UnionsWithDropFields: UnionsWithDropFields,
 167
 168             TypeAliasBounds: TypeAliasBounds,
 169
 170             TrivialConstraints: TrivialConstraints,
 171             TypeLimits: TypeLimits::new(),
 172
 173             NonSnakeCase: NonSnakeCase,
 174             InvalidNoMangleItems: InvalidNoMangleItems,
 175
 176             // Depends on access levels
 177             UnreachablePub: UnreachablePub,
 178
 179             ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 180         ]);
 181     )
 182 }
 183
 184 macro_rules! declare_combined_late_pass {
 185     ([$v:vis $name:ident], $passes:tt) => (
 186         late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
 187     )
 188 }
 189
 190 // FIXME: Make a separate lint type which do not require typeck tables
 191 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
 192
 193 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
 194
 195 /// Tell the `LintStore` about all the built-in lints (the ones
 196 /// defined in this crate and the ones defined in
 197 /// `rustc::lint::builtin`).
 198 pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
 199     macro_rules! add_lint_group {
 200         ($sess:ident, $name:expr, $($lint:ident),*) => (
 201             store.register_group($sess, false, $name, None, vec![$(LintId::of($lint)),*]);
 202         )
 203     }
 204
 205     macro_rules! register_pass {
 206         ($method:ident, $constructor:expr, [$($args:expr),*]) => (
 207             store.$method(sess, false, false, $($args,)* box $constructor);
 208         )
 209     }
 210
 211     macro_rules! register_passes {
 212         ([$method:ident, $args:tt], [$($passes:ident: $constructor:expr,)*]) => (
 213             $(
 214                 register_pass!($method, $constructor, $args);
 215             )*
 216         )
 217     }
 218
 219     if sess.map(|sess| sess.opts.debugging_opts.no_interleave_lints).unwrap_or(false) {
 220         pre_expansion_lint_passes!(register_passes, [register_pre_expansion_pass, []]);
 221         early_lint_passes!(register_passes, [register_early_pass, []]);
 222         late_lint_passes!(register_passes, [register_late_pass, [false]]);
 223         late_lint_mod_passes!(register_passes, [register_late_pass, [true]]);
 224     } else {
 225         store.register_pre_expansion_pass(
 226             sess,
 227             false,
 228             true,
 229             box BuiltinCombinedPreExpansionLintPass::new()
 230         );
 231         store.register_early_pass(sess, false, true, box BuiltinCombinedEarlyLintPass::new());
 232         store.register_late_pass(
 233             sess, false, true, true, box BuiltinCombinedModuleLateLintPass::new()
 234         );
 235         store.register_late_pass(
 236             sess, false, true, false, box BuiltinCombinedLateLintPass::new()
 237         );
 238     }
 239
 240     add_lint_group!(sess,
 241                     "nonstandard_style",
 242                     NON_CAMEL_CASE_TYPES,
 243                     NON_SNAKE_CASE,
 244                     NON_UPPER_CASE_GLOBALS);
 245
 246     add_lint_group!(sess,
 247                     "unused",
 248                     UNUSED_IMPORTS,
 249                     UNUSED_VARIABLES,
 250                     UNUSED_ASSIGNMENTS,
 251                     DEAD_CODE,
 252                     UNUSED_MUT,
 253                     UNREACHABLE_CODE,
 254                     UNREACHABLE_PATTERNS,
 255                     UNUSED_MUST_USE,
 256                     UNUSED_UNSAFE,
 257                     PATH_STATEMENTS,
 258                     UNUSED_ATTRIBUTES,
 259                     UNUSED_MACROS,
 260                     UNUSED_ALLOCATION,
 261                     UNUSED_DOC_COMMENTS,
 262                     UNUSED_EXTERN_CRATES,
 263                     UNUSED_FEATURES,
 264                     UNUSED_LABELS,
 265                     UNUSED_PARENS);
 266
 267     add_lint_group!(sess,
 268                     "rust_2018_idioms",
 269                     BARE_TRAIT_OBJECTS,
 270                     UNUSED_EXTERN_CRATES,
 271                     ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 272                     ELIDED_LIFETIMES_IN_PATHS,
 273                     EXPLICIT_OUTLIVES_REQUIREMENTS
 274
 275                     // FIXME(#52665, #47816) not always applicable and not all
 276                     // macros are ready for this yet.
 277                     // UNREACHABLE_PUB,
 278
 279                     // FIXME macro crates are not up for this yet, too much
 280                     // breakage is seen if we try to encourage this lint.
 281                     // MACRO_USE_EXTERN_CRATE,
 282                     );
 283
 284     add_lint_group!(sess,
 285                     "rustdoc",
 286                     INTRA_DOC_LINK_RESOLUTION_FAILURE,
 287                     MISSING_DOC_CODE_EXAMPLES,
 288                     PRIVATE_DOC_TESTS);
 289
 290     // Guidelines for creating a future incompatibility lint:
 291     //
 292     // - Create a lint defaulting to warn as normal, with ideally the same error
 293     //   message you would normally give
 294     // - Add a suitable reference, typically an RFC or tracking issue. Go ahead
 295     //   and include the full URL, sort items in ascending order of issue numbers.
 296     // - Later, change lint to error
 297     // - Eventually, remove lint
 298     store.register_future_incompatible(sess, vec![
 299         FutureIncompatibleInfo {
 300             id: LintId::of(PRIVATE_IN_PUBLIC),
 301             reference: "issue #34537 <https://github.com/rust-lang/rust/issues/34537>",
 302             edition: None,
 303         },
 304         FutureIncompatibleInfo {
 305             id: LintId::of(PUB_USE_OF_PRIVATE_EXTERN_CRATE),
 306             reference: "issue #34537 <https://github.com/rust-lang/rust/issues/34537>",
 307             edition: None,
 308         },
 309         FutureIncompatibleInfo {
 310             id: LintId::of(PATTERNS_IN_FNS_WITHOUT_BODY),
 311             reference: "issue #35203 <https://github.com/rust-lang/rust/issues/35203>",
 312             edition: None,
 313         },
 314         FutureIncompatibleInfo {
 315             id: LintId::of(DUPLICATE_MACRO_EXPORTS),
 316             reference: "issue #35896 <https://github.com/rust-lang/rust/issues/35896>",
 317             edition: Some(Edition::Edition2018),
 318         },
 319         FutureIncompatibleInfo {
 320             id: LintId::of(KEYWORD_IDENTS),
 321             reference: "issue #49716 <https://github.com/rust-lang/rust/issues/49716>",
 322             edition: Some(Edition::Edition2018),
 323         },
 324         FutureIncompatibleInfo {
 325             id: LintId::of(SAFE_EXTERN_STATICS),
 326             reference: "issue #36247 <https://github.com/rust-lang/rust/issues/36247>",
 327             edition: None,
 328         },
 329         FutureIncompatibleInfo {
 330             id: LintId::of(INVALID_TYPE_PARAM_DEFAULT),
 331             reference: "issue #36887 <https://github.com/rust-lang/rust/issues/36887>",
 332             edition: None,
 333         },
 334         FutureIncompatibleInfo {
 335             id: LintId::of(LEGACY_DIRECTORY_OWNERSHIP),
 336             reference: "issue #37872 <https://github.com/rust-lang/rust/issues/37872>",
 337             edition: None,
 338         },
 339         FutureIncompatibleInfo {
 340             id: LintId::of(LEGACY_CONSTRUCTOR_VISIBILITY),
 341             reference: "issue #39207 <https://github.com/rust-lang/rust/issues/39207>",
 342             edition: None,
 343         },
 344         FutureIncompatibleInfo {
 345             id: LintId::of(MISSING_FRAGMENT_SPECIFIER),
 346             reference: "issue #40107 <https://github.com/rust-lang/rust/issues/40107>",
 347             edition: None,
 348         },
 349         FutureIncompatibleInfo {
 350             id: LintId::of(ILLEGAL_FLOATING_POINT_LITERAL_PATTERN),
 351             reference: "issue #41620 <https://github.com/rust-lang/rust/issues/41620>",
 352             edition: None,
 353         },
 354         FutureIncompatibleInfo {
 355             id: LintId::of(ANONYMOUS_PARAMETERS),
 356             reference: "issue #41686 <https://github.com/rust-lang/rust/issues/41686>",
 357             edition: Some(Edition::Edition2018),
 358         },
 359         FutureIncompatibleInfo {
 360             id: LintId::of(PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES),
 361             reference: "issue #42238 <https://github.com/rust-lang/rust/issues/42238>",
 362             edition: None,
 363         },
 364         FutureIncompatibleInfo {
 365             id: LintId::of(LATE_BOUND_LIFETIME_ARGUMENTS),
 366             reference: "issue #42868 <https://github.com/rust-lang/rust/issues/42868>",
 367             edition: None,
 368         },
 369         FutureIncompatibleInfo {
 370             id: LintId::of(SAFE_PACKED_BORROWS),
 371             reference: "issue #46043 <https://github.com/rust-lang/rust/issues/46043>",
 372             edition: None,
 373         },
 374         FutureIncompatibleInfo {
 375             id: LintId::of(INCOHERENT_FUNDAMENTAL_IMPLS),
 376             reference: "issue #46205 <https://github.com/rust-lang/rust/issues/46205>",
 377             edition: None,
 378         },
 379         FutureIncompatibleInfo {
 380             id: LintId::of(ORDER_DEPENDENT_TRAIT_OBJECTS),
 381             reference: "issue #56484 <https://github.com/rust-lang/rust/issues/56484>",
 382             edition: None,
 383         },
 384         FutureIncompatibleInfo {
 385             id: LintId::of(TYVAR_BEHIND_RAW_POINTER),
 386             reference: "issue #46906 <https://github.com/rust-lang/rust/issues/46906>",
 387             edition: Some(Edition::Edition2018),
 388         },
 389         FutureIncompatibleInfo {
 390             id: LintId::of(UNSTABLE_NAME_COLLISIONS),
 391             reference: "issue #48919 <https://github.com/rust-lang/rust/issues/48919>",
 392             edition: None,
 393             // Note: this item represents future incompatibility of all unstable functions in the
 394             //       standard library, and thus should never be removed or changed to an error.
 395         },
 396         FutureIncompatibleInfo {
 397             id: LintId::of(ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE),
 398             reference: "issue #53130 <https://github.com/rust-lang/rust/issues/53130>",
 399             edition: Some(Edition::Edition2018),
 400         },
 401         FutureIncompatibleInfo {
 402             id: LintId::of(WHERE_CLAUSES_OBJECT_SAFETY),
 403             reference: "issue #51443 <https://github.com/rust-lang/rust/issues/51443>",
 404             edition: None,
 405         },
 406         FutureIncompatibleInfo {
 407             id: LintId::of(PROC_MACRO_DERIVE_RESOLUTION_FALLBACK),
 408             reference: "issue #50504 <https://github.com/rust-lang/rust/issues/50504>",
 409             edition: None,
 410         },
 411         FutureIncompatibleInfo {
 412             id: LintId::of(QUESTION_MARK_MACRO_SEP),
 413             reference: "issue #48075 <https://github.com/rust-lang/rust/issues/48075>",
 414             edition: Some(Edition::Edition2018),
 415         },
 416         FutureIncompatibleInfo {
 417             id: LintId::of(MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS),
 418             reference: "issue #52234 <https://github.com/rust-lang/rust/issues/52234>",
 419             edition: None,
 420         },
 421         FutureIncompatibleInfo {
 422             id: LintId::of(ILL_FORMED_ATTRIBUTE_INPUT),
 423             reference: "issue #57571 <https://github.com/rust-lang/rust/issues/57571>",
 424             edition: None,
 425         },
 426         FutureIncompatibleInfo {
 427             id: LintId::of(AMBIGUOUS_ASSOCIATED_ITEMS),
 428             reference: "issue #57644 <https://github.com/rust-lang/rust/issues/57644>",
 429             edition: None,
 430         },
 431         FutureIncompatibleInfo {
 432             id: LintId::of(NESTED_IMPL_TRAIT),
 433             reference: "issue #59014 <https://github.com/rust-lang/rust/issues/59014>",
 434             edition: None,
 435         },
 436         FutureIncompatibleInfo {
 437             id: LintId::of(MUTABLE_BORROW_RESERVATION_CONFLICT),
 438             reference: "issue #59159 <https://github.com/rust-lang/rust/issues/59159>",
 439             edition: None,
 440         }
 441         ]);
 442
 443     // Register renamed and removed lints.
 444     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 445     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 446     store.register_renamed("bare_trait_object", "bare_trait_objects");
 447     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 448     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 449     store.register_renamed("async_idents", "keyword_idents");
 450     store.register_removed("unknown_features", "replaced by an error");
 451     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 452     store.register_removed("negate_unsigned", "cast a signed value instead");
 453     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 454     // Register lint group aliases.
 455     store.register_group_alias("nonstandard_style", "bad_style");
 456     // This was renamed to `raw_pointer_derive`, which was then removed,
 457     // so it is also considered removed.
 458     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 459     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 460     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 461     store.register_removed("deprecated_attr", "use `deprecated` instead");
 462     store.register_removed("transmute_from_fn_item_types",
 463         "always cast functions before transmuting them");
 464     store.register_removed("hr_lifetime_in_assoc_type",
 465         "converted into hard error, see https://github.com/rust-lang/rust/issues/33685");
 466     store.register_removed("inaccessible_extern_crate",
 467         "converted into hard error, see https://github.com/rust-lang/rust/issues/36886");
 468     store.register_removed("super_or_self_in_global_path",
 469         "converted into hard error, see https://github.com/rust-lang/rust/issues/36888");
 470     store.register_removed("overlapping_inherent_impls",
 471         "converted into hard error, see https://github.com/rust-lang/rust/issues/36889");
 472     store.register_removed("illegal_floating_point_constant_pattern",
 473         "converted into hard error, see https://github.com/rust-lang/rust/issues/36890");
 474     store.register_removed("illegal_struct_or_enum_constant_pattern",
 475         "converted into hard error, see https://github.com/rust-lang/rust/issues/36891");
 476     store.register_removed("lifetime_underscore",
 477         "converted into hard error, see https://github.com/rust-lang/rust/issues/36892");
 478     store.register_removed("extra_requirement_in_impl",
 479         "converted into hard error, see https://github.com/rust-lang/rust/issues/37166");
 480     store.register_removed("legacy_imports",
 481         "converted into hard error, see https://github.com/rust-lang/rust/issues/38260");
 482     store.register_removed("coerce_never",
 483         "converted into hard error, see https://github.com/rust-lang/rust/issues/48950");
 484     store.register_removed("resolve_trait_on_defaulted_unit",
 485         "converted into hard error, see https://github.com/rust-lang/rust/issues/48950");
 486     store.register_removed("private_no_mangle_fns",
 487         "no longer a warning, #[no_mangle] functions always exported");
 488     store.register_removed("private_no_mangle_statics",
 489         "no longer a warning, #[no_mangle] statics always exported");
 490     store.register_removed("bad_repr",
 491         "replaced with a generic attribute input check");
 492     store.register_removed("duplicate_matcher_binding_name",
 493         "converted into hard error, see https://github.com/rust-lang/rust/issues/57742");
 494 }
 495
 496 pub fn register_internals(store: &mut lint::LintStore, sess: Option<&Session>) {
 497     store.register_early_pass(sess, false, false, box DefaultHashTypes::new());
 498     store.register_late_pass(sess, false, false, false, box TyKindUsage);
 499     store.register_group(
 500         sess,
 501         false,
 502         "internal",
 503         None,
 504         vec![
 505             LintId::of(DEFAULT_HASH_TYPES),
 506             LintId::of(USAGE_OF_TY_TYKIND),
 507         ],
 508     );
 509 }