compiler/rustc_lint/src/levels.rs

   1 use crate::context::{CheckLintNameResult, LintStore};
   2 use crate::late::unerased_lint_store;
   3 use rustc_ast as 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::LevelSource;
  14 use rustc_middle::lint::LintDiagnosticBuilder;
  15 use rustc_middle::lint::{struct_lint_level, LintLevelMap, LintLevelSets, LintSet, LintSource};
  16 use rustc_middle::ty::query::Providers;
  17 use rustc_middle::ty::TyCtxt;
  18 use rustc_session::lint::{builtin, Level, Lint, LintId};
  19 use rustc_session::parse::feature_err;
  20 use rustc_session::Session;
  21 use rustc_span::symbol::{sym, Symbol};
  22 use rustc_span::{source_map::MultiSpan, Span, DUMMY_SP};
  23
  24 use std::cmp;
  25
  26 fn lint_levels(tcx: TyCtxt<'_>, cnum: CrateNum) -> LintLevelMap {
  27     assert_eq!(cnum, LOCAL_CRATE);
  28     let store = unerased_lint_store(tcx);
  29     let levels = LintLevelsBuilder::new(tcx.sess, false, &store);
  30     let mut builder = LintLevelMapBuilder { levels, tcx, store };
  31     let krate = tcx.hir().krate();
  32
  33     builder.levels.id_to_set.reserve(krate.exported_macros.len() + 1);
  34
  35     let push = builder.levels.push(&krate.item.attrs, &store, true);
  36     builder.levels.register_id(hir::CRATE_HIR_ID);
  37     for macro_def in krate.exported_macros {
  38         builder.levels.register_id(macro_def.hir_id);
  39     }
  40     intravisit::walk_crate(&mut builder, krate);
  41     builder.levels.pop(push);
  42
  43     builder.levels.build_map()
  44 }
  45
  46 pub struct LintLevelsBuilder<'s> {
  47     sess: &'s Session,
  48     sets: LintLevelSets,
  49     id_to_set: FxHashMap<HirId, u32>,
  50     cur: u32,
  51     warn_about_weird_lints: bool,
  52 }
  53
  54 pub struct BuilderPush {
  55     prev: u32,
  56     pub changed: bool,
  57 }
  58
  59 impl<'s> LintLevelsBuilder<'s> {
  60     pub fn new(sess: &'s Session, warn_about_weird_lints: bool, store: &LintStore) -> Self {
  61         let mut builder = LintLevelsBuilder {
  62             sess,
  63             sets: LintLevelSets::new(),
  64             cur: 0,
  65             id_to_set: Default::default(),
  66             warn_about_weird_lints,
  67         };
  68         builder.process_command_line(sess, store);
  69         assert_eq!(builder.sets.list.len(), 1);
  70         builder
  71     }
  72
  73     fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
  74         let mut specs = FxHashMap::default();
  75         self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
  76
  77         for &(ref lint_name, level) in &sess.opts.lint_opts {
  78             store.check_lint_name_cmdline(sess, &lint_name, level);
  79             let orig_level = level;
  80
  81             // If the cap is less than this specified level, e.g., if we've got
  82             // `--cap-lints allow` but we've also got `-D foo` then we ignore
  83             // this specification as the lint cap will set it to allow anyway.
  84             let level = cmp::min(level, self.sets.lint_cap);
  85
  86             let lint_flag_val = Symbol::intern(lint_name);
  87
  88             let ids = match store.find_lints(&lint_name) {
  89                 Ok(ids) => ids,
  90                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
  91             };
  92             for id in ids {
  93                 self.check_gated_lint(id, DUMMY_SP);
  94                 let src = LintSource::CommandLine(lint_flag_val, orig_level);
  95                 specs.insert(id, (level, src));
  96             }
  97         }
  98
  99         self.sets.list.push(LintSet::CommandLine { specs });
 100     }
 101
 102     /// Attempts to insert the `id` to `level_src` map entry. If unsuccessful
 103     /// (e.g. if a forbid was already inserted on the same scope), then emits a
 104     /// diagnostic with no change to `specs`.
 105     fn insert_spec(
 106         &mut self,
 107         specs: &mut FxHashMap<LintId, LevelSource>,
 108         id: LintId,
 109         (level, src): LevelSource,
 110     ) {
 111         if let Some((old_level, old_src)) = specs.get(&id) {
 112             if old_level == &Level::Forbid && level != Level::Forbid {
 113                 let mut diag_builder = struct_span_err!(
 114                     self.sess,
 115                     src.span(),
 116                     E0453,
 117                     "{}({}) incompatible with previous forbid in same scope",
 118                     level.as_str(),
 119                     src.name(),
 120                 );
 121                 match *old_src {
 122                     LintSource::Default => {}
 123                     LintSource::Node(_, forbid_source_span, reason) => {
 124                         diag_builder.span_label(forbid_source_span, "`forbid` level set here");
 125                         if let Some(rationale) = reason {
 126                             diag_builder.note(&rationale.as_str());
 127                         }
 128                     }
 129                     LintSource::CommandLine(_, _) => {
 130                         diag_builder.note("`forbid` lint level was set on command line");
 131                     }
 132                 }
 133                 diag_builder.emit();
 134                 return;
 135             }
 136         }
 137         specs.insert(id, (level, src));
 138     }
 139
 140     /// Pushes a list of AST lint attributes onto this context.
 141     ///
 142     /// This function will return a `BuilderPush` object which should be passed
 143     /// to `pop` when this scope for the attributes provided is exited.
 144     ///
 145     /// This function will perform a number of tasks:
 146     ///
 147     /// * It'll validate all lint-related attributes in `attrs`
 148     /// * It'll mark all lint-related attributes as used
 149     /// * Lint levels will be updated based on the attributes provided
 150     /// * Lint attributes are validated, e.g., a `#[forbid]` can't be switched to
 151     ///   `#[allow]`
 152     ///
 153     /// Don't forget to call `pop`!
 154     pub(crate) fn push(
 155         &mut self,
 156         attrs: &[ast::Attribute],
 157         store: &LintStore,
 158         is_crate_node: bool,
 159     ) -> BuilderPush {
 160         let mut specs = FxHashMap::default();
 161         let sess = self.sess;
 162         let bad_attr = |span| struct_span_err!(sess, span, E0452, "malformed lint attribute input");
 163         for attr in attrs {
 164             let level = match Level::from_symbol(attr.name_or_empty()) {
 165                 None => continue,
 166                 Some(lvl) => lvl,
 167             };
 168
 169             let meta = unwrap_or!(attr.meta(), continue);
 170             self.sess.mark_attr_used(attr);
 171
 172             let mut metas = unwrap_or!(meta.meta_item_list(), continue);
 173
 174             if metas.is_empty() {
 175                 // FIXME (#55112): issue unused-attributes lint for `#[level()]`
 176                 continue;
 177             }
 178
 179             // Before processing the lint names, look for a reason (RFC 2383)
 180             // at the end.
 181             let mut reason = None;
 182             let tail_li = &metas[metas.len() - 1];
 183             if let Some(item) = tail_li.meta_item() {
 184                 match item.kind {
 185                     ast::MetaItemKind::Word => {} // actual lint names handled later
 186                     ast::MetaItemKind::NameValue(ref name_value) => {
 187                         if item.path == sym::reason {
 188                             // found reason, reslice meta list to exclude it
 189                             metas = &metas[0..metas.len() - 1];
 190                             // FIXME (#55112): issue unused-attributes lint if we thereby
 191                             // don't have any lint names (`#[level(reason = "foo")]`)
 192                             if let ast::LitKind::Str(rationale, _) = name_value.kind {
 193                                 if !self.sess.features_untracked().lint_reasons {
 194                                     feature_err(
 195                                         &self.sess.parse_sess,
 196                                         sym::lint_reasons,
 197                                         item.span,
 198                                         "lint reasons are experimental",
 199                                     )
 200                                     .emit();
 201                                 }
 202                                 reason = Some(rationale);
 203                             } else {
 204                                 bad_attr(name_value.span)
 205                                     .span_label(name_value.span, "reason must be a string literal")
 206                                     .emit();
 207                             }
 208                         } else {
 209                             bad_attr(item.span)
 210                                 .span_label(item.span, "bad attribute argument")
 211                                 .emit();
 212                         }
 213                     }
 214                     ast::MetaItemKind::List(_) => {
 215                         bad_attr(item.span).span_label(item.span, "bad attribute argument").emit();
 216                     }
 217                 }
 218             }
 219
 220             for li in metas {
 221                 let meta_item = match li.meta_item() {
 222                     Some(meta_item) if meta_item.is_word() => meta_item,
 223                     _ => {
 224                         let sp = li.span();
 225                         let mut err = bad_attr(sp);
 226                         let mut add_label = true;
 227                         if let Some(item) = li.meta_item() {
 228                             if let ast::MetaItemKind::NameValue(_) = item.kind {
 229                                 if item.path == sym::reason {
 230                                     err.span_label(sp, "reason in lint attribute must come last");
 231                                     add_label = false;
 232                                 }
 233                             }
 234                         }
 235                         if add_label {
 236                             err.span_label(sp, "bad attribute argument");
 237                         }
 238                         err.emit();
 239                         continue;
 240                     }
 241                 };
 242                 let tool_name = if meta_item.path.segments.len() > 1 {
 243                     let tool_ident = meta_item.path.segments[0].ident;
 244                     if !attr::is_known_lint_tool(tool_ident) {
 245                         struct_span_err!(
 246                             sess,
 247                             tool_ident.span,
 248                             E0710,
 249                             "an unknown tool name found in scoped lint: `{}`",
 250                             pprust::path_to_string(&meta_item.path),
 251                         )
 252                         .emit();
 253                         continue;
 254                     }
 255
 256                     Some(tool_ident.name)
 257                 } else {
 258                     None
 259                 };
 260                 let name = meta_item.path.segments.last().expect("empty lint name").ident.name;
 261                 match store.check_lint_name(&name.as_str(), tool_name) {
 262                     CheckLintNameResult::Ok(ids) => {
 263                         let src = LintSource::Node(name, li.span(), reason);
 264                         for &id in ids {
 265                             self.check_gated_lint(id, attr.span);
 266                             self.insert_spec(&mut specs, id, (level, src));
 267                         }
 268                     }
 269
 270                     CheckLintNameResult::Tool(result) => {
 271                         match result {
 272                             Ok(ids) => {
 273                                 let complete_name = &format!("{}::{}", tool_name.unwrap(), name);
 274                                 let src = LintSource::Node(
 275                                     Symbol::intern(complete_name),
 276                                     li.span(),
 277                                     reason,
 278                                 );
 279                                 for id in ids {
 280                                     self.insert_spec(&mut specs, *id, (level, src));
 281                                 }
 282                             }
 283                             Err((Some(ids), new_lint_name)) => {
 284                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 285                                 let (lvl, src) =
 286                                     self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
 287                                 struct_lint_level(
 288                                     self.sess,
 289                                     lint,
 290                                     lvl,
 291                                     src,
 292                                     Some(li.span().into()),
 293                                     |lint| {
 294                                         let msg = format!(
 295                                             "lint name `{}` is deprecated \
 296                                              and may not have an effect in the future. \
 297                                              Also `cfg_attr(cargo-clippy)` won't be necessary anymore",
 298                                             name
 299                                         );
 300                                         lint.build(&msg)
 301                                             .span_suggestion(
 302                                                 li.span(),
 303                                                 "change it to",
 304                                                 new_lint_name.to_string(),
 305                                                 Applicability::MachineApplicable,
 306                                             )
 307                                             .emit();
 308                                     },
 309                                 );
 310
 311                                 let src = LintSource::Node(
 312                                     Symbol::intern(&new_lint_name),
 313                                     li.span(),
 314                                     reason,
 315                                 );
 316                                 for id in ids {
 317                                     self.insert_spec(&mut specs, *id, (level, src));
 318                                 }
 319                             }
 320                             Err((None, _)) => {
 321                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 322                                 // exist in the tool or the code was not compiled with the tool and
 323                                 // therefore the lint was never added to the `LintStore`. To detect
 324                                 // this is the responsibility of the lint tool.
 325                             }
 326                         }
 327                     }
 328
 329                     _ if !self.warn_about_weird_lints => {}
 330
 331                     CheckLintNameResult::Warning(msg, renamed) => {
 332                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 333                         let (level, src) =
 334                             self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
 335                         struct_lint_level(
 336                             self.sess,
 337                             lint,
 338                             level,
 339                             src,
 340                             Some(li.span().into()),
 341                             |lint| {
 342                                 let mut err = lint.build(&msg);
 343                                 if let Some(new_name) = renamed {
 344                                     err.span_suggestion(
 345                                         li.span(),
 346                                         "use the new name",
 347                                         new_name,
 348                                         Applicability::MachineApplicable,
 349                                     );
 350                                 }
 351                                 err.emit();
 352                             },
 353                         );
 354                     }
 355                     CheckLintNameResult::NoLint(suggestion) => {
 356                         let lint = builtin::UNKNOWN_LINTS;
 357                         let (level, src) =
 358                             self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
 359                         struct_lint_level(
 360                             self.sess,
 361                             lint,
 362                             level,
 363                             src,
 364                             Some(li.span().into()),
 365                             |lint| {
 366                                 let mut db = lint.build(&format!("unknown lint: `{}`", name));
 367                                 if let Some(suggestion) = suggestion {
 368                                     db.span_suggestion(
 369                                         li.span(),
 370                                         "did you mean",
 371                                         suggestion.to_string(),
 372                                         Applicability::MachineApplicable,
 373                                     );
 374                                 }
 375                                 db.emit();
 376                             },
 377                         );
 378                     }
 379                 }
 380             }
 381         }
 382
 383         if !is_crate_node {
 384             for (id, &(level, ref src)) in specs.iter() {
 385                 if !id.lint.crate_level_only {
 386                     continue;
 387                 }
 388
 389                 let (lint_attr_name, lint_attr_span) = match *src {
 390                     LintSource::Node(name, span, _) => (name, span),
 391                     _ => continue,
 392                 };
 393
 394                 let lint = builtin::UNUSED_ATTRIBUTES;
 395                 let (lint_level, lint_src) =
 396                     self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
 397                 struct_lint_level(
 398                     self.sess,
 399                     lint,
 400                     lint_level,
 401                     lint_src,
 402                     Some(lint_attr_span.into()),
 403                     |lint| {
 404                         let mut db = lint.build(&format!(
 405                             "{}({}) is ignored unless specified at crate level",
 406                             level.as_str(),
 407                             lint_attr_name
 408                         ));
 409                         db.emit();
 410                     },
 411                 );
 412                 // don't set a separate error for every lint in the group
 413                 break;
 414             }
 415         }
 416
 417         for (id, &(level, ref src)) in specs.iter() {
 418             if level == Level::Forbid {
 419                 continue;
 420             }
 421             let forbid_src = match self.sets.get_lint_id_level(*id, self.cur, None) {
 422                 (Some(Level::Forbid), src) => src,
 423                 _ => continue,
 424             };
 425             let forbidden_lint_name = match forbid_src {
 426                 LintSource::Default => id.to_string(),
 427                 LintSource::Node(name, _, _) => name.to_string(),
 428                 LintSource::CommandLine(name, _) => name.to_string(),
 429             };
 430             let (lint_attr_name, lint_attr_span) = match *src {
 431                 LintSource::Node(name, span, _) => (name, span),
 432                 _ => continue,
 433             };
 434             let mut diag_builder = struct_span_err!(
 435                 self.sess,
 436                 lint_attr_span,
 437                 E0453,
 438                 "{}({}) overruled by outer forbid({})",
 439                 level.as_str(),
 440                 lint_attr_name,
 441                 forbidden_lint_name
 442             );
 443             diag_builder.span_label(lint_attr_span, "overruled by previous forbid");
 444             match forbid_src {
 445                 LintSource::Default => {}
 446                 LintSource::Node(_, forbid_source_span, reason) => {
 447                     diag_builder.span_label(forbid_source_span, "`forbid` level set here");
 448                     if let Some(rationale) = reason {
 449                         diag_builder.note(&rationale.as_str());
 450                     }
 451                 }
 452                 LintSource::CommandLine(_, _) => {
 453                     diag_builder.note("`forbid` lint level was set on command line");
 454                 }
 455             }
 456             diag_builder.emit();
 457             // don't set a separate error for every lint in the group
 458             break;
 459         }
 460
 461         let prev = self.cur;
 462         if !specs.is_empty() {
 463             self.cur = self.sets.list.len() as u32;
 464             self.sets.list.push(LintSet::Node { specs, parent: prev });
 465         }
 466
 467         BuilderPush { prev, changed: prev != self.cur }
 468     }
 469
 470     /// Checks if the lint is gated on a feature that is not enabled.
 471     fn check_gated_lint(&self, lint_id: LintId, span: Span) {
 472         if let Some(feature) = lint_id.lint.feature_gate {
 473             if !self.sess.features_untracked().enabled(feature) {
 474                 feature_err(
 475                     &self.sess.parse_sess,
 476                     feature,
 477                     span,
 478                     &format!("the `{}` lint is unstable", lint_id.lint.name_lower()),
 479                 )
 480                 .emit();
 481             }
 482         }
 483     }
 484
 485     /// Called after `push` when the scope of a set of attributes are exited.
 486     pub fn pop(&mut self, push: BuilderPush) {
 487         self.cur = push.prev;
 488     }
 489
 490     /// Find the lint level for a lint.
 491     pub fn lint_level(&self, lint: &'static Lint) -> (Level, LintSource) {
 492         self.sets.get_lint_level(lint, self.cur, None, self.sess)
 493     }
 494
 495     /// Used to emit a lint-related diagnostic based on the current state of
 496     /// this lint context.
 497     pub fn struct_lint(
 498         &self,
 499         lint: &'static Lint,
 500         span: Option<MultiSpan>,
 501         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 502     ) {
 503         let (level, src) = self.lint_level(lint);
 504         struct_lint_level(self.sess, lint, level, src, span, decorate)
 505     }
 506
 507     /// Registers the ID provided with the current set of lints stored in
 508     /// this context.
 509     pub fn register_id(&mut self, id: HirId) {
 510         self.id_to_set.insert(id, self.cur);
 511     }
 512
 513     pub fn build(self) -> LintLevelSets {
 514         self.sets
 515     }
 516
 517     pub fn build_map(self) -> LintLevelMap {
 518         LintLevelMap { sets: self.sets, id_to_set: self.id_to_set }
 519     }
 520 }
 521
 522 struct LintLevelMapBuilder<'a, 'tcx> {
 523     levels: LintLevelsBuilder<'tcx>,
 524     tcx: TyCtxt<'tcx>,
 525     store: &'a LintStore,
 526 }
 527
 528 impl LintLevelMapBuilder<'_, '_> {
 529     fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &[ast::Attribute], f: F)
 530     where
 531         F: FnOnce(&mut Self),
 532     {
 533         let is_crate_hir = id == hir::CRATE_HIR_ID;
 534         let push = self.levels.push(attrs, self.store, is_crate_hir);
 535         if push.changed {
 536             self.levels.register_id(id);
 537         }
 538         f(self);
 539         self.levels.pop(push);
 540     }
 541 }
 542
 543 impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'_, 'tcx> {
 544     type Map = Map<'tcx>;
 545
 546     fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
 547         intravisit::NestedVisitorMap::All(self.tcx.hir())
 548     }
 549
 550     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
 551         self.with_lint_attrs(param.hir_id, &param.attrs, |builder| {
 552             intravisit::walk_param(builder, param);
 553         });
 554     }
 555
 556     fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
 557         self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
 558             intravisit::walk_item(builder, it);
 559         });
 560     }
 561
 562     fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
 563         self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
 564             intravisit::walk_foreign_item(builder, it);
 565         })
 566     }
 567
 568     fn visit_stmt(&mut self, e: &'tcx hir::Stmt<'tcx>) {
 569         // We will call `with_lint_attrs` when we walk
 570         // the `StmtKind`. The outer statement itself doesn't
 571         // define the lint levels.
 572         intravisit::walk_stmt(self, e);
 573     }
 574
 575     fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
 576         self.with_lint_attrs(e.hir_id, &e.attrs, |builder| {
 577             intravisit::walk_expr(builder, e);
 578         })
 579     }
 580
 581     fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
 582         self.with_lint_attrs(s.hir_id, &s.attrs, |builder| {
 583             intravisit::walk_struct_field(builder, s);
 584         })
 585     }
 586
 587     fn visit_variant(
 588         &mut self,
 589         v: &'tcx hir::Variant<'tcx>,
 590         g: &'tcx hir::Generics<'tcx>,
 591         item_id: hir::HirId,
 592     ) {
 593         self.with_lint_attrs(v.id, &v.attrs, |builder| {
 594             intravisit::walk_variant(builder, v, g, item_id);
 595         })
 596     }
 597
 598     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
 599         self.with_lint_attrs(l.hir_id, &l.attrs, |builder| {
 600             intravisit::walk_local(builder, l);
 601         })
 602     }
 603
 604     fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
 605         self.with_lint_attrs(a.hir_id, &a.attrs, |builder| {
 606             intravisit::walk_arm(builder, a);
 607         })
 608     }
 609
 610     fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
 611         self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |builder| {
 612             intravisit::walk_trait_item(builder, trait_item);
 613         });
 614     }
 615
 616     fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
 617         self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |builder| {
 618             intravisit::walk_impl_item(builder, impl_item);
 619         });
 620     }
 621 }
 622
 623 pub fn provide(providers: &mut Providers) {
 624     providers.lint_levels = lint_levels;
 625 }