src/librustc/lint/builtin.rs

   1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Some lints that are built in to the compiler.
  12 //!
  13 //! These are the built-in lints that are emitted direct in the main
  14 //! compiler code, rather than using their own custom pass. Those
  15 //! lints are all available in `rustc_lint::builtin`.
  16
  17 use errors::{Applicability, DiagnosticBuilder};
  18 use lint::{LintPass, LateLintPass, LintArray};
  19 use session::Session;
  20 use syntax::ast;
  21 use syntax::codemap::Span;
  22
  23 declare_lint! {
  24     pub EXCEEDING_BITSHIFTS,
  25     Deny,
  26     "shift exceeds the type's number of bits"
  27 }
  28
  29 declare_lint! {
  30     pub CONST_ERR,
  31     Deny,
  32     "constant evaluation detected erroneous expression"
  33 }
  34
  35 declare_lint! {
  36     pub UNUSED_IMPORTS,
  37     Warn,
  38     "imports that are never used"
  39 }
  40
  41 declare_lint! {
  42     pub UNUSED_EXTERN_CRATES,
  43     Allow,
  44     "extern crates that are never used"
  45 }
  46
  47 declare_lint! {
  48     pub UNUSED_QUALIFICATIONS,
  49     Allow,
  50     "detects unnecessarily qualified names"
  51 }
  52
  53 declare_lint! {
  54     pub UNKNOWN_LINTS,
  55     Warn,
  56     "unrecognized lint attribute"
  57 }
  58
  59 declare_lint! {
  60     pub UNUSED_VARIABLES,
  61     Warn,
  62     "detect variables which are not used in any way"
  63 }
  64
  65 declare_lint! {
  66     pub UNUSED_ASSIGNMENTS,
  67     Warn,
  68     "detect assignments that will never be read"
  69 }
  70
  71 declare_lint! {
  72     pub DEAD_CODE,
  73     Warn,
  74     "detect unused, unexported items"
  75 }
  76
  77 declare_lint! {
  78     pub UNREACHABLE_CODE,
  79     Warn,
  80     "detects unreachable code paths",
  81     report_in_external_macro: true
  82 }
  83
  84 declare_lint! {
  85     pub UNREACHABLE_PATTERNS,
  86     Warn,
  87     "detects unreachable patterns"
  88 }
  89
  90 declare_lint! {
  91     pub UNUSED_MACROS,
  92     Warn,
  93     "detects macros that were not used"
  94 }
  95
  96 declare_lint! {
  97     pub WARNINGS,
  98     Warn,
  99     "mass-change the level for lints which produce warnings"
 100 }
 101
 102 declare_lint! {
 103     pub UNUSED_FEATURES,
 104     Warn,
 105     "unused or unknown features found in crate-level #[feature] directives"
 106 }
 107
 108 declare_lint! {
 109     pub STABLE_FEATURES,
 110     Warn,
 111     "stable features found in #[feature] directive"
 112 }
 113
 114 declare_lint! {
 115     pub UNKNOWN_CRATE_TYPES,
 116     Deny,
 117     "unknown crate type found in #[crate_type] directive"
 118 }
 119
 120 declare_lint! {
 121     pub TRIVIAL_CASTS,
 122     Allow,
 123     "detects trivial casts which could be removed"
 124 }
 125
 126 declare_lint! {
 127     pub TRIVIAL_NUMERIC_CASTS,
 128     Allow,
 129     "detects trivial casts of numeric types which could be removed"
 130 }
 131
 132 declare_lint! {
 133     pub PRIVATE_IN_PUBLIC,
 134     Warn,
 135     "detect private items in public interfaces not caught by the old implementation"
 136 }
 137
 138 declare_lint! {
 139     pub PUB_USE_OF_PRIVATE_EXTERN_CRATE,
 140     Deny,
 141     "detect public re-exports of private extern crates"
 142 }
 143
 144 declare_lint! {
 145     pub INVALID_TYPE_PARAM_DEFAULT,
 146     Deny,
 147     "type parameter default erroneously allowed in invalid location"
 148 }
 149
 150 declare_lint! {
 151     pub RENAMED_AND_REMOVED_LINTS,
 152     Warn,
 153     "lints that have been renamed or removed"
 154 }
 155
 156 declare_lint! {
 157     pub SAFE_EXTERN_STATICS,
 158     Deny,
 159     "safe access to extern statics was erroneously allowed"
 160 }
 161
 162 declare_lint! {
 163     pub SAFE_PACKED_BORROWS,
 164     Warn,
 165     "safe borrows of fields of packed structs were was erroneously allowed"
 166 }
 167
 168 declare_lint! {
 169     pub PATTERNS_IN_FNS_WITHOUT_BODY,
 170     Warn,
 171     "patterns in functions without body were erroneously allowed"
 172 }
 173
 174 declare_lint! {
 175     pub LEGACY_DIRECTORY_OWNERSHIP,
 176     Deny,
 177     "non-inline, non-`#[path]` modules (e.g. `mod foo;`) were erroneously allowed in some files \
 178      not named `mod.rs`"
 179 }
 180
 181 declare_lint! {
 182     pub LEGACY_CONSTRUCTOR_VISIBILITY,
 183     Deny,
 184     "detects use of struct constructors that would be invisible with new visibility rules"
 185 }
 186
 187 declare_lint! {
 188     pub MISSING_FRAGMENT_SPECIFIER,
 189     Deny,
 190     "detects missing fragment specifiers in unused `macro_rules!` patterns"
 191 }
 192
 193 declare_lint! {
 194     pub PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
 195     Deny,
 196     "detects parenthesized generic parameters in type and module names"
 197 }
 198
 199 declare_lint! {
 200     pub LATE_BOUND_LIFETIME_ARGUMENTS,
 201     Warn,
 202     "detects generic lifetime arguments in path segments with late bound lifetime parameters"
 203 }
 204
 205 declare_lint! {
 206     pub INCOHERENT_FUNDAMENTAL_IMPLS,
 207     Deny,
 208     "potentially-conflicting impls were erroneously allowed"
 209 }
 210
 211 declare_lint! {
 212     pub BAD_REPR,
 213     Warn,
 214     "detects incorrect use of `repr` attribute"
 215 }
 216
 217 declare_lint! {
 218     pub DEPRECATED,
 219     Warn,
 220     "detects use of deprecated items",
 221     report_in_external_macro: true
 222 }
 223
 224 declare_lint! {
 225     pub UNUSED_UNSAFE,
 226     Warn,
 227     "unnecessary use of an `unsafe` block"
 228 }
 229
 230 declare_lint! {
 231     pub UNUSED_MUT,
 232     Warn,
 233     "detect mut variables which don't need to be mutable"
 234 }
 235
 236 declare_lint! {
 237     pub SINGLE_USE_LIFETIMES,
 238     Allow,
 239     "detects lifetime parameters that are only used once"
 240 }
 241
 242 declare_lint! {
 243     pub UNUSED_LIFETIMES,
 244     Allow,
 245     "detects lifetime parameters that are never used"
 246 }
 247
 248 declare_lint! {
 249     pub TYVAR_BEHIND_RAW_POINTER,
 250     Warn,
 251     "raw pointer to an inference variable"
 252 }
 253
 254 declare_lint! {
 255     pub ELIDED_LIFETIMES_IN_PATHS,
 256     Allow,
 257     "hidden lifetime parameters are deprecated, try `Foo<'_>`"
 258 }
 259
 260 declare_lint! {
 261     pub BARE_TRAIT_OBJECTS,
 262     Allow,
 263     "suggest using `dyn Trait` for trait objects"
 264 }
 265
 266 declare_lint! {
 267     pub ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
 268     Allow,
 269     "fully qualified paths that start with a module name \
 270      instead of `crate`, `self`, or an extern crate name"
 271 }
 272
 273 declare_lint! {
 274     pub ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
 275     Warn,
 276     "floating-point literals cannot be used in patterns"
 277 }
 278
 279 declare_lint! {
 280     pub UNSTABLE_NAME_COLLISIONS,
 281     Warn,
 282     "detects name collision with an existing but unstable method"
 283 }
 284
 285 declare_lint! {
 286     pub IRREFUTABLE_LET_PATTERNS,
 287     Deny,
 288     "detects irrefutable patterns in if-let and while-let statements"
 289 }
 290
 291 declare_lint! {
 292     pub UNUSED_LABELS,
 293     Allow,
 294     "detects labels that are never used"
 295 }
 296
 297 declare_lint! {
 298     pub DUPLICATE_ASSOCIATED_TYPE_BINDINGS,
 299     Warn,
 300     "warns about duplicate associated type bindings in generics"
 301 }
 302
 303 declare_lint! {
 304     pub DUPLICATE_MACRO_EXPORTS,
 305     Deny,
 306     "detects duplicate macro exports"
 307 }
 308
 309 declare_lint! {
 310     pub INTRA_DOC_LINK_RESOLUTION_FAILURE,
 311     Warn,
 312     "warn about documentation intra links resolution failure"
 313 }
 314
 315 declare_lint! {
 316     pub WHERE_CLAUSES_OBJECT_SAFETY,
 317     Warn,
 318     "checks the object safety of where clauses"
 319 }
 320
 321 declare_lint! {
 322     pub PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
 323     Warn,
 324     "detects proc macro derives using inaccessible names from parent modules"
 325 }
 326
 327 declare_lint! {
 328     pub MACRO_USE_EXTERN_CRATE,
 329     Allow,
 330     "the `#[macro_use]` attribute is now deprecated in favor of using macros \
 331      via the module system"
 332 }
 333
 334 /// Does nothing as a lint pass, but registers some `Lint`s
 335 /// which are used by other parts of the compiler.
 336 #[derive(Copy, Clone)]
 337 pub struct HardwiredLints;
 338
 339 impl LintPass for HardwiredLints {
 340     fn get_lints(&self) -> LintArray {
 341         lint_array!(
 342             ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
 343             EXCEEDING_BITSHIFTS,
 344             UNUSED_IMPORTS,
 345             UNUSED_EXTERN_CRATES,
 346             UNUSED_QUALIFICATIONS,
 347             UNKNOWN_LINTS,
 348             UNUSED_VARIABLES,
 349             UNUSED_ASSIGNMENTS,
 350             DEAD_CODE,
 351             UNREACHABLE_CODE,
 352             UNREACHABLE_PATTERNS,
 353             UNUSED_MACROS,
 354             WARNINGS,
 355             UNUSED_FEATURES,
 356             STABLE_FEATURES,
 357             UNKNOWN_CRATE_TYPES,
 358             TRIVIAL_CASTS,
 359             TRIVIAL_NUMERIC_CASTS,
 360             PRIVATE_IN_PUBLIC,
 361             PUB_USE_OF_PRIVATE_EXTERN_CRATE,
 362             INVALID_TYPE_PARAM_DEFAULT,
 363             CONST_ERR,
 364             RENAMED_AND_REMOVED_LINTS,
 365             SAFE_EXTERN_STATICS,
 366             SAFE_PACKED_BORROWS,
 367             PATTERNS_IN_FNS_WITHOUT_BODY,
 368             LEGACY_DIRECTORY_OWNERSHIP,
 369             LEGACY_CONSTRUCTOR_VISIBILITY,
 370             MISSING_FRAGMENT_SPECIFIER,
 371             PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
 372             LATE_BOUND_LIFETIME_ARGUMENTS,
 373             INCOHERENT_FUNDAMENTAL_IMPLS,
 374             DEPRECATED,
 375             UNUSED_UNSAFE,
 376             UNUSED_MUT,
 377             SINGLE_USE_LIFETIMES,
 378             UNUSED_LIFETIMES,
 379             UNUSED_LABELS,
 380             TYVAR_BEHIND_RAW_POINTER,
 381             ELIDED_LIFETIMES_IN_PATHS,
 382             BARE_TRAIT_OBJECTS,
 383             ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
 384             UNSTABLE_NAME_COLLISIONS,
 385             IRREFUTABLE_LET_PATTERNS,
 386             DUPLICATE_ASSOCIATED_TYPE_BINDINGS,
 387             DUPLICATE_MACRO_EXPORTS,
 388             INTRA_DOC_LINK_RESOLUTION_FAILURE,
 389             WHERE_CLAUSES_OBJECT_SAFETY,
 390             PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
 391             MACRO_USE_EXTERN_CRATE,
 392         )
 393     }
 394 }
 395
 396 // this could be a closure, but then implementing derive traits
 397 // becomes hacky (and it gets allocated)
 398 #[derive(PartialEq, RustcEncodable, RustcDecodable, Debug)]
 399 pub enum BuiltinLintDiagnostics {
 400     Normal,
 401     BareTraitObject(Span, /* is_global */ bool),
 402     AbsPathWithModule(Span),
 403     DuplicatedMacroExports(ast::Ident, Span, Span),
 404     ProcMacroDeriveResolutionFallback(Span),
 405 }
 406
 407 impl BuiltinLintDiagnostics {
 408     pub fn run(self, sess: &Session, db: &mut DiagnosticBuilder) {
 409         match self {
 410             BuiltinLintDiagnostics::Normal => (),
 411             BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
 412                 let (sugg, app) = match sess.codemap().span_to_snippet(span) {
 413                     Ok(ref s) if is_global => (format!("dyn ({})", s),
 414                                                Applicability::MachineApplicable),
 415                     Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
 416                     Err(_) => (format!("dyn <type>"), Applicability::HasPlaceholders)
 417                 };
 418                 db.span_suggestion_with_applicability(span, "use `dyn`", sugg, app);
 419             }
 420             BuiltinLintDiagnostics::AbsPathWithModule(span) => {
 421                 let (sugg, app) = match sess.codemap().span_to_snippet(span) {
 422                     Ok(ref s) => {
 423                         // FIXME(Manishearth) ideally the emitting code
 424                         // can tell us whether or not this is global
 425                         let opt_colon = if s.trim_left().starts_with("::") {
 426                             ""
 427                         } else {
 428                             "::"
 429                         };
 430
 431                         (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
 432                     }
 433                     Err(_) => (format!("crate::<path>"), Applicability::HasPlaceholders)
 434                 };
 435                 db.span_suggestion_with_applicability(span, "use `crate`", sugg, app);
 436             }
 437             BuiltinLintDiagnostics::DuplicatedMacroExports(ident, earlier_span, later_span) => {
 438                 db.span_label(later_span, format!("`{}` already exported", ident));
 439                 db.span_note(earlier_span, "previous macro export is now shadowed");
 440             }
 441             BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
 442                 db.span_label(span, "names from parent modules are not \
 443                                      accessible without an explicit import");
 444             }
 445         }
 446     }
 447 }
 448
 449 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for HardwiredLints {}