1 //! This module implements some validity checks for attributes.
2 //! In particular it verifies that `#[inline]` and `#[repr]` attributes are
3 //! attached to items that actually support them and if there are
4 //! conflicts between multiple such attributes attached to the same
8 use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
9 use rustc_data_structures::fx::FxHashMap;
10 use rustc_errors::{fluent, struct_span_err, Applicability, MultiSpan};
11 use rustc_expand::base::resolve_path;
12 use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
14 use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
15 use rustc_hir::intravisit::{self, Visitor};
16 use rustc_hir::{self, FnSig, ForeignItem, HirId, Item, ItemKind, TraitItem, CRATE_HIR_ID};
17 use rustc_hir::{MethodKind, Target};
18 use rustc_middle::hir::nested_filter;
19 use rustc_middle::middle::resolve_lifetime::ObjectLifetimeDefault;
20 use rustc_middle::ty::query::Providers;
21 use rustc_middle::ty::TyCtxt;
22 use rustc_session::lint::builtin::{
23 CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, UNUSED_ATTRIBUTES,
25 use rustc_session::parse::feature_err;
26 use rustc_span::symbol::{kw, sym, Symbol};
27 use rustc_span::{Span, DUMMY_SP};
28 use rustc_target::spec::abi::Abi;
29 use std::collections::hash_map::Entry;
31 pub(crate) fn target_from_impl_item<'tcx>(
33 impl_item: &hir::ImplItem<'_>,
35 match impl_item.kind {
36 hir::ImplItemKind::Const(..) => Target::AssocConst,
37 hir::ImplItemKind::Fn(..) => {
38 let parent_hir_id = tcx.hir().get_parent_item(impl_item.hir_id());
39 let containing_item = tcx.hir().expect_item(parent_hir_id);
40 let containing_impl_is_for_trait = match &containing_item.kind {
41 hir::ItemKind::Impl(impl_) => impl_.of_trait.is_some(),
42 _ => bug!("parent of an ImplItem must be an Impl"),
44 if containing_impl_is_for_trait {
45 Target::Method(MethodKind::Trait { body: true })
47 Target::Method(MethodKind::Inherent)
50 hir::ImplItemKind::TyAlias(..) => Target::AssocTy,
54 #[derive(Clone, Copy)]
56 Item(&'tcx Item<'tcx>),
60 struct CheckAttrVisitor<'tcx> {
64 impl CheckAttrVisitor<'_> {
65 /// Checks any attribute.
71 item: Option<ItemLike<'_>>,
73 let mut doc_aliases = FxHashMap::default();
74 let mut is_valid = true;
75 let mut specified_inline = None;
76 let mut seen = FxHashMap::default();
77 let attrs = self.tcx.hir().attrs(hir_id);
79 let attr_is_valid = match attr.name_or_empty() {
80 sym::inline => self.check_inline(hir_id, attr, span, target),
81 sym::no_coverage => self.check_no_coverage(hir_id, attr, span, target),
82 sym::non_exhaustive => self.check_non_exhaustive(hir_id, attr, span, target),
83 sym::marker => self.check_marker(hir_id, attr, span, target),
84 sym::rustc_must_implement_one_of => {
85 self.check_rustc_must_implement_one_of(attr, span, target)
87 sym::target_feature => self.check_target_feature(hir_id, attr, span, target),
88 sym::thread_local => self.check_thread_local(attr, span, target),
89 sym::track_caller => {
90 self.check_track_caller(hir_id, attr.span, attrs, span, target)
92 sym::doc => self.check_doc_attrs(
96 &mut specified_inline,
99 sym::no_link => self.check_no_link(hir_id, &attr, span, target),
100 sym::export_name => self.check_export_name(hir_id, &attr, span, target),
101 sym::rustc_layout_scalar_valid_range_start
102 | sym::rustc_layout_scalar_valid_range_end => {
103 self.check_rustc_layout_scalar_valid_range(&attr, span, target)
105 sym::allow_internal_unstable => {
106 self.check_allow_internal_unstable(hir_id, &attr, span, target, &attrs)
108 sym::debugger_visualizer => self.check_debugger_visualizer(&attr, target),
109 sym::rustc_allow_const_fn_unstable => {
110 self.check_rustc_allow_const_fn_unstable(hir_id, &attr, span, target)
112 sym::rustc_std_internal_symbol => {
113 self.check_rustc_std_internal_symbol(&attr, span, target)
115 sym::naked => self.check_naked(hir_id, attr, span, target),
116 sym::rustc_legacy_const_generics => {
117 self.check_rustc_legacy_const_generics(&attr, span, target, item)
119 sym::rustc_lint_query_instability => {
120 self.check_rustc_lint_query_instability(&attr, span, target)
122 sym::rustc_lint_diagnostics => {
123 self.check_rustc_lint_diagnostics(&attr, span, target)
125 sym::rustc_lint_opt_ty => self.check_rustc_lint_opt_ty(&attr, span, target),
126 sym::rustc_lint_opt_deny_field_access => {
127 self.check_rustc_lint_opt_deny_field_access(&attr, span, target)
131 | sym::rustc_if_this_changed
132 | sym::rustc_then_this_would_need => self.check_rustc_dirty_clean(&attr),
133 sym::cmse_nonsecure_entry => self.check_cmse_nonsecure_entry(attr, span, target),
134 sym::collapse_debuginfo => self.check_collapse_debuginfo(attr, span, target),
135 sym::const_trait => self.check_const_trait(attr, span, target),
136 sym::must_not_suspend => self.check_must_not_suspend(&attr, span, target),
137 sym::must_use => self.check_must_use(hir_id, &attr, span, target),
138 sym::rustc_pass_by_value => self.check_pass_by_value(&attr, span, target),
139 sym::rustc_allow_incoherent_impl => {
140 self.check_allow_incoherent_impl(&attr, span, target)
142 sym::rustc_has_incoherent_inherent_impls => {
143 self.check_has_incoherent_inherent_impls(&attr, span, target)
145 sym::rustc_const_unstable
146 | sym::rustc_const_stable
149 | sym::rustc_allowed_through_unstable_modules
150 | sym::rustc_promotable => self.check_stability_promotable(&attr, span, target),
151 sym::link_ordinal => self.check_link_ordinal(&attr, span, target),
154 is_valid &= attr_is_valid;
157 match attr.name_or_empty() {
158 sym::cold => self.check_cold(hir_id, attr, span, target),
159 sym::link => self.check_link(hir_id, attr, span, target),
160 sym::link_name => self.check_link_name(hir_id, attr, span, target),
161 sym::link_section => self.check_link_section(hir_id, attr, span, target),
162 sym::no_mangle => self.check_no_mangle(hir_id, attr, span, target),
163 sym::deprecated => self.check_deprecated(hir_id, attr, span, target),
164 sym::macro_use | sym::macro_escape => self.check_macro_use(hir_id, attr, target),
165 sym::path => self.check_generic_attr(hir_id, attr, target, &[Target::Mod]),
166 sym::plugin_registrar => self.check_plugin_registrar(hir_id, attr, target),
167 sym::macro_export => self.check_macro_export(hir_id, attr, target),
168 sym::ignore | sym::should_panic | sym::proc_macro_derive => {
169 self.check_generic_attr(hir_id, attr, target, &[Target::Fn])
171 sym::automatically_derived => {
172 self.check_generic_attr(hir_id, attr, target, &[Target::Impl])
174 sym::no_implicit_prelude => {
175 self.check_generic_attr(hir_id, attr, target, &[Target::Mod])
177 sym::rustc_object_lifetime_default => self.check_object_lifetime_default(hir_id),
181 let builtin = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
183 if hir_id != CRATE_HIR_ID {
184 if let Some(BuiltinAttribute { type_: AttributeType::CrateLevel, .. }) =
185 attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name))
188 ast::AttrStyle::Outer => self.tcx.emit_spanned_lint(
192 errors::OuterCrateLevelAttr,
194 ast::AttrStyle::Inner => self.tcx.emit_spanned_lint(
198 errors::InnerCrateLevelAttr,
204 if let Some(BuiltinAttribute { duplicates, .. }) = builtin {
205 check_duplicates(self.tcx, attr, hir_id, *duplicates, &mut seen);
208 self.check_unused_attribute(hir_id, attr)
215 // FIXME(@lcnr): this doesn't belong here.
222 | Target::ForeignStatic
224 self.tcx.ensure().codegen_fn_attrs(self.tcx.hir().local_def_id(hir_id));
227 self.check_repr(attrs, span, target, item, hir_id);
228 self.check_used(attrs, target);
231 fn inline_attr_str_error_with_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
232 self.tcx.emit_spanned_lint(
236 errors::IgnoredAttrWithMacro { sym },
240 fn inline_attr_str_error_without_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
241 self.tcx.emit_spanned_lint(
245 errors::IgnoredAttr { sym },
249 /// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid.
250 fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
254 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
255 Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
256 self.tcx.emit_spanned_lint(
260 errors::IgnoredInlineAttrFnProto,
264 // FIXME(#65833): We permit associated consts to have an `#[inline]` attribute with
265 // just a lint, because we previously erroneously allowed it and some crates used it
266 // accidentally, to to be compatible with crates depending on them, we can't throw an
268 Target::AssocConst => {
269 self.tcx.emit_spanned_lint(
273 errors::IgnoredInlineAttrConstants,
277 // FIXME(#80564): Same for fields, arms, and macro defs
278 Target::Field | Target::Arm | Target::MacroDef => {
279 self.inline_attr_str_error_with_macro_def(hir_id, attr, "inline");
283 self.tcx.sess.emit_err(errors::InlineNotFnOrClosure {
284 attr_span: attr.span,
292 /// Checks if a `#[no_coverage]` is applied directly to a function
293 fn check_no_coverage(
301 // no_coverage on function is fine
304 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
306 // function prototypes can't be covered
307 Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
308 self.tcx.emit_spanned_lint(
312 errors::IgnoredNoCoverageFnProto,
317 Target::Mod | Target::ForeignMod | Target::Impl | Target::Trait => {
318 self.tcx.emit_spanned_lint(
322 errors::IgnoredNoCoveragePropagate,
327 Target::Expression | Target::Statement | Target::Arm => {
328 self.tcx.emit_spanned_lint(
332 errors::IgnoredNoCoverageFnDefn,
338 self.tcx.sess.emit_err(errors::IgnoredNoCoverageNotCoverable {
339 attr_span: attr.span,
347 fn check_generic_attr(
352 allowed_targets: &[Target],
354 if !allowed_targets.iter().any(|t| t == &target) {
355 let name = attr.name_or_empty();
356 let mut i = allowed_targets.iter();
358 let b = i.next().map_or_else(String::new, |t| t.to_string() + "s");
359 let supported_names = i.enumerate().fold(b, |mut b, (i, allowed_target)| {
360 if allowed_targets.len() > 2 && i == allowed_targets.len() - 2 {
361 b.push_str(", and ");
362 } else if allowed_targets.len() == 2 && i == allowed_targets.len() - 2 {
368 b.push_str(&(allowed_target.to_string() + "s"));
371 self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
372 lint.build(&format!("`#[{name}]` only has an effect on {}", supported_names))
378 /// Checks if `#[naked]` is applied to a function definition.
379 fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
382 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
383 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
384 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
385 // erroneously allowed it and some crates used it accidentally, to to be compatible
386 // with crates depending on them, we can't throw an error here.
387 Target::Field | Target::Arm | Target::MacroDef => {
388 self.inline_attr_str_error_with_macro_def(hir_id, attr, "naked");
392 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
393 attr_span: attr.span,
401 /// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition.
402 fn check_cmse_nonsecure_entry(&self, attr: &Attribute, span: Span, target: Target) -> bool {
405 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
407 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
408 attr_span: attr.span,
416 /// Debugging aid for `object_lifetime_default` query.
417 fn check_object_lifetime_default(&self, hir_id: HirId) {
419 if let Some(generics) = tcx.hir().get_generics(tcx.hir().local_def_id(hir_id)) {
420 for p in generics.params {
421 let hir::GenericParamKind::Type { .. } = p.kind else { continue };
422 let param_id = tcx.hir().local_def_id(p.hir_id);
423 let default = tcx.object_lifetime_default(param_id);
424 let repr = match default {
425 ObjectLifetimeDefault::Empty => "BaseDefault".to_owned(),
426 ObjectLifetimeDefault::Static => "'static".to_owned(),
427 ObjectLifetimeDefault::Param(def_id) => tcx.item_name(def_id).to_string(),
428 ObjectLifetimeDefault::Ambiguous => "Ambiguous".to_owned(),
430 tcx.sess.span_err(p.span, &repr);
435 /// Checks if `#[collapse_debuginfo]` is applied to a macro.
436 fn check_collapse_debuginfo(&self, attr: &Attribute, span: Span, target: Target) -> bool {
438 Target::MacroDef => true,
442 .emit_err(errors::CollapseDebuginfo { attr_span: attr.span, defn_span: span });
448 /// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid.
449 fn check_track_caller(
458 _ if attrs.iter().any(|attr| attr.has_name(sym::naked)) => {
459 self.tcx.sess.emit_err(errors::NakedTrackedCaller { attr_span });
462 Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => true,
463 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
464 // `#[track_caller]` attribute with just a lint, because we previously
465 // erroneously allowed it and some crates used it accidentally, to to be compatible
466 // with crates depending on them, we can't throw an error here.
467 Target::Field | Target::Arm | Target::MacroDef => {
469 self.inline_attr_str_error_with_macro_def(hir_id, attr, "track_caller");
476 .emit_err(errors::TrackedCallerWrongLocation { attr_span, defn_span: span });
482 /// Checks if the `#[non_exhaustive]` attribute on an `item` is valid. Returns `true` if valid.
483 fn check_non_exhaustive(
491 Target::Struct | Target::Enum | Target::Variant => true,
492 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
493 // `#[non_exhaustive]` attribute with just a lint, because we previously
494 // erroneously allowed it and some crates used it accidentally, to to be compatible
495 // with crates depending on them, we can't throw an error here.
496 Target::Field | Target::Arm | Target::MacroDef => {
497 self.inline_attr_str_error_with_macro_def(hir_id, attr, "non_exhaustive");
501 self.tcx.sess.emit_err(errors::NonExhaustiveWrongLocation {
502 attr_span: attr.span,
510 /// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid.
511 fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
513 Target::Trait => true,
514 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
515 // `#[marker]` attribute with just a lint, because we previously
516 // erroneously allowed it and some crates used it accidentally, to to be compatible
517 // with crates depending on them, we can't throw an error here.
518 Target::Field | Target::Arm | Target::MacroDef => {
519 self.inline_attr_str_error_with_macro_def(hir_id, attr, "marker");
523 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
524 attr_span: attr.span,
532 /// Checks if the `#[rustc_must_implement_one_of]` attribute on a `target` is valid. Returns `true` if valid.
533 fn check_rustc_must_implement_one_of(
540 Target::Trait => true,
542 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
543 attr_span: attr.span,
551 /// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid.
552 fn check_target_feature(
561 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
562 // FIXME: #[target_feature] was previously erroneously allowed on statements and some
563 // crates used this, so only emit a warning.
564 Target::Statement => {
565 self.tcx.emit_spanned_lint(
569 errors::TargetFeatureOnStatement,
573 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
574 // `#[target_feature]` attribute with just a lint, because we previously
575 // erroneously allowed it and some crates used it accidentally, to to be compatible
576 // with crates depending on them, we can't throw an error here.
577 Target::Field | Target::Arm | Target::MacroDef => {
578 self.inline_attr_str_error_with_macro_def(hir_id, attr, "target_feature");
582 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
583 attr_span: attr.span,
591 /// Checks if the `#[thread_local]` attribute on `item` is valid. Returns `true` if valid.
592 fn check_thread_local(&self, attr: &Attribute, span: Span, target: Target) -> bool {
594 Target::ForeignStatic | Target::Static => true,
596 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToStatic {
597 attr_span: attr.span,
605 fn doc_attr_str_error(&self, meta: &NestedMetaItem, attr_name: &str) {
606 self.tcx.sess.emit_err(errors::DocExpectStr { attr_span: meta.span(), attr_name });
609 fn check_doc_alias_value(
611 meta: &NestedMetaItem,
616 aliases: &mut FxHashMap<String, Span>,
619 let span = meta.name_value_literal_span().unwrap_or_else(|| meta.span());
621 &format!("`#[doc(alias{})]`", if is_list { "(\"...\")" } else { " = \"...\"" });
622 if doc_alias == kw::Empty {
623 tcx.sess.emit_err(errors::DocAliasEmpty { span, attr_str });
627 let doc_alias_str = doc_alias.as_str();
628 if let Some(c) = doc_alias_str
630 .find(|&c| c == '"' || c == '\'' || (c.is_whitespace() && c != ' '))
632 tcx.sess.emit_err(errors::DocAliasBadChar { span, attr_str, char_: c });
635 if doc_alias_str.starts_with(' ') || doc_alias_str.ends_with(' ') {
636 tcx.sess.emit_err(errors::DocAliasStartEnd { span, attr_str });
640 let span = meta.span();
641 if let Some(location) = match target {
643 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
644 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
645 if Target::from_item(containing_item) == Target::Impl {
646 Some("type alias in implementation block")
651 Target::AssocConst => {
652 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
653 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
654 // We can't link to trait impl's consts.
655 let err = "associated constant in trait implementation block";
656 match containing_item.kind {
657 ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) => Some(err),
661 // we check the validity of params elsewhere
662 Target::Param => return false,
668 | Target::Impl => Some(target.name()),
678 | Target::ImplTraitPlaceholder
688 | Target::ForeignStatic
690 | Target::GenericParam(..)
693 | Target::ExprField => None,
695 tcx.sess.emit_err(errors::DocAliasBadLocation { span, attr_str, location });
698 let item_name = self.tcx.hir().name(hir_id);
699 if item_name == doc_alias {
700 tcx.sess.emit_err(errors::DocAliasNotAnAlias { span, attr_str });
703 if let Err(entry) = aliases.try_insert(doc_alias_str.to_owned(), span) {
704 self.tcx.emit_spanned_lint(
708 errors::DocAliasDuplicated { first_defn: *entry.entry.get() },
716 meta: &NestedMetaItem,
719 aliases: &mut FxHashMap<String, Span>,
721 if let Some(values) = meta.meta_item_list() {
725 Some(l) => match l.kind {
726 LitKind::Str(s, _) => {
727 if !self.check_doc_alias_value(v, s, hir_id, target, true, aliases) {
734 .emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
739 self.tcx.sess.emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
745 } else if let Some(doc_alias) = meta.value_str() {
746 self.check_doc_alias_value(meta, doc_alias, hir_id, target, false, aliases)
748 self.tcx.sess.emit_err(errors::DocAliasMalformed { span: meta.span() });
753 fn check_doc_keyword(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
754 let doc_keyword = meta.value_str().unwrap_or(kw::Empty);
755 if doc_keyword == kw::Empty {
756 self.doc_attr_str_error(meta, "keyword");
759 match self.tcx.hir().find(hir_id).and_then(|node| match node {
760 hir::Node::Item(item) => Some(&item.kind),
763 Some(ItemKind::Mod(ref module)) => {
764 if !module.item_ids.is_empty() {
765 self.tcx.sess.emit_err(errors::DocKeywordEmptyMod { span: meta.span() });
770 self.tcx.sess.emit_err(errors::DocKeywordNotMod { span: meta.span() });
774 if !rustc_lexer::is_ident(doc_keyword.as_str()) {
775 self.tcx.sess.emit_err(errors::DocKeywordInvalidIdent {
776 span: meta.name_value_literal_span().unwrap_or_else(|| meta.span()),
784 fn check_doc_fake_variadic(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
785 match self.tcx.hir().find(hir_id).and_then(|node| match node {
786 hir::Node::Item(item) => Some(&item.kind),
789 Some(ItemKind::Impl(ref i)) => {
790 let is_valid = matches!(&i.self_ty.kind, hir::TyKind::Tup([_]))
791 || if let hir::TyKind::BareFn(bare_fn_ty) = &i.self_ty.kind {
792 bare_fn_ty.decl.inputs.len() == 1
797 self.tcx.sess.emit_err(errors::DocFakeVariadicNotValid { span: meta.span() });
802 self.tcx.sess.emit_err(errors::DocKeywordOnlyImpl { span: meta.span() });
809 /// Checks `#[doc(inline)]`/`#[doc(no_inline)]` attributes. Returns `true` if valid.
811 /// A doc inlining attribute is invalid if it is applied to a non-`use` item, or
812 /// if there are conflicting attributes for one item.
814 /// `specified_inline` is used to keep track of whether we have
815 /// already seen an inlining attribute for this item.
816 /// If so, `specified_inline` holds the value and the span of
817 /// the first `inline`/`no_inline` attribute.
821 meta: &NestedMetaItem,
824 specified_inline: &mut Option<(bool, Span)>,
826 if target == Target::Use || target == Target::ExternCrate {
827 let do_inline = meta.name_or_empty() == sym::inline;
828 if let Some((prev_inline, prev_span)) = *specified_inline {
829 if do_inline != prev_inline {
830 let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]);
831 spans.push_span_label(prev_span, fluent::passes::doc_inline_conflict_first);
832 spans.push_span_label(meta.span(), fluent::passes::doc_inline_conflict_second);
833 self.tcx.sess.emit_err(errors::DocKeywordConflict { spans });
838 *specified_inline = Some((do_inline, meta.span()));
842 self.tcx.emit_spanned_lint(
843 INVALID_DOC_ATTRIBUTES,
846 errors::DocInlineOnlyUse {
847 attr_span: meta.span(),
848 item_span: (attr.style == AttrStyle::Outer)
849 .then(|| self.tcx.hir().span(hir_id)),
856 /// Checks that an attribute is *not* used at the crate level. Returns `true` if valid.
857 fn check_attr_not_crate_level(
859 meta: &NestedMetaItem,
863 if CRATE_HIR_ID == hir_id {
864 self.tcx.sess.emit_err(errors::DocAttrNotCrateLevel { span: meta.span(), attr_name });
870 /// Checks that an attribute is used at the crate level. Returns `true` if valid.
871 fn check_attr_crate_level(
874 meta: &NestedMetaItem,
877 if hir_id != CRATE_HIR_ID {
878 self.tcx.struct_span_lint_hir(INVALID_DOC_ATTRIBUTES, hir_id, meta.span(), |lint| {
879 let mut err = lint.build(fluent::passes::attr_crate_level);
880 if attr.style == AttrStyle::Outer
881 && self.tcx.hir().get_parent_item(hir_id) == CRATE_DEF_ID
883 if let Ok(mut src) = self.tcx.sess.source_map().span_to_snippet(attr.span) {
885 err.span_suggestion_verbose(
887 fluent::passes::suggestion,
889 Applicability::MaybeIncorrect,
892 err.span_help(attr.span, fluent::passes::help);
895 err.note(fluent::passes::note).emit();
902 /// Checks that `doc(test(...))` attribute contains only valid attributes. Returns `true` if
904 fn check_test_attr(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
905 let mut is_valid = true;
906 if let Some(metas) = meta.meta_item_list() {
907 for i_meta in metas {
908 match i_meta.name_or_empty() {
909 sym::attr | sym::no_crate_inject => {}
911 self.tcx.emit_spanned_lint(
912 INVALID_DOC_ATTRIBUTES,
915 errors::DocTestUnknown {
916 path: rustc_ast_pretty::pprust::path_to_string(
917 &i_meta.meta_item().unwrap().path,
926 self.tcx.emit_spanned_lint(
927 INVALID_DOC_ATTRIBUTES,
930 errors::DocTestTakesList,
937 /// Runs various checks on `#[doc]` attributes. Returns `true` if valid.
939 /// `specified_inline` should be initialized to `None` and kept for the scope
940 /// of one item. Read the documentation of [`check_doc_inline`] for more information.
942 /// [`check_doc_inline`]: Self::check_doc_inline
948 specified_inline: &mut Option<(bool, Span)>,
949 aliases: &mut FxHashMap<String, Span>,
951 let mut is_valid = true;
953 if let Some(mi) = attr.meta() && let Some(list) = mi.meta_item_list() {
955 if let Some(i_meta) = meta.meta_item() {
956 match i_meta.name_or_empty() {
958 if !self.check_attr_not_crate_level(meta, hir_id, "alias")
959 || !self.check_doc_alias(meta, hir_id, target, aliases) =>
965 if !self.check_attr_not_crate_level(meta, hir_id, "keyword")
966 || !self.check_doc_keyword(meta, hir_id) =>
972 if !self.check_attr_not_crate_level(meta, hir_id, "fake_variadic")
973 || !self.check_doc_fake_variadic(meta, hir_id) =>
978 sym::html_favicon_url
980 | sym::html_playground_url
981 | sym::issue_tracker_base_url
983 | sym::html_no_source
985 if !self.check_attr_crate_level(attr, meta, hir_id) =>
990 sym::inline | sym::no_inline
991 if !self.check_doc_inline(
1002 // no_default_passes: deprecated
1003 // passes: deprecated
1004 // plugins: removed, but rustdoc warns about it itself
1009 | sym::html_favicon_url
1010 | sym::html_logo_url
1011 | sym::html_no_source
1012 | sym::html_playground_url
1013 | sym::html_root_url
1015 | sym::issue_tracker_base_url
1018 | sym::no_default_passes
1020 | sym::notable_trait
1023 | sym::fake_variadic => {}
1026 if !self.check_test_attr(meta, hir_id) {
1032 if !self.tcx.features().rustdoc_internals {
1033 self.tcx.emit_spanned_lint(
1034 INVALID_DOC_ATTRIBUTES,
1037 errors::DocPrimitive,
1043 let path = rustc_ast_pretty::pprust::path_to_string(&i_meta.path);
1044 if i_meta.has_name(sym::spotlight) {
1045 self.tcx.emit_spanned_lint(
1046 INVALID_DOC_ATTRIBUTES,
1049 errors::DocTestUnknownSpotlight {
1054 } else if i_meta.has_name(sym::include) &&
1055 let Some(value) = i_meta.value_str() {
1056 let applicability = if list.len() == 1 {
1057 Applicability::MachineApplicable
1059 Applicability::MaybeIncorrect
1061 // If there are multiple attributes, the suggestion would suggest
1062 // deleting all of them, which is incorrect.
1063 self.tcx.emit_spanned_lint(
1064 INVALID_DOC_ATTRIBUTES,
1067 errors::DocTestUnknownInclude {
1069 value: value.to_string(),
1070 inner: (attr.style == AttrStyle::Inner)
1073 sugg: (attr.meta().unwrap().span, applicability),
1077 self.tcx.emit_spanned_lint(
1078 INVALID_DOC_ATTRIBUTES,
1081 errors::DocTestUnknownAny { path }
1088 self.tcx.emit_spanned_lint(
1089 INVALID_DOC_ATTRIBUTES,
1102 /// Warns against some misuses of `#[pass_by_value]`
1103 fn check_pass_by_value(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1105 Target::Struct | Target::Enum | Target::TyAlias => true,
1107 self.tcx.sess.emit_err(errors::PassByValue { attr_span: attr.span, span });
1113 fn check_allow_incoherent_impl(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1115 Target::Method(MethodKind::Inherent) => true,
1117 self.tcx.sess.emit_err(errors::AllowIncoherentImpl { attr_span: attr.span, span });
1123 fn check_has_incoherent_inherent_impls(
1130 Target::Trait | Target::Struct | Target::Enum | Target::Union | Target::ForeignTy => {
1136 .emit_err(errors::HasIncoherentInherentImpl { attr_span: attr.span, span });
1142 /// Warns against some misuses of `#[must_use]`
1143 fn check_must_use(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
1144 let node = self.tcx.hir().get(hir_id);
1145 if let Some(kind) = node.fn_kind() && let rustc_hir::IsAsync::Async = kind.asyncness() {
1146 self.tcx.emit_spanned_lint(
1150 errors::MustUseAsync { span }
1162 // `impl Trait` in return position can trip
1163 // `unused_must_use` if `Trait` is marked as
1167 let article = match target {
1172 | Target::Expression
1174 | Target::AssocConst
1175 | Target::AssocTy => "an",
1179 self.tcx.emit_spanned_lint(
1183 errors::MustUseNoEffect { article, target },
1187 // For now, its always valid
1191 /// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid.
1192 fn check_must_not_suspend(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1194 Target::Struct | Target::Enum | Target::Union | Target::Trait => true,
1196 self.tcx.sess.emit_err(errors::MustNotSuspend { attr_span: attr.span, span });
1202 /// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid.
1203 fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1205 Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {}
1206 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1207 // `#[cold]` attribute with just a lint, because we previously
1208 // erroneously allowed it and some crates used it accidentally, to to be compatible
1209 // with crates depending on them, we can't throw an error here.
1210 Target::Field | Target::Arm | Target::MacroDef => {
1211 self.inline_attr_str_error_with_macro_def(hir_id, attr, "cold");
1214 // FIXME: #[cold] was previously allowed on non-functions and some crates used
1215 // this, so only emit a warning.
1216 self.tcx.emit_spanned_lint(
1220 errors::Cold { span },
1226 /// Checks if `#[link]` is applied to an item other than a foreign module.
1227 fn check_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1228 if target == Target::ForeignMod
1229 && let hir::Node::Item(item) = self.tcx.hir().get(hir_id)
1230 && let Item { kind: ItemKind::ForeignMod { abi, .. }, .. } = item
1231 && !matches!(abi, Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic)
1236 self.tcx.emit_spanned_lint(
1240 errors::Link { span: (target != Target::ForeignMod).then_some(span) },
1244 /// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
1245 fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1247 Target::ForeignFn | Target::ForeignStatic => {}
1248 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1249 // `#[link_name]` attribute with just a lint, because we previously
1250 // erroneously allowed it and some crates used it accidentally, to to be compatible
1251 // with crates depending on them, we can't throw an error here.
1252 Target::Field | Target::Arm | Target::MacroDef => {
1253 self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_name");
1256 // FIXME: #[cold] was previously allowed on non-functions/statics and some crates
1257 // used this, so only emit a warning.
1258 let attr_span = matches!(target, Target::ForeignMod).then_some(attr.span);
1259 if let Some(s) = attr.value_str() {
1260 self.tcx.emit_spanned_lint(
1264 errors::LinkName { span, attr_span, value: s.as_str() },
1267 self.tcx.emit_spanned_lint(
1271 errors::LinkName { span, attr_span, value: "..." },
1278 /// Checks if `#[no_link]` is applied to an `extern crate`. Returns `true` if valid.
1279 fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
1281 Target::ExternCrate => true,
1282 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1283 // `#[no_link]` attribute with just a lint, because we previously
1284 // erroneously allowed it and some crates used it accidentally, to to be compatible
1285 // with crates depending on them, we can't throw an error here.
1286 Target::Field | Target::Arm | Target::MacroDef => {
1287 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_link");
1291 self.tcx.sess.emit_err(errors::NoLink { attr_span: attr.span, span });
1297 fn is_impl_item(&self, hir_id: HirId) -> bool {
1298 matches!(self.tcx.hir().get(hir_id), hir::Node::ImplItem(..))
1301 /// Checks if `#[export_name]` is applied to a function or static. Returns `true` if valid.
1302 fn check_export_name(
1310 Target::Static | Target::Fn => true,
1311 Target::Method(..) if self.is_impl_item(hir_id) => true,
1312 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1313 // `#[export_name]` attribute with just a lint, because we previously
1314 // erroneously allowed it and some crates used it accidentally, to to be compatible
1315 // with crates depending on them, we can't throw an error here.
1316 Target::Field | Target::Arm | Target::MacroDef => {
1317 self.inline_attr_str_error_with_macro_def(hir_id, attr, "export_name");
1321 self.tcx.sess.emit_err(errors::ExportName { attr_span: attr.span, span });
1327 fn check_rustc_layout_scalar_valid_range(
1333 if target != Target::Struct {
1334 self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeNotStruct {
1335 attr_span: attr.span,
1341 let Some(list) = attr.meta_item_list() else {
1345 if matches!(&list[..], &[NestedMetaItem::Literal(Lit { kind: LitKind::Int(..), .. })]) {
1348 self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeArg { attr_span: attr.span });
1353 /// Checks if `#[rustc_legacy_const_generics]` is applied to a function and has a valid argument.
1354 fn check_rustc_legacy_const_generics(
1359 item: Option<ItemLike<'_>>,
1361 let is_function = matches!(target, Target::Fn);
1363 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
1364 attr_span: attr.span,
1370 let Some(list) = attr.meta_item_list() else {
1371 // The attribute form is validated on AST.
1375 let Some(ItemLike::Item(Item {
1376 kind: ItemKind::Fn(FnSig { decl, .. }, generics, _),
1379 bug!("should be a function item");
1382 for param in generics.params {
1384 hir::GenericParamKind::Const { .. } => {}
1386 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsOnly {
1387 attr_span: attr.span,
1388 param_span: param.span,
1395 if list.len() != generics.params.len() {
1396 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndex {
1397 attr_span: attr.span,
1398 generics_span: generics.span,
1403 let arg_count = decl.inputs.len() as u128 + generics.params.len() as u128;
1404 let mut invalid_args = vec![];
1406 if let Some(LitKind::Int(val, _)) = meta.literal().map(|lit| &lit.kind) {
1407 if *val >= arg_count {
1408 let span = meta.span();
1409 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexExceed {
1411 arg_count: arg_count as usize,
1416 invalid_args.push(meta.span());
1420 if !invalid_args.is_empty() {
1421 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexNegative { invalid_args });
1428 /// Helper function for checking that the provided attribute is only applied to a function or
1430 fn check_applied_to_fn_or_method(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1431 let is_function = matches!(target, Target::Fn | Target::Method(..));
1433 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
1434 attr_span: attr.span,
1443 /// Checks that the `#[rustc_lint_query_instability]` attribute is only applied to a function
1445 fn check_rustc_lint_query_instability(
1451 self.check_applied_to_fn_or_method(attr, span, target)
1454 /// Checks that the `#[rustc_lint_diagnostics]` attribute is only applied to a function or
1456 fn check_rustc_lint_diagnostics(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1457 self.check_applied_to_fn_or_method(attr, span, target)
1460 /// Checks that the `#[rustc_lint_opt_ty]` attribute is only applied to a struct.
1461 fn check_rustc_lint_opt_ty(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1463 Target::Struct => true,
1465 self.tcx.sess.emit_err(errors::RustcLintOptTy { attr_span: attr.span, span });
1471 /// Checks that the `#[rustc_lint_opt_deny_field_access]` attribute is only applied to a field.
1472 fn check_rustc_lint_opt_deny_field_access(
1479 Target::Field => true,
1483 .emit_err(errors::RustcLintOptDenyFieldAccess { attr_span: attr.span, span });
1489 /// Checks that the dep-graph debugging attributes are only present when the query-dep-graph
1490 /// option is passed to the compiler.
1491 fn check_rustc_dirty_clean(&self, attr: &Attribute) -> bool {
1492 if self.tcx.sess.opts.unstable_opts.query_dep_graph {
1495 self.tcx.sess.emit_err(errors::RustcDirtyClean { span: attr.span });
1500 /// Checks if `#[link_section]` is applied to a function or static.
1501 fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1503 Target::Static | Target::Fn | Target::Method(..) => {}
1504 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1505 // `#[link_section]` attribute with just a lint, because we previously
1506 // erroneously allowed it and some crates used it accidentally, to to be compatible
1507 // with crates depending on them, we can't throw an error here.
1508 Target::Field | Target::Arm | Target::MacroDef => {
1509 self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_section");
1512 // FIXME: #[link_section] was previously allowed on non-functions/statics and some
1513 // crates used this, so only emit a warning.
1514 self.tcx.emit_spanned_lint(
1518 errors::LinkSection { span },
1524 /// Checks if `#[no_mangle]` is applied to a function or static.
1525 fn check_no_mangle(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1527 Target::Static | Target::Fn => {}
1528 Target::Method(..) if self.is_impl_item(hir_id) => {}
1529 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1530 // `#[no_mangle]` attribute with just a lint, because we previously
1531 // erroneously allowed it and some crates used it accidentally, to to be compatible
1532 // with crates depending on them, we can't throw an error here.
1533 Target::Field | Target::Arm | Target::MacroDef => {
1534 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_mangle");
1536 // FIXME: #[no_mangle] was previously allowed on non-functions/statics, this should be an error
1537 // The error should specify that the item that is wrong is specifically a *foreign* fn/static
1538 // otherwise the error seems odd
1539 Target::ForeignFn | Target::ForeignStatic => {
1540 let foreign_item_kind = match target {
1541 Target::ForeignFn => "function",
1542 Target::ForeignStatic => "static",
1543 _ => unreachable!(),
1545 self.tcx.emit_spanned_lint(
1549 errors::NoMangleForeign { span, attr_span: attr.span, foreign_item_kind },
1553 // FIXME: #[no_mangle] was previously allowed on non-functions/statics and some
1554 // crates used this, so only emit a warning.
1555 self.tcx.emit_spanned_lint(
1559 errors::NoMangle { span },
1565 /// Checks if the `#[repr]` attributes on `item` are valid.
1568 attrs: &[Attribute],
1571 item: Option<ItemLike<'_>>,
1574 // Extract the names of all repr hints, e.g., [foo, bar, align] for:
1577 // #[repr(bar, align(8))]
1579 let hints: Vec<_> = attrs
1581 .filter(|attr| attr.has_name(sym::repr))
1582 .filter_map(|attr| attr.meta_item_list())
1586 let mut int_reprs = 0;
1587 let mut is_c = false;
1588 let mut is_simd = false;
1589 let mut is_transparent = false;
1591 for hint in &hints {
1592 if !hint.is_meta_item() {
1593 self.tcx.sess.emit_err(errors::ReprIdent { span: hint.span() });
1597 let (article, allowed_targets) = match hint.name_or_empty() {
1601 Target::Struct | Target::Union | Target::Enum => continue,
1602 _ => ("a", "struct, enum, or union"),
1606 if let (Target::Fn, false) = (target, self.tcx.features().fn_align) {
1608 &self.tcx.sess.parse_sess,
1611 "`repr(align)` attributes on functions are unstable",
1617 Target::Struct | Target::Union | Target::Enum | Target::Fn => continue,
1618 _ => ("a", "struct, enum, function, or union"),
1622 if target != Target::Struct && target != Target::Union {
1623 ("a", "struct or union")
1630 if target != Target::Struct {
1636 sym::transparent => {
1637 is_transparent = true;
1639 Target::Struct | Target::Union | Target::Enum => continue,
1640 _ => ("a", "struct, enum, or union"),
1656 if target != Target::Enum {
1667 "unrecognized representation hint"
1669 .help("valid reprs are `C`, `align`, `packed`, `transparent`, `simd`, `i8`, `u8`, \
1670 `i16`, `u16`, `i32`, `u32`, `i64`, `u64`, `i128`, `u128`, `isize`, `usize`")
1682 &format!("attribute should be applied to {article} {allowed_targets}")
1684 .span_label(span, &format!("not {article} {allowed_targets}"))
1688 // Just point at all repr hints if there are any incompatibilities.
1689 // This is not ideal, but tracking precisely which ones are at fault is a huge hassle.
1690 let hint_spans = hints.iter().map(|hint| hint.span());
1692 // Error on repr(transparent, <anything else>).
1693 if is_transparent && hints.len() > 1 {
1694 let hint_spans: Vec<_> = hint_spans.clone().collect();
1699 "transparent {} cannot have other repr hints",
1704 // Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8)
1706 || (is_simd && is_c)
1709 && item.map_or(false, |item| {
1710 if let ItemLike::Item(item) = item {
1711 return is_c_like_enum(item);
1716 self.tcx.emit_spanned_lint(
1717 CONFLICTING_REPR_HINTS,
1719 hint_spans.collect::<Vec<Span>>(),
1720 errors::ReprConflicting,
1725 fn check_used(&self, attrs: &[Attribute], target: Target) {
1726 let mut used_linker_span = None;
1727 let mut used_compiler_span = None;
1728 for attr in attrs.iter().filter(|attr| attr.has_name(sym::used)) {
1729 if target != Target::Static {
1730 self.tcx.sess.emit_err(errors::UsedStatic { span: attr.span });
1732 let inner = attr.meta_item_list();
1733 match inner.as_deref() {
1734 Some([item]) if item.has_name(sym::linker) => {
1735 if used_linker_span.is_none() {
1736 used_linker_span = Some(attr.span);
1739 Some([item]) if item.has_name(sym::compiler) => {
1740 if used_compiler_span.is_none() {
1741 used_compiler_span = Some(attr.span);
1745 // This error case is handled in rustc_typeck::collect.
1748 // Default case (compiler) when arg isn't defined.
1749 if used_compiler_span.is_none() {
1750 used_compiler_span = Some(attr.span);
1755 if let (Some(linker_span), Some(compiler_span)) = (used_linker_span, used_compiler_span) {
1758 .emit_err(errors::UsedCompilerLinker { spans: vec![linker_span, compiler_span] });
1762 /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
1763 /// (Allows proc_macro functions)
1764 fn check_allow_internal_unstable(
1770 attrs: &[Attribute],
1772 debug!("Checking target: {:?}", target);
1776 if self.tcx.sess.is_proc_macro_attr(attr) {
1777 debug!("Is proc macro attr");
1781 debug!("Is not proc macro attr");
1784 Target::MacroDef => true,
1785 // FIXME(#80564): We permit struct fields and match arms to have an
1786 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
1787 // erroneously allowed it and some crates used it accidentally, to to be compatible
1788 // with crates depending on them, we can't throw an error here.
1789 Target::Field | Target::Arm => {
1790 self.inline_attr_str_error_without_macro_def(
1793 "allow_internal_unstable",
1800 .emit_err(errors::AllowInternalUnstable { attr_span: attr.span, span });
1806 /// Checks if the items on the `#[debugger_visualizer]` attribute are valid.
1807 fn check_debugger_visualizer(&self, attr: &Attribute, target: Target) -> bool {
1811 self.tcx.sess.emit_err(errors::DebugVisualizerPlacement { span: attr.span });
1816 let Some(hints) = attr.meta_item_list() else {
1817 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1821 let hint = match hints.len() {
1824 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1829 let Some(meta_item) = hint.meta_item() else {
1830 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1834 let visualizer_path = match (meta_item.name_or_empty(), meta_item.value_str()) {
1835 (sym::natvis_file, Some(value)) => value,
1836 (sym::gdb_script_file, Some(value)) => value,
1838 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: meta_item.span });
1844 match resolve_path(&self.tcx.sess.parse_sess, visualizer_path.as_str(), attr.span) {
1852 match std::fs::File::open(&file) {
1859 &format!("couldn't read {}: {}", file.display(), err),
1867 /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
1868 /// (Allows proc_macro functions)
1869 fn check_rustc_allow_const_fn_unstable(
1877 Target::Fn | Target::Method(_)
1878 if self.tcx.is_const_fn_raw(self.tcx.hir().local_def_id(hir_id).to_def_id()) =>
1882 // FIXME(#80564): We permit struct fields and match arms to have an
1883 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
1884 // erroneously allowed it and some crates used it accidentally, to to be compatible
1885 // with crates depending on them, we can't throw an error here.
1886 Target::Field | Target::Arm | Target::MacroDef => {
1887 self.inline_attr_str_error_with_macro_def(hir_id, attr, "allow_internal_unstable");
1893 .emit_err(errors::RustcAllowConstFnUnstable { attr_span: attr.span, span });
1899 fn check_rustc_std_internal_symbol(
1906 Target::Fn | Target::Static => true,
1910 .emit_err(errors::RustcStdInternalSymbol { attr_span: attr.span, span });
1916 /// `#[const_trait]` only applies to traits.
1917 fn check_const_trait(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1919 Target::Trait => true,
1921 self.tcx.sess.emit_err(errors::ConstTrait { attr_span: attr.span });
1927 fn check_stability_promotable(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1929 Target::Expression => {
1930 self.tcx.sess.emit_err(errors::StabilityPromotable { attr_span: attr.span });
1937 fn check_link_ordinal(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1939 Target::ForeignFn | Target::ForeignStatic => true,
1941 self.tcx.sess.emit_err(errors::LinkOrdinal { attr_span: attr.span });
1947 fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) {
1949 Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
1950 self.tcx.emit_spanned_lint(
1961 fn check_macro_use(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1962 let name = attr.name_or_empty();
1964 Target::ExternCrate | Target::Mod => {}
1966 self.tcx.emit_spanned_lint(
1970 errors::MacroUse { name },
1976 fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1977 if target != Target::MacroDef {
1978 self.tcx.emit_spanned_lint(UNUSED_ATTRIBUTES, hir_id, attr.span, errors::MacroExport);
1982 fn check_plugin_registrar(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1983 if target != Target::Fn {
1984 self.tcx.emit_spanned_lint(
1988 errors::PluginRegistrar,
1993 fn check_unused_attribute(&self, hir_id: HirId, attr: &Attribute) {
1994 // Warn on useless empty attributes.
1995 let note = if matches!(
1996 attr.name_or_empty(),
2005 | sym::target_feature
2006 ) && attr.meta_item_list().map_or(false, |list| list.is_empty())
2008 errors::UnusedNote::EmptyList { name: attr.name_or_empty() }
2010 attr.name_or_empty(),
2011 sym::allow | sym::warn | sym::deny | sym::forbid | sym::expect
2012 ) && let Some(meta) = attr.meta_item_list()
2014 && let Some(item) = meta[0].meta_item()
2015 && let MetaItemKind::NameValue(_) = &item.kind
2016 && item.path == sym::reason
2018 errors::UnusedNote::NoLints { name: attr.name_or_empty() }
2019 } else if attr.name_or_empty() == sym::default_method_body_is_const {
2020 errors::UnusedNote::DefaultMethodBodyConst
2025 self.tcx.emit_spanned_lint(
2029 errors::Unused { attr_span: attr.span, note },
2034 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
2035 type NestedFilter = nested_filter::OnlyBodies;
2037 fn nested_visit_map(&mut self) -> Self::Map {
2041 fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
2042 // Historically we've run more checks on non-exported than exported macros,
2043 // so this lets us continue to run them while maintaining backwards compatibility.
2044 // In the long run, the checks should be harmonized.
2045 if let ItemKind::Macro(ref macro_def, _) = item.kind {
2046 let def_id = item.def_id.to_def_id();
2047 if macro_def.macro_rules && !self.tcx.has_attr(def_id, sym::macro_export) {
2048 check_non_exported_macro_for_invalid_attrs(self.tcx, item);
2052 let target = Target::from_item(item);
2053 self.check_attributes(item.hir_id(), item.span, target, Some(ItemLike::Item(item)));
2054 intravisit::walk_item(self, item)
2057 fn visit_generic_param(&mut self, generic_param: &'tcx hir::GenericParam<'tcx>) {
2058 let target = Target::from_generic_param(generic_param);
2059 self.check_attributes(generic_param.hir_id, generic_param.span, target, None);
2060 intravisit::walk_generic_param(self, generic_param)
2063 fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>) {
2064 let target = Target::from_trait_item(trait_item);
2065 self.check_attributes(trait_item.hir_id(), trait_item.span, target, None);
2066 intravisit::walk_trait_item(self, trait_item)
2069 fn visit_field_def(&mut self, struct_field: &'tcx hir::FieldDef<'tcx>) {
2070 self.check_attributes(struct_field.hir_id, struct_field.span, Target::Field, None);
2071 intravisit::walk_field_def(self, struct_field);
2074 fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
2075 self.check_attributes(arm.hir_id, arm.span, Target::Arm, None);
2076 intravisit::walk_arm(self, arm);
2079 fn visit_foreign_item(&mut self, f_item: &'tcx ForeignItem<'tcx>) {
2080 let target = Target::from_foreign_item(f_item);
2081 self.check_attributes(f_item.hir_id(), f_item.span, target, Some(ItemLike::ForeignItem));
2082 intravisit::walk_foreign_item(self, f_item)
2085 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
2086 let target = target_from_impl_item(self.tcx, impl_item);
2087 self.check_attributes(impl_item.hir_id(), impl_item.span, target, None);
2088 intravisit::walk_impl_item(self, impl_item)
2091 fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
2092 // When checking statements ignore expressions, they will be checked later.
2093 if let hir::StmtKind::Local(ref l) = stmt.kind {
2094 self.check_attributes(l.hir_id, stmt.span, Target::Statement, None);
2096 intravisit::walk_stmt(self, stmt)
2099 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
2100 let target = match expr.kind {
2101 hir::ExprKind::Closure { .. } => Target::Closure,
2102 _ => Target::Expression,
2105 self.check_attributes(expr.hir_id, expr.span, target, None);
2106 intravisit::walk_expr(self, expr)
2109 fn visit_expr_field(&mut self, field: &'tcx hir::ExprField<'tcx>) {
2110 self.check_attributes(field.hir_id, field.span, Target::ExprField, None);
2111 intravisit::walk_expr_field(self, field)
2114 fn visit_variant(&mut self, variant: &'tcx hir::Variant<'tcx>) {
2115 self.check_attributes(variant.id, variant.span, Target::Variant, None);
2116 intravisit::walk_variant(self, variant)
2119 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
2120 self.check_attributes(param.hir_id, param.span, Target::Param, None);
2122 intravisit::walk_param(self, param);
2125 fn visit_pat_field(&mut self, field: &'tcx hir::PatField<'tcx>) {
2126 self.check_attributes(field.hir_id, field.span, Target::PatField, None);
2127 intravisit::walk_pat_field(self, field);
2131 fn is_c_like_enum(item: &Item<'_>) -> bool {
2132 if let ItemKind::Enum(ref def, _) = item.kind {
2133 for variant in def.variants {
2134 match variant.data {
2135 hir::VariantData::Unit(..) => { /* continue */ }
2145 // FIXME: Fix "Cannot determine resolution" error and remove built-in macros
2147 fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
2148 // Check for builtin attributes at the crate level
2149 // which were unsuccessfully resolved due to cannot determine
2150 // resolution for the attribute macro error.
2151 const ATTRS_TO_CHECK: &[Symbol] = &[
2155 sym::automatically_derived,
2162 sym::global_allocator,
2167 // This function should only be called with crate attributes
2168 // which are inner attributes always but lets check to make sure
2169 if attr.style == AttrStyle::Inner {
2170 for attr_to_check in ATTRS_TO_CHECK {
2171 if attr.has_name(*attr_to_check) {
2172 let mut err = tcx.sess.struct_span_err(
2175 "`{}` attribute cannot be used at crate level",
2176 attr_to_check.to_ident_string()
2179 // Only emit an error with a suggestion if we can create a
2180 // string out of the attribute span
2181 if let Ok(src) = tcx.sess.source_map().span_to_snippet(attr.span) {
2182 let replacement = src.replace("#!", "#");
2183 err.span_suggestion_verbose(
2185 "perhaps you meant to use an outer attribute",
2187 rustc_errors::Applicability::MachineApplicable,
2197 fn check_non_exported_macro_for_invalid_attrs(tcx: TyCtxt<'_>, item: &Item<'_>) {
2198 let attrs = tcx.hir().attrs(item.hir_id());
2201 if attr.has_name(sym::inline) {
2202 tcx.sess.emit_err(errors::NonExportedMacroInvalidAttrs { attr_span: attr.span });
2207 fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
2208 let check_attr_visitor = &mut CheckAttrVisitor { tcx };
2209 tcx.hir().visit_item_likes_in_module(module_def_id, check_attr_visitor);
2210 if module_def_id.is_top_level_module() {
2211 check_attr_visitor.check_attributes(CRATE_HIR_ID, DUMMY_SP, Target::Mod, None);
2212 check_invalid_crate_level_attr(tcx, tcx.hir().krate_attrs());
2216 pub(crate) fn provide(providers: &mut Providers) {
2217 *providers = Providers { check_mod_attrs, ..*providers };
2220 fn check_duplicates(
2224 duplicates: AttributeDuplicates,
2225 seen: &mut FxHashMap<Symbol, Span>,
2227 use AttributeDuplicates::*;
2228 if matches!(duplicates, WarnFollowingWordOnly) && !attr.is_word() {
2233 WarnFollowing | FutureWarnFollowing | WarnFollowingWordOnly | FutureWarnPreceding => {
2234 match seen.entry(attr.name_or_empty()) {
2235 Entry::Occupied(mut entry) => {
2236 let (this, other) = if matches!(duplicates, FutureWarnPreceding) {
2237 let to_remove = entry.insert(attr.span);
2238 (to_remove, attr.span)
2240 (attr.span, *entry.get())
2242 tcx.emit_spanned_lint(
2246 errors::UnusedDuplicate {
2251 FutureWarnFollowing | FutureWarnPreceding
2257 Entry::Vacant(entry) => {
2258 entry.insert(attr.span);
2262 ErrorFollowing | ErrorPreceding => match seen.entry(attr.name_or_empty()) {
2263 Entry::Occupied(mut entry) => {
2264 let (this, other) = if matches!(duplicates, ErrorPreceding) {
2265 let to_remove = entry.insert(attr.span);
2266 (to_remove, attr.span)
2268 (attr.span, *entry.get())
2270 tcx.sess.emit_err(errors::UnusedMultiple {
2273 name: attr.name_or_empty(),
2276 Entry::Vacant(entry) => {
2277 entry.insert(attr.span);