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(box_patterns)]
  34 #![feature(crate_visibility_modifier)]
  35 #![feature(iter_order_by)]
  36 #![feature(never_type)]
  37 #![feature(nll)]
  38 #![feature(or_patterns)]
  39 #![feature(half_open_range_patterns)]
  40 #![feature(exclusive_range_pattern)]
  41 #![feature(control_flow_enum)]
  42 #![recursion_limit = "256"]
  43
  44 #[macro_use]
  45 extern crate rustc_middle;
  46 #[macro_use]
  47 extern crate rustc_session;
  48
  49 mod array_into_iter;
  50 pub mod builtin;
  51 mod context;
  52 mod early;
  53 mod internal;
  54 mod late;
  55 mod levels;
  56 mod methods;
  57 mod non_ascii_idents;
  58 mod non_fmt_panic;
  59 mod nonstandard_style;
  60 mod passes;
  61 mod redundant_semicolon;
  62 mod traits;
  63 mod types;
  64 mod unused;
  65
  66 use rustc_ast as ast;
  67 use rustc_hir as hir;
  68 use rustc_hir::def_id::LocalDefId;
  69 use rustc_middle::ty::query::Providers;
  70 use rustc_middle::ty::TyCtxt;
  71 use rustc_session::lint::builtin::{
  72     BARE_TRAIT_OBJECTS, ELIDED_LIFETIMES_IN_PATHS, EXPLICIT_OUTLIVES_REQUIREMENTS,
  73 };
  74 use rustc_span::symbol::{Ident, Symbol};
  75 use rustc_span::Span;
  76
  77 use array_into_iter::ArrayIntoIter;
  78 use builtin::*;
  79 use internal::*;
  80 use methods::*;
  81 use non_ascii_idents::*;
  82 use non_fmt_panic::NonPanicFmt;
  83 use nonstandard_style::*;
  84 use redundant_semicolon::*;
  85 use traits::*;
  86 use types::*;
  87 use unused::*;
  88
  89 /// Useful for other parts of the compiler / Clippy.
  90 pub use builtin::SoftLints;
  91 pub use context::{CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore};
  92 pub use early::check_ast_crate;
  93 pub use late::check_crate;
  94 pub use passes::{EarlyLintPass, LateLintPass};
  95 pub use rustc_session::lint::Level::{self, *};
  96 pub use rustc_session::lint::{BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId};
  97 pub use rustc_session::lint::{LintArray, LintPass};
  98
  99 pub fn provide(providers: &mut Providers) {
 100     levels::provide(providers);
 101     *providers = Providers { lint_mod, ..*providers };
 102 }
 103
 104 fn lint_mod(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
 105     late::late_lint_mod(tcx, module_def_id, BuiltinCombinedModuleLateLintPass::new());
 106 }
 107
 108 macro_rules! pre_expansion_lint_passes {
 109     ($macro:path, $args:tt) => {
 110         $macro!($args, [KeywordIdents: KeywordIdents,]);
 111     };
 112 }
 113
 114 macro_rules! early_lint_passes {
 115     ($macro:path, $args:tt) => {
 116         $macro!(
 117             $args,
 118             [
 119                 UnusedParens: UnusedParens,
 120                 UnusedBraces: UnusedBraces,
 121                 UnusedImportBraces: UnusedImportBraces,
 122                 UnsafeCode: UnsafeCode,
 123                 AnonymousParameters: AnonymousParameters,
 124                 EllipsisInclusiveRangePatterns: EllipsisInclusiveRangePatterns::default(),
 125                 NonCamelCaseTypes: NonCamelCaseTypes,
 126                 DeprecatedAttr: DeprecatedAttr::new(),
 127                 WhileTrue: WhileTrue,
 128                 NonAsciiIdents: NonAsciiIdents,
 129                 IncompleteFeatures: IncompleteFeatures,
 130                 RedundantSemicolons: RedundantSemicolons,
 131                 UnusedDocComment: UnusedDocComment,
 132             ]
 133         );
 134     };
 135 }
 136
 137 macro_rules! declare_combined_early_pass {
 138     ([$name:ident], $passes:tt) => (
 139         early_lint_methods!(declare_combined_early_lint_pass, [pub $name, $passes]);
 140     )
 141 }
 142
 143 pre_expansion_lint_passes!(declare_combined_early_pass, [BuiltinCombinedPreExpansionLintPass]);
 144 early_lint_passes!(declare_combined_early_pass, [BuiltinCombinedEarlyLintPass]);
 145
 146 macro_rules! late_lint_passes {
 147     ($macro:path, $args:tt) => {
 148         $macro!(
 149             $args,
 150             [
 151                 // FIXME: Look into regression when this is used as a module lint
 152                 // May Depend on constants elsewhere
 153                 UnusedBrokenConst: UnusedBrokenConst,
 154                 // Uses attr::is_used which is untracked, can't be an incremental module pass.
 155                 UnusedAttributes: UnusedAttributes::new(),
 156                 // Needs to run after UnusedAttributes as it marks all `feature` attributes as used.
 157                 UnstableFeatures: UnstableFeatures,
 158                 // Tracks state across modules
 159                 UnnameableTestItems: UnnameableTestItems::new(),
 160                 // Tracks attributes of parents
 161                 MissingDoc: MissingDoc::new(),
 162                 // Depends on access levels
 163                 // FIXME: Turn the computation of types which implement Debug into a query
 164                 // and change this to a module lint pass
 165                 MissingDebugImplementations: MissingDebugImplementations::default(),
 166                 ArrayIntoIter: ArrayIntoIter,
 167                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
 168                 DropTraitConstraints: DropTraitConstraints,
 169                 TemporaryCStringAsPtr: TemporaryCStringAsPtr,
 170                 NonPanicFmt: NonPanicFmt,
 171             ]
 172         );
 173     };
 174 }
 175
 176 macro_rules! late_lint_mod_passes {
 177     ($macro:path, $args:tt) => {
 178         $macro!(
 179             $args,
 180             [
 181                 HardwiredLints: HardwiredLints,
 182                 ImproperCTypesDeclarations: ImproperCTypesDeclarations,
 183                 ImproperCTypesDefinitions: ImproperCTypesDefinitions,
 184                 VariantSizeDifferences: VariantSizeDifferences,
 185                 BoxPointers: BoxPointers,
 186                 PathStatements: PathStatements,
 187                 // Depends on referenced function signatures in expressions
 188                 UnusedResults: UnusedResults,
 189                 NonUpperCaseGlobals: NonUpperCaseGlobals,
 190                 NonShorthandFieldPatterns: NonShorthandFieldPatterns,
 191                 UnusedAllocation: UnusedAllocation,
 192                 // Depends on types used in type definitions
 193                 MissingCopyImplementations: MissingCopyImplementations,
 194                 // Depends on referenced function signatures in expressions
 195                 MutableTransmutes: MutableTransmutes,
 196                 TypeAliasBounds: TypeAliasBounds,
 197                 TrivialConstraints: TrivialConstraints,
 198                 TypeLimits: TypeLimits::new(),
 199                 NonSnakeCase: NonSnakeCase,
 200                 InvalidNoMangleItems: InvalidNoMangleItems,
 201                 // Depends on access levels
 202                 UnreachablePub: UnreachablePub,
 203                 ExplicitOutlivesRequirements: ExplicitOutlivesRequirements,
 204                 InvalidValue: InvalidValue,
 205             ]
 206         );
 207     };
 208 }
 209
 210 macro_rules! declare_combined_late_pass {
 211     ([$v:vis $name:ident], $passes:tt) => (
 212         late_lint_methods!(declare_combined_late_lint_pass, [$v $name, $passes], ['tcx]);
 213     )
 214 }
 215
 216 // FIXME: Make a separate lint type which do not require typeck tables
 217 late_lint_passes!(declare_combined_late_pass, [pub BuiltinCombinedLateLintPass]);
 218
 219 late_lint_mod_passes!(declare_combined_late_pass, [BuiltinCombinedModuleLateLintPass]);
 220
 221 pub fn new_lint_store(no_interleave_lints: bool, internal_lints: bool) -> LintStore {
 222     let mut lint_store = LintStore::new();
 223
 224     register_builtins(&mut lint_store, no_interleave_lints);
 225     if internal_lints {
 226         register_internals(&mut lint_store);
 227     }
 228
 229     lint_store
 230 }
 231
 232 /// Tell the `LintStore` about all the built-in lints (the ones
 233 /// defined in this crate and the ones defined in
 234 /// `rustc_session::lint::builtin`).
 235 fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
 236     macro_rules! add_lint_group {
 237         ($name:expr, $($lint:ident),*) => (
 238             store.register_group(false, $name, None, vec![$(LintId::of($lint)),*]);
 239         )
 240     }
 241
 242     macro_rules! register_pass {
 243         ($method:ident, $ty:ident, $constructor:expr) => {
 244             store.register_lints(&$ty::get_lints());
 245             store.$method(|| box $constructor);
 246         };
 247     }
 248
 249     macro_rules! register_passes {
 250         ($method:ident, [$($passes:ident: $constructor:expr,)*]) => (
 251             $(
 252                 register_pass!($method, $passes, $constructor);
 253             )*
 254         )
 255     }
 256
 257     if no_interleave_lints {
 258         pre_expansion_lint_passes!(register_passes, register_pre_expansion_pass);
 259         early_lint_passes!(register_passes, register_early_pass);
 260         late_lint_passes!(register_passes, register_late_pass);
 261         late_lint_mod_passes!(register_passes, register_late_mod_pass);
 262     } else {
 263         store.register_lints(&BuiltinCombinedPreExpansionLintPass::get_lints());
 264         store.register_lints(&BuiltinCombinedEarlyLintPass::get_lints());
 265         store.register_lints(&BuiltinCombinedModuleLateLintPass::get_lints());
 266         store.register_lints(&BuiltinCombinedLateLintPass::get_lints());
 267     }
 268
 269     add_lint_group!(
 270         "nonstandard_style",
 271         NON_CAMEL_CASE_TYPES,
 272         NON_SNAKE_CASE,
 273         NON_UPPER_CASE_GLOBALS
 274     );
 275
 276     add_lint_group!(
 277         "unused",
 278         UNUSED_IMPORTS,
 279         UNUSED_VARIABLES,
 280         UNUSED_ASSIGNMENTS,
 281         DEAD_CODE,
 282         UNUSED_MUT,
 283         UNREACHABLE_CODE,
 284         UNREACHABLE_PATTERNS,
 285         UNUSED_MUST_USE,
 286         UNUSED_UNSAFE,
 287         PATH_STATEMENTS,
 288         UNUSED_ATTRIBUTES,
 289         UNUSED_MACROS,
 290         UNUSED_ALLOCATION,
 291         UNUSED_DOC_COMMENTS,
 292         UNUSED_EXTERN_CRATES,
 293         UNUSED_FEATURES,
 294         UNUSED_LABELS,
 295         UNUSED_PARENS,
 296         UNUSED_BRACES,
 297         REDUNDANT_SEMICOLONS
 298     );
 299
 300     add_lint_group!(
 301         "rust_2018_idioms",
 302         BARE_TRAIT_OBJECTS,
 303         UNUSED_EXTERN_CRATES,
 304         ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
 305         ELIDED_LIFETIMES_IN_PATHS,
 306         EXPLICIT_OUTLIVES_REQUIREMENTS // FIXME(#52665, #47816) not always applicable and not all
 307                                        // macros are ready for this yet.
 308                                        // UNREACHABLE_PUB,
 309
 310                                        // FIXME macro crates are not up for this yet, too much
 311                                        // breakage is seen if we try to encourage this lint.
 312                                        // MACRO_USE_EXTERN_CRATE
 313     );
 314
 315     // Register renamed and removed lints.
 316     store.register_renamed("single_use_lifetime", "single_use_lifetimes");
 317     store.register_renamed("elided_lifetime_in_path", "elided_lifetimes_in_paths");
 318     store.register_renamed("bare_trait_object", "bare_trait_objects");
 319     store.register_renamed("unstable_name_collision", "unstable_name_collisions");
 320     store.register_renamed("unused_doc_comment", "unused_doc_comments");
 321     store.register_renamed("async_idents", "keyword_idents");
 322     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
 323     store.register_renamed("redundant_semicolon", "redundant_semicolons");
 324     store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
 325
 326     // These were moved to tool lints, but rustc still sees them when compiling normally, before
 327     // tool lints are registered, so `check_tool_name_for_backwards_compat` doesn't work. Use
 328     // `register_removed` explicitly.
 329     const RUSTDOC_LINTS: &[&str] = &[
 330         "broken_intra_doc_links",
 331         "private_intra_doc_links",
 332         "missing_crate_level_docs",
 333         "missing_doc_code_examples",
 334         "private_doc_tests",
 335         "invalid_codeblock_attributes",
 336         "invalid_html_tags",
 337         "non_autolinks",
 338     ];
 339     for rustdoc_lint in RUSTDOC_LINTS {
 340         store.register_removed(rustdoc_lint, &format!("use `rustdoc::{}` instead", rustdoc_lint));
 341     }
 342     store.register_removed(
 343         "intra_doc_link_resolution_failure",
 344         "use `rustdoc::broken_intra_doc_links` instead",
 345     );
 346
 347     store.register_removed("unknown_features", "replaced by an error");
 348     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
 349     store.register_removed("negate_unsigned", "cast a signed value instead");
 350     store.register_removed("raw_pointer_derive", "using derive with raw pointers is ok");
 351     // Register lint group aliases.
 352     store.register_group_alias("nonstandard_style", "bad_style");
 353     // This was renamed to `raw_pointer_derive`, which was then removed,
 354     // so it is also considered removed.
 355     store.register_removed("raw_pointer_deriving", "using derive with raw pointers is ok");
 356     store.register_removed("drop_with_repr_extern", "drop flags have been removed");
 357     store.register_removed("fat_ptr_transmutes", "was accidentally removed back in 2014");
 358     store.register_removed("deprecated_attr", "use `deprecated` instead");
 359     store.register_removed(
 360         "transmute_from_fn_item_types",
 361         "always cast functions before transmuting them",
 362     );
 363     store.register_removed(
 364         "hr_lifetime_in_assoc_type",
 365         "converted into hard error, see issue #33685 \
 366          <https://github.com/rust-lang/rust/issues/33685> for more information",
 367     );
 368     store.register_removed(
 369         "inaccessible_extern_crate",
 370         "converted into hard error, see issue #36886 \
 371          <https://github.com/rust-lang/rust/issues/36886> for more information",
 372     );
 373     store.register_removed(
 374         "super_or_self_in_global_path",
 375         "converted into hard error, see issue #36888 \
 376          <https://github.com/rust-lang/rust/issues/36888> for more information",
 377     );
 378     store.register_removed(
 379         "overlapping_inherent_impls",
 380         "converted into hard error, see issue #36889 \
 381          <https://github.com/rust-lang/rust/issues/36889> for more information",
 382     );
 383     store.register_removed(
 384         "illegal_floating_point_constant_pattern",
 385         "converted into hard error, see issue #36890 \
 386          <https://github.com/rust-lang/rust/issues/36890> for more information",
 387     );
 388     store.register_removed(
 389         "illegal_struct_or_enum_constant_pattern",
 390         "converted into hard error, see issue #36891 \
 391          <https://github.com/rust-lang/rust/issues/36891> for more information",
 392     );
 393     store.register_removed(
 394         "lifetime_underscore",
 395         "converted into hard error, see issue #36892 \
 396          <https://github.com/rust-lang/rust/issues/36892> for more information",
 397     );
 398     store.register_removed(
 399         "extra_requirement_in_impl",
 400         "converted into hard error, see issue #37166 \
 401          <https://github.com/rust-lang/rust/issues/37166> for more information",
 402     );
 403     store.register_removed(
 404         "legacy_imports",
 405         "converted into hard error, see issue #38260 \
 406          <https://github.com/rust-lang/rust/issues/38260> for more information",
 407     );
 408     store.register_removed(
 409         "coerce_never",
 410         "converted into hard error, see issue #48950 \
 411          <https://github.com/rust-lang/rust/issues/48950> for more information",
 412     );
 413     store.register_removed(
 414         "resolve_trait_on_defaulted_unit",
 415         "converted into hard error, see issue #48950 \
 416          <https://github.com/rust-lang/rust/issues/48950> for more information",
 417     );
 418     store.register_removed(
 419         "private_no_mangle_fns",
 420         "no longer a warning, `#[no_mangle]` functions always exported",
 421     );
 422     store.register_removed(
 423         "private_no_mangle_statics",
 424         "no longer a warning, `#[no_mangle]` statics always exported",
 425     );
 426     store.register_removed("bad_repr", "replaced with a generic attribute input check");
 427     store.register_removed(
 428         "duplicate_matcher_binding_name",
 429         "converted into hard error, see issue #57742 \
 430          <https://github.com/rust-lang/rust/issues/57742> for more information",
 431     );
 432     store.register_removed(
 433         "incoherent_fundamental_impls",
 434         "converted into hard error, see issue #46205 \
 435          <https://github.com/rust-lang/rust/issues/46205> for more information",
 436     );
 437     store.register_removed(
 438         "legacy_constructor_visibility",
 439         "converted into hard error, see issue #39207 \
 440          <https://github.com/rust-lang/rust/issues/39207> for more information",
 441     );
 442     store.register_removed(
 443         "legacy_directory_ownership",
 444         "converted into hard error, see issue #37872 \
 445          <https://github.com/rust-lang/rust/issues/37872> for more information",
 446     );
 447     store.register_removed(
 448         "safe_extern_statics",
 449         "converted into hard error, see issue #36247 \
 450          <https://github.com/rust-lang/rust/issues/36247> for more information",
 451     );
 452     store.register_removed(
 453         "parenthesized_params_in_types_and_modules",
 454         "converted into hard error, see issue #42238 \
 455          <https://github.com/rust-lang/rust/issues/42238> for more information",
 456     );
 457     store.register_removed(
 458         "duplicate_macro_exports",
 459         "converted into hard error, see issue #35896 \
 460          <https://github.com/rust-lang/rust/issues/35896> for more information",
 461     );
 462     store.register_removed(
 463         "nested_impl_trait",
 464         "converted into hard error, see issue #59014 \
 465          <https://github.com/rust-lang/rust/issues/59014> for more information",
 466     );
 467     store.register_removed("plugin_as_library", "plugins have been deprecated and retired");
 468 }
 469
 470 fn register_internals(store: &mut LintStore) {
 471     store.register_lints(&DefaultHashTypes::get_lints());
 472     store.register_early_pass(|| box DefaultHashTypes::new());
 473     store.register_lints(&LintPassImpl::get_lints());
 474     store.register_early_pass(|| box LintPassImpl);
 475     store.register_lints(&ExistingDocKeyword::get_lints());
 476     store.register_late_pass(|| box ExistingDocKeyword);
 477     store.register_lints(&TyTyKind::get_lints());
 478     store.register_late_pass(|| box TyTyKind);
 479     store.register_group(
 480         false,
 481         "rustc::internal",
 482         None,
 483         vec![
 484             LintId::of(DEFAULT_HASH_TYPES),
 485             LintId::of(USAGE_OF_TY_TYKIND),
 486             LintId::of(LINT_PASS_IMPL_WITHOUT_MACRO),
 487             LintId::of(TY_PASS_BY_REFERENCE),
 488             LintId::of(USAGE_OF_QUALIFIED_TY),
 489             LintId::of(EXISTING_DOC_KEYWORD),
 490         ],
 491     );
 492 }