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::{struct_span_err, Applicability, Diagnostic, MultiSpan};
8 use rustc_hir::{intravisit, HirId};
9 use rustc_middle::hir::nested_filter;
10 use rustc_middle::lint::{
11 struct_lint_level, LevelAndSource, LintDiagnosticBuilder, LintExpectation, LintLevelMap,
12 LintLevelSets, 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};
26 fn lint_levels(tcx: TyCtxt<'_>, (): ()) -> LintLevelMap {
27 let store = unerased_lint_store(tcx);
29 LintLevelsBuilder::new(tcx.sess, false, &store, &tcx.resolutions(()).registered_tools);
30 let mut builder = LintLevelMapBuilder { levels, tcx };
31 let krate = tcx.hir().krate();
33 builder.levels.id_to_set.reserve(krate.owners.len() + 1);
36 builder.levels.push(tcx.hir().attrs(hir::CRATE_HIR_ID), true, Some(hir::CRATE_HIR_ID));
38 builder.levels.register_id(hir::CRATE_HIR_ID);
39 tcx.hir().walk_toplevel_module(&mut builder);
40 builder.levels.pop(push);
42 builder.levels.update_unstable_expectation_ids();
43 builder.levels.build_map()
46 pub struct LintLevelsBuilder<'s> {
48 lint_expectations: Vec<(LintExpectationId, LintExpectation)>,
49 /// Each expectation has a stable and an unstable identifier. This map
50 /// is used to map from unstable to stable [`LintExpectationId`]s.
51 expectation_id_map: FxHashMap<LintExpectationId, LintExpectationId>,
53 id_to_set: FxHashMap<HirId, LintStackIndex>,
55 warn_about_weird_lints: bool,
57 registered_tools: &'s RegisteredTools,
60 pub struct BuilderPush {
65 impl<'s> LintLevelsBuilder<'s> {
68 warn_about_weird_lints: bool,
70 registered_tools: &'s RegisteredTools,
72 let mut builder = LintLevelsBuilder {
74 lint_expectations: Default::default(),
75 expectation_id_map: Default::default(),
76 sets: LintLevelSets::new(),
78 id_to_set: Default::default(),
79 warn_about_weird_lints,
83 builder.process_command_line(sess, store);
84 assert_eq!(builder.sets.list.len(), 1);
88 pub(crate) fn sess(&self) -> &Session {
92 pub(crate) fn lint_store(&self) -> &LintStore {
96 fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
97 &self.sets.list[self.cur].specs
100 fn current_specs_mut(&mut self) -> &mut FxHashMap<LintId, LevelAndSource> {
101 &mut self.sets.list[self.cur].specs
104 fn process_command_line(&mut self, sess: &Session, store: &LintStore) {
105 self.sets.lint_cap = sess.opts.lint_cap.unwrap_or(Level::Forbid);
108 self.sets.list.push(LintSet { specs: FxHashMap::default(), parent: COMMAND_LINE });
109 for &(ref lint_name, level) in &sess.opts.lint_opts {
110 store.check_lint_name_cmdline(sess, &lint_name, level, self.registered_tools);
111 let orig_level = level;
112 let lint_flag_val = Symbol::intern(lint_name);
114 let Ok(ids) = store.find_lints(&lint_name) else {
115 // errors handled in check_lint_name_cmdline above
119 // ForceWarn and Forbid cannot be overridden
120 if let Some((Level::ForceWarn(_) | Level::Forbid, _)) =
121 self.current_specs().get(&id)
126 if self.check_gated_lint(id, DUMMY_SP) {
127 let src = LintLevelSource::CommandLine(lint_flag_val, orig_level);
128 self.current_specs_mut().insert(id, (level, src));
134 /// Attempts to insert the `id` to `level_src` map entry. If unsuccessful
135 /// (e.g. if a forbid was already inserted on the same scope), then emits a
136 /// diagnostic with no change to `specs`.
137 fn insert_spec(&mut self, id: LintId, (level, src): LevelAndSource) {
138 let (old_level, old_src) =
139 self.sets.get_lint_level(id.lint, self.cur, Some(self.current_specs()), &self.sess);
140 // Setting to a non-forbid level is an error if the lint previously had
141 // a forbid level. Note that this is not necessarily true even with a
142 // `#[forbid(..)]` attribute present, as that is overridden by `--cap-lints`.
144 // This means that this only errors if we're truly lowering the lint
145 // level from forbid.
146 if level != Level::Forbid {
147 if let Level::Forbid = old_level {
148 // Backwards compatibility check:
150 // We used to not consider `forbid(lint_group)`
151 // as preventing `allow(lint)` for some lint `lint` in
152 // `lint_group`. For now, issue a future-compatibility
153 // warning for this case.
154 let id_name = id.lint.name_lower();
155 let fcw_warning = match old_src {
156 LintLevelSource::Default => false,
157 LintLevelSource::Node(symbol, _, _) => self.store.is_lint_group(symbol),
158 LintLevelSource::CommandLine(symbol, _) => self.store.is_lint_group(symbol),
161 "fcw_warning={:?}, specs.get(&id) = {:?}, old_src={:?}, id_name={:?}",
163 self.current_specs(),
168 let decorate_diag = |diag: &mut Diagnostic| {
169 diag.span_label(src.span(), "overruled by previous forbid");
171 LintLevelSource::Default => {
173 "`forbid` lint level is the default for {}",
177 LintLevelSource::Node(_, forbid_source_span, reason) => {
178 diag.span_label(forbid_source_span, "`forbid` level set here");
179 if let Some(rationale) = reason {
180 diag.note(rationale.as_str());
183 LintLevelSource::CommandLine(_, _) => {
184 diag.note("`forbid` lint level was set on command line");
189 let mut diag_builder = struct_span_err!(
193 "{}({}) incompatible with previous forbid",
197 decorate_diag(&mut diag_builder);
201 FORBIDDEN_LINT_GROUPS,
202 Some(src.span().into()),
204 let mut diag_builder = diag_builder.build(&format!(
205 "{}({}) incompatible with previous forbid",
209 decorate_diag(&mut diag_builder);
215 // Retain the forbid lint level, unless we are
216 // issuing a FCW. In the FCW case, we want to
217 // respect the new setting.
224 // The lint `unfulfilled_lint_expectations` can't be expected, as it would suppress itself.
225 // Handling expectations of this lint would add additional complexity with little to no
226 // benefit. The expect level for this lint will therefore be ignored.
227 if let Level::Expect(_) = level && id == LintId::of(UNFULFILLED_LINT_EXPECTATIONS) {
231 match (old_level, level) {
232 // If the new level is an expectation store it in `ForceWarn`
233 (Level::ForceWarn(_), Level::Expect(expectation_id)) => self
235 .insert(id, (Level::ForceWarn(Some(expectation_id)), old_src)),
236 // Keep `ForceWarn` level but drop the expectation
237 (Level::ForceWarn(_), _) => {
238 self.current_specs_mut().insert(id, (Level::ForceWarn(None), old_src))
240 // Set the lint level as normal
241 _ => self.current_specs_mut().insert(id, (level, src)),
245 /// Pushes a list of AST lint attributes onto this context.
247 /// This function will return a `BuilderPush` object which should be passed
248 /// to `pop` when this scope for the attributes provided is exited.
250 /// This function will perform a number of tasks:
252 /// * It'll validate all lint-related attributes in `attrs`
253 /// * It'll mark all lint-related attributes as used
254 /// * Lint levels will be updated based on the attributes provided
255 /// * Lint attributes are validated, e.g., a `#[forbid]` can't be switched to
258 /// Don't forget to call `pop`!
261 attrs: &[ast::Attribute],
263 source_hir_id: Option<HirId>,
266 self.cur = self.sets.list.push(LintSet { specs: FxHashMap::default(), parent: prev });
268 let sess = self.sess;
269 let bad_attr = |span| struct_span_err!(sess, span, E0452, "malformed lint attribute input");
270 for (attr_index, attr) in attrs.iter().enumerate() {
271 if attr.has_name(sym::automatically_derived) {
272 self.current_specs_mut().insert(
273 LintId::of(SINGLE_USE_LIFETIMES),
274 (Level::Allow, LintLevelSource::Default),
279 let level = match Level::from_attr(attr) {
281 // This is the only lint level with a `LintExpectationId` that can be created from an attribute
282 Some(Level::Expect(unstable_id)) if let Some(hir_id) = source_hir_id => {
283 let stable_id = self.create_stable_id(unstable_id, hir_id, attr_index);
285 Level::Expect(stable_id)
290 let Some(mut metas) = attr.meta_item_list() else {
294 if metas.is_empty() {
295 // This emits the unused_attributes lint for `#[level()]`
299 // Before processing the lint names, look for a reason (RFC 2383)
301 let mut reason = None;
302 let tail_li = &metas[metas.len() - 1];
303 if let Some(item) = tail_li.meta_item() {
305 ast::MetaItemKind::Word => {} // actual lint names handled later
306 ast::MetaItemKind::NameValue(ref name_value) => {
307 if item.path == sym::reason {
308 if let ast::LitKind::Str(rationale, _) = name_value.kind {
309 if !self.sess.features_untracked().lint_reasons {
311 &self.sess.parse_sess,
314 "lint reasons are experimental",
318 reason = Some(rationale);
320 bad_attr(name_value.span)
321 .span_label(name_value.span, "reason must be a string literal")
324 // found reason, reslice meta list to exclude it
325 metas.pop().unwrap();
328 .span_label(item.span, "bad attribute argument")
332 ast::MetaItemKind::List(_) => {
333 bad_attr(item.span).span_label(item.span, "bad attribute argument").emit();
338 for (lint_index, li) in metas.iter_mut().enumerate() {
339 let level = match level {
340 Level::Expect(mut id) => {
341 id.set_lint_index(Some(lint_index as u16));
348 let meta_item = match li {
349 ast::NestedMetaItem::MetaItem(meta_item) if meta_item.is_word() => meta_item,
351 let mut err = bad_attr(sp);
352 let mut add_label = true;
353 if let Some(item) = li.meta_item() {
354 if let ast::MetaItemKind::NameValue(_) = item.kind {
355 if item.path == sym::reason {
356 err.span_label(sp, "reason in lint attribute must come last");
362 err.span_label(sp, "bad attribute argument");
368 let tool_ident = if meta_item.path.segments.len() > 1 {
369 Some(meta_item.path.segments.remove(0).ident)
373 let tool_name = tool_ident.map(|ident| ident.name);
374 let name = pprust::path_to_string(&meta_item.path);
376 self.store.check_lint_name(&name, tool_name, self.registered_tools);
378 CheckLintNameResult::Ok(ids) => {
379 // This checks for instances where the user writes `#[expect(unfulfilled_lint_expectations)]`
380 // in that case we want to avoid overriding the lint level but instead add an expectation that
381 // can't be fulfilled. The lint message will include an explanation, that the
382 // `unfulfilled_lint_expectations` lint can't be expected.
383 if let Level::Expect(expect_id) = level {
384 // The `unfulfilled_lint_expectations` lint is not part of any lint groups. Therefore. we
385 // only need to check the slice if it contains a single lint.
386 let is_unfulfilled_lint_expectations = match ids {
387 [lint] => *lint == LintId::of(UNFULFILLED_LINT_EXPECTATIONS),
390 self.lint_expectations.push((
392 LintExpectation::new(
395 is_unfulfilled_lint_expectations,
400 let src = LintLevelSource::Node(
401 meta_item.path.segments.last().expect("empty lint name").ident.name,
406 if self.check_gated_lint(id, attr.span) {
407 self.insert_spec(id, (level, src));
412 CheckLintNameResult::Tool(result) => {
416 &format!("{}::{}", tool_ident.unwrap().name, name);
417 let src = LintLevelSource::Node(
418 Symbol::intern(complete_name),
423 self.insert_spec(*id, (level, src));
425 if let Level::Expect(expect_id) = level {
426 self.lint_expectations.push((
428 LintExpectation::new(reason, sp, false, tool_name),
432 Err((Some(ids), ref new_lint_name)) => {
433 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
434 let (lvl, src) = self.sets.get_lint_level(
437 Some(self.current_specs()),
448 "lint name `{}` is deprecated \
449 and may not have an effect in the future.",
457 Applicability::MachineApplicable,
463 let src = LintLevelSource::Node(
464 Symbol::intern(&new_lint_name),
469 self.insert_spec(*id, (level, src));
471 if let Level::Expect(expect_id) = level {
472 self.lint_expectations.push((
474 LintExpectation::new(reason, sp, false, tool_name),
479 // If Tool(Err(None, _)) is returned, then either the lint does not
480 // exist in the tool or the code was not compiled with the tool and
481 // therefore the lint was never added to the `LintStore`. To detect
482 // this is the responsibility of the lint tool.
487 &CheckLintNameResult::NoTool => {
488 let mut err = struct_span_err!(
490 tool_ident.map_or(DUMMY_SP, |ident| ident.span),
492 "unknown tool name `{}` found in scoped lint: `{}::{}`",
495 pprust::path_to_string(&meta_item.path),
497 if sess.is_nightly_build() {
499 "add `#![register_tool({})]` to the crate root",
507 _ if !self.warn_about_weird_lints => {}
509 CheckLintNameResult::Warning(msg, renamed) => {
510 let lint = builtin::RENAMED_AND_REMOVED_LINTS;
511 let (renamed_lint_level, src) = self.sets.get_lint_level(
514 Some(self.current_specs()),
524 let mut err = lint.build(&msg);
525 if let Some(new_name) = &renamed {
530 Applicability::MachineApplicable,
537 CheckLintNameResult::NoLint(suggestion) => {
538 let lint = builtin::UNKNOWN_LINTS;
539 let (level, src) = self.sets.get_lint_level(
542 Some(self.current_specs()),
545 struct_lint_level(self.sess, lint, level, src, Some(sp.into()), |lint| {
546 let name = if let Some(tool_ident) = tool_ident {
547 format!("{}::{}", tool_ident.name, name)
551 let mut db = lint.build(&format!("unknown lint: `{}`", name));
552 if let Some(suggestion) = suggestion {
557 Applicability::MachineApplicable,
564 // If this lint was renamed, apply the new lint instead of ignoring the attribute.
565 // This happens outside of the match because the new lint should be applied even if
566 // we don't warn about the name change.
567 if let CheckLintNameResult::Warning(_, Some(new_name)) = lint_result {
568 // Ignore any errors or warnings that happen because the new name is inaccurate
569 // NOTE: `new_name` already includes the tool name, so we don't have to add it again.
570 if let CheckLintNameResult::Ok(ids) =
571 self.store.check_lint_name(&new_name, None, self.registered_tools)
573 let src = LintLevelSource::Node(Symbol::intern(&new_name), sp, reason);
575 if self.check_gated_lint(id, attr.span) {
576 self.insert_spec(id, (level, src));
579 if let Level::Expect(expect_id) = level {
580 self.lint_expectations.push((
582 LintExpectation::new(reason, sp, false, tool_name),
586 panic!("renamed lint does not exist: {}", new_name);
593 for (id, &(level, ref src)) in self.current_specs().iter() {
594 if !id.lint.crate_level_only {
598 let LintLevelSource::Node(lint_attr_name, lint_attr_span, _) = *src else {
602 let lint = builtin::UNUSED_ATTRIBUTES;
603 let (lint_level, lint_src) =
604 self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), self.sess);
610 Some(lint_attr_span.into()),
612 let mut db = lint.build(&format!(
613 "{}({}) is ignored unless specified at crate level",
620 // don't set a separate error for every lint in the group
625 if self.current_specs().is_empty() {
626 self.sets.list.pop();
630 BuilderPush { prev, changed: prev != self.cur }
635 unstable_id: LintExpectationId,
638 ) -> LintExpectationId {
640 LintExpectationId::Stable { hir_id, attr_index: attr_index as u16, lint_index: None };
642 self.expectation_id_map.insert(unstable_id, stable_id);
647 /// Checks if the lint is gated on a feature that is not enabled.
649 /// Returns `true` if the lint's feature is enabled.
650 fn check_gated_lint(&self, lint_id: LintId, span: Span) -> bool {
651 if let Some(feature) = lint_id.lint.feature_gate {
652 if !self.sess.features_untracked().enabled(feature) {
653 let lint = builtin::UNKNOWN_LINTS;
654 let (level, src) = self.lint_level(builtin::UNKNOWN_LINTS);
655 struct_lint_level(self.sess, lint, level, src, Some(span.into()), |lint_db| {
657 lint_db.build(&format!("unknown lint: `{}`", lint_id.lint.name_lower()));
658 db.note(&format!("the `{}` lint is unstable", lint_id.lint.name_lower(),));
659 add_feature_diagnostics(&mut db, &self.sess.parse_sess, feature);
668 /// Called after `push` when the scope of a set of attributes are exited.
669 pub fn pop(&mut self, push: BuilderPush) {
670 self.cur = push.prev;
673 /// Find the lint level for a lint.
674 pub fn lint_level(&self, lint: &'static Lint) -> (Level, LintLevelSource) {
675 self.sets.get_lint_level(lint, self.cur, None, self.sess)
678 /// Used to emit a lint-related diagnostic based on the current state of
679 /// this lint context.
683 span: Option<MultiSpan>,
684 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
686 let (level, src) = self.lint_level(lint);
687 struct_lint_level(self.sess, lint, level, src, span, decorate)
690 /// Registers the ID provided with the current set of lints stored in
692 pub fn register_id(&mut self, id: HirId) {
693 self.id_to_set.insert(id, self.cur);
696 fn update_unstable_expectation_ids(&self) {
697 self.sess.diagnostic().update_unstable_expectation_id(&self.expectation_id_map);
700 pub fn build_map(self) -> LintLevelMap {
703 id_to_set: self.id_to_set,
704 lint_expectations: self.lint_expectations,
709 struct LintLevelMapBuilder<'tcx> {
710 levels: LintLevelsBuilder<'tcx>,
714 impl LintLevelMapBuilder<'_> {
715 fn with_lint_attrs<F>(&mut self, id: hir::HirId, f: F)
717 F: FnOnce(&mut Self),
719 let is_crate_hir = id == hir::CRATE_HIR_ID;
720 let attrs = self.tcx.hir().attrs(id);
721 let push = self.levels.push(attrs, is_crate_hir, Some(id));
724 self.levels.register_id(id);
727 self.levels.pop(push);
731 impl<'tcx> intravisit::Visitor<'tcx> for LintLevelMapBuilder<'tcx> {
732 type NestedFilter = nested_filter::All;
734 fn nested_visit_map(&mut self) -> Self::Map {
738 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
739 self.with_lint_attrs(param.hir_id, |builder| {
740 intravisit::walk_param(builder, param);
744 fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
745 self.with_lint_attrs(it.hir_id(), |builder| {
746 intravisit::walk_item(builder, it);
750 fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
751 self.with_lint_attrs(it.hir_id(), |builder| {
752 intravisit::walk_foreign_item(builder, it);
756 fn visit_stmt(&mut self, e: &'tcx hir::Stmt<'tcx>) {
757 // We will call `with_lint_attrs` when we walk
758 // the `StmtKind`. The outer statement itself doesn't
759 // define the lint levels.
760 intravisit::walk_stmt(self, e);
763 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
764 self.with_lint_attrs(e.hir_id, |builder| {
765 intravisit::walk_expr(builder, e);
769 fn visit_field_def(&mut self, s: &'tcx hir::FieldDef<'tcx>) {
770 self.with_lint_attrs(s.hir_id, |builder| {
771 intravisit::walk_field_def(builder, s);
777 v: &'tcx hir::Variant<'tcx>,
778 g: &'tcx hir::Generics<'tcx>,
781 self.with_lint_attrs(v.id, |builder| {
782 intravisit::walk_variant(builder, v, g, item_id);
786 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
787 self.with_lint_attrs(l.hir_id, |builder| {
788 intravisit::walk_local(builder, l);
792 fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
793 self.with_lint_attrs(a.hir_id, |builder| {
794 intravisit::walk_arm(builder, a);
798 fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
799 self.with_lint_attrs(trait_item.hir_id(), |builder| {
800 intravisit::walk_trait_item(builder, trait_item);
804 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
805 self.with_lint_attrs(impl_item.hir_id(), |builder| {
806 intravisit::walk_impl_item(builder, impl_item);
811 pub fn provide(providers: &mut Providers) {
812 providers.lint_levels = lint_levels;