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_pretty::pprust;
   5 use rustc_data_structures::fx::FxHashMap;
   6 use rustc_errors::{Applicability, Diagnostic, LintDiagnosticBuilder, MultiSpan};
   7 use rustc_hir as hir;
   8 use rustc_hir::{intravisit, HirId};
   9 use rustc_middle::hir::nested_filter;
  10 use rustc_middle::lint::{
  11     struct_lint_level, LevelAndSource, LintExpectation, LintLevelMap, LintLevelSets,
  12     LintLevelSource, LintSet, LintStackIndex, COMMAND_LINE,
  13 };
  14 use rustc_middle::ty::query::Providers;
  15 use rustc_middle::ty::{RegisteredTools, TyCtxt};
  16 use rustc_session::lint::{
  17     builtin::{self, FORBIDDEN_LINT_GROUPS, SINGLE_USE_LIFETIMES, UNFULFILLED_LINT_EXPECTATIONS},
  18     Level, Lint, LintExpectationId, LintId,
  19 };
  20 use rustc_session::parse::{add_feature_diagnostics, feature_err};
  21 use rustc_session::Session;
  22 use rustc_span::symbol::{sym, Symbol};
  23 use rustc_span::{Span, DUMMY_SP};
  24
  25 use crate::errors::{
  26     MalformedAttribute, MalformedAttributeSub, OverruledAttribute, OverruledAttributeSub,
  27     UnknownToolInScopedLint,
  28 };
  29
  30 fn lint_levels(tcx: TyCtxt<'_>, (): ()) -> LintLevelMap {
  31     let store = unerased_lint_store(tcx);
  32     let levels =
  33         LintLevelsBuilder::new(tcx.sess, false, &store, &tcx.resolutions(()).registered_tools);
  34     let mut builder = LintLevelMapBuilder { levels, tcx };
  35     let krate = tcx.hir().krate();
  36
  37     builder.levels.id_to_set.reserve(krate.owners.len() + 1);
  38
  39     let push =
  40         builder.levels.push(tcx.hir().attrs(hir::CRATE_HIR_ID), true, Some(hir::CRATE_HIR_ID));
  41
  42     builder.levels.register_id(hir::CRATE_HIR_ID);
  43     tcx.hir().walk_toplevel_module(&mut builder);
  44     builder.levels.pop(push);
  45
  46     builder.levels.update_unstable_expectation_ids();
  47     builder.levels.build_map()
  48 }
  49
  50 pub struct LintLevelsBuilder<'s> {
  51     sess: &'s Session,
  52     lint_expectations: Vec<(LintExpectationId, LintExpectation)>,
  53     /// Each expectation has a stable and an unstable identifier. This map
  54     /// is used to map from unstable to stable [`LintExpectationId`]s.
  55     expectation_id_map: FxHashMap<LintExpectationId, LintExpectationId>,
  56     sets: LintLevelSets,
  57     id_to_set: FxHashMap<HirId, LintStackIndex>,
  58     cur: LintStackIndex,
  59     warn_about_weird_lints: bool,
  60     store: &'s LintStore,
  61     registered_tools: &'s RegisteredTools,
  62 }
  63
  64 pub struct BuilderPush {
  65     prev: LintStackIndex,
  66     pub changed: bool,
  67 }
  68
  69 impl<'s> LintLevelsBuilder<'s> {
  70     pub fn new(
  71         sess: &'s Session,
  72         warn_about_weird_lints: bool,
  73         store: &'s LintStore,
  74         registered_tools: &'s RegisteredTools,
  75     ) -> Self {
  76         let mut builder = LintLevelsBuilder {
  77             sess,
  78             lint_expectations: Default::default(),
  79             expectation_id_map: Default::default(),
  80             sets: LintLevelSets::new(),
  81             cur: COMMAND_LINE,
  82             id_to_set: Default::default(),
  83             warn_about_weird_lints,
  84             store,
  85             registered_tools,
  86         };
  87         builder.process_command_line(sess, store);
  88         assert_eq!(builder.sets.list.len(), 1);
  89         builder
  90     }
  91
  92     pub(crate) fn sess(&self) -> &Session {
  93         self.sess
  94     }
  95
  96     pub(crate) fn lint_store(&self) -> &LintStore {
  97         self.store
  98     }
  99
 100     fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
 101         &self.sets.list[self.cur].specs
 102     }
 103
 104     fn current_specs_mut(&mut self) -> &mut FxHashMap<LintId, LevelAndSource> {
 105         &mut self.sets.list[self.cur].specs
 106     }
 107
 108     fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
 109         self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
 110
 111         self.cur =
 112             self.sets.list.push(LintSet { specs: FxHashMap::default(), parent: COMMAND_LINE });
 113         for &(ref lint_name, level) in &sess.opts.lint_opts {
 114             store.check_lint_name_cmdline(sess, &lint_name, level, self.registered_tools);
 115             let orig_level = level;
 116             let lint_flag_val = Symbol::intern(lint_name);
 117
 118             let Ok(ids) = store.find_lints(&lint_name) else {
 119                 // errors handled in check_lint_name_cmdline above
 120                 continue
 121             };
 122             for id in ids {
 123                 // ForceWarn and Forbid cannot be overridden
 124                 if let Some((Level::ForceWarn(_) | Level::Forbid, _)) =
 125                     self.current_specs().get(&id)
 126                 {
 127                     continue;
 128                 }
 129
 130                 if self.check_gated_lint(id, DUMMY_SP) {
 131                     let src = LintLevelSource::CommandLine(lint_flag_val, orig_level);
 132                     self.current_specs_mut().insert(id, (level, src));
 133                 }
 134             }
 135         }
 136     }
 137
 138     /// Attempts to insert the `id` to `level_src` map entry. If unsuccessful
 139     /// (e.g. if a forbid was already inserted on the same scope), then emits a
 140     /// diagnostic with no change to `specs`.
 141     fn insert_spec(&mut self, id: LintId, (level, src): LevelAndSource) {
 142         let (old_level, old_src) =
 143             self.sets.get_lint_level(id.lint, self.cur, Some(self.current_specs()), &self.sess);
 144         // Setting to a non-forbid level is an error if the lint previously had
 145         // a forbid level. Note that this is not necessarily true even with a
 146         // `#[forbid(..)]` attribute present, as that is overridden by `--cap-lints`.
 147         //
 148         // This means that this only errors if we're truly lowering the lint
 149         // level from forbid.
 150         if level != Level::Forbid {
 151             if let Level::Forbid = old_level {
 152                 // Backwards compatibility check:
 153                 //
 154                 // We used to not consider `forbid(lint_group)`
 155                 // as preventing `allow(lint)` for some lint `lint` in
 156                 // `lint_group`. For now, issue a future-compatibility
 157                 // warning for this case.
 158                 let id_name = id.lint.name_lower();
 159                 let fcw_warning = match old_src {
 160                     LintLevelSource::Default => false,
 161                     LintLevelSource::Node(symbol, _, _) => self.store.is_lint_group(symbol),
 162                     LintLevelSource::CommandLine(symbol, _) => self.store.is_lint_group(symbol),
 163                 };
 164                 debug!(
 165                     "fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
 166                     fcw_warning,
 167                     self.current_specs(),
 168                     old_src,
 169                     id_name
 170                 );
 171
 172                 let decorate_diag = |diag: &mut Diagnostic| {
 173                     diag.span_label(src.span(), "overruled by previous forbid");
 174                     match old_src {
 175                         LintLevelSource::Default => {
 176                             diag.note(&format!(
 177                                 "`forbid` lint level is the default for {}",
 178                                 id.to_string()
 179                             ));
 180                         }
 181                         LintLevelSource::Node(_, forbid_source_span, reason) => {
 182                             diag.span_label(forbid_source_span, "`forbid` level set here");
 183                             if let Some(rationale) = reason {
 184                                 diag.note(rationale.as_str());
 185                             }
 186                         }
 187                         LintLevelSource::CommandLine(_, _) => {
 188                             diag.note("`forbid` lint level was set on command line");
 189                         }
 190                     }
 191                 };
 192                 if !fcw_warning {
 193                     self.sess.emit_err(OverruledAttribute {
 194                         span: src.span(),
 195                         overruled: src.span(),
 196                         lint_level: level.as_str().to_string(),
 197                         lint_source: src.name(),
 198                         sub: match old_src {
 199                             LintLevelSource::Default => {
 200                                 OverruledAttributeSub::DefaultSource { id: id.to_string() }
 201                             }
 202                             LintLevelSource::Node(_, forbid_source_span, reason) => {
 203                                 OverruledAttributeSub::NodeSource {
 204                                     span: forbid_source_span,
 205                                     reason,
 206                                 }
 207                             }
 208                             LintLevelSource::CommandLine(_, _) => {
 209                                 OverruledAttributeSub::CommandLineSource
 210                             }
 211                         },
 212                     });
 213                 } else {
 214                     self.struct_lint(
 215                         FORBIDDEN_LINT_GROUPS,
 216                         Some(src.span().into()),
 217                         |diag_builder| {
 218                             let mut diag_builder = diag_builder.build(&format!(
 219                                 "{}({}) incompatible with previous forbid",
 220                                 level.as_str(),
 221                                 src.name(),
 222                             ));
 223                             decorate_diag(&mut diag_builder);
 224                             diag_builder.emit();
 225                         },
 226                     );
 227                 }
 228
 229                 // Retain the forbid lint level, unless we are
 230                 // issuing a FCW. In the FCW case, we want to
 231                 // respect the new setting.
 232                 if !fcw_warning {
 233                     return;
 234                 }
 235             }
 236         }
 237
 238         // The lint `unfulfilled_lint_expectations` can't be expected, as it would suppress itself.
 239         // Handling expectations of this lint would add additional complexity with little to no
 240         // benefit. The expect level for this lint will therefore be ignored.
 241         if let Level::Expect(_) = level && id == LintId::of(UNFULFILLED_LINT_EXPECTATIONS) {
 242             return;
 243         }
 244
 245         match (old_level, level) {
 246             // If the new level is an expectation store it in `ForceWarn`
 247             (Level::ForceWarn(_), Level::Expect(expectation_id)) => self
 248                 .current_specs_mut()
 249                 .insert(id, (Level::ForceWarn(Some(expectation_id)), old_src)),
 250             // Keep `ForceWarn` level but drop the expectation
 251             (Level::ForceWarn(_), _) => {
 252                 self.current_specs_mut().insert(id, (Level::ForceWarn(None), old_src))
 253             }
 254             // Set the lint level as normal
 255             _ => self.current_specs_mut().insert(id, (level, src)),
 256         };
 257     }
 258
 259     /// Pushes a list of AST lint attributes onto this context.
 260     ///
 261     /// This function will return a `BuilderPush` object which should be passed
 262     /// to `pop` when this scope for the attributes provided is exited.
 263     ///
 264     /// This function will perform a number of tasks:
 265     ///
 266     /// * It'll validate all lint-related attributes in `attrs`
 267     /// * It'll mark all lint-related attributes as used
 268     /// * Lint levels will be updated based on the attributes provided
 269     /// * Lint attributes are validated, e.g., a `#[forbid]` can't be switched to
 270     ///   `#[allow]`
 271     ///
 272     /// Don't forget to call `pop`!
 273     pub(crate) fn push(
 274         &mut self,
 275         attrs: &[ast::Attribute],
 276         is_crate_node: bool,
 277         source_hir_id: Option<HirId>,
 278     ) -> BuilderPush {
 279         let prev = self.cur;
 280         self.cur = self.sets.list.push(LintSet { specs: FxHashMap::default(), parent: prev });
 281
 282         let sess = self.sess;
 283         for (attr_index, attr) in attrs.iter().enumerate() {
 284             if attr.has_name(sym::automatically_derived) {
 285                 self.current_specs_mut().insert(
 286                     LintId::of(SINGLE_USE_LIFETIMES),
 287                     (Level::Allow, LintLevelSource::Default),
 288                 );
 289                 continue;
 290             }
 291
 292             let level = match Level::from_attr(attr) {
 293                 None => continue,
 294                 // This is the only lint level with a `LintExpectationId` that can be created from an attribute
 295                 Some(Level::Expect(unstable_id)) if let Some(hir_id) = source_hir_id => {
 296                     let stable_id = self.create_stable_id(unstable_id, hir_id, attr_index);
 297
 298                     Level::Expect(stable_id)
 299                 }
 300                 Some(lvl) => lvl,
 301             };
 302
 303             let Some(mut metas) = attr.meta_item_list() else {
 304                 continue
 305             };
 306
 307             if metas.is_empty() {
 308                 // This emits the unused_attributes lint for `#[level()]`
 309                 continue;
 310             }
 311
 312             // Before processing the lint names, look for a reason (RFC 2383)
 313             // at the end.
 314             let mut reason = None;
 315             let tail_li = &metas[metas.len() - 1];
 316             if let Some(item) = tail_li.meta_item() {
 317                 match item.kind {
 318                     ast::MetaItemKind::Word => {} // actual lint names handled later
 319                     ast::MetaItemKind::NameValue(ref name_value) => {
 320                         if item.path == sym::reason {
 321                             if let ast::LitKind::Str(rationale, _) = name_value.kind {
 322                                 if !self.sess.features_untracked().lint_reasons {
 323                                     feature_err(
 324                                         &self.sess.parse_sess,
 325                                         sym::lint_reasons,
 326                                         item.span,
 327                                         "lint reasons are experimental",
 328                                     )
 329                                     .emit();
 330                                 }
 331                                 reason = Some(rationale);
 332                             } else {
 333                                 sess.emit_err(MalformedAttribute {
 334                                     span: name_value.span,
 335                                     sub: MalformedAttributeSub::ReasonMustBeStringLiteral(
 336                                         name_value.span,
 337                                     ),
 338                                 });
 339                             }
 340                             // found reason, reslice meta list to exclude it
 341                             metas.pop().unwrap();
 342                         } else {
 343                             sess.emit_err(MalformedAttribute {
 344                                 span: item.span,
 345                                 sub: MalformedAttributeSub::BadAttributeArgument(item.span),
 346                             });
 347                         }
 348                     }
 349                     ast::MetaItemKind::List(_) => {
 350                         sess.emit_err(MalformedAttribute {
 351                             span: item.span,
 352                             sub: MalformedAttributeSub::BadAttributeArgument(item.span),
 353                         });
 354                     }
 355                 }
 356             }
 357
 358             for (lint_index, li) in metas.iter_mut().enumerate() {
 359                 let level = match level {
 360                     Level::Expect(mut id) => {
 361                         id.set_lint_index(Some(lint_index as u16));
 362                         Level::Expect(id)
 363                     }
 364                     level => level,
 365                 };
 366
 367                 let sp = li.span();
 368                 let meta_item = match li {
 369                     ast::NestedMetaItem::MetaItem(meta_item) if meta_item.is_word() => meta_item,
 370                     _ => {
 371                         if let Some(item) = li.meta_item() {
 372                             if let ast::MetaItemKind::NameValue(_) = item.kind {
 373                                 if item.path == sym::reason {
 374                                     sess.emit_err(MalformedAttribute {
 375                                         span: sp,
 376                                         sub: MalformedAttributeSub::ReasonMustComeLast(sp),
 377                                     });
 378                                     continue;
 379                                 }
 380                             }
 381                         }
 382                         sess.emit_err(MalformedAttribute {
 383                             span: sp,
 384                             sub: MalformedAttributeSub::BadAttributeArgument(sp),
 385                         });
 386                         continue;
 387                     }
 388                 };
 389                 let tool_ident = if meta_item.path.segments.len() > 1 {
 390                     Some(meta_item.path.segments.remove(0).ident)
 391                 } else {
 392                     None
 393                 };
 394                 let tool_name = tool_ident.map(|ident| ident.name);
 395                 let name = pprust::path_to_string(&meta_item.path);
 396                 let lint_result =
 397                     self.store.check_lint_name(&name, tool_name, self.registered_tools);
 398                 match &lint_result {
 399                     CheckLintNameResult::Ok(ids) => {
 400                         // This checks for instances where the user writes `#[expect(unfulfilled_lint_expectations)]`
 401                         // in that case we want to avoid overriding the lint level but instead add an expectation that
 402                         // can't be fulfilled. The lint message will include an explanation, that the
 403                         // `unfulfilled_lint_expectations` lint can't be expected.
 404                         if let Level::Expect(expect_id) = level {
 405                             // The `unfulfilled_lint_expectations` lint is not part of any lint groups. Therefore. we
 406                             // only need to check the slice if it contains a single lint.
 407                             let is_unfulfilled_lint_expectations = match ids {
 408                                 [lint] => *lint == LintId::of(UNFULFILLED_LINT_EXPECTATIONS),
 409                                 _ => false,
 410                             };
 411                             self.lint_expectations.push((
 412                                 expect_id,
 413                                 LintExpectation::new(
 414                                     reason,
 415                                     sp,
 416                                     is_unfulfilled_lint_expectations,
 417                                     tool_name,
 418                                 ),
 419                             ));
 420                         }
 421                         let src = LintLevelSource::Node(
 422                             meta_item.path.segments.last().expect("empty lint name").ident.name,
 423                             sp,
 424                             reason,
 425                         );
 426                         for &id in *ids {
 427                             if self.check_gated_lint(id, attr.span) {
 428                                 self.insert_spec(id, (level, src));
 429                             }
 430                         }
 431                     }
 432
 433                     CheckLintNameResult::Tool(result) => {
 434                         match *result {
 435                             Ok(ids) => {
 436                                 let complete_name =
 437                                     &format!("{}::{}", tool_ident.unwrap().name, name);
 438                                 let src = LintLevelSource::Node(
 439                                     Symbol::intern(complete_name),
 440                                     sp,
 441                                     reason,
 442                                 );
 443                                 for id in ids {
 444                                     self.insert_spec(*id, (level, src));
 445                                 }
 446                                 if let Level::Expect(expect_id) = level {
 447                                     self.lint_expectations.push((
 448                                         expect_id,
 449                                         LintExpectation::new(reason, sp, false, tool_name),
 450                                     ));
 451                                 }
 452                             }
 453                             Err((Some(ids), ref new_lint_name)) => {
 454                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 455                                 let (lvl, src) = self.sets.get_lint_level(
 456                                     lint,
 457                                     self.cur,
 458                                     Some(self.current_specs()),
 459                                     &sess,
 460                                 );
 461                                 struct_lint_level(
 462                                     self.sess,
 463                                     lint,
 464                                     lvl,
 465                                     src,
 466                                     Some(sp.into()),
 467                                     |lint| {
 468                                         let msg = format!(
 469                                             "lint name `{}` is deprecated \
 470                                              and may not have an effect in the future.",
 471                                             name
 472                                         );
 473                                         lint.build(&msg)
 474                                             .span_suggestion(
 475                                                 sp,
 476                                                 "change it to",
 477                                                 new_lint_name,
 478                                                 Applicability::MachineApplicable,
 479                                             )
 480                                             .emit();
 481                                     },
 482                                 );
 483
 484                                 let src = LintLevelSource::Node(
 485                                     Symbol::intern(&new_lint_name),
 486                                     sp,
 487                                     reason,
 488                                 );
 489                                 for id in ids {
 490                                     self.insert_spec(*id, (level, src));
 491                                 }
 492                                 if let Level::Expect(expect_id) = level {
 493                                     self.lint_expectations.push((
 494                                         expect_id,
 495                                         LintExpectation::new(reason, sp, false, tool_name),
 496                                     ));
 497                                 }
 498                             }
 499                             Err((None, _)) => {
 500                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 501                                 // exist in the tool or the code was not compiled with the tool and
 502                                 // therefore the lint was never added to the `LintStore`. To detect
 503                                 // this is the responsibility of the lint tool.
 504                             }
 505                         }
 506                     }
 507
 508                     &CheckLintNameResult::NoTool => {
 509                         sess.emit_err(UnknownToolInScopedLint {
 510                             span: tool_ident.map(|ident| ident.span),
 511                             tool_name: tool_name.unwrap(),
 512                             lint_name: pprust::path_to_string(&meta_item.path),
 513                             is_nightly_build: sess.is_nightly_build().then_some(()),
 514                         });
 515                         continue;
 516                     }
 517
 518                     _ if !self.warn_about_weird_lints => {}
 519
 520                     CheckLintNameResult::Warning(msg, renamed) => {
 521                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 522                         let (renamed_lint_level, src) = self.sets.get_lint_level(
 523                             lint,
 524                             self.cur,
 525                             Some(self.current_specs()),
 526                             &sess,
 527                         );
 528                         struct_lint_level(
 529                             self.sess,
 530                             lint,
 531                             renamed_lint_level,
 532                             src,
 533                             Some(sp.into()),
 534                             |lint| {
 535                                 let mut err = lint.build(msg);
 536                                 if let Some(new_name) = &renamed {
 537                                     err.span_suggestion(
 538                                         sp,
 539                                         "use the new name",
 540                                         new_name,
 541                                         Applicability::MachineApplicable,
 542                                     );
 543                                 }
 544                                 err.emit();
 545                             },
 546                         );
 547                     }
 548                     CheckLintNameResult::NoLint(suggestion) => {
 549                         let lint = builtin::UNKNOWN_LINTS;
 550                         let (level, src) = self.sets.get_lint_level(
 551                             lint,
 552                             self.cur,
 553                             Some(self.current_specs()),
 554                             self.sess,
 555                         );
 556                         struct_lint_level(self.sess, lint, level, src, Some(sp.into()), |lint| {
 557                             let name = if let Some(tool_ident) = tool_ident {
 558                                 format!("{}::{}", tool_ident.name, name)
 559                             } else {
 560                                 name.to_string()
 561                             };
 562                             let mut db = lint.build(format!("unknown lint: `{}`", name));
 563                             if let Some(suggestion) = suggestion {
 564                                 db.span_suggestion(
 565                                     sp,
 566                                     "did you mean",
 567                                     suggestion,
 568                                     Applicability::MachineApplicable,
 569                                 );
 570                             }
 571                             db.emit();
 572                         });
 573                     }
 574                 }
 575                 // If this lint was renamed, apply the new lint instead of ignoring the attribute.
 576                 // This happens outside of the match because the new lint should be applied even if
 577                 // we don't warn about the name change.
 578                 if let CheckLintNameResult::Warning(_, Some(new_name)) = lint_result {
 579                     // Ignore any errors or warnings that happen because the new name is inaccurate
 580                     // NOTE: `new_name` already includes the tool name, so we don't have to add it again.
 581                     if let CheckLintNameResult::Ok(ids) =
 582                         self.store.check_lint_name(&new_name, None, self.registered_tools)
 583                     {
 584                         let src = LintLevelSource::Node(Symbol::intern(&new_name), sp, reason);
 585                         for &id in ids {
 586                             if self.check_gated_lint(id, attr.span) {
 587                                 self.insert_spec(id, (level, src));
 588                             }
 589                         }
 590                         if let Level::Expect(expect_id) = level {
 591                             self.lint_expectations.push((
 592                                 expect_id,
 593                                 LintExpectation::new(reason, sp, false, tool_name),
 594                             ));
 595                         }
 596                     } else {
 597                         panic!("renamed lint does not exist: {}", new_name);
 598                     }
 599                 }
 600             }
 601         }
 602
 603         if !is_crate_node {
 604             for (id, &(level, ref src)) in self.current_specs().iter() {
 605                 if !id.lint.crate_level_only {
 606                     continue;
 607                 }
 608
 609                 let LintLevelSource::Node(lint_attr_name, lint_attr_span, _) = *src else {
 610                     continue
 611                 };
 612
 613                 let lint = builtin::UNUSED_ATTRIBUTES;
 614                 let (lint_level, lint_src) =
 615                     self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), self.sess);
 616                 struct_lint_level(
 617                     self.sess,
 618                     lint,
 619                     lint_level,
 620                     lint_src,
 621                     Some(lint_attr_span.into()),
 622                     |lint| {
 623                         let mut db = lint.build(&format!(
 624                             "{}({}) is ignored unless specified at crate level",
 625                             level.as_str(),
 626                             lint_attr_name
 627                         ));
 628                         db.emit();
 629                     },
 630                 );
 631                 // don't set a separate error for every lint in the group
 632                 break;
 633             }
 634         }
 635
 636         if self.current_specs().is_empty() {
 637             self.sets.list.pop();
 638             self.cur = prev;
 639         }
 640
 641         BuilderPush { prev, changed: prev != self.cur }
 642     }
 643
 644     fn create_stable_id(
 645         &mut self,
 646         unstable_id: LintExpectationId,
 647         hir_id: HirId,
 648         attr_index: usize,
 649     ) -> LintExpectationId {
 650         let stable_id =
 651             LintExpectationId::Stable { hir_id, attr_index: attr_index as u16, lint_index: None };
 652
 653         self.expectation_id_map.insert(unstable_id, stable_id);
 654
 655         stable_id
 656     }
 657
 658     /// Checks if the lint is gated on a feature that is not enabled.
 659     ///
 660     /// Returns `true` if the lint's feature is enabled.
 661     fn check_gated_lint(&self, lint_id: LintId, span: Span) -> bool {
 662         if let Some(feature) = lint_id.lint.feature_gate {
 663             if !self.sess.features_untracked().enabled(feature) {
 664                 let lint = builtin::UNKNOWN_LINTS;
 665                 let (level, src) = self.lint_level(builtin::UNKNOWN_LINTS);
 666                 struct_lint_level(self.sess, lint, level, src, Some(span.into()), |lint_db| {
 667                     let mut db =
 668                         lint_db.build(&format!("unknown lint: `{}`", lint_id.lint.name_lower()));
 669                     db.note(&format!("the `{}` lint is unstable", lint_id.lint.name_lower(),));
 670                     add_feature_diagnostics(&mut db, &self.sess.parse_sess, feature);
 671                     db.emit();
 672                 });
 673                 return false;
 674             }
 675         }
 676         true
 677     }
 678
 679     /// Called after `push` when the scope of a set of attributes are exited.
 680     pub fn pop(&mut self, push: BuilderPush) {
 681         self.cur = push.prev;
 682     }
 683
 684     /// Find the lint level for a lint.
 685     pub fn lint_level(&self, lint: &'static Lint) -> (Level, LintLevelSource) {
 686         self.sets.get_lint_level(lint, self.cur, None, self.sess)
 687     }
 688
 689     /// Used to emit a lint-related diagnostic based on the current state of
 690     /// this lint context.
 691     pub fn struct_lint(
 692         &self,
 693         lint: &'static Lint,
 694         span: Option<MultiSpan>,
 695         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
 696     ) {
 697         let (level, src) = self.lint_level(lint);
 698         struct_lint_level(self.sess, lint, level, src, span, decorate)
 699     }
 700
 701     /// Registers the ID provided with the current set of lints stored in
 702     /// this context.
 703     pub fn register_id(&mut self, id: HirId) {
 704         self.id_to_set.insert(id, self.cur);
 705     }
 706
 707     fn update_unstable_expectation_ids(&self) {
 708         self.sess.diagnostic().update_unstable_expectation_id(&self.expectation_id_map);
 709     }
 710
 711     pub fn build_map(self) -> LintLevelMap {
 712         LintLevelMap {
 713             sets: self.sets,
 714             id_to_set: self.id_to_set,
 715             lint_expectations: self.lint_expectations,
 716         }
 717     }
 718 }
 719
 720 struct LintLevelMapBuilder<'tcx> {
 721     levels: LintLevelsBuilder<'tcx>,
 722     tcx: TyCtxt<'tcx>,
 723 }
 724
 725 impl LintLevelMapBuilder<'_> {
 726     fn with_lint_attrs<F>(&mut self, id: hir::HirId, f: F)
 727     where
 728         F: FnOnce(&mut Self),
 729     {
 730         let is_crate_hir = id == hir::CRATE_HIR_ID;
 731         let attrs = self.tcx.hir().attrs(id);
 732         let push = self.levels.push(attrs, is_crate_hir, Some(id));
 733
 734         if push.changed {
 735             self.levels.register_id(id);
 736         }
 737         f(self);
 738         self.levels.pop(push);
 739     }
 740 }
 741
 742 impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'tcx> {
 743     type NestedFilter = nested_filter::All;
 744
 745     fn nested_visit_map(&mut self) -> Self::Map {
 746         self.tcx.hir()
 747     }
 748
 749     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
 750         self.with_lint_attrs(param.hir_id, |builder| {
 751             intravisit::walk_param(builder, param);
 752         });
 753     }
 754
 755     fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
 756         self.with_lint_attrs(it.hir_id(), |builder| {
 757             intravisit::walk_item(builder, it);
 758         });
 759     }
 760
 761     fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
 762         self.with_lint_attrs(it.hir_id(), |builder| {
 763             intravisit::walk_foreign_item(builder, it);
 764         })
 765     }
 766
 767     fn visit_stmt(&mut self, e: &'tcx hir::Stmt<'tcx>) {
 768         // We will call `with_lint_attrs` when we walk
 769         // the `StmtKind`. The outer statement itself doesn't
 770         // define the lint levels.
 771         intravisit::walk_stmt(self, e);
 772     }
 773
 774     fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
 775         self.with_lint_attrs(e.hir_id, |builder| {
 776             intravisit::walk_expr(builder, e);
 777         })
 778     }
 779
 780     fn visit_expr_field(&mut self, field: &'tcx hir::ExprField<'tcx>) {
 781         self.with_lint_attrs(field.hir_id, |builder| {
 782             intravisit::walk_expr_field(builder, field);
 783         })
 784     }
 785
 786     fn visit_field_def(&mut self, s: &'tcx hir::FieldDef<'tcx>) {
 787         self.with_lint_attrs(s.hir_id, |builder| {
 788             intravisit::walk_field_def(builder, s);
 789         })
 790     }
 791
 792     fn visit_variant(&mut self, v: &'tcx hir::Variant<'tcx>) {
 793         self.with_lint_attrs(v.id, |builder| {
 794             intravisit::walk_variant(builder, v);
 795         })
 796     }
 797
 798     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
 799         self.with_lint_attrs(l.hir_id, |builder| {
 800             intravisit::walk_local(builder, l);
 801         })
 802     }
 803
 804     fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
 805         self.with_lint_attrs(a.hir_id, |builder| {
 806             intravisit::walk_arm(builder, a);
 807         })
 808     }
 809
 810     fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
 811         self.with_lint_attrs(trait_item.hir_id(), |builder| {
 812             intravisit::walk_trait_item(builder, trait_item);
 813         });
 814     }
 815
 816     fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
 817         self.with_lint_attrs(impl_item.hir_id(), |builder| {
 818             intravisit::walk_impl_item(builder, impl_item);
 819         });
 820     }
 821
 822     fn visit_pat_field(&mut self, field: &'tcx hir::PatField<'tcx>) {
 823         self.with_lint_attrs(field.hir_id, |builder| {
 824             intravisit::walk_pat_field(builder, field);
 825         })
 826     }
 827
 828     fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
 829         self.with_lint_attrs(p.hir_id, |builder| {
 830             intravisit::walk_generic_param(builder, p);
 831         });
 832     }
 833 }
 834
 835 pub fn provide(providers: &mut Providers) {
 836     providers.lint_levels = lint_levels;
 837 }