src/librustc_lint/levels.rs

   1 use crate::context::{CheckLintNameResult, LintStore};
   2 use crate::late::unerased_lint_store;
   3 use rustc_ast::ast;
   4 use rustc_ast::attr;
   5 use rustc_ast::unwrap_or;
   6 use rustc_ast_pretty::pprust;
   7 use rustc_data_structures::fx::FxHashMap;
   8 use rustc_errors::{struct_span_err, Applicability};
   9 use rustc_hir as hir;
  10 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
  11 use rustc_hir::{intravisit, HirId};
  12 use rustc_middle::hir::map::Map;
  13 use rustc_middle::lint::LintDiagnosticBuilder;
  14 use rustc_middle::lint::{struct_lint_level, LintLevelMap, LintLevelSets, LintSet, LintSource};
  15 use rustc_middle::ty::query::Providers;
  16 use rustc_middle::ty::TyCtxt;
  17 use rustc_session::lint::{builtin, Level, Lint, LintId};
  18 use rustc_session::parse::feature_err;
  19 use rustc_session::Session;
  20 use rustc_span::symbol::{sym, Symbol};
  21 use rustc_span::{source_map::MultiSpan, Span, DUMMY_SP};
  22
  23 use std::cmp;
  24
  25 fn lint_levels(tcx: TyCtxt<'_>, cnum: CrateNum) -> LintLevelMap {
  26     assert_eq!(cnum, LOCAL_CRATE);
  27     let store = unerased_lint_store(tcx);
  28     let levels = LintLevelsBuilder::new(tcx.sess, false, &store);
  29     let mut builder = LintLevelMapBuilder { levels, tcx, store };
  30     let krate = tcx.hir().krate();
  31
  32     let push = builder.levels.push(&krate.item.attrs, &store, true);
  33     builder.levels.register_id(hir::CRATE_HIR_ID);
  34     for macro_def in krate.exported_macros {
  35         builder.levels.register_id(macro_def.hir_id);
  36     }
  37     intravisit::walk_crate(&mut builder, krate);
  38     builder.levels.pop(push);
  39
  40     builder.levels.build_map()
  41 }
  42
  43 pub struct LintLevelsBuilder<'s> {
  44     sess: &'s Session,
  45     sets: LintLevelSets,
  46     id_to_set: FxHashMap<HirId, u32>,
  47     cur: u32,
  48     warn_about_weird_lints: bool,
  49 }
  50
  51 pub struct BuilderPush {
  52     prev: u32,
  53     pub changed: bool,
  54 }
  55
  56 impl<'s> LintLevelsBuilder<'s> {
  57     pub fn new(sess: &'s Session, warn_about_weird_lints: bool, store: &LintStore) -> Self {
  58         let mut builder = LintLevelsBuilder {
  59             sess,
  60             sets: LintLevelSets::new(),
  61             cur: 0,
  62             id_to_set: Default::default(),
  63             warn_about_weird_lints,
  64         };
  65         builder.process_command_line(sess, store);
  66         assert_eq!(builder.sets.list.len(), 1);
  67         builder
  68     }
  69
  70     fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
  71         let mut specs = FxHashMap::default();
  72         self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
  73
  74         for &(ref lint_name, level) in &sess.opts.lint_opts {
  75             store.check_lint_name_cmdline(sess, &lint_name, level);
  76
  77             // If the cap is less than this specified level, e.g., if we've got
  78             // `--cap-lints allow` but we've also got `-D foo` then we ignore
  79             // this specification as the lint cap will set it to allow anyway.
  80             let level = cmp::min(level, self.sets.lint_cap);
  81
  82             let lint_flag_val = Symbol::intern(lint_name);
  83
  84             let ids = match store.find_lints(&lint_name) {
  85                 Ok(ids) => ids,
  86                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
  87             };
  88             for id in ids {
  89                 self.check_gated_lint(id, DUMMY_SP);
  90                 let src = LintSource::CommandLine(lint_flag_val);
  91                 specs.insert(id, (level, src));
  92             }
  93         }
  94
  95         self.sets.list.push(LintSet::CommandLine { specs });
  96     }
  97
  98     /// Pushes a list of AST lint attributes onto this context.
  99     ///
 100     /// This function will return a `BuilderPush` object which should be passed
 101     /// to `pop` when this scope for the attributes provided is exited.
 102     ///
 103     /// This function will perform a number of tasks:
 104     ///
 105     /// * It'll validate all lint-related attributes in `attrs`
 106     /// * It'll mark all lint-related attributes as used
 107     /// * Lint levels will be updated based on the attributes provided
 108     /// * Lint attributes are validated, e.g., a `#[forbid]` can't be switched to
 109     ///   `#[allow]`
 110     ///
 111     /// Don't forget to call `pop`!
 112     pub fn push(
 113         &mut self,
 114         attrs: &[ast::Attribute],
 115         store: &LintStore,
 116         is_crate_node: bool,
 117     ) -> BuilderPush {
 118         let mut specs = FxHashMap::default();
 119         let sess = self.sess;
 120         let bad_attr = |span| struct_span_err!(sess, span, E0452, "malformed lint attribute input");
 121         for attr in attrs {
 122             let level = match Level::from_symbol(attr.name_or_empty()) {
 123                 None => continue,
 124                 Some(lvl) => lvl,
 125             };
 126
 127             let meta = unwrap_or!(attr.meta(), continue);
 128             attr::mark_used(attr);
 129
 130             let mut metas = unwrap_or!(meta.meta_item_list(), continue);
 131
 132             if metas.is_empty() {
 133                 // FIXME (#55112): issue unused-attributes lint for `#[level()]`
 134                 continue;
 135             }
 136
 137             // Before processing the lint names, look for a reason (RFC 2383)
 138             // at the end.
 139             let mut reason = None;
 140             let tail_li = &metas[metas.len() - 1];
 141             if let Some(item) = tail_li.meta_item() {
 142                 match item.kind {
 143                     ast::MetaItemKind::Word => {} // actual lint names handled later
 144                     ast::MetaItemKind::NameValue(ref name_value) => {
 145                         if item.path == sym::reason {
 146                             // found reason, reslice meta list to exclude it
 147                             metas = &metas[0..metas.len() - 1];
 148                             // FIXME (#55112): issue unused-attributes lint if we thereby
 149                             // don't have any lint names (`#[level(reason = "foo")]`)
 150                             if let ast::LitKind::Str(rationale, _) = name_value.kind {
 151                                 if !self.sess.features_untracked().lint_reasons {
 152                                     feature_err(
 153                                         &self.sess.parse_sess,
 154                                         sym::lint_reasons,
 155                                         item.span,
 156                                         "lint reasons are experimental",
 157                                     )
 158                                     .emit();
 159                                 }
 160                                 reason = Some(rationale);
 161                             } else {
 162                                 bad_attr(name_value.span)
 163                                     .span_label(name_value.span, "reason must be a string literal")
 164                                     .emit();
 165                             }
 166                         } else {
 167                             bad_attr(item.span)
 168                                 .span_label(item.span, "bad attribute argument")
 169                                 .emit();
 170                         }
 171                     }
 172                     ast::MetaItemKind::List(_) => {
 173                         bad_attr(item.span).span_label(item.span, "bad attribute argument").emit();
 174                     }
 175                 }
 176             }
 177
 178             for li in metas {
 179                 let meta_item = match li.meta_item() {
 180                     Some(meta_item) if meta_item.is_word() => meta_item,
 181                     _ => {
 182                         let sp = li.span();
 183                         let mut err = bad_attr(sp);
 184                         let mut add_label = true;
 185                         if let Some(item) = li.meta_item() {
 186                             if let ast::MetaItemKind::NameValue(_) = item.kind {
 187                                 if item.path == sym::reason {
 188                                     err.span_label(sp, "reason in lint attribute must come last");
 189                                     add_label = false;
 190                                 }
 191                             }
 192                         }
 193                         if add_label {
 194                             err.span_label(sp, "bad attribute argument");
 195                         }
 196                         err.emit();
 197                         continue;
 198                     }
 199                 };
 200                 let tool_name = if meta_item.path.segments.len() > 1 {
 201                     let tool_ident = meta_item.path.segments[0].ident;
 202                     if !attr::is_known_lint_tool(tool_ident) {
 203                         struct_span_err!(
 204                             sess,
 205                             tool_ident.span,
 206                             E0710,
 207                             "an unknown tool name found in scoped lint: `{}`",
 208                             pprust::path_to_string(&meta_item.path),
 209                         )
 210                         .emit();
 211                         continue;
 212                     }
 213
 214                     Some(tool_ident.name)
 215                 } else {
 216                     None
 217                 };
 218                 let name = meta_item.path.segments.last().expect("empty lint name").ident.name;
 219                 match store.check_lint_name(&name.as_str(), tool_name) {
 220                     CheckLintNameResult::Ok(ids) => {
 221                         let src = LintSource::Node(name, li.span(), reason);
 222                         for &id in ids {
 223                             self.check_gated_lint(id, attr.span);
 224                             specs.insert(id, (level, src));
 225                         }
 226                     }
 227
 228                     CheckLintNameResult::Tool(result) => {
 229                         match result {
 230                             Ok(ids) => {
 231                                 let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
 232                                 let src = LintSource::Node(
 233                                     Symbol::intern(complete_name),
 234                                     li.span(),
 235                                     reason,
 236                                 );
 237                                 for id in ids {
 238                                     specs.insert(*id, (level, src));
 239                                 }
 240                             }
 241                             Err((Some(ids), new_lint_name)) => {
 242                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 243                                 let (lvl, src) =
 244                                     self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
 245                                 struct_lint_level(
 246                                     self.sess,
 247                                     lint,
 248                                     lvl,
 249                                     src,
 250                                     Some(li.span().into()),
 251                                     |lint| {
 252                                         let msg = format!(
 253                                             "lint name `{}` is deprecated \
 254                                              and may not have an effect in the future. \
 255                                              Also `cfg_attr(cargo-clippy)` won't be necessary anymore",
 256                                             name
 257                                         );
 258                                         lint.build(&msg)
 259                                             .span_suggestion(
 260                                                 li.span(),
 261                                                 "change it to",
 262                                                 new_lint_name.to_string(),
 263                                                 Applicability::MachineApplicable,
 264                                             )
 265                                             .emit();
 266                                     },
 267                                 );
 268
 269                                 let src = LintSource::Node(
 270                                     Symbol::intern(&new_lint_name),
 271                                     li.span(),
 272                                     reason,
 273                                 );
 274                                 for id in ids {
 275                                     specs.insert(*id, (level, src));
 276                                 }
 277                             }
 278                             Err((None, _)) => {
 279                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 280                                 // exist in the tool or the code was not compiled with the tool and
 281                                 // therefore the lint was never added to the `LintStore`. To detect
 282                                 // this is the responsibility of the lint tool.
 283                             }
 284                         }
 285                     }
 286
 287                     _ if !self.warn_about_weird_lints => {}
 288
 289                     CheckLintNameResult::Warning(msg, renamed) => {
 290                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 291                         let (level, src) =
 292                             self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
 293                         struct_lint_level(
 294                             self.sess,
 295                             lint,
 296                             level,
 297                             src,
 298                             Some(li.span().into()),
 299                             |lint| {
 300                                 let mut err = lint.build(&msg);
 301                                 if let Some(new_name) = renamed {
 302                                     err.span_suggestion(
 303                                         li.span(),
 304                                         "use the new name",
 305                                         new_name,
 306                                         Applicability::MachineApplicable,
 307                                     );
 308                                 }
 309                                 err.emit();
 310                             },
 311                         );
 312                     }
 313                     CheckLintNameResult::NoLint(suggestion) => {
 314                         let lint = builtin::UNKNOWN_LINTS;
 315                         let (level, src) =
 316                             self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
 317                         struct_lint_level(
 318                             self.sess,
 319                             lint,
 320                             level,
 321                             src,
 322                             Some(li.span().into()),
 323                             |lint| {
 324                                 let mut db = lint.build(&format!("unknown lint: `{}`", name));
 325                                 if let Some(suggestion) = suggestion {
 326                                     db.span_suggestion(
 327                                         li.span(),
 328                                         "did you mean",
 329                                         suggestion.to_string(),
 330                                         Applicability::MachineApplicable,
 331                                     );
 332                                 }
 333                                 db.emit();
 334                             },
 335                         );
 336                     }
 337                 }
 338             }
 339         }
 340
 341         if !is_crate_node {
 342             for (id, &(level, ref src)) in specs.iter() {
 343                 if !id.lint.crate_level_only {
 344                     continue;
 345                 }
 346
 347                 let (lint_attr_name, lint_attr_span) = match *src {
 348                     LintSource::Node(name, span, _) => (name, span),
 349                     _ => continue,
 350                 };
 351
 352                 let lint = builtin::UNUSED_ATTRIBUTES;
 353                 let (lint_level, lint_src) =
 354                     self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
 355                 struct_lint_level(
 356                     self.sess,
 357                     lint,
 358                     lint_level,
 359                     lint_src,
 360                     Some(lint_attr_span.into()),
 361                     |lint| {
 362                         let mut db = lint.build(&format!(
 363                             "{}({}) is ignored unless specified at crate level",
 364                             level.as_str(),
 365                             lint_attr_name
 366                         ));
 367                         db.emit();
 368                     },
 369                 );
 370                 // don't set a separate error for every lint in the group
 371                 break;
 372             }
 373         }
 374
 375         for (id, &(level, ref src)) in specs.iter() {
 376             if level == Level::Forbid {
 377                 continue;
 378             }
 379             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 380                 (Some(Level::Forbid), src) => src,
 381                 _ => continue,
 382             };
 383             let forbidden_lint_name = match forbid_src {
 384                 LintSource::Default => id.to_string(),
 385                 LintSource::Node(name, _, _) => name.to_string(),
 386                 LintSource::CommandLine(name) => name.to_string(),
 387             };
 388             let (lint_attr_name, lint_attr_span) = match *src {
 389                 LintSource::Node(name, span, _) => (name, span),
 390                 _ => continue,
 391             };
 392             let mut diag_builder = struct_span_err!(
 393                 self.sess,
 394                 lint_attr_span,
 395                 E0453,
 396                 "{}({}) overruled by outer forbid({})",
 397                 level.as_str(),
 398                 lint_attr_name,
 399                 forbidden_lint_name
 400             );
 401             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 402             match forbid_src {
 403                 LintSource::Default => {}
 404                 LintSource::Node(_, forbid_source_span, reason) => {
 405                     diag_builder.span_label(forbid_source_span, "`forbid` level set here");
 406                     if let Some(rationale) = reason {
 407                         diag_builder.note(&rationale.as_str());
 408                     }
 409                 }
 410                 LintSource::CommandLine(_) => {
 411                     diag_builder.note("`forbid` lint level was set on command line");
 412                 }
 413             }
 414             diag_builder.emit();
 415             // don't set a separate error for every lint in the group
 416             break;
 417         }
 418
 419         let prev = self.cur;
 420         if !specs.is_empty() {
 421             self.cur = self.sets.list.len() as u32;
 422             self.sets.list.push(LintSet::Node { specs, parent: prev });
 423         }
 424
 425         BuilderPush { prev, changed: prev != self.cur }
 426     }
 427
 428     /// Checks if the lint is gated on a feature that is not enabled.
 429     fn check_gated_lint(&self, lint_id: LintId, span: Span) {
 430         if let Some(feature) = lint_id.lint.feature_gate {
 431             if !self.sess.features_untracked().enabled(feature) {
 432                 feature_err(
 433                     &self.sess.parse_sess,
 434                     feature,
 435                     span,
 436                     &format!("the `{}` lint is unstable", lint_id.lint.name_lower()),
 437                 )
 438                 .emit();
 439             }
 440         }
 441     }
 442
 443     /// Called after `push` when the scope of a set of attributes are exited.
 444     pub fn pop(&mut self, push: BuilderPush) {
 445         self.cur = push.prev;
 446     }
 447
 448     /// Find the lint level for a lint.
 449     pub fn lint_level(&self, lint: &'static Lint) -> (Level, LintSource) {
 450         self.sets.get_lint_level(lint, self.cur, None, self.sess)
 451     }
 452
 453     /// Used to emit a lint-related diagnostic based on the current state of
 454     /// this lint context.
 455     pub fn struct_lint(
 456         &self,
 457         lint: &'static Lint,
 458         span: Option<MultiSpan>,
 459         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 460     ) {
 461         let (level, src) = self.lint_level(lint);
 462         struct_lint_level(self.sess, lint, level, src, span, decorate)
 463     }
 464
 465     /// Registers the ID provided with the current set of lints stored in
 466     /// this context.
 467     pub fn register_id(&mut self, id: HirId) {
 468         self.id_to_set.insert(id, self.cur);
 469     }
 470
 471     pub fn build(self) -> LintLevelSets {
 472         self.sets
 473     }
 474
 475     pub fn build_map(self) -> LintLevelMap {
 476         LintLevelMap { sets: self.sets, id_to_set: self.id_to_set }
 477     }
 478 }
 479
 480 struct LintLevelMapBuilder<'a, 'tcx> {
 481     levels: LintLevelsBuilder<'tcx>,
 482     tcx: TyCtxt<'tcx>,
 483     store: &'a LintStore,
 484 }
 485
 486 impl LintLevelMapBuilder<'_, '_> {
 487     fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &[ast::Attribute], f: F)
 488     where
 489         F: FnOnce(&mut Self),
 490     {
 491         let is_crate_hir = id == hir::CRATE_HIR_ID;
 492         let push = self.levels.push(attrs, self.store, is_crate_hir);
 493         if push.changed {
 494             self.levels.register_id(id);
 495         }
 496         f(self);
 497         self.levels.pop(push);
 498     }
 499 }
 500
 501 impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'_, 'tcx> {
 502     type Map = Map<'tcx>;
 503
 504     fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
 505         intravisit::NestedVisitorMap::All(self.tcx.hir())
 506     }
 507
 508     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
 509         self.with_lint_attrs(param.hir_id, &param.attrs, |builder| {
 510             intravisit::walk_param(builder, param);
 511         });
 512     }
 513
 514     fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
 515         self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
 516             intravisit::walk_item(builder, it);
 517         });
 518     }
 519
 520     fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
 521         self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
 522             intravisit::walk_foreign_item(builder, it);
 523         })
 524     }
 525
 526     fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
 527         self.with_lint_attrs(e.hir_id, &e.attrs, |builder| {
 528             intravisit::walk_expr(builder, e);
 529         })
 530     }
 531
 532     fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
 533         self.with_lint_attrs(s.hir_id, &s.attrs, |builder| {
 534             intravisit::walk_struct_field(builder, s);
 535         })
 536     }
 537
 538     fn visit_variant(
 539         &mut self,
 540         v: &'tcx hir::Variant<'tcx>,
 541         g: &'tcx hir::Generics<'tcx>,
 542         item_id: hir::HirId,
 543     ) {
 544         self.with_lint_attrs(v.id, &v.attrs, |builder| {
 545             intravisit::walk_variant(builder, v, g, item_id);
 546         })
 547     }
 548
 549     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
 550         self.with_lint_attrs(l.hir_id, &l.attrs, |builder| {
 551             intravisit::walk_local(builder, l);
 552         })
 553     }
 554
 555     fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
 556         self.with_lint_attrs(a.hir_id, &a.attrs, |builder| {
 557             intravisit::walk_arm(builder, a);
 558         })
 559     }
 560
 561     fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
 562         self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |builder| {
 563             intravisit::walk_trait_item(builder, trait_item);
 564         });
 565     }
 566
 567     fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
 568         self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |builder| {
 569             intravisit::walk_impl_item(builder, impl_item);
 570         });
 571     }
 572 }
 573
 574 pub fn provide(providers: &mut Providers) {
 575     providers.lint_levels = lint_levels;
 576 }