1 use crate::context::{CheckLintNameResult, LintStore};
2 use crate::late::unerased_lint_store;
4 use rustc_ast_pretty::pprust;
5 use rustc_data_structures::fx::FxHashMap;
6 use rustc_errors::{Applicability, Diagnostic, LintDiagnosticBuilder, MultiSpan};
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,
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,
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};
27 MalformedAttribute, MalformedAttributeSub, OverruledAttribute, OverruledAttributeSub,
28 UnknownToolInScopedLint,
31 fn lint_levels(tcx: TyCtxt<'_>, (): ()) -> LintLevelMap {
32 let store = unerased_lint_store(tcx);
34 LintLevelsBuilder::new(tcx.sess, false, &store, &tcx.resolutions(()).registered_tools);
35 let mut builder = LintLevelMapBuilder { levels, tcx };
36 let krate = tcx.hir().krate();
38 builder.levels.id_to_set.reserve(krate.owners.len() + 1);
41 builder.levels.push(tcx.hir().attrs(hir::CRATE_HIR_ID), true, Some(hir::CRATE_HIR_ID));
43 builder.levels.register_id(hir::CRATE_HIR_ID);
44 tcx.hir().walk_toplevel_module(&mut builder);
45 builder.levels.pop(push);
47 builder.levels.update_unstable_expectation_ids();
48 builder.levels.build_map()
51 pub struct LintLevelsBuilder<'s> {
53 lint_expectations: Vec<(LintExpectationId, LintExpectation)>,
54 /// Each expectation has a stable and an unstable identifier. This map
55 /// is used to map from unstable to stable [`LintExpectationId`]s.
56 expectation_id_map: FxHashMap<LintExpectationId, LintExpectationId>,
58 id_to_set: FxHashMap<HirId, LintStackIndex>,
60 warn_about_weird_lints: bool,
62 registered_tools: &'s RegisteredTools,
65 pub struct BuilderPush {
70 impl<'s> LintLevelsBuilder<'s> {
73 warn_about_weird_lints: bool,
75 registered_tools: &'s RegisteredTools,
77 let mut builder = LintLevelsBuilder {
79 lint_expectations: Default::default(),
80 expectation_id_map: Default::default(),
81 sets: LintLevelSets::new(),
83 id_to_set: Default::default(),
84 warn_about_weird_lints,
88 builder.process_command_line(sess, store);
89 assert_eq!(builder.sets.list.len(), 1);
93 pub(crate) fn sess(&self) -> &Session {
97 pub(crate) fn lint_store(&self) -> &LintStore {
101 fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
102 &self.sets.list[self.cur].specs
105 fn current_specs_mut(&mut self) -> &mut FxHashMap<LintId, LevelAndSource> {
106 &mut self.sets.list[self.cur].specs
109 fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
110 self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
113 self.sets.list.push(LintSet { specs: FxHashMap::default(), parent: COMMAND_LINE });
114 for &(ref lint_name, level) in &sess.opts.lint_opts {
115 store.check_lint_name_cmdline(sess, &lint_name, level, self.registered_tools);
116 let orig_level = level;
117 let lint_flag_val = Symbol::intern(lint_name);
119 let Ok(ids) = store.find_lints(&lint_name) else {
120 // errors handled in check_lint_name_cmdline above
124 // ForceWarn and Forbid cannot be overridden
125 if let Some((Level::ForceWarn(_) | Level::Forbid, _)) =
126 self.current_specs().get(&id)
131 if self.check_gated_lint(id, DUMMY_SP) {
132 let src = LintLevelSource::CommandLine(lint_flag_val, orig_level);
133 self.current_specs_mut().insert(id, (level, src));
139 /// Attempts to insert the `id` to `level_src` map entry. If unsuccessful
140 /// (e.g. if a forbid was already inserted on the same scope), then emits a
141 /// diagnostic with no change to `specs`.
142 fn insert_spec(&mut self, id: LintId, (level, src): LevelAndSource) {
143 let (old_level, old_src) =
144 self.sets.get_lint_level(id.lint, self.cur, Some(self.current_specs()), &self.sess);
145 // Setting to a non-forbid level is an error if the lint previously had
146 // a forbid level. Note that this is not necessarily true even with a
147 // `#[forbid(..)]` attribute present, as that is overridden by `--cap-lints`.
149 // This means that this only errors if we're truly lowering the lint
150 // level from forbid.
151 if level != Level::Forbid {
152 if let Level::Forbid = old_level {
153 // Backwards compatibility check:
155 // We used to not consider `forbid(lint_group)`
156 // as preventing `allow(lint)` for some lint `lint` in
157 // `lint_group`. For now, issue a future-compatibility
158 // warning for this case.
159 let id_name = id.lint.name_lower();
160 let fcw_warning = match old_src {
161 LintLevelSource::Default => false,
162 LintLevelSource::Node(symbol, _, _) => self.store.is_lint_group(symbol),
163 LintLevelSource::CommandLine(symbol, _) => self.store.is_lint_group(symbol),
166 "fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
168 self.current_specs(),
173 let decorate_diag = |diag: &mut Diagnostic| {
174 diag.span_label(src.span(), "overruled by previous forbid");
176 LintLevelSource::Default => {
178 "`forbid` lint level is the default for {}",
182 LintLevelSource::Node(_, forbid_source_span, reason) => {
183 diag.span_label(forbid_source_span, "`forbid` level set here");
184 if let Some(rationale) = reason {
185 diag.note(rationale.as_str());
188 LintLevelSource::CommandLine(_, _) => {
189 diag.note("`forbid` lint level was set on command line");
194 self.sess.emit_err(OverruledAttribute {
196 overruled: src.span(),
197 lint_level: level.as_str().to_string(),
198 lint_source: src.name(),
200 LintLevelSource::Default => {
201 OverruledAttributeSub::DefaultSource { id: id.to_string() }
203 LintLevelSource::Node(_, forbid_source_span, reason) => {
204 OverruledAttributeSub::NodeSource {
205 span: forbid_source_span,
209 LintLevelSource::CommandLine(_, _) => {
210 OverruledAttributeSub::CommandLineSource
216 FORBIDDEN_LINT_GROUPS,
217 Some(src.span().into()),
219 let mut diag_builder = diag_builder.build(&format!(
220 "{}({}) incompatible with previous forbid",
224 decorate_diag(&mut diag_builder);
230 // Retain the forbid lint level, unless we are
231 // issuing a FCW. In the FCW case, we want to
232 // respect the new setting.
239 // The lint `unfulfilled_lint_expectations` can't be expected, as it would suppress itself.
240 // Handling expectations of this lint would add additional complexity with little to no
241 // benefit. The expect level for this lint will therefore be ignored.
242 if let Level::Expect(_) = level && id == LintId::of(UNFULFILLED_LINT_EXPECTATIONS) {
246 match (old_level, level) {
247 // If the new level is an expectation store it in `ForceWarn`
248 (Level::ForceWarn(_), Level::Expect(expectation_id)) => self
250 .insert(id, (Level::ForceWarn(Some(expectation_id)), old_src)),
251 // Keep `ForceWarn` level but drop the expectation
252 (Level::ForceWarn(_), _) => {
253 self.current_specs_mut().insert(id, (Level::ForceWarn(None), old_src))
255 // Set the lint level as normal
256 _ => self.current_specs_mut().insert(id, (level, src)),
260 /// Pushes a list of AST lint attributes onto this context.
262 /// This function will return a `BuilderPush` object which should be passed
263 /// to `pop` when this scope for the attributes provided is exited.
265 /// This function will perform a number of tasks:
267 /// * It'll validate all lint-related attributes in `attrs`
268 /// * It'll mark all lint-related attributes as used
269 /// * Lint levels will be updated based on the attributes provided
270 /// * Lint attributes are validated, e.g., a `#[forbid]` can't be switched to
273 /// Don't forget to call `pop`!
276 attrs: &[ast::Attribute],
278 source_hir_id: Option<HirId>,
281 self.cur = self.sets.list.push(LintSet { specs: FxHashMap::default(), parent: prev });
283 let sess = self.sess;
284 for (attr_index, attr) in attrs.iter().enumerate() {
285 if attr.has_name(sym::automatically_derived) {
286 self.current_specs_mut().insert(
287 LintId::of(SINGLE_USE_LIFETIMES),
288 (Level::Allow, LintLevelSource::Default),
293 let level = match Level::from_attr(attr) {
295 // This is the only lint level with a `LintExpectationId` that can be created from an attribute
296 Some(Level::Expect(unstable_id)) if let Some(hir_id) = source_hir_id => {
297 let stable_id = self.create_stable_id(unstable_id, hir_id, attr_index);
299 Level::Expect(stable_id)
304 let Some(mut metas) = attr.meta_item_list() else {
308 if metas.is_empty() {
309 // This emits the unused_attributes lint for `#[level()]`
313 // Before processing the lint names, look for a reason (RFC 2383)
315 let mut reason = None;
316 let tail_li = &metas[metas.len() - 1];
317 if let Some(item) = tail_li.meta_item() {
319 ast::MetaItemKind::Word => {} // actual lint names handled later
320 ast::MetaItemKind::NameValue(ref name_value) => {
321 if item.path == sym::reason {
322 if let ast::LitKind::Str(rationale, _) = name_value.kind {
323 if !self.sess.features_untracked().lint_reasons {
325 &self.sess.parse_sess,
328 "lint reasons are experimental",
332 reason = Some(rationale);
334 sess.emit_err(MalformedAttribute {
335 span: name_value.span,
336 sub: MalformedAttributeSub::ReasonMustBeStringLiteral(
341 // found reason, reslice meta list to exclude it
342 metas.pop().unwrap();
344 sess.emit_err(MalformedAttribute {
346 sub: MalformedAttributeSub::BadAttributeArgument(item.span),
350 ast::MetaItemKind::List(_) => {
351 sess.emit_err(MalformedAttribute {
353 sub: MalformedAttributeSub::BadAttributeArgument(item.span),
359 for (lint_index, li) in metas.iter_mut().enumerate() {
360 let level = match level {
361 Level::Expect(mut id) => {
362 id.set_lint_index(Some(lint_index as u16));
369 let meta_item = match li {
370 ast::NestedMetaItem::MetaItem(meta_item) if meta_item.is_word() => meta_item,
372 if let Some(item) = li.meta_item() {
373 if let ast::MetaItemKind::NameValue(_) = item.kind {
374 if item.path == sym::reason {
375 sess.emit_err(MalformedAttribute {
377 sub: MalformedAttributeSub::ReasonMustComeLast(sp),
383 sess.emit_err(MalformedAttribute {
385 sub: MalformedAttributeSub::BadAttributeArgument(sp),
390 let tool_ident = if meta_item.path.segments.len() > 1 {
391 Some(meta_item.path.segments.remove(0).ident)
395 let tool_name = tool_ident.map(|ident| ident.name);
396 let name = pprust::path_to_string(&meta_item.path);
398 self.store.check_lint_name(&name, tool_name, self.registered_tools);
400 CheckLintNameResult::Ok(ids) => {
401 // This checks for instances where the user writes `#[expect(unfulfilled_lint_expectations)]`
402 // in that case we want to avoid overriding the lint level but instead add an expectation that
403 // can't be fulfilled. The lint message will include an explanation, that the
404 // `unfulfilled_lint_expectations` lint can't be expected.
405 if let Level::Expect(expect_id) = level {
406 // The `unfulfilled_lint_expectations` lint is not part of any lint groups. Therefore. we
407 // only need to check the slice if it contains a single lint.
408 let is_unfulfilled_lint_expectations = match ids {
409 [lint] => *lint == LintId::of(UNFULFILLED_LINT_EXPECTATIONS),
412 self.lint_expectations.push((
414 LintExpectation::new(
417 is_unfulfilled_lint_expectations,
422 let src = LintLevelSource::Node(
423 meta_item.path.segments.last().expect("empty lint name").ident.name,
428 if self.check_gated_lint(id, attr.span) {
429 self.insert_spec(id, (level, src));
434 CheckLintNameResult::Tool(result) => {
438 &format!("{}::{}", tool_ident.unwrap().name, name);
439 let src = LintLevelSource::Node(
440 Symbol::intern(complete_name),
445 self.insert_spec(*id, (level, src));
447 if let Level::Expect(expect_id) = level {
448 self.lint_expectations.push((
450 LintExpectation::new(reason, sp, false, tool_name),
454 Err((Some(ids), ref new_lint_name)) => {
455 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
456 let (lvl, src) = self.sets.get_lint_level(
459 Some(self.current_specs()),
470 "lint name `{}` is deprecated \
471 and may not have an effect in the future.",
479 Applicability::MachineApplicable,
485 let src = LintLevelSource::Node(
486 Symbol::intern(&new_lint_name),
491 self.insert_spec(*id, (level, src));
493 if let Level::Expect(expect_id) = level {
494 self.lint_expectations.push((
496 LintExpectation::new(reason, sp, false, tool_name),
501 // If Tool(Err(None, _)) is returned, then either the lint does not
502 // exist in the tool or the code was not compiled with the tool and
503 // therefore the lint was never added to the `LintStore`. To detect
504 // this is the responsibility of the lint tool.
509 &CheckLintNameResult::NoTool => {
510 sess.emit_err(UnknownToolInScopedLint {
511 span: tool_ident.map(|ident| ident.span),
512 tool_name: tool_name.unwrap(),
513 lint_name: pprust::path_to_string(&meta_item.path),
514 is_nightly_build: sess.is_nightly_build().then_some(()),
519 _ if !self.warn_about_weird_lints => {}
521 CheckLintNameResult::Warning(msg, renamed) => {
522 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
523 let (renamed_lint_level, src) = self.sets.get_lint_level(
526 Some(self.current_specs()),
536 let mut err = lint.build(msg);
537 if let Some(new_name) = &renamed {
542 Applicability::MachineApplicable,
549 CheckLintNameResult::NoLint(suggestion) => {
550 let lint = builtin::UNKNOWN_LINTS;
551 let (level, src) = self.sets.get_lint_level(
554 Some(self.current_specs()),
557 struct_lint_level(self.sess, lint, level, src, Some(sp.into()), |lint| {
558 let name = if let Some(tool_ident) = tool_ident {
559 format!("{}::{}", tool_ident.name, name)
563 let mut db = lint.build(format!("unknown lint: `{}`", name));
564 if let Some(suggestion) = suggestion {
569 Applicability::MachineApplicable,
576 // If this lint was renamed, apply the new lint instead of ignoring the attribute.
577 // This happens outside of the match because the new lint should be applied even if
578 // we don't warn about the name change.
579 if let CheckLintNameResult::Warning(_, Some(new_name)) = lint_result {
580 // Ignore any errors or warnings that happen because the new name is inaccurate
581 // NOTE: `new_name` already includes the tool name, so we don't have to add it again.
582 if let CheckLintNameResult::Ok(ids) =
583 self.store.check_lint_name(&new_name, None, self.registered_tools)
585 let src = LintLevelSource::Node(Symbol::intern(&new_name), sp, reason);
587 if self.check_gated_lint(id, attr.span) {
588 self.insert_spec(id, (level, src));
591 if let Level::Expect(expect_id) = level {
592 self.lint_expectations.push((
594 LintExpectation::new(reason, sp, false, tool_name),
598 panic!("renamed lint does not exist: {}", new_name);
605 for (id, &(level, ref src)) in self.current_specs().iter() {
606 if !id.lint.crate_level_only {
610 let LintLevelSource::Node(lint_attr_name, lint_attr_span, _) = *src else {
614 let lint = builtin::UNUSED_ATTRIBUTES;
615 let (lint_level, lint_src) =
616 self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), self.sess);
622 Some(lint_attr_span.into()),
624 let mut db = lint.build(&format!(
625 "{}({}) is ignored unless specified at crate level",
632 // don't set a separate error for every lint in the group
637 if self.current_specs().is_empty() {
638 self.sets.list.pop();
642 BuilderPush { prev, changed: prev != self.cur }
647 unstable_id: LintExpectationId,
650 ) -> LintExpectationId {
652 LintExpectationId::Stable { hir_id, attr_index: attr_index as u16, lint_index: None };
654 self.expectation_id_map.insert(unstable_id, stable_id);
659 /// Checks if the lint is gated on a feature that is not enabled.
661 /// Returns `true` if the lint's feature is enabled.
662 fn check_gated_lint(&self, lint_id: LintId, span: Span) -> bool {
663 if let Some(feature) = lint_id.lint.feature_gate {
664 if !self.sess.features_untracked().enabled(feature) {
665 let lint = builtin::UNKNOWN_LINTS;
666 let (level, src) = self.lint_level(builtin::UNKNOWN_LINTS);
667 struct_lint_level(self.sess, lint, level, src, Some(span.into()), |lint_db| {
669 lint_db.build(&format!("unknown lint: `{}`", lint_id.lint.name_lower()));
670 db.note(&format!("the `{}` lint is unstable", lint_id.lint.name_lower(),));
671 add_feature_diagnostics(&mut db, &self.sess.parse_sess, feature);
680 /// Called after `push` when the scope of a set of attributes are exited.
681 pub fn pop(&mut self, push: BuilderPush) {
682 self.cur = push.prev;
685 /// Find the lint level for a lint.
686 pub fn lint_level(&self, lint: &'static Lint) -> (Level, LintLevelSource) {
687 self.sets.get_lint_level(lint, self.cur, None, self.sess)
690 /// Used to emit a lint-related diagnostic based on the current state of
691 /// this lint context.
695 span: Option<MultiSpan>,
696 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
698 let (level, src) = self.lint_level(lint);
699 struct_lint_level(self.sess, lint, level, src, span, decorate)
702 /// Registers the ID provided with the current set of lints stored in
704 pub fn register_id(&mut self, id: HirId) {
705 self.id_to_set.insert(id, self.cur);
708 fn update_unstable_expectation_ids(&self) {
709 self.sess.diagnostic().update_unstable_expectation_id(&self.expectation_id_map);
712 pub fn build_map(self) -> LintLevelMap {
715 id_to_set: self.id_to_set,
716 lint_expectations: self.lint_expectations,
721 struct LintLevelMapBuilder<'tcx> {
722 levels: LintLevelsBuilder<'tcx>,
726 impl LintLevelMapBuilder<'_> {
727 fn with_lint_attrs<F>(&mut self, id: hir::HirId, f: F)
729 F: FnOnce(&mut Self),
731 let is_crate_hir = id == hir::CRATE_HIR_ID;
732 let attrs = self.tcx.hir().attrs(id);
733 let push = self.levels.push(attrs, is_crate_hir, Some(id));
736 self.levels.register_id(id);
739 self.levels.pop(push);
743 impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'tcx> {
744 type NestedFilter = nested_filter::All;
746 fn nested_visit_map(&mut self) -> Self::Map {
750 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
751 self.with_lint_attrs(param.hir_id, |builder| {
752 intravisit::walk_param(builder, param);
756 fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
757 self.with_lint_attrs(it.hir_id(), |builder| {
758 intravisit::walk_item(builder, it);
762 fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
763 self.with_lint_attrs(it.hir_id(), |builder| {
764 intravisit::walk_foreign_item(builder, it);
768 fn visit_stmt(&mut self, e: &'tcx hir::Stmt<'tcx>) {
769 // We will call `with_lint_attrs` when we walk
770 // the `StmtKind`. The outer statement itself doesn't
771 // define the lint levels.
772 intravisit::walk_stmt(self, e);
775 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
776 self.with_lint_attrs(e.hir_id, |builder| {
777 intravisit::walk_expr(builder, e);
781 fn visit_expr_field(&mut self, field: &'tcx hir::ExprField<'tcx>) {
782 self.with_lint_attrs(field.hir_id, |builder| {
783 intravisit::walk_expr_field(builder, field);
787 fn visit_field_def(&mut self, s: &'tcx hir::FieldDef<'tcx>) {
788 self.with_lint_attrs(s.hir_id, |builder| {
789 intravisit::walk_field_def(builder, s);
793 fn visit_variant(&mut self, v: &'tcx hir::Variant<'tcx>) {
794 self.with_lint_attrs(v.id, |builder| {
795 intravisit::walk_variant(builder, v);
799 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
800 self.with_lint_attrs(l.hir_id, |builder| {
801 intravisit::walk_local(builder, l);
805 fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
806 self.with_lint_attrs(a.hir_id, |builder| {
807 intravisit::walk_arm(builder, a);
811 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
812 self.with_lint_attrs(trait_item.hir_id(), |builder| {
813 intravisit::walk_trait_item(builder, trait_item);
817 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
818 self.with_lint_attrs(impl_item.hir_id(), |builder| {
819 intravisit::walk_impl_item(builder, impl_item);
823 fn visit_pat_field(&mut self, field: &'tcx hir::PatField<'tcx>) {
824 self.with_lint_attrs(field.hir_id, |builder| {
825 intravisit::walk_pat_field(builder, field);
829 fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
830 self.with_lint_attrs(p.hir_id, |builder| {
831 intravisit::walk_generic_param(builder, p);
836 pub fn provide(providers: &mut Providers) {
837 providers.lint_levels = lint_levels;