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::ty::query::Providers;
20 use rustc_middle::ty::TyCtxt;
21 use rustc_session::lint::builtin::{
22 CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, UNUSED_ATTRIBUTES,
24 use rustc_session::parse::feature_err;
25 use rustc_span::symbol::{kw, sym, Symbol};
26 use rustc_span::{Span, DUMMY_SP};
27 use rustc_target::spec::abi::Abi;
28 use std::collections::hash_map::Entry;
30 pub(crate) fn target_from_impl_item<'tcx>(
32 impl_item: &hir::ImplItem<'_>,
34 match impl_item.kind {
35 hir::ImplItemKind::Const(..) => Target::AssocConst,
36 hir::ImplItemKind::Fn(..) => {
37 let parent_hir_id = tcx.hir().get_parent_item(impl_item.hir_id());
38 let containing_item = tcx.hir().expect_item(parent_hir_id);
39 let containing_impl_is_for_trait = match &containing_item.kind {
40 hir::ItemKind::Impl(impl_) => impl_.of_trait.is_some(),
41 _ => bug!("parent of an ImplItem must be an Impl"),
43 if containing_impl_is_for_trait {
44 Target::Method(MethodKind::Trait { body: true })
46 Target::Method(MethodKind::Inherent)
49 hir::ImplItemKind::TyAlias(..) => Target::AssocTy,
53 #[derive(Clone, Copy)]
55 Item(&'tcx Item<'tcx>),
59 struct CheckAttrVisitor<'tcx> {
63 impl CheckAttrVisitor<'_> {
64 /// Checks any attribute.
70 item: Option<ItemLike<'_>>,
72 let mut doc_aliases = FxHashMap::default();
73 let mut is_valid = true;
74 let mut specified_inline = None;
75 let mut seen = FxHashMap::default();
76 let attrs = self.tcx.hir().attrs(hir_id);
78 let attr_is_valid = match attr.name_or_empty() {
79 sym::inline => self.check_inline(hir_id, attr, span, target),
80 sym::no_coverage => self.check_no_coverage(hir_id, attr, span, target),
81 sym::non_exhaustive => self.check_non_exhaustive(hir_id, attr, span, target),
82 sym::marker => self.check_marker(hir_id, attr, span, target),
83 sym::rustc_must_implement_one_of => {
84 self.check_rustc_must_implement_one_of(attr, span, target)
86 sym::target_feature => self.check_target_feature(hir_id, attr, span, target),
87 sym::thread_local => self.check_thread_local(attr, span, target),
88 sym::track_caller => {
89 self.check_track_caller(hir_id, attr.span, attrs, span, target)
91 sym::doc => self.check_doc_attrs(
95 &mut specified_inline,
98 sym::no_link => self.check_no_link(hir_id, &attr, span, target),
99 sym::export_name => self.check_export_name(hir_id, &attr, span, target),
100 sym::rustc_layout_scalar_valid_range_start
101 | sym::rustc_layout_scalar_valid_range_end => {
102 self.check_rustc_layout_scalar_valid_range(&attr, span, target)
104 sym::allow_internal_unstable => {
105 self.check_allow_internal_unstable(hir_id, &attr, span, target, &attrs)
107 sym::debugger_visualizer => self.check_debugger_visualizer(&attr, target),
108 sym::rustc_allow_const_fn_unstable => {
109 self.check_rustc_allow_const_fn_unstable(hir_id, &attr, span, target)
111 sym::rustc_std_internal_symbol => {
112 self.check_rustc_std_internal_symbol(&attr, span, target)
114 sym::naked => self.check_naked(hir_id, attr, span, target),
115 sym::rustc_legacy_const_generics => {
116 self.check_rustc_legacy_const_generics(&attr, span, target, item)
118 sym::rustc_lint_query_instability => {
119 self.check_rustc_lint_query_instability(&attr, span, target)
121 sym::rustc_lint_diagnostics => {
122 self.check_rustc_lint_diagnostics(&attr, span, target)
124 sym::rustc_lint_opt_ty => self.check_rustc_lint_opt_ty(&attr, span, target),
125 sym::rustc_lint_opt_deny_field_access => {
126 self.check_rustc_lint_opt_deny_field_access(&attr, span, target)
130 | sym::rustc_if_this_changed
131 | sym::rustc_then_this_would_need => self.check_rustc_dirty_clean(&attr),
132 sym::cmse_nonsecure_entry => self.check_cmse_nonsecure_entry(attr, span, target),
133 sym::const_trait => self.check_const_trait(attr, span, target),
134 sym::must_not_suspend => self.check_must_not_suspend(&attr, span, target),
135 sym::must_use => self.check_must_use(hir_id, &attr, span, target),
136 sym::rustc_pass_by_value => self.check_pass_by_value(&attr, span, target),
137 sym::rustc_allow_incoherent_impl => {
138 self.check_allow_incoherent_impl(&attr, span, target)
140 sym::rustc_has_incoherent_inherent_impls => {
141 self.check_has_incoherent_inherent_impls(&attr, span, target)
143 sym::rustc_const_unstable
144 | sym::rustc_const_stable
147 | sym::rustc_allowed_through_unstable_modules
148 | sym::rustc_promotable => self.check_stability_promotable(&attr, span, target),
149 sym::link_ordinal => self.check_link_ordinal(&attr, span, target),
152 is_valid &= attr_is_valid;
155 match attr.name_or_empty() {
156 sym::cold => self.check_cold(hir_id, attr, span, target),
157 sym::link => self.check_link(hir_id, attr, span, target),
158 sym::link_name => self.check_link_name(hir_id, attr, span, target),
159 sym::link_section => self.check_link_section(hir_id, attr, span, target),
160 sym::no_mangle => self.check_no_mangle(hir_id, attr, span, target),
161 sym::deprecated => self.check_deprecated(hir_id, attr, span, target),
162 sym::macro_use | sym::macro_escape => self.check_macro_use(hir_id, attr, target),
163 sym::path => self.check_generic_attr(hir_id, attr, target, &[Target::Mod]),
164 sym::plugin_registrar => self.check_plugin_registrar(hir_id, attr, target),
165 sym::macro_export => self.check_macro_export(hir_id, attr, target),
166 sym::ignore | sym::should_panic | sym::proc_macro_derive => {
167 self.check_generic_attr(hir_id, attr, target, &[Target::Fn])
169 sym::automatically_derived => {
170 self.check_generic_attr(hir_id, attr, target, &[Target::Impl])
172 sym::no_implicit_prelude => {
173 self.check_generic_attr(hir_id, attr, target, &[Target::Mod])
178 let builtin = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
180 if hir_id != CRATE_HIR_ID {
181 if let Some(BuiltinAttribute { type_: AttributeType::CrateLevel, .. }) =
182 attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name))
185 ast::AttrStyle::Outer => self.tcx.emit_spanned_lint(
189 errors::OuterCrateLevelAttr,
191 ast::AttrStyle::Inner => self.tcx.emit_spanned_lint(
195 errors::InnerCrateLevelAttr,
201 if let Some(BuiltinAttribute { duplicates, .. }) = builtin {
202 check_duplicates(self.tcx, attr, hir_id, *duplicates, &mut seen);
205 self.check_unused_attribute(hir_id, attr)
212 // FIXME(@lcnr): this doesn't belong here.
219 | Target::ForeignStatic
221 self.tcx.ensure().codegen_fn_attrs(self.tcx.hir().local_def_id(hir_id));
224 self.check_repr(attrs, span, target, item, hir_id);
225 self.check_used(attrs, target);
228 fn inline_attr_str_error_with_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
229 self.tcx.emit_spanned_lint(
233 errors::IgnoredAttrWithMacro { sym },
237 fn inline_attr_str_error_without_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
238 self.tcx.emit_spanned_lint(
242 errors::IgnoredAttr { sym },
246 /// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid.
247 fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
251 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
252 Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
253 self.tcx.emit_spanned_lint(
257 errors::IgnoredInlineAttrFnProto,
261 // FIXME(#65833): We permit associated consts to have an `#[inline]` attribute with
262 // just a lint, because we previously erroneously allowed it and some crates used it
263 // accidentally, to to be compatible with crates depending on them, we can't throw an
265 Target::AssocConst => {
266 self.tcx.emit_spanned_lint(
270 errors::IgnoredInlineAttrConstants,
274 // FIXME(#80564): Same for fields, arms, and macro defs
275 Target::Field | Target::Arm | Target::MacroDef => {
276 self.inline_attr_str_error_with_macro_def(hir_id, attr, "inline");
280 self.tcx.sess.emit_err(errors::InlineNotFnOrClosure {
281 attr_span: attr.span,
289 /// Checks if a `#[no_coverage]` is applied directly to a function
290 fn check_no_coverage(
298 // no_coverage on function is fine
301 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
303 // function prototypes can't be covered
304 Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
305 self.tcx.emit_spanned_lint(
309 errors::IgnoredNoCoverageFnProto,
314 Target::Mod | Target::ForeignMod | Target::Impl | Target::Trait => {
315 self.tcx.emit_spanned_lint(
319 errors::IgnoredNoCoveragePropagate,
324 Target::Expression | Target::Statement | Target::Arm => {
325 self.tcx.emit_spanned_lint(
329 errors::IgnoredNoCoverageFnDefn,
335 self.tcx.sess.emit_err(errors::IgnoredNoCoverageNotCoverable {
336 attr_span: attr.span,
344 fn check_generic_attr(
349 allowed_targets: &[Target],
351 if !allowed_targets.iter().any(|t| t == &target) {
352 let name = attr.name_or_empty();
353 let mut i = allowed_targets.iter();
355 let b = i.next().map_or_else(String::new, |t| t.to_string() + "s");
356 let supported_names = i.enumerate().fold(b, |mut b, (i, allowed_target)| {
357 if allowed_targets.len() > 2 && i == allowed_targets.len() - 2 {
358 b.push_str(", and ");
359 } else if allowed_targets.len() == 2 && i == allowed_targets.len() - 2 {
365 b.push_str(&(allowed_target.to_string() + "s"));
368 self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
369 lint.build(&format!("`#[{name}]` only has an effect on {}", supported_names))
375 /// Checks if `#[naked]` is applied to a function definition.
376 fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
379 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
380 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
381 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
382 // erroneously allowed it and some crates used it accidentally, to to be compatible
383 // with crates depending on them, we can't throw an error here.
384 Target::Field | Target::Arm | Target::MacroDef => {
385 self.inline_attr_str_error_with_macro_def(hir_id, attr, "naked");
389 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
390 attr_span: attr.span,
398 /// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition.
399 fn check_cmse_nonsecure_entry(&self, attr: &Attribute, span: Span, target: Target) -> bool {
402 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
404 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
405 attr_span: attr.span,
413 /// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid.
414 fn check_track_caller(
423 _ if attrs.iter().any(|attr| attr.has_name(sym::naked)) => {
424 self.tcx.sess.emit_err(errors::NakedTrackedCaller { attr_span });
427 Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => true,
428 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
429 // `#[track_caller]` attribute with just a lint, because we previously
430 // erroneously allowed it and some crates used it accidentally, to to be compatible
431 // with crates depending on them, we can't throw an error here.
432 Target::Field | Target::Arm | Target::MacroDef => {
434 self.inline_attr_str_error_with_macro_def(hir_id, attr, "track_caller");
441 .emit_err(errors::TrackedCallerWrongLocation { attr_span, defn_span: span });
447 /// Checks if the `#[non_exhaustive]` attribute on an `item` is valid. Returns `true` if valid.
448 fn check_non_exhaustive(
456 Target::Struct | Target::Enum | Target::Variant => true,
457 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
458 // `#[non_exhaustive]` attribute with just a lint, because we previously
459 // erroneously allowed it and some crates used it accidentally, to to be compatible
460 // with crates depending on them, we can't throw an error here.
461 Target::Field | Target::Arm | Target::MacroDef => {
462 self.inline_attr_str_error_with_macro_def(hir_id, attr, "non_exhaustive");
466 self.tcx.sess.emit_err(errors::NonExhaustiveWrongLocation {
467 attr_span: attr.span,
475 /// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid.
476 fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
478 Target::Trait => true,
479 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
480 // `#[marker]` attribute with just a lint, because we previously
481 // erroneously allowed it and some crates used it accidentally, to to be compatible
482 // with crates depending on them, we can't throw an error here.
483 Target::Field | Target::Arm | Target::MacroDef => {
484 self.inline_attr_str_error_with_macro_def(hir_id, attr, "marker");
488 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
489 attr_span: attr.span,
497 /// Checks if the `#[rustc_must_implement_one_of]` attribute on a `target` is valid. Returns `true` if valid.
498 fn check_rustc_must_implement_one_of(
505 Target::Trait => true,
507 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
508 attr_span: attr.span,
516 /// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid.
517 fn check_target_feature(
526 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
527 // FIXME: #[target_feature] was previously erroneously allowed on statements and some
528 // crates used this, so only emit a warning.
529 Target::Statement => {
530 self.tcx.emit_spanned_lint(
534 errors::TargetFeatureOnStatement,
538 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
539 // `#[target_feature]` attribute with just a lint, because we previously
540 // erroneously allowed it and some crates used it accidentally, to to be compatible
541 // with crates depending on them, we can't throw an error here.
542 Target::Field | Target::Arm | Target::MacroDef => {
543 self.inline_attr_str_error_with_macro_def(hir_id, attr, "target_feature");
547 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
548 attr_span: attr.span,
556 /// Checks if the `#[thread_local]` attribute on `item` is valid. Returns `true` if valid.
557 fn check_thread_local(&self, attr: &Attribute, span: Span, target: Target) -> bool {
559 Target::ForeignStatic | Target::Static => true,
561 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToStatic {
562 attr_span: attr.span,
570 fn doc_attr_str_error(&self, meta: &NestedMetaItem, attr_name: &str) {
571 self.tcx.sess.emit_err(errors::DocExpectStr { attr_span: meta.span(), attr_name });
574 fn check_doc_alias_value(
576 meta: &NestedMetaItem,
581 aliases: &mut FxHashMap<String, Span>,
584 let span = meta.name_value_literal_span().unwrap_or_else(|| meta.span());
586 &format!("`#[doc(alias{})]`", if is_list { "(\"...\")" } else { " = \"...\"" });
587 if doc_alias == kw::Empty {
588 tcx.sess.emit_err(errors::DocAliasEmpty { span, attr_str });
592 let doc_alias_str = doc_alias.as_str();
593 if let Some(c) = doc_alias_str
595 .find(|&c| c == '"' || c == '\'' || (c.is_whitespace() && c != ' '))
597 tcx.sess.emit_err(errors::DocAliasBadChar { span, attr_str, char_: c });
600 if doc_alias_str.starts_with(' ') || doc_alias_str.ends_with(' ') {
601 tcx.sess.emit_err(errors::DocAliasStartEnd { span, attr_str });
605 let span = meta.span();
606 if let Some(location) = match target {
608 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
609 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
610 if Target::from_item(containing_item) == Target::Impl {
611 Some("type alias in implementation block")
616 Target::AssocConst => {
617 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
618 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
619 // We can't link to trait impl's consts.
620 let err = "associated constant in trait implementation block";
621 match containing_item.kind {
622 ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) => Some(err),
626 // we check the validity of params elsewhere
627 Target::Param => return false,
633 | Target::Impl => Some(target.name()),
652 | Target::ForeignStatic
654 | Target::GenericParam(..)
655 | Target::MacroDef => None,
657 tcx.sess.emit_err(errors::DocAliasBadLocation { span, attr_str, location });
660 let item_name = self.tcx.hir().name(hir_id);
661 if item_name == doc_alias {
662 tcx.sess.emit_err(errors::DocAliasNotAnAlias { span, attr_str });
665 if let Err(entry) = aliases.try_insert(doc_alias_str.to_owned(), span) {
666 self.tcx.emit_spanned_lint(
670 errors::DocAliasDuplicated { first_defn: *entry.entry.get() },
678 meta: &NestedMetaItem,
681 aliases: &mut FxHashMap<String, Span>,
683 if let Some(values) = meta.meta_item_list() {
687 Some(l) => match l.kind {
688 LitKind::Str(s, _) => {
689 if !self.check_doc_alias_value(v, s, hir_id, target, true, aliases) {
696 .emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
701 self.tcx.sess.emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
707 } else if let Some(doc_alias) = meta.value_str() {
708 self.check_doc_alias_value(meta, doc_alias, hir_id, target, false, aliases)
710 self.tcx.sess.emit_err(errors::DocAliasMalformed { span: meta.span() });
715 fn check_doc_keyword(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
716 let doc_keyword = meta.value_str().unwrap_or(kw::Empty);
717 if doc_keyword == kw::Empty {
718 self.doc_attr_str_error(meta, "keyword");
721 match self.tcx.hir().find(hir_id).and_then(|node| match node {
722 hir::Node::Item(item) => Some(&item.kind),
725 Some(ItemKind::Mod(ref module)) => {
726 if !module.item_ids.is_empty() {
727 self.tcx.sess.emit_err(errors::DocKeywordEmptyMod { span: meta.span() });
732 self.tcx.sess.emit_err(errors::DocKeywordNotMod { span: meta.span() });
736 if !rustc_lexer::is_ident(doc_keyword.as_str()) {
737 self.tcx.sess.emit_err(errors::DocKeywordInvalidIdent {
738 span: meta.name_value_literal_span().unwrap_or_else(|| meta.span()),
746 fn check_doc_fake_variadic(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
747 match self.tcx.hir().find(hir_id).and_then(|node| match node {
748 hir::Node::Item(item) => Some(&item.kind),
751 Some(ItemKind::Impl(ref i)) => {
752 let is_valid = matches!(&i.self_ty.kind, hir::TyKind::Tup([_]))
753 || if let hir::TyKind::BareFn(bare_fn_ty) = &i.self_ty.kind {
754 bare_fn_ty.decl.inputs.len() == 1
759 self.tcx.sess.emit_err(errors::DocFakeVariadicNotValid { span: meta.span() });
764 self.tcx.sess.emit_err(errors::DocKeywordOnlyImpl { span: meta.span() });
771 /// Checks `#[doc(inline)]`/`#[doc(no_inline)]` attributes. Returns `true` if valid.
773 /// A doc inlining attribute is invalid if it is applied to a non-`use` item, or
774 /// if there are conflicting attributes for one item.
776 /// `specified_inline` is used to keep track of whether we have
777 /// already seen an inlining attribute for this item.
778 /// If so, `specified_inline` holds the value and the span of
779 /// the first `inline`/`no_inline` attribute.
783 meta: &NestedMetaItem,
786 specified_inline: &mut Option<(bool, Span)>,
788 if target == Target::Use || target == Target::ExternCrate {
789 let do_inline = meta.name_or_empty() == sym::inline;
790 if let Some((prev_inline, prev_span)) = *specified_inline {
791 if do_inline != prev_inline {
792 let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]);
793 spans.push_span_label(prev_span, fluent::passes::doc_inline_conflict_first);
794 spans.push_span_label(meta.span(), fluent::passes::doc_inline_conflict_second);
795 self.tcx.sess.emit_err(errors::DocKeywordConflict { spans });
800 *specified_inline = Some((do_inline, meta.span()));
804 self.tcx.emit_spanned_lint(
805 INVALID_DOC_ATTRIBUTES,
808 errors::DocInlineOnlyUse {
809 attr_span: meta.span(),
810 item_span: (attr.style == AttrStyle::Outer)
811 .then(|| self.tcx.hir().span(hir_id)),
818 /// Checks that an attribute is *not* used at the crate level. Returns `true` if valid.
819 fn check_attr_not_crate_level(
821 meta: &NestedMetaItem,
825 if CRATE_HIR_ID == hir_id {
826 self.tcx.sess.emit_err(errors::DocAttrNotCrateLevel { span: meta.span(), attr_name });
832 /// Checks that an attribute is used at the crate level. Returns `true` if valid.
833 fn check_attr_crate_level(
836 meta: &NestedMetaItem,
839 if hir_id != CRATE_HIR_ID {
840 self.tcx.struct_span_lint_hir(INVALID_DOC_ATTRIBUTES, hir_id, meta.span(), |lint| {
841 let mut err = lint.build(fluent::passes::attr_crate_level);
842 if attr.style == AttrStyle::Outer
843 && self.tcx.hir().get_parent_item(hir_id) == CRATE_DEF_ID
845 if let Ok(mut src) = self.tcx.sess.source_map().span_to_snippet(attr.span) {
847 err.span_suggestion_verbose(
849 fluent::passes::suggestion,
851 Applicability::MaybeIncorrect,
854 err.span_help(attr.span, fluent::passes::help);
857 err.note(fluent::passes::note).emit();
864 /// Checks that `doc(test(...))` attribute contains only valid attributes. Returns `true` if
866 fn check_test_attr(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
867 let mut is_valid = true;
868 if let Some(metas) = meta.meta_item_list() {
869 for i_meta in metas {
870 match i_meta.name_or_empty() {
871 sym::attr | sym::no_crate_inject => {}
873 self.tcx.emit_spanned_lint(
874 INVALID_DOC_ATTRIBUTES,
877 errors::DocTestUnknown {
878 path: rustc_ast_pretty::pprust::path_to_string(
879 &i_meta.meta_item().unwrap().path,
888 self.tcx.emit_spanned_lint(
889 INVALID_DOC_ATTRIBUTES,
892 errors::DocTestTakesList,
899 /// Runs various checks on `#[doc]` attributes. Returns `true` if valid.
901 /// `specified_inline` should be initialized to `None` and kept for the scope
902 /// of one item. Read the documentation of [`check_doc_inline`] for more information.
904 /// [`check_doc_inline`]: Self::check_doc_inline
910 specified_inline: &mut Option<(bool, Span)>,
911 aliases: &mut FxHashMap<String, Span>,
913 let mut is_valid = true;
915 if let Some(mi) = attr.meta() && let Some(list) = mi.meta_item_list() {
917 if let Some(i_meta) = meta.meta_item() {
918 match i_meta.name_or_empty() {
920 if !self.check_attr_not_crate_level(meta, hir_id, "alias")
921 || !self.check_doc_alias(meta, hir_id, target, aliases) =>
927 if !self.check_attr_not_crate_level(meta, hir_id, "keyword")
928 || !self.check_doc_keyword(meta, hir_id) =>
934 if !self.check_attr_not_crate_level(meta, hir_id, "fake_variadic")
935 || !self.check_doc_fake_variadic(meta, hir_id) =>
940 sym::html_favicon_url
942 | sym::html_playground_url
943 | sym::issue_tracker_base_url
945 | sym::html_no_source
947 if !self.check_attr_crate_level(attr, meta, hir_id) =>
952 sym::inline | sym::no_inline
953 if !self.check_doc_inline(
964 // no_default_passes: deprecated
965 // passes: deprecated
966 // plugins: removed, but rustdoc warns about it itself
971 | sym::html_favicon_url
973 | sym::html_no_source
974 | sym::html_playground_url
977 | sym::issue_tracker_base_url
980 | sym::no_default_passes
985 | sym::fake_variadic => {}
988 if !self.check_test_attr(meta, hir_id) {
994 if !self.tcx.features().rustdoc_internals {
995 self.tcx.emit_spanned_lint(
996 INVALID_DOC_ATTRIBUTES,
999 errors::DocPrimitive,
1005 let path = rustc_ast_pretty::pprust::path_to_string(&i_meta.path);
1006 if i_meta.has_name(sym::spotlight) {
1007 self.tcx.emit_spanned_lint(
1008 INVALID_DOC_ATTRIBUTES,
1011 errors::DocTestUnknownSpotlight {
1016 } else if i_meta.has_name(sym::include) &&
1017 let Some(value) = i_meta.value_str() {
1018 let applicability = if list.len() == 1 {
1019 Applicability::MachineApplicable
1021 Applicability::MaybeIncorrect
1023 // If there are multiple attributes, the suggestion would suggest
1024 // deleting all of them, which is incorrect.
1025 self.tcx.emit_spanned_lint(
1026 INVALID_DOC_ATTRIBUTES,
1029 errors::DocTestUnknownInclude {
1031 value: value.to_string(),
1032 inner: (attr.style == AttrStyle::Inner)
1035 sugg: (attr.meta().unwrap().span, applicability),
1039 self.tcx.emit_spanned_lint(
1040 INVALID_DOC_ATTRIBUTES,
1043 errors::DocTestUnknownAny { path }
1050 self.tcx.emit_spanned_lint(
1051 INVALID_DOC_ATTRIBUTES,
1064 /// Warns against some misuses of `#[pass_by_value]`
1065 fn check_pass_by_value(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1067 Target::Struct | Target::Enum | Target::TyAlias => true,
1069 self.tcx.sess.emit_err(errors::PassByValue { attr_span: attr.span, span });
1075 fn check_allow_incoherent_impl(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1077 Target::Method(MethodKind::Inherent) => true,
1079 self.tcx.sess.emit_err(errors::AllowIncoherentImpl { attr_span: attr.span, span });
1085 fn check_has_incoherent_inherent_impls(
1092 Target::Trait | Target::Struct | Target::Enum | Target::Union | Target::ForeignTy => {
1098 .emit_err(errors::HasIncoherentInherentImpl { attr_span: attr.span, span });
1104 /// Warns against some misuses of `#[must_use]`
1105 fn check_must_use(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
1106 let node = self.tcx.hir().get(hir_id);
1107 if let Some(kind) = node.fn_kind() && let rustc_hir::IsAsync::Async = kind.asyncness() {
1108 self.tcx.emit_spanned_lint(
1112 errors::MustUseAsync { span }
1124 // `impl Trait` in return position can trip
1125 // `unused_must_use` if `Trait` is marked as
1129 let article = match target {
1134 | Target::Expression
1136 | Target::AssocConst
1137 | Target::AssocTy => "an",
1141 self.tcx.emit_spanned_lint(
1145 errors::MustUseNoEffect { article, target },
1149 // For now, its always valid
1153 /// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid.
1154 fn check_must_not_suspend(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1156 Target::Struct | Target::Enum | Target::Union | Target::Trait => true,
1158 self.tcx.sess.emit_err(errors::MustNotSuspend { attr_span: attr.span, span });
1164 /// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid.
1165 fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1167 Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {}
1168 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1169 // `#[cold]` attribute with just a lint, because we previously
1170 // erroneously allowed it and some crates used it accidentally, to to be compatible
1171 // with crates depending on them, we can't throw an error here.
1172 Target::Field | Target::Arm | Target::MacroDef => {
1173 self.inline_attr_str_error_with_macro_def(hir_id, attr, "cold");
1176 // FIXME: #[cold] was previously allowed on non-functions and some crates used
1177 // this, so only emit a warning.
1178 self.tcx.emit_spanned_lint(
1182 errors::Cold { span },
1188 /// Checks if `#[link]` is applied to an item other than a foreign module.
1189 fn check_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1190 if target == Target::ForeignMod
1191 && let hir::Node::Item(item) = self.tcx.hir().get(hir_id)
1192 && let Item { kind: ItemKind::ForeignMod { abi, .. }, .. } = item
1193 && !matches!(abi, Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic)
1198 self.tcx.emit_spanned_lint(
1202 errors::Link { span: (target != Target::ForeignMod).then_some(span) },
1206 /// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
1207 fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1209 Target::ForeignFn | Target::ForeignStatic => {}
1210 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1211 // `#[link_name]` attribute with just a lint, because we previously
1212 // erroneously allowed it and some crates used it accidentally, to to be compatible
1213 // with crates depending on them, we can't throw an error here.
1214 Target::Field | Target::Arm | Target::MacroDef => {
1215 self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_name");
1218 // FIXME: #[cold] was previously allowed on non-functions/statics and some crates
1219 // used this, so only emit a warning.
1220 let attr_span = matches!(target, Target::ForeignMod).then_some(attr.span);
1221 if let Some(s) = attr.value_str() {
1222 self.tcx.emit_spanned_lint(
1226 errors::LinkName { span, attr_span, value: s.as_str() },
1229 self.tcx.emit_spanned_lint(
1233 errors::LinkName { span, attr_span, value: "..." },
1240 /// Checks if `#[no_link]` is applied to an `extern crate`. Returns `true` if valid.
1241 fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
1243 Target::ExternCrate => true,
1244 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1245 // `#[no_link]` attribute with just a lint, because we previously
1246 // erroneously allowed it and some crates used it accidentally, to to be compatible
1247 // with crates depending on them, we can't throw an error here.
1248 Target::Field | Target::Arm | Target::MacroDef => {
1249 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_link");
1253 self.tcx.sess.emit_err(errors::NoLink { attr_span: attr.span, span });
1259 fn is_impl_item(&self, hir_id: HirId) -> bool {
1260 matches!(self.tcx.hir().get(hir_id), hir::Node::ImplItem(..))
1263 /// Checks if `#[export_name]` is applied to a function or static. Returns `true` if valid.
1264 fn check_export_name(
1272 Target::Static | Target::Fn => true,
1273 Target::Method(..) if self.is_impl_item(hir_id) => true,
1274 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1275 // `#[export_name]` attribute with just a lint, because we previously
1276 // erroneously allowed it and some crates used it accidentally, to to be compatible
1277 // with crates depending on them, we can't throw an error here.
1278 Target::Field | Target::Arm | Target::MacroDef => {
1279 self.inline_attr_str_error_with_macro_def(hir_id, attr, "export_name");
1283 self.tcx.sess.emit_err(errors::ExportName { attr_span: attr.span, span });
1289 fn check_rustc_layout_scalar_valid_range(
1295 if target != Target::Struct {
1296 self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeNotStruct {
1297 attr_span: attr.span,
1303 let Some(list) = attr.meta_item_list() else {
1307 if matches!(&list[..], &[NestedMetaItem::Literal(Lit { kind: LitKind::Int(..), .. })]) {
1310 self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeArg { attr_span: attr.span });
1315 /// Checks if `#[rustc_legacy_const_generics]` is applied to a function and has a valid argument.
1316 fn check_rustc_legacy_const_generics(
1321 item: Option<ItemLike<'_>>,
1323 let is_function = matches!(target, Target::Fn);
1325 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
1326 attr_span: attr.span,
1332 let Some(list) = attr.meta_item_list() else {
1333 // The attribute form is validated on AST.
1337 let Some(ItemLike::Item(Item {
1338 kind: ItemKind::Fn(FnSig { decl, .. }, generics, _),
1341 bug!("should be a function item");
1344 for param in generics.params {
1346 hir::GenericParamKind::Const { .. } => {}
1348 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsOnly {
1349 attr_span: attr.span,
1350 param_span: param.span,
1357 if list.len() != generics.params.len() {
1358 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndex {
1359 attr_span: attr.span,
1360 generics_span: generics.span,
1365 let arg_count = decl.inputs.len() as u128 + generics.params.len() as u128;
1366 let mut invalid_args = vec![];
1368 if let Some(LitKind::Int(val, _)) = meta.literal().map(|lit| &lit.kind) {
1369 if *val >= arg_count {
1370 let span = meta.span();
1371 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexExceed {
1373 arg_count: arg_count as usize,
1378 invalid_args.push(meta.span());
1382 if !invalid_args.is_empty() {
1383 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexNegative { invalid_args });
1390 /// Helper function for checking that the provided attribute is only applied to a function or
1392 fn check_applied_to_fn_or_method(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1393 let is_function = matches!(target, Target::Fn | Target::Method(..));
1395 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
1396 attr_span: attr.span,
1405 /// Checks that the `#[rustc_lint_query_instability]` attribute is only applied to a function
1407 fn check_rustc_lint_query_instability(
1413 self.check_applied_to_fn_or_method(attr, span, target)
1416 /// Checks that the `#[rustc_lint_diagnostics]` attribute is only applied to a function or
1418 fn check_rustc_lint_diagnostics(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1419 self.check_applied_to_fn_or_method(attr, span, target)
1422 /// Checks that the `#[rustc_lint_opt_ty]` attribute is only applied to a struct.
1423 fn check_rustc_lint_opt_ty(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1425 Target::Struct => true,
1427 self.tcx.sess.emit_err(errors::RustcLintOptTy { attr_span: attr.span, span });
1433 /// Checks that the `#[rustc_lint_opt_deny_field_access]` attribute is only applied to a field.
1434 fn check_rustc_lint_opt_deny_field_access(
1441 Target::Field => true,
1445 .emit_err(errors::RustcLintOptDenyFieldAccess { attr_span: attr.span, span });
1451 /// Checks that the dep-graph debugging attributes are only present when the query-dep-graph
1452 /// option is passed to the compiler.
1453 fn check_rustc_dirty_clean(&self, attr: &Attribute) -> bool {
1454 if self.tcx.sess.opts.unstable_opts.query_dep_graph {
1457 self.tcx.sess.emit_err(errors::RustcDirtyClean { span: attr.span });
1462 /// Checks if `#[link_section]` is applied to a function or static.
1463 fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1465 Target::Static | Target::Fn | Target::Method(..) => {}
1466 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1467 // `#[link_section]` attribute with just a lint, because we previously
1468 // erroneously allowed it and some crates used it accidentally, to to be compatible
1469 // with crates depending on them, we can't throw an error here.
1470 Target::Field | Target::Arm | Target::MacroDef => {
1471 self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_section");
1474 // FIXME: #[link_section] was previously allowed on non-functions/statics and some
1475 // crates used this, so only emit a warning.
1476 self.tcx.emit_spanned_lint(
1480 errors::LinkSection { span },
1486 /// Checks if `#[no_mangle]` is applied to a function or static.
1487 fn check_no_mangle(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1489 Target::Static | Target::Fn => {}
1490 Target::Method(..) if self.is_impl_item(hir_id) => {}
1491 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1492 // `#[no_mangle]` attribute with just a lint, because we previously
1493 // erroneously allowed it and some crates used it accidentally, to to be compatible
1494 // with crates depending on them, we can't throw an error here.
1495 Target::Field | Target::Arm | Target::MacroDef => {
1496 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_mangle");
1498 // FIXME: #[no_mangle] was previously allowed on non-functions/statics, this should be an error
1499 // The error should specify that the item that is wrong is specifically a *foreign* fn/static
1500 // otherwise the error seems odd
1501 Target::ForeignFn | Target::ForeignStatic => {
1502 let foreign_item_kind = match target {
1503 Target::ForeignFn => "function",
1504 Target::ForeignStatic => "static",
1505 _ => unreachable!(),
1507 self.tcx.emit_spanned_lint(
1511 errors::NoMangleForeign { span, attr_span: attr.span, foreign_item_kind },
1515 // FIXME: #[no_mangle] was previously allowed on non-functions/statics and some
1516 // crates used this, so only emit a warning.
1517 self.tcx.emit_spanned_lint(
1521 errors::NoMangle { span },
1527 /// Checks if the `#[repr]` attributes on `item` are valid.
1530 attrs: &[Attribute],
1533 item: Option<ItemLike<'_>>,
1536 // Extract the names of all repr hints, e.g., [foo, bar, align] for:
1539 // #[repr(bar, align(8))]
1541 let hints: Vec<_> = attrs
1543 .filter(|attr| attr.has_name(sym::repr))
1544 .filter_map(|attr| attr.meta_item_list())
1548 let mut int_reprs = 0;
1549 let mut is_c = false;
1550 let mut is_simd = false;
1551 let mut is_transparent = false;
1553 for hint in &hints {
1554 if !hint.is_meta_item() {
1555 self.tcx.sess.emit_err(errors::ReprIdent { span: hint.span() });
1559 let (article, allowed_targets) = match hint.name_or_empty() {
1563 Target::Struct | Target::Union | Target::Enum => continue,
1564 _ => ("a", "struct, enum, or union"),
1568 if let (Target::Fn, false) = (target, self.tcx.features().fn_align) {
1570 &self.tcx.sess.parse_sess,
1573 "`repr(align)` attributes on functions are unstable",
1579 Target::Struct | Target::Union | Target::Enum | Target::Fn => continue,
1580 _ => ("a", "struct, enum, function, or union"),
1584 if target != Target::Struct && target != Target::Union {
1585 ("a", "struct or union")
1592 if target != Target::Struct {
1598 sym::transparent => {
1599 is_transparent = true;
1601 Target::Struct | Target::Union | Target::Enum => continue,
1602 _ => ("a", "struct, enum, or union"),
1618 if target != Target::Enum {
1629 "unrecognized representation hint"
1642 &format!("attribute should be applied to {article} {allowed_targets}")
1644 .span_label(span, &format!("not {article} {allowed_targets}"))
1648 // Just point at all repr hints if there are any incompatibilities.
1649 // This is not ideal, but tracking precisely which ones are at fault is a huge hassle.
1650 let hint_spans = hints.iter().map(|hint| hint.span());
1652 // Error on repr(transparent, <anything else>).
1653 if is_transparent && hints.len() > 1 {
1654 let hint_spans: Vec<_> = hint_spans.clone().collect();
1659 "transparent {} cannot have other repr hints",
1664 // Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8)
1666 || (is_simd && is_c)
1669 && item.map_or(false, |item| {
1670 if let ItemLike::Item(item) = item {
1671 return is_c_like_enum(item);
1676 self.tcx.emit_spanned_lint(
1677 CONFLICTING_REPR_HINTS,
1679 hint_spans.collect::<Vec<Span>>(),
1680 errors::ReprConflicting,
1685 fn check_used(&self, attrs: &[Attribute], target: Target) {
1686 let mut used_linker_span = None;
1687 let mut used_compiler_span = None;
1688 for attr in attrs.iter().filter(|attr| attr.has_name(sym::used)) {
1689 if target != Target::Static {
1690 self.tcx.sess.emit_err(errors::UsedStatic { span: attr.span });
1692 let inner = attr.meta_item_list();
1693 match inner.as_deref() {
1694 Some([item]) if item.has_name(sym::linker) => {
1695 if used_linker_span.is_none() {
1696 used_linker_span = Some(attr.span);
1699 Some([item]) if item.has_name(sym::compiler) => {
1700 if used_compiler_span.is_none() {
1701 used_compiler_span = Some(attr.span);
1705 // This error case is handled in rustc_typeck::collect.
1708 // Default case (compiler) when arg isn't defined.
1709 if used_compiler_span.is_none() {
1710 used_compiler_span = Some(attr.span);
1715 if let (Some(linker_span), Some(compiler_span)) = (used_linker_span, used_compiler_span) {
1718 .emit_err(errors::UsedCompilerLinker { spans: vec![linker_span, compiler_span] });
1722 /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
1723 /// (Allows proc_macro functions)
1724 fn check_allow_internal_unstable(
1730 attrs: &[Attribute],
1732 debug!("Checking target: {:?}", target);
1736 if self.tcx.sess.is_proc_macro_attr(attr) {
1737 debug!("Is proc macro attr");
1741 debug!("Is not proc macro attr");
1744 Target::MacroDef => true,
1745 // FIXME(#80564): We permit struct fields and match arms to have an
1746 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
1747 // erroneously allowed it and some crates used it accidentally, to to be compatible
1748 // with crates depending on them, we can't throw an error here.
1749 Target::Field | Target::Arm => {
1750 self.inline_attr_str_error_without_macro_def(
1753 "allow_internal_unstable",
1760 .emit_err(errors::AllowInternalUnstable { attr_span: attr.span, span });
1766 /// Checks if the items on the `#[debugger_visualizer]` attribute are valid.
1767 fn check_debugger_visualizer(&self, attr: &Attribute, target: Target) -> bool {
1771 self.tcx.sess.emit_err(errors::DebugVisualizerPlacement { span: attr.span });
1776 let Some(hints) = attr.meta_item_list() else {
1777 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1781 let hint = match hints.len() {
1784 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1789 let Some(meta_item) = hint.meta_item() else {
1790 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1794 let visualizer_path = match (meta_item.name_or_empty(), meta_item.value_str()) {
1795 (sym::natvis_file, Some(value)) => value,
1796 (sym::gdb_script_file, Some(value)) => value,
1798 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: meta_item.span });
1804 match resolve_path(&self.tcx.sess.parse_sess, visualizer_path.as_str(), attr.span) {
1812 match std::fs::File::open(&file) {
1819 &format!("couldn't read {}: {}", file.display(), err),
1827 /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
1828 /// (Allows proc_macro functions)
1829 fn check_rustc_allow_const_fn_unstable(
1837 Target::Fn | Target::Method(_)
1838 if self.tcx.is_const_fn_raw(self.tcx.hir().local_def_id(hir_id).to_def_id()) =>
1842 // FIXME(#80564): We permit struct fields and match arms to have an
1843 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
1844 // erroneously allowed it and some crates used it accidentally, to to be compatible
1845 // with crates depending on them, we can't throw an error here.
1846 Target::Field | Target::Arm | Target::MacroDef => {
1847 self.inline_attr_str_error_with_macro_def(hir_id, attr, "allow_internal_unstable");
1853 .emit_err(errors::RustcAllowConstFnUnstable { attr_span: attr.span, span });
1859 fn check_rustc_std_internal_symbol(
1866 Target::Fn | Target::Static => true,
1870 .emit_err(errors::RustcStdInternalSymbol { attr_span: attr.span, span });
1876 /// `#[const_trait]` only applies to traits.
1877 fn check_const_trait(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1879 Target::Trait => true,
1881 self.tcx.sess.emit_err(errors::ConstTrait { attr_span: attr.span });
1887 fn check_stability_promotable(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1889 Target::Expression => {
1890 self.tcx.sess.emit_err(errors::StabilityPromotable { attr_span: attr.span });
1897 fn check_link_ordinal(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1899 Target::ForeignFn | Target::ForeignStatic => true,
1901 self.tcx.sess.emit_err(errors::LinkOrdinal { attr_span: attr.span });
1907 fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) {
1909 Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
1910 self.tcx.emit_spanned_lint(
1921 fn check_macro_use(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1922 let name = attr.name_or_empty();
1924 Target::ExternCrate | Target::Mod => {}
1926 self.tcx.emit_spanned_lint(
1930 errors::MacroUse { name },
1936 fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1937 if target != Target::MacroDef {
1938 self.tcx.emit_spanned_lint(UNUSED_ATTRIBUTES, hir_id, attr.span, errors::MacroExport);
1942 fn check_plugin_registrar(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1943 if target != Target::Fn {
1944 self.tcx.emit_spanned_lint(
1948 errors::PluginRegistrar,
1953 fn check_unused_attribute(&self, hir_id: HirId, attr: &Attribute) {
1954 // Warn on useless empty attributes.
1955 let note = if matches!(
1956 attr.name_or_empty(),
1965 | sym::target_feature
1966 ) && attr.meta_item_list().map_or(false, |list| list.is_empty())
1968 errors::UnusedNote::EmptyList { name: attr.name_or_empty() }
1970 attr.name_or_empty(),
1971 sym::allow | sym::warn | sym::deny | sym::forbid | sym::expect
1972 ) && let Some(meta) = attr.meta_item_list()
1974 && let Some(item) = meta[0].meta_item()
1975 && let MetaItemKind::NameValue(_) = &item.kind
1976 && item.path == sym::reason
1978 errors::UnusedNote::NoLints { name: attr.name_or_empty() }
1979 } else if attr.name_or_empty() == sym::default_method_body_is_const {
1980 errors::UnusedNote::DefaultMethodBodyConst
1985 self.tcx.emit_spanned_lint(
1989 errors::Unused { attr_span: attr.span, note },
1994 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
1995 type NestedFilter = nested_filter::OnlyBodies;
1997 fn nested_visit_map(&mut self) -> Self::Map {
2001 fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
2002 // Historically we've run more checks on non-exported than exported macros,
2003 // so this lets us continue to run them while maintaining backwards compatibility.
2004 // In the long run, the checks should be harmonized.
2005 if let ItemKind::Macro(ref macro_def, _) = item.kind {
2006 let def_id = item.def_id.to_def_id();
2007 if macro_def.macro_rules && !self.tcx.has_attr(def_id, sym::macro_export) {
2008 check_non_exported_macro_for_invalid_attrs(self.tcx, item);
2012 let target = Target::from_item(item);
2013 self.check_attributes(item.hir_id(), item.span, target, Some(ItemLike::Item(item)));
2014 intravisit::walk_item(self, item)
2017 fn visit_generic_param(&mut self, generic_param: &'tcx hir::GenericParam<'tcx>) {
2018 let target = Target::from_generic_param(generic_param);
2019 self.check_attributes(generic_param.hir_id, generic_param.span, target, None);
2020 intravisit::walk_generic_param(self, generic_param)
2023 fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>) {
2024 let target = Target::from_trait_item(trait_item);
2025 self.check_attributes(trait_item.hir_id(), trait_item.span, target, None);
2026 intravisit::walk_trait_item(self, trait_item)
2029 fn visit_field_def(&mut self, struct_field: &'tcx hir::FieldDef<'tcx>) {
2030 self.check_attributes(struct_field.hir_id, struct_field.span, Target::Field, None);
2031 intravisit::walk_field_def(self, struct_field);
2034 fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
2035 self.check_attributes(arm.hir_id, arm.span, Target::Arm, None);
2036 intravisit::walk_arm(self, arm);
2039 fn visit_foreign_item(&mut self, f_item: &'tcx ForeignItem<'tcx>) {
2040 let target = Target::from_foreign_item(f_item);
2041 self.check_attributes(f_item.hir_id(), f_item.span, target, Some(ItemLike::ForeignItem));
2042 intravisit::walk_foreign_item(self, f_item)
2045 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
2046 let target = target_from_impl_item(self.tcx, impl_item);
2047 self.check_attributes(impl_item.hir_id(), impl_item.span, target, None);
2048 intravisit::walk_impl_item(self, impl_item)
2051 fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
2052 // When checking statements ignore expressions, they will be checked later.
2053 if let hir::StmtKind::Local(ref l) = stmt.kind {
2054 self.check_attributes(l.hir_id, stmt.span, Target::Statement, None);
2056 intravisit::walk_stmt(self, stmt)
2059 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
2060 let target = match expr.kind {
2061 hir::ExprKind::Closure { .. } => Target::Closure,
2062 _ => Target::Expression,
2065 self.check_attributes(expr.hir_id, expr.span, target, None);
2066 intravisit::walk_expr(self, expr)
2071 variant: &'tcx hir::Variant<'tcx>,
2072 generics: &'tcx hir::Generics<'tcx>,
2075 self.check_attributes(variant.id, variant.span, Target::Variant, None);
2076 intravisit::walk_variant(self, variant, generics, item_id)
2079 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
2080 self.check_attributes(param.hir_id, param.span, Target::Param, None);
2082 intravisit::walk_param(self, param);
2086 fn is_c_like_enum(item: &Item<'_>) -> bool {
2087 if let ItemKind::Enum(ref def, _) = item.kind {
2088 for variant in def.variants {
2089 match variant.data {
2090 hir::VariantData::Unit(..) => { /* continue */ }
2100 // FIXME: Fix "Cannot determine resolution" error and remove built-in macros
2102 fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
2103 // Check for builtin attributes at the crate level
2104 // which were unsuccessfully resolved due to cannot determine
2105 // resolution for the attribute macro error.
2106 const ATTRS_TO_CHECK: &[Symbol] = &[
2110 sym::automatically_derived,
2116 sym::global_allocator,
2121 // This function should only be called with crate attributes
2122 // which are inner attributes always but lets check to make sure
2123 if attr.style == AttrStyle::Inner {
2124 for attr_to_check in ATTRS_TO_CHECK {
2125 if attr.has_name(*attr_to_check) {
2126 let mut err = tcx.sess.struct_span_err(
2129 "`{}` attribute cannot be used at crate level",
2130 attr_to_check.to_ident_string()
2133 // Only emit an error with a suggestion if we can create a
2134 // string out of the attribute span
2135 if let Ok(src) = tcx.sess.source_map().span_to_snippet(attr.span) {
2136 let replacement = src.replace("#!", "#");
2137 err.span_suggestion_verbose(
2139 "perhaps you meant to use an outer attribute",
2141 rustc_errors::Applicability::MachineApplicable,
2151 fn check_non_exported_macro_for_invalid_attrs(tcx: TyCtxt<'_>, item: &Item<'_>) {
2152 let attrs = tcx.hir().attrs(item.hir_id());
2155 if attr.has_name(sym::inline) {
2156 tcx.sess.emit_err(errors::NonExportedMacroInvalidAttrs { attr_span: attr.span });
2161 fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
2162 let check_attr_visitor = &mut CheckAttrVisitor { tcx };
2163 tcx.hir().visit_item_likes_in_module(module_def_id, check_attr_visitor);
2164 if module_def_id.is_top_level_module() {
2165 check_attr_visitor.check_attributes(CRATE_HIR_ID, DUMMY_SP, Target::Mod, None);
2166 check_invalid_crate_level_attr(tcx, tcx.hir().krate_attrs());
2170 pub(crate) fn provide(providers: &mut Providers) {
2171 *providers = Providers { check_mod_attrs, ..*providers };
2174 fn check_duplicates(
2178 duplicates: AttributeDuplicates,
2179 seen: &mut FxHashMap<Symbol, Span>,
2181 use AttributeDuplicates::*;
2182 if matches!(duplicates, WarnFollowingWordOnly) && !attr.is_word() {
2187 WarnFollowing | FutureWarnFollowing | WarnFollowingWordOnly | FutureWarnPreceding => {
2188 match seen.entry(attr.name_or_empty()) {
2189 Entry::Occupied(mut entry) => {
2190 let (this, other) = if matches!(duplicates, FutureWarnPreceding) {
2191 let to_remove = entry.insert(attr.span);
2192 (to_remove, attr.span)
2194 (attr.span, *entry.get())
2196 tcx.emit_spanned_lint(
2200 errors::UnusedDuplicate {
2205 FutureWarnFollowing | FutureWarnPreceding
2211 Entry::Vacant(entry) => {
2212 entry.insert(attr.span);
2216 ErrorFollowing | ErrorPreceding => match seen.entry(attr.name_or_empty()) {
2217 Entry::Occupied(mut entry) => {
2218 let (this, other) = if matches!(duplicates, ErrorPreceding) {
2219 let to_remove = entry.insert(attr.span);
2220 (to_remove, attr.span)
2222 (attr.span, *entry.get())
2224 tcx.sess.emit_err(errors::UnusedMultiple {
2227 name: attr.name_or_empty(),
2230 Entry::Vacant(entry) => {
2231 entry.insert(attr.span);