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::unwrap_or;
   5 use rustc_ast_pretty::pprust;
   6 use rustc_data_structures::fx::FxHashMap;
   7 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
   8 use rustc_hir as hir;
   9 use rustc_hir::{intravisit, HirId, CRATE_HIR_ID};
  10 use rustc_middle::hir::map::Map;
  11 use rustc_middle::lint::LevelAndSource;
  12 use rustc_middle::lint::LintDiagnosticBuilder;
  13 use rustc_middle::lint::{
  14     struct_lint_level, LintLevelMap, LintLevelSets, LintLevelSource, LintSet, LintStackIndex,
  15     COMMAND_LINE,
  16 };
  17 use rustc_middle::ty::query::Providers;
  18 use rustc_middle::ty::TyCtxt;
  19 use rustc_session::lint::{
  20     builtin::{self, FORBIDDEN_LINT_GROUPS},
  21     Level, Lint, LintId,
  22 };
  23 use rustc_session::parse::feature_err;
  24 use rustc_session::Session;
  25 use rustc_span::symbol::{sym, Symbol};
  26 use rustc_span::{source_map::MultiSpan, Span, DUMMY_SP};
  27 use tracing::debug;
  28
  29 fn lint_levels(tcx: TyCtxt<'_>, (): ()) -> LintLevelMap {
  30     let store = unerased_lint_store(tcx);
  31     let crate_attrs = tcx.hir().attrs(CRATE_HIR_ID);
  32     let levels = LintLevelsBuilder::new(tcx.sess, false, &store, crate_attrs);
  33     let mut builder = LintLevelMapBuilder { levels, tcx, store };
  34     let krate = tcx.hir().krate();
  35
  36     builder.levels.id_to_set.reserve(krate.owners.len() + 1);
  37
  38     let push = builder.levels.push(tcx.hir().attrs(hir::CRATE_HIR_ID), &store, true);
  39     builder.levels.register_id(hir::CRATE_HIR_ID);
  40     tcx.hir().walk_toplevel_module(&mut builder);
  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, LintStackIndex>,
  50     cur: LintStackIndex,
  51     warn_about_weird_lints: bool,
  52     store: &'s LintStore,
  53     crate_attrs: &'s [ast::Attribute],
  54 }
  55
  56 pub struct BuilderPush {
  57     prev: LintStackIndex,
  58     pub changed: bool,
  59 }
  60
  61 impl<'s> LintLevelsBuilder<'s> {
  62     pub fn new(
  63         sess: &'s Session,
  64         warn_about_weird_lints: bool,
  65         store: &'s LintStore,
  66         crate_attrs: &'s [ast::Attribute],
  67     ) -> Self {
  68         let mut builder = LintLevelsBuilder {
  69             sess,
  70             sets: LintLevelSets::new(),
  71             cur: COMMAND_LINE,
  72             id_to_set: Default::default(),
  73             warn_about_weird_lints,
  74             store,
  75             crate_attrs,
  76         };
  77         builder.process_command_line(sess, store);
  78         assert_eq!(builder.sets.list.len(), 1);
  79         builder
  80     }
  81
  82     fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
  83         let mut specs = FxHashMap::default();
  84         self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
  85
  86         for &(ref lint_name, level) in &sess.opts.lint_opts {
  87             store.check_lint_name_cmdline(sess, &lint_name, level, self.crate_attrs);
  88             let orig_level = level;
  89             let lint_flag_val = Symbol::intern(lint_name);
  90
  91             let ids = match store.find_lints(&lint_name) {
  92                 Ok(ids) => ids,
  93                 Err(_) => continue, // errors handled in check_lint_name_cmdline above
  94             };
  95             for id in ids {
  96                 // ForceWarn and Forbid cannot be overriden
  97                 if let Some((Level::ForceWarn | Level::Forbid, _)) = specs.get(&id) {
  98                     continue;
  99                 }
 100
 101                 self.check_gated_lint(id, DUMMY_SP);
 102                 let src = LintLevelSource::CommandLine(lint_flag_val, orig_level);
 103                 specs.insert(id, (level, src));
 104             }
 105         }
 106
 107         self.cur = self.sets.list.push(LintSet { specs, parent: COMMAND_LINE });
 108     }
 109
 110     /// Attempts to insert the `id` to `level_src` map entry. If unsuccessful
 111     /// (e.g. if a forbid was already inserted on the same scope), then emits a
 112     /// diagnostic with no change to `specs`.
 113     fn insert_spec(
 114         &mut self,
 115         specs: &mut FxHashMap<LintId, LevelAndSource>,
 116         id: LintId,
 117         (level, src): LevelAndSource,
 118     ) {
 119         let (old_level, old_src) =
 120             self.sets.get_lint_level(id.lint, self.cur, Some(&specs), &self.sess);
 121         // Setting to a non-forbid level is an error if the lint previously had
 122         // a forbid level. Note that this is not necessarily true even with a
 123         // `#[forbid(..)]` attribute present, as that is overriden by `--cap-lints`.
 124         //
 125         // This means that this only errors if we're truly lowering the lint
 126         // level from forbid.
 127         if level != Level::Forbid {
 128             if let Level::Forbid = old_level {
 129                 // Backwards compatibility check:
 130                 //
 131                 // We used to not consider `forbid(lint_group)`
 132                 // as preventing `allow(lint)` for some lint `lint` in
 133                 // `lint_group`. For now, issue a future-compatibility
 134                 // warning for this case.
 135                 let id_name = id.lint.name_lower();
 136                 let fcw_warning = match old_src {
 137                     LintLevelSource::Default => false,
 138                     LintLevelSource::Node(symbol, _, _) => self.store.is_lint_group(symbol),
 139                     LintLevelSource::CommandLine(symbol, _) => self.store.is_lint_group(symbol),
 140                 };
 141                 debug!(
 142                     "fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
 143                     fcw_warning, specs, old_src, id_name
 144                 );
 145
 146                 let decorate_diag_builder = |mut diag_builder: DiagnosticBuilder<'_>| {
 147                     diag_builder.span_label(src.span(), "overruled by previous forbid");
 148                     match old_src {
 149                         LintLevelSource::Default => {
 150                             diag_builder.note(&format!(
 151                                 "`forbid` lint level is the default for {}",
 152                                 id.to_string()
 153                             ));
 154                         }
 155                         LintLevelSource::Node(_, forbid_source_span, reason) => {
 156                             diag_builder.span_label(forbid_source_span, "`forbid` level set here");
 157                             if let Some(rationale) = reason {
 158                                 diag_builder.note(&rationale.as_str());
 159                             }
 160                         }
 161                         LintLevelSource::CommandLine(_, _) => {
 162                             diag_builder.note("`forbid` lint level was set on command line");
 163                         }
 164                     }
 165                     diag_builder.emit();
 166                 };
 167                 if !fcw_warning {
 168                     let diag_builder = struct_span_err!(
 169                         self.sess,
 170                         src.span(),
 171                         E0453,
 172                         "{}({}) incompatible with previous forbid",
 173                         level.as_str(),
 174                         src.name(),
 175                     );
 176                     decorate_diag_builder(diag_builder);
 177                 } else {
 178                     self.struct_lint(
 179                         FORBIDDEN_LINT_GROUPS,
 180                         Some(src.span().into()),
 181                         |diag_builder| {
 182                             let diag_builder = diag_builder.build(&format!(
 183                                 "{}({}) incompatible with previous forbid",
 184                                 level.as_str(),
 185                                 src.name(),
 186                             ));
 187                             decorate_diag_builder(diag_builder);
 188                         },
 189                     );
 190                 }
 191
 192                 // Retain the forbid lint level, unless we are
 193                 // issuing a FCW. In the FCW case, we want to
 194                 // respect the new setting.
 195                 if !fcw_warning {
 196                     return;
 197                 }
 198             }
 199         }
 200         if let Level::ForceWarn = old_level {
 201             specs.insert(id, (old_level, old_src));
 202         } else {
 203             specs.insert(id, (level, src));
 204         }
 205     }
 206
 207     /// Pushes a list of AST lint attributes onto this context.
 208     ///
 209     /// This function will return a `BuilderPush` object which should be passed
 210     /// to `pop` when this scope for the attributes provided is exited.
 211     ///
 212     /// This function will perform a number of tasks:
 213     ///
 214     /// * It'll validate all lint-related attributes in `attrs`
 215     /// * It'll mark all lint-related attributes as used
 216     /// * Lint levels will be updated based on the attributes provided
 217     /// * Lint attributes are validated, e.g., a `#[forbid]` can't be switched to
 218     ///   `#[allow]`
 219     ///
 220     /// Don't forget to call `pop`!
 221     pub(crate) fn push(
 222         &mut self,
 223         attrs: &[ast::Attribute],
 224         store: &LintStore,
 225         is_crate_node: bool,
 226     ) -> BuilderPush {
 227         let mut specs = FxHashMap::default();
 228         let sess = self.sess;
 229         let bad_attr = |span| struct_span_err!(sess, span, E0452, "malformed lint attribute input");
 230         for attr in attrs {
 231             let level = match Level::from_symbol(attr.name_or_empty()) {
 232                 None => continue,
 233                 Some(lvl) => lvl,
 234             };
 235
 236             let mut metas = unwrap_or!(attr.meta_item_list(), continue);
 237
 238             if metas.is_empty() {
 239                 // FIXME (#55112): issue unused-attributes lint for `#[level()]`
 240                 continue;
 241             }
 242
 243             // Before processing the lint names, look for a reason (RFC 2383)
 244             // at the end.
 245             let mut reason = None;
 246             let tail_li = &metas[metas.len() - 1];
 247             if let Some(item) = tail_li.meta_item() {
 248                 match item.kind {
 249                     ast::MetaItemKind::Word => {} // actual lint names handled later
 250                     ast::MetaItemKind::NameValue(ref name_value) => {
 251                         if item.path == sym::reason {
 252                             // FIXME (#55112): issue unused-attributes lint if we thereby
 253                             // don't have any lint names (`#[level(reason = "foo")]`)
 254                             if let ast::LitKind::Str(rationale, _) = name_value.kind {
 255                                 if !self.sess.features_untracked().lint_reasons {
 256                                     feature_err(
 257                                         &self.sess.parse_sess,
 258                                         sym::lint_reasons,
 259                                         item.span,
 260                                         "lint reasons are experimental",
 261                                     )
 262                                     .emit();
 263                                 }
 264                                 reason = Some(rationale);
 265                             } else {
 266                                 bad_attr(name_value.span)
 267                                     .span_label(name_value.span, "reason must be a string literal")
 268                                     .emit();
 269                             }
 270                             // found reason, reslice meta list to exclude it
 271                             metas.pop().unwrap();
 272                         } else {
 273                             bad_attr(item.span)
 274                                 .span_label(item.span, "bad attribute argument")
 275                                 .emit();
 276                         }
 277                     }
 278                     ast::MetaItemKind::List(_) => {
 279                         bad_attr(item.span).span_label(item.span, "bad attribute argument").emit();
 280                     }
 281                 }
 282             }
 283
 284             for li in metas {
 285                 let sp = li.span();
 286                 let mut meta_item = match li {
 287                     ast::NestedMetaItem::MetaItem(meta_item) if meta_item.is_word() => meta_item,
 288                     _ => {
 289                         let mut err = bad_attr(sp);
 290                         let mut add_label = true;
 291                         if let Some(item) = li.meta_item() {
 292                             if let ast::MetaItemKind::NameValue(_) = item.kind {
 293                                 if item.path == sym::reason {
 294                                     err.span_label(sp, "reason in lint attribute must come last");
 295                                     add_label = false;
 296                                 }
 297                             }
 298                         }
 299                         if add_label {
 300                             err.span_label(sp, "bad attribute argument");
 301                         }
 302                         err.emit();
 303                         continue;
 304                     }
 305                 };
 306                 let tool_ident = if meta_item.path.segments.len() > 1 {
 307                     Some(meta_item.path.segments.remove(0).ident)
 308                 } else {
 309                     None
 310                 };
 311                 let tool_name = tool_ident.map(|ident| ident.name);
 312                 let name = pprust::path_to_string(&meta_item.path);
 313                 let lint_result = store.check_lint_name(sess, &name, tool_name, self.crate_attrs);
 314                 match &lint_result {
 315                     CheckLintNameResult::Ok(ids) => {
 316                         let src = LintLevelSource::Node(
 317                             meta_item.path.segments.last().expect("empty lint name").ident.name,
 318                             sp,
 319                             reason,
 320                         );
 321                         for &id in *ids {
 322                             self.check_gated_lint(id, attr.span);
 323                             self.insert_spec(&mut specs, id, (level, src));
 324                         }
 325                     }
 326
 327                     CheckLintNameResult::Tool(result) => {
 328                         match *result {
 329                             Ok(ids) => {
 330                                 let complete_name =
 331                                     &format!("{}::{}", tool_ident.unwrap().name, name);
 332                                 let src = LintLevelSource::Node(
 333                                     Symbol::intern(complete_name),
 334                                     sp,
 335                                     reason,
 336                                 );
 337                                 for id in ids {
 338                                     self.insert_spec(&mut specs, *id, (level, src));
 339                                 }
 340                             }
 341                             Err((Some(ids), ref new_lint_name)) => {
 342                                 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 343                                 let (lvl, src) =
 344                                     self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
 345                                 struct_lint_level(
 346                                     self.sess,
 347                                     lint,
 348                                     lvl,
 349                                     src,
 350                                     Some(sp.into()),
 351                                     |lint| {
 352                                         let msg = format!(
 353                                             "lint name `{}` is deprecated \
 354                                              and may not have an effect in the future.",
 355                                             name
 356                                         );
 357                                         lint.build(&msg)
 358                                             .span_suggestion(
 359                                                 sp,
 360                                                 "change it to",
 361                                                 new_lint_name.to_string(),
 362                                                 Applicability::MachineApplicable,
 363                                             )
 364                                             .emit();
 365                                     },
 366                                 );
 367
 368                                 let src = LintLevelSource::Node(
 369                                     Symbol::intern(&new_lint_name),
 370                                     sp,
 371                                     reason,
 372                                 );
 373                                 for id in ids {
 374                                     self.insert_spec(&mut specs, *id, (level, src));
 375                                 }
 376                             }
 377                             Err((None, _)) => {
 378                                 // If Tool(Err(None, _)) is returned, then either the lint does not
 379                                 // exist in the tool or the code was not compiled with the tool and
 380                                 // therefore the lint was never added to the `LintStore`. To detect
 381                                 // this is the responsibility of the lint tool.
 382                             }
 383                         }
 384                     }
 385
 386                     &CheckLintNameResult::NoTool => {
 387                         let mut err = struct_span_err!(
 388                             sess,
 389                             tool_ident.map_or(DUMMY_SP, |ident| ident.span),
 390                             E0710,
 391                             "unknown tool name `{}` found in scoped lint: `{}::{}`",
 392                             tool_name.unwrap(),
 393                             tool_name.unwrap(),
 394                             pprust::path_to_string(&meta_item.path),
 395                         );
 396                         if sess.is_nightly_build() {
 397                             err.help(&format!(
 398                                 "add `#![register_tool({})]` to the crate root",
 399                                 tool_name.unwrap()
 400                             ));
 401                         }
 402                         err.emit();
 403                         continue;
 404                     }
 405
 406                     _ if !self.warn_about_weird_lints => {}
 407
 408                     CheckLintNameResult::Warning(msg, renamed) => {
 409                         let lint = builtin::RENAMED_AND_REMOVED_LINTS;
 410                         let (renamed_lint_level, src) =
 411                             self.sets.get_lint_level(lint, self.cur, Some(&specs), &sess);
 412                         struct_lint_level(
 413                             self.sess,
 414                             lint,
 415                             renamed_lint_level,
 416                             src,
 417                             Some(sp.into()),
 418                             |lint| {
 419                                 let mut err = lint.build(&msg);
 420                                 if let Some(new_name) = &renamed {
 421                                     err.span_suggestion(
 422                                         sp,
 423                                         "use the new name",
 424                                         new_name.to_string(),
 425                                         Applicability::MachineApplicable,
 426                                     );
 427                                 }
 428                                 err.emit();
 429                             },
 430                         );
 431                     }
 432                     CheckLintNameResult::NoLint(suggestion) => {
 433                         let lint = builtin::UNKNOWN_LINTS;
 434                         let (level, src) =
 435                             self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
 436                         struct_lint_level(self.sess, lint, level, src, Some(sp.into()), |lint| {
 437                             let name = if let Some(tool_ident) = tool_ident {
 438                                 format!("{}::{}", tool_ident.name, name)
 439                             } else {
 440                                 name.to_string()
 441                             };
 442                             let mut db = lint.build(&format!("unknown lint: `{}`", name));
 443                             if let Some(suggestion) = suggestion {
 444                                 db.span_suggestion(
 445                                     sp,
 446                                     "did you mean",
 447                                     suggestion.to_string(),
 448                                     Applicability::MachineApplicable,
 449                                 );
 450                             }
 451                             db.emit();
 452                         });
 453                     }
 454                 }
 455                 // If this lint was renamed, apply the new lint instead of ignoring the attribute.
 456                 // This happens outside of the match because the new lint should be applied even if
 457                 // we don't warn about the name change.
 458                 if let CheckLintNameResult::Warning(_, Some(new_name)) = lint_result {
 459                     // Ignore any errors or warnings that happen because the new name is inaccurate
 460                     // NOTE: `new_name` already includes the tool name, so we don't have to add it again.
 461                     if let CheckLintNameResult::Ok(ids) =
 462                         store.check_lint_name(sess, &new_name, None, self.crate_attrs)
 463                     {
 464                         let src = LintLevelSource::Node(Symbol::intern(&new_name), sp, reason);
 465                         for &id in ids {
 466                             self.check_gated_lint(id, attr.span);
 467                             self.insert_spec(&mut specs, id, (level, src));
 468                         }
 469                     } else {
 470                         panic!("renamed lint does not exist: {}", new_name);
 471                     }
 472                 }
 473             }
 474         }
 475
 476         if !is_crate_node {
 477             for (id, &(level, ref src)) in specs.iter() {
 478                 if !id.lint.crate_level_only {
 479                     continue;
 480                 }
 481
 482                 let (lint_attr_name, lint_attr_span) = match *src {
 483                     LintLevelSource::Node(name, span, _) => (name, span),
 484                     _ => continue,
 485                 };
 486
 487                 let lint = builtin::UNUSED_ATTRIBUTES;
 488                 let (lint_level, lint_src) =
 489                     self.sets.get_lint_level(lint, self.cur, Some(&specs), self.sess);
 490                 struct_lint_level(
 491                     self.sess,
 492                     lint,
 493                     lint_level,
 494                     lint_src,
 495                     Some(lint_attr_span.into()),
 496                     |lint| {
 497                         let mut db = lint.build(&format!(
 498                             "{}({}) is ignored unless specified at crate level",
 499                             level.as_str(),
 500                             lint_attr_name
 501                         ));
 502                         db.emit();
 503                     },
 504                 );
 505                 // don't set a separate error for every lint in the group
 506                 break;
 507             }
 508         }
 509
 510         let prev = self.cur;
 511         if !specs.is_empty() {
 512             self.cur = self.sets.list.push(LintSet { specs, parent: prev });
 513         }
 514
 515         BuilderPush { prev, changed: prev != self.cur }
 516     }
 517
 518     /// Checks if the lint is gated on a feature that is not enabled.
 519     fn check_gated_lint(&self, lint_id: LintId, span: Span) {
 520         if let Some(feature) = lint_id.lint.feature_gate {
 521             if !self.sess.features_untracked().enabled(feature) {
 522                 feature_err(
 523                     &self.sess.parse_sess,
 524                     feature,
 525                     span,
 526                     &format!("the `{}` lint is unstable", lint_id.lint.name_lower()),
 527                 )
 528                 .emit();
 529             }
 530         }
 531     }
 532
 533     /// Called after `push` when the scope of a set of attributes are exited.
 534     pub fn pop(&mut self, push: BuilderPush) {
 535         self.cur = push.prev;
 536     }
 537
 538     /// Find the lint level for a lint.
 539     pub fn lint_level(&self, lint: &'static Lint) -> (Level, LintLevelSource) {
 540         self.sets.get_lint_level(lint, self.cur, None, self.sess)
 541     }
 542
 543     /// Used to emit a lint-related diagnostic based on the current state of
 544     /// this lint context.
 545     pub fn struct_lint(
 546         &self,
 547         lint: &'static Lint,
 548         span: Option<MultiSpan>,
 549         decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
 550     ) {
 551         let (level, src) = self.lint_level(lint);
 552         struct_lint_level(self.sess, lint, level, src, span, decorate)
 553     }
 554
 555     /// Registers the ID provided with the current set of lints stored in
 556     /// this context.
 557     pub fn register_id(&mut self, id: HirId) {
 558         self.id_to_set.insert(id, self.cur);
 559     }
 560
 561     pub fn build_map(self) -> LintLevelMap {
 562         LintLevelMap { sets: self.sets, id_to_set: self.id_to_set }
 563     }
 564 }
 565
 566 pub fn is_known_lint_tool(m_item: Symbol, sess: &Session, attrs: &[ast::Attribute]) -> bool {
 567     if [sym::clippy, sym::rustc, sym::rustdoc].contains(&m_item) {
 568         return true;
 569     }
 570     // Look for registered tools
 571     // NOTE: does no error handling; error handling is done by rustc_resolve.
 572     sess.filter_by_name(attrs, sym::register_tool)
 573         .filter_map(|attr| attr.meta_item_list())
 574         .flatten()
 575         .filter_map(|nested_meta| nested_meta.ident())
 576         .map(|ident| ident.name)
 577         .any(|name| name == m_item)
 578 }
 579
 580 struct LintLevelMapBuilder<'a, 'tcx> {
 581     levels: LintLevelsBuilder<'tcx>,
 582     tcx: TyCtxt<'tcx>,
 583     store: &'a LintStore,
 584 }
 585
 586 impl LintLevelMapBuilder<'_, '_> {
 587     fn with_lint_attrs<F>(&mut self, id: hir::HirId, f: F)
 588     where
 589         F: FnOnce(&mut Self),
 590     {
 591         let is_crate_hir = id == hir::CRATE_HIR_ID;
 592         let attrs = self.tcx.hir().attrs(id);
 593         let push = self.levels.push(attrs, self.store, is_crate_hir);
 594         if push.changed {
 595             self.levels.register_id(id);
 596         }
 597         f(self);
 598         self.levels.pop(push);
 599     }
 600 }
 601
 602 impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'_, 'tcx> {
 603     type Map = Map<'tcx>;
 604
 605     fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
 606         intravisit::NestedVisitorMap::All(self.tcx.hir())
 607     }
 608
 609     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
 610         self.with_lint_attrs(param.hir_id, |builder| {
 611             intravisit::walk_param(builder, param);
 612         });
 613     }
 614
 615     fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
 616         self.with_lint_attrs(it.hir_id(), |builder| {
 617             intravisit::walk_item(builder, it);
 618         });
 619     }
 620
 621     fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
 622         self.with_lint_attrs(it.hir_id(), |builder| {
 623             intravisit::walk_foreign_item(builder, it);
 624         })
 625     }
 626
 627     fn visit_stmt(&mut self, e: &'tcx hir::Stmt<'tcx>) {
 628         // We will call `with_lint_attrs` when we walk
 629         // the `StmtKind`. The outer statement itself doesn't
 630         // define the lint levels.
 631         intravisit::walk_stmt(self, e);
 632     }
 633
 634     fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
 635         self.with_lint_attrs(e.hir_id, |builder| {
 636             intravisit::walk_expr(builder, e);
 637         })
 638     }
 639
 640     fn visit_field_def(&mut self, s: &'tcx hir::FieldDef<'tcx>) {
 641         self.with_lint_attrs(s.hir_id, |builder| {
 642             intravisit::walk_field_def(builder, s);
 643         })
 644     }
 645
 646     fn visit_variant(
 647         &mut self,
 648         v: &'tcx hir::Variant<'tcx>,
 649         g: &'tcx hir::Generics<'tcx>,
 650         item_id: hir::HirId,
 651     ) {
 652         self.with_lint_attrs(v.id, |builder| {
 653             intravisit::walk_variant(builder, v, g, item_id);
 654         })
 655     }
 656
 657     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
 658         self.with_lint_attrs(l.hir_id, |builder| {
 659             intravisit::walk_local(builder, l);
 660         })
 661     }
 662
 663     fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
 664         self.with_lint_attrs(a.hir_id, |builder| {
 665             intravisit::walk_arm(builder, a);
 666         })
 667     }
 668
 669     fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
 670         self.with_lint_attrs(trait_item.hir_id(), |builder| {
 671             intravisit::walk_trait_item(builder, trait_item);
 672         });
 673     }
 674
 675     fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
 676         self.with_lint_attrs(impl_item.hir_id(), |builder| {
 677             intravisit::walk_impl_item(builder, impl_item);
 678         });
 679     }
 680 }
 681
 682 pub fn provide(providers: &mut Providers) {
 683     providers.lint_levels = lint_levels;
 684 }