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>),
56 ForeignItem(&'tcx ForeignItem<'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),
151 is_valid &= attr_is_valid;
154 match attr.name_or_empty() {
155 sym::cold => self.check_cold(hir_id, attr, span, target),
156 sym::link => self.check_link(hir_id, attr, span, target),
157 sym::link_name => self.check_link_name(hir_id, attr, span, target),
158 sym::link_section => self.check_link_section(hir_id, attr, span, target),
159 sym::no_mangle => self.check_no_mangle(hir_id, attr, span, target),
160 sym::deprecated => self.check_deprecated(hir_id, attr, span, target),
161 sym::macro_use | sym::macro_escape => self.check_macro_use(hir_id, attr, target),
162 sym::path => self.check_generic_attr(hir_id, attr, target, &[Target::Mod]),
163 sym::plugin_registrar => self.check_plugin_registrar(hir_id, attr, target),
164 sym::macro_export => self.check_macro_export(hir_id, attr, target),
165 sym::ignore | sym::should_panic | sym::proc_macro_derive => {
166 self.check_generic_attr(hir_id, attr, target, &[Target::Fn])
168 sym::automatically_derived => {
169 self.check_generic_attr(hir_id, attr, target, &[Target::Impl])
171 sym::no_implicit_prelude => {
172 self.check_generic_attr(hir_id, attr, target, &[Target::Mod])
177 let builtin = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
179 if hir_id != CRATE_HIR_ID {
180 if let Some(BuiltinAttribute { type_: AttributeType::CrateLevel, .. }) =
181 attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name))
184 ast::AttrStyle::Outer => self.tcx.emit_spanned_lint(
188 errors::OuterCrateLevelAttr,
190 ast::AttrStyle::Inner => self.tcx.emit_spanned_lint(
194 errors::InnerCrateLevelAttr,
200 if let Some(BuiltinAttribute { duplicates, .. }) = builtin {
201 check_duplicates(self.tcx, attr, hir_id, *duplicates, &mut seen);
204 self.check_unused_attribute(hir_id, attr)
211 // FIXME(@lcnr): this doesn't belong here.
212 if matches!(target, Target::Closure | Target::Fn | Target::Method(_) | Target::ForeignFn) {
213 self.tcx.ensure().codegen_fn_attrs(self.tcx.hir().local_def_id(hir_id));
216 self.check_repr(attrs, span, target, item, hir_id);
217 self.check_used(attrs, target);
220 fn inline_attr_str_error_with_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
221 self.tcx.emit_spanned_lint(
225 errors::IgnoredAttrWithMacro { sym },
229 fn inline_attr_str_error_without_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
230 self.tcx.emit_spanned_lint(
234 errors::IgnoredAttr { sym },
238 /// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid.
239 fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
243 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
244 Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
245 self.tcx.emit_spanned_lint(
249 errors::IgnoredInlineAttrFnProto,
253 // FIXME(#65833): We permit associated consts to have an `#[inline]` attribute with
254 // just a lint, because we previously erroneously allowed it and some crates used it
255 // accidentally, to to be compatible with crates depending on them, we can't throw an
257 Target::AssocConst => {
258 self.tcx.emit_spanned_lint(
262 errors::IgnoredInlineAttrConstants,
266 // FIXME(#80564): Same for fields, arms, and macro defs
267 Target::Field | Target::Arm | Target::MacroDef => {
268 self.inline_attr_str_error_with_macro_def(hir_id, attr, "inline");
272 self.tcx.sess.emit_err(errors::InlineNotFnOrClosure {
273 attr_span: attr.span,
281 /// Checks if a `#[no_coverage]` is applied directly to a function
282 fn check_no_coverage(
290 // no_coverage on function is fine
293 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
295 // function prototypes can't be covered
296 Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
297 self.tcx.emit_spanned_lint(
301 errors::IgnoredNoCoverageFnProto,
306 Target::Mod | Target::ForeignMod | Target::Impl | Target::Trait => {
307 self.tcx.emit_spanned_lint(
311 errors::IgnoredNoCoveragePropagate,
316 Target::Expression | Target::Statement | Target::Arm => {
317 self.tcx.emit_spanned_lint(
321 errors::IgnoredNoCoverageFnDefn,
327 self.tcx.sess.emit_err(errors::IgnoredNoCoverageNotCoverable {
328 attr_span: attr.span,
336 fn check_generic_attr(
341 allowed_targets: &[Target],
343 if !allowed_targets.iter().any(|t| t == &target) {
344 let name = attr.name_or_empty();
345 let mut i = allowed_targets.iter();
347 let b = i.next().map_or_else(String::new, |t| t.to_string() + "s");
348 let supported_names = i.enumerate().fold(b, |mut b, (i, allowed_target)| {
349 if allowed_targets.len() > 2 && i == allowed_targets.len() - 2 {
350 b.push_str(", and ");
351 } else if allowed_targets.len() == 2 && i == allowed_targets.len() - 2 {
357 b.push_str(&(allowed_target.to_string() + "s"));
360 self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
361 lint.build(&format!("`#[{name}]` only has an effect on {}", supported_names))
367 /// Checks if `#[naked]` is applied to a function definition.
368 fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
371 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
372 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
373 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
374 // erroneously allowed it and some crates used it accidentally, to to be compatible
375 // with crates depending on them, we can't throw an error here.
376 Target::Field | Target::Arm | Target::MacroDef => {
377 self.inline_attr_str_error_with_macro_def(hir_id, attr, "naked");
381 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
382 attr_span: attr.span,
390 /// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition.
391 fn check_cmse_nonsecure_entry(&self, attr: &Attribute, span: Span, target: Target) -> bool {
394 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
396 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
397 attr_span: attr.span,
405 /// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid.
406 fn check_track_caller(
415 _ if attrs.iter().any(|attr| attr.has_name(sym::naked)) => {
416 self.tcx.sess.emit_err(errors::NakedTrackedCaller { attr_span });
419 Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => true,
420 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
421 // `#[track_caller]` attribute with just a lint, because we previously
422 // erroneously allowed it and some crates used it accidentally, to to be compatible
423 // with crates depending on them, we can't throw an error here.
424 Target::Field | Target::Arm | Target::MacroDef => {
426 self.inline_attr_str_error_with_macro_def(hir_id, attr, "track_caller");
433 .emit_err(errors::TrackedCallerWrongLocation { attr_span, defn_span: span });
439 /// Checks if the `#[non_exhaustive]` attribute on an `item` is valid. Returns `true` if valid.
440 fn check_non_exhaustive(
448 Target::Struct | Target::Enum | Target::Variant => true,
449 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
450 // `#[non_exhaustive]` attribute with just a lint, because we previously
451 // erroneously allowed it and some crates used it accidentally, to to be compatible
452 // with crates depending on them, we can't throw an error here.
453 Target::Field | Target::Arm | Target::MacroDef => {
454 self.inline_attr_str_error_with_macro_def(hir_id, attr, "non_exhaustive");
458 self.tcx.sess.emit_err(errors::NonExhaustiveWrongLocation {
459 attr_span: attr.span,
467 /// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid.
468 fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
470 Target::Trait => true,
471 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
472 // `#[marker]` attribute with just a lint, because we previously
473 // erroneously allowed it and some crates used it accidentally, to to be compatible
474 // with crates depending on them, we can't throw an error here.
475 Target::Field | Target::Arm | Target::MacroDef => {
476 self.inline_attr_str_error_with_macro_def(hir_id, attr, "marker");
480 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
481 attr_span: attr.span,
489 /// Checks if the `#[rustc_must_implement_one_of]` attribute on a `target` is valid. Returns `true` if valid.
490 fn check_rustc_must_implement_one_of(
497 Target::Trait => true,
499 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
500 attr_span: attr.span,
508 /// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid.
509 fn check_target_feature(
518 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
519 // FIXME: #[target_feature] was previously erroneously allowed on statements and some
520 // crates used this, so only emit a warning.
521 Target::Statement => {
522 self.tcx.emit_spanned_lint(
526 errors::TargetFeatureOnStatement,
530 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
531 // `#[target_feature]` attribute with just a lint, because we previously
532 // erroneously allowed it and some crates used it accidentally, to to be compatible
533 // with crates depending on them, we can't throw an error here.
534 Target::Field | Target::Arm | Target::MacroDef => {
535 self.inline_attr_str_error_with_macro_def(hir_id, attr, "target_feature");
539 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
540 attr_span: attr.span,
548 /// Checks if the `#[thread_local]` attribute on `item` is valid. Returns `true` if valid.
549 fn check_thread_local(&self, attr: &Attribute, span: Span, target: Target) -> bool {
551 Target::ForeignStatic | Target::Static => true,
553 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToStatic {
554 attr_span: attr.span,
562 fn doc_attr_str_error(&self, meta: &NestedMetaItem, attr_name: &str) {
563 self.tcx.sess.emit_err(errors::DocExpectStr { attr_span: meta.span(), attr_name });
566 fn check_doc_alias_value(
568 meta: &NestedMetaItem,
573 aliases: &mut FxHashMap<String, Span>,
576 let span = meta.name_value_literal_span().unwrap_or_else(|| meta.span());
578 &format!("`#[doc(alias{})]`", if is_list { "(\"...\")" } else { " = \"...\"" });
579 if doc_alias == kw::Empty {
580 tcx.sess.emit_err(errors::DocAliasEmpty { span, attr_str });
584 let doc_alias_str = doc_alias.as_str();
585 if let Some(c) = doc_alias_str
587 .find(|&c| c == '"' || c == '\'' || (c.is_whitespace() && c != ' '))
589 tcx.sess.emit_err(errors::DocAliasBadChar { span, attr_str, char_: c });
592 if doc_alias_str.starts_with(' ') || doc_alias_str.ends_with(' ') {
593 tcx.sess.emit_err(errors::DocAliasStartEnd { span, attr_str });
597 let span = meta.span();
598 if let Some(location) = match target {
599 Target::Impl => Some("implementation block"),
600 Target::ForeignMod => Some("extern block"),
602 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
603 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
604 if Target::from_item(containing_item) == Target::Impl {
605 Some("type alias in implementation block")
610 Target::AssocConst => {
611 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
612 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
613 // We can't link to trait impl's consts.
614 let err = "associated constant in trait implementation block";
615 match containing_item.kind {
616 ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) => Some(err),
620 // we check the validity of params elsewhere
621 Target::Param => return false,
624 tcx.sess.emit_err(errors::DocAliasBadLocation { span, attr_str, location });
627 let item_name = self.tcx.hir().name(hir_id);
628 if item_name == doc_alias {
629 tcx.sess.emit_err(errors::DocAliasNotAnAlias { span, attr_str });
632 if let Err(entry) = aliases.try_insert(doc_alias_str.to_owned(), span) {
633 self.tcx.emit_spanned_lint(
637 errors::DocAliasDuplicated { first_defn: *entry.entry.get() },
645 meta: &NestedMetaItem,
648 aliases: &mut FxHashMap<String, Span>,
650 if let Some(values) = meta.meta_item_list() {
654 Some(l) => match l.kind {
655 LitKind::Str(s, _) => {
656 if !self.check_doc_alias_value(v, s, hir_id, target, true, aliases) {
663 .emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
668 self.tcx.sess.emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
674 } else if let Some(doc_alias) = meta.value_str() {
675 self.check_doc_alias_value(meta, doc_alias, hir_id, target, false, aliases)
677 self.tcx.sess.emit_err(errors::DocAliasMalformed { span: meta.span() });
682 fn check_doc_keyword(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
683 let doc_keyword = meta.value_str().unwrap_or(kw::Empty);
684 if doc_keyword == kw::Empty {
685 self.doc_attr_str_error(meta, "keyword");
688 match self.tcx.hir().find(hir_id).and_then(|node| match node {
689 hir::Node::Item(item) => Some(&item.kind),
692 Some(ItemKind::Mod(ref module)) => {
693 if !module.item_ids.is_empty() {
694 self.tcx.sess.emit_err(errors::DocKeywordEmptyMod { span: meta.span() });
699 self.tcx.sess.emit_err(errors::DocKeywordNotMod { span: meta.span() });
703 if !rustc_lexer::is_ident(doc_keyword.as_str()) {
704 self.tcx.sess.emit_err(errors::DocKeywordInvalidIdent {
705 span: meta.name_value_literal_span().unwrap_or_else(|| meta.span()),
713 fn check_doc_fake_variadic(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
714 match self.tcx.hir().find(hir_id).and_then(|node| match node {
715 hir::Node::Item(item) => Some(&item.kind),
718 Some(ItemKind::Impl(ref i)) => {
719 let is_valid = matches!(&i.self_ty.kind, hir::TyKind::Tup([_]))
720 || if let hir::TyKind::BareFn(bare_fn_ty) = &i.self_ty.kind {
721 bare_fn_ty.decl.inputs.len() == 1
726 self.tcx.sess.emit_err(errors::DocFakeVariadicNotValid { span: meta.span() });
731 self.tcx.sess.emit_err(errors::DocKeywordOnlyImpl { span: meta.span() });
738 /// Checks `#[doc(inline)]`/`#[doc(no_inline)]` attributes. Returns `true` if valid.
740 /// A doc inlining attribute is invalid if it is applied to a non-`use` item, or
741 /// if there are conflicting attributes for one item.
743 /// `specified_inline` is used to keep track of whether we have
744 /// already seen an inlining attribute for this item.
745 /// If so, `specified_inline` holds the value and the span of
746 /// the first `inline`/`no_inline` attribute.
750 meta: &NestedMetaItem,
753 specified_inline: &mut Option<(bool, Span)>,
755 if target == Target::Use || target == Target::ExternCrate {
756 let do_inline = meta.name_or_empty() == sym::inline;
757 if let Some((prev_inline, prev_span)) = *specified_inline {
758 if do_inline != prev_inline {
759 let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]);
760 spans.push_span_label(prev_span, fluent::passes::doc_inline_conflict_first);
761 spans.push_span_label(meta.span(), fluent::passes::doc_inline_conflict_second);
762 self.tcx.sess.emit_err(errors::DocKeywordConflict { spans });
767 *specified_inline = Some((do_inline, meta.span()));
771 self.tcx.emit_spanned_lint(
772 INVALID_DOC_ATTRIBUTES,
775 errors::DocInlineOnlyUse {
776 attr_span: meta.span(),
777 item_span: (attr.style == AttrStyle::Outer)
778 .then(|| self.tcx.hir().span(hir_id)),
785 /// Checks that an attribute is *not* used at the crate level. Returns `true` if valid.
786 fn check_attr_not_crate_level(
788 meta: &NestedMetaItem,
792 if CRATE_HIR_ID == hir_id {
793 self.tcx.sess.emit_err(errors::DocAttrNotCrateLevel { span: meta.span(), attr_name });
799 /// Checks that an attribute is used at the crate level. Returns `true` if valid.
800 fn check_attr_crate_level(
803 meta: &NestedMetaItem,
806 if hir_id != CRATE_HIR_ID {
807 self.tcx.struct_span_lint_hir(INVALID_DOC_ATTRIBUTES, hir_id, meta.span(), |lint| {
808 let mut err = lint.build(fluent::passes::attr_crate_level);
809 if attr.style == AttrStyle::Outer
810 && self.tcx.hir().get_parent_item(hir_id) == CRATE_DEF_ID
812 if let Ok(mut src) = self.tcx.sess.source_map().span_to_snippet(attr.span) {
814 err.span_suggestion_verbose(
816 fluent::passes::suggestion,
818 Applicability::MaybeIncorrect,
821 err.span_help(attr.span, fluent::passes::help);
824 err.note(fluent::passes::note).emit();
831 /// Checks that `doc(test(...))` attribute contains only valid attributes. Returns `true` if
833 fn check_test_attr(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
834 let mut is_valid = true;
835 if let Some(metas) = meta.meta_item_list() {
836 for i_meta in metas {
837 match i_meta.name_or_empty() {
838 sym::attr | sym::no_crate_inject => {}
840 self.tcx.emit_spanned_lint(
841 INVALID_DOC_ATTRIBUTES,
844 errors::DocTestUnknown {
845 path: rustc_ast_pretty::pprust::path_to_string(
846 &i_meta.meta_item().unwrap().path,
855 self.tcx.emit_spanned_lint(
856 INVALID_DOC_ATTRIBUTES,
859 errors::DocTestTakesList,
866 /// Runs various checks on `#[doc]` attributes. Returns `true` if valid.
868 /// `specified_inline` should be initialized to `None` and kept for the scope
869 /// of one item. Read the documentation of [`check_doc_inline`] for more information.
871 /// [`check_doc_inline`]: Self::check_doc_inline
877 specified_inline: &mut Option<(bool, Span)>,
878 aliases: &mut FxHashMap<String, Span>,
880 let mut is_valid = true;
882 if let Some(mi) = attr.meta() && let Some(list) = mi.meta_item_list() {
884 if let Some(i_meta) = meta.meta_item() {
885 match i_meta.name_or_empty() {
887 if !self.check_attr_not_crate_level(meta, hir_id, "alias")
888 || !self.check_doc_alias(meta, hir_id, target, aliases) =>
894 if !self.check_attr_not_crate_level(meta, hir_id, "keyword")
895 || !self.check_doc_keyword(meta, hir_id) =>
901 if !self.check_attr_not_crate_level(meta, hir_id, "fake_variadic")
902 || !self.check_doc_fake_variadic(meta, hir_id) =>
907 sym::html_favicon_url
909 | sym::html_playground_url
910 | sym::issue_tracker_base_url
912 | sym::html_no_source
914 if !self.check_attr_crate_level(attr, meta, hir_id) =>
919 sym::inline | sym::no_inline
920 if !self.check_doc_inline(
931 // no_default_passes: deprecated
932 // passes: deprecated
933 // plugins: removed, but rustdoc warns about it itself
938 | sym::html_favicon_url
940 | sym::html_no_source
941 | sym::html_playground_url
944 | sym::issue_tracker_base_url
947 | sym::no_default_passes
952 | sym::fake_variadic => {}
955 if !self.check_test_attr(meta, hir_id) {
961 if !self.tcx.features().rustdoc_internals {
962 self.tcx.emit_spanned_lint(
963 INVALID_DOC_ATTRIBUTES,
966 errors::DocPrimitive,
972 let path = rustc_ast_pretty::pprust::path_to_string(&i_meta.path);
973 if i_meta.has_name(sym::spotlight) {
974 self.tcx.emit_spanned_lint(
975 INVALID_DOC_ATTRIBUTES,
978 errors::DocTestUnknownSpotlight {
983 } else if i_meta.has_name(sym::include) &&
984 let Some(value) = i_meta.value_str() {
985 let applicability = if list.len() == 1 {
986 Applicability::MachineApplicable
988 Applicability::MaybeIncorrect
990 // If there are multiple attributes, the suggestion would suggest
991 // deleting all of them, which is incorrect.
992 self.tcx.emit_spanned_lint(
993 INVALID_DOC_ATTRIBUTES,
996 errors::DocTestUnknownInclude {
998 value: value.to_string(),
999 inner: (attr.style == AttrStyle::Inner)
1002 sugg: (attr.meta().unwrap().span, applicability),
1006 self.tcx.emit_spanned_lint(
1007 INVALID_DOC_ATTRIBUTES,
1010 errors::DocTestUnknownAny { path }
1017 self.tcx.emit_spanned_lint(
1018 INVALID_DOC_ATTRIBUTES,
1031 /// Warns against some misuses of `#[pass_by_value]`
1032 fn check_pass_by_value(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1034 Target::Struct | Target::Enum | Target::TyAlias => true,
1036 self.tcx.sess.emit_err(errors::PassByValue { attr_span: attr.span, span });
1042 fn check_allow_incoherent_impl(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1044 Target::Method(MethodKind::Inherent) => true,
1046 self.tcx.sess.emit_err(errors::AllowIncoherentImpl { attr_span: attr.span, span });
1052 fn check_has_incoherent_inherent_impls(
1059 Target::Trait | Target::Struct | Target::Enum | Target::Union | Target::ForeignTy => {
1065 .emit_err(errors::HasIncoherentInherentImpl { attr_span: attr.span, span });
1071 /// Warns against some misuses of `#[must_use]`
1072 fn check_must_use(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
1073 let node = self.tcx.hir().get(hir_id);
1074 if let Some(kind) = node.fn_kind() && let rustc_hir::IsAsync::Async = kind.asyncness() {
1075 self.tcx.emit_spanned_lint(
1079 errors::MustUseAsync { span }
1091 // `impl Trait` in return position can trip
1092 // `unused_must_use` if `Trait` is marked as
1096 let article = match target {
1101 | Target::Expression
1103 | Target::AssocConst
1104 | Target::AssocTy => "an",
1108 self.tcx.emit_spanned_lint(
1112 errors::MustUseNoEffect { article, target },
1116 // For now, its always valid
1120 /// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid.
1121 fn check_must_not_suspend(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1123 Target::Struct | Target::Enum | Target::Union | Target::Trait => true,
1125 self.tcx.sess.emit_err(errors::MustNotSuspend { attr_span: attr.span, span });
1131 /// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid.
1132 fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1134 Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {}
1135 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1136 // `#[cold]` attribute with just a lint, because we previously
1137 // erroneously allowed it and some crates used it accidentally, to to be compatible
1138 // with crates depending on them, we can't throw an error here.
1139 Target::Field | Target::Arm | Target::MacroDef => {
1140 self.inline_attr_str_error_with_macro_def(hir_id, attr, "cold");
1143 // FIXME: #[cold] was previously allowed on non-functions and some crates used
1144 // this, so only emit a warning.
1145 self.tcx.emit_spanned_lint(
1149 errors::Cold { span },
1155 /// Checks if `#[link]` is applied to an item other than a foreign module.
1156 fn check_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1157 if target == Target::ForeignMod
1158 && let hir::Node::Item(item) = self.tcx.hir().get(hir_id)
1159 && let Item { kind: ItemKind::ForeignMod { abi, .. }, .. } = item
1160 && !matches!(abi, Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic)
1165 self.tcx.emit_spanned_lint(
1169 errors::Link { span: (target != Target::ForeignMod).then_some(span) },
1173 /// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
1174 fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1176 Target::ForeignFn | Target::ForeignStatic => {}
1177 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1178 // `#[link_name]` attribute with just a lint, because we previously
1179 // erroneously allowed it and some crates used it accidentally, to to be compatible
1180 // with crates depending on them, we can't throw an error here.
1181 Target::Field | Target::Arm | Target::MacroDef => {
1182 self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_name");
1185 // FIXME: #[cold] was previously allowed on non-functions/statics and some crates
1186 // used this, so only emit a warning.
1187 let attr_span = matches!(target, Target::ForeignMod).then_some(attr.span);
1188 if let Some(s) = attr.value_str() {
1189 self.tcx.emit_spanned_lint(
1193 errors::LinkName { span, attr_span, value: s.as_str() },
1196 self.tcx.emit_spanned_lint(
1200 errors::LinkName { span, attr_span, value: "..." },
1207 /// Checks if `#[no_link]` is applied to an `extern crate`. Returns `true` if valid.
1208 fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
1210 Target::ExternCrate => true,
1211 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1212 // `#[no_link]` attribute with just a lint, because we previously
1213 // erroneously allowed it and some crates used it accidentally, to to be compatible
1214 // with crates depending on them, we can't throw an error here.
1215 Target::Field | Target::Arm | Target::MacroDef => {
1216 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_link");
1220 self.tcx.sess.emit_err(errors::NoLink { attr_span: attr.span, span });
1226 fn is_impl_item(&self, hir_id: HirId) -> bool {
1227 matches!(self.tcx.hir().get(hir_id), hir::Node::ImplItem(..))
1230 /// Checks if `#[export_name]` is applied to a function or static. Returns `true` if valid.
1231 fn check_export_name(
1239 Target::Static | Target::Fn => true,
1240 Target::Method(..) if self.is_impl_item(hir_id) => true,
1241 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1242 // `#[export_name]` attribute with just a lint, because we previously
1243 // erroneously allowed it and some crates used it accidentally, to to be compatible
1244 // with crates depending on them, we can't throw an error here.
1245 Target::Field | Target::Arm | Target::MacroDef => {
1246 self.inline_attr_str_error_with_macro_def(hir_id, attr, "export_name");
1250 self.tcx.sess.emit_err(errors::ExportName { attr_span: attr.span, span });
1256 fn check_rustc_layout_scalar_valid_range(
1262 if target != Target::Struct {
1263 self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeNotStruct {
1264 attr_span: attr.span,
1270 let Some(list) = attr.meta_item_list() else {
1274 if matches!(&list[..], &[NestedMetaItem::Literal(Lit { kind: LitKind::Int(..), .. })]) {
1277 self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeArg { attr_span: attr.span });
1282 /// Checks if `#[rustc_legacy_const_generics]` is applied to a function and has a valid argument.
1283 fn check_rustc_legacy_const_generics(
1288 item: Option<ItemLike<'_>>,
1290 let is_function = matches!(target, Target::Fn);
1292 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
1293 attr_span: attr.span,
1299 let Some(list) = attr.meta_item_list() else {
1300 // The attribute form is validated on AST.
1304 let Some(ItemLike::Item(Item {
1305 kind: ItemKind::Fn(FnSig { decl, .. }, generics, _),
1308 bug!("should be a function item");
1311 for param in generics.params {
1313 hir::GenericParamKind::Const { .. } => {}
1315 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsOnly {
1316 attr_span: attr.span,
1317 param_span: param.span,
1324 if list.len() != generics.params.len() {
1325 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndex {
1326 attr_span: attr.span,
1327 generics_span: generics.span,
1332 let arg_count = decl.inputs.len() as u128 + generics.params.len() as u128;
1333 let mut invalid_args = vec![];
1335 if let Some(LitKind::Int(val, _)) = meta.literal().map(|lit| &lit.kind) {
1336 if *val >= arg_count {
1337 let span = meta.span();
1338 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexExceed {
1340 arg_count: arg_count as usize,
1345 invalid_args.push(meta.span());
1349 if !invalid_args.is_empty() {
1350 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexNegative { invalid_args });
1357 /// Helper function for checking that the provided attribute is only applied to a function or
1359 fn check_applied_to_fn_or_method(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1360 let is_function = matches!(target, Target::Fn | Target::Method(..));
1362 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
1363 attr_span: attr.span,
1372 /// Checks that the `#[rustc_lint_query_instability]` attribute is only applied to a function
1374 fn check_rustc_lint_query_instability(
1380 self.check_applied_to_fn_or_method(attr, span, target)
1383 /// Checks that the `#[rustc_lint_diagnostics]` attribute is only applied to a function or
1385 fn check_rustc_lint_diagnostics(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1386 self.check_applied_to_fn_or_method(attr, span, target)
1389 /// Checks that the `#[rustc_lint_opt_ty]` attribute is only applied to a struct.
1390 fn check_rustc_lint_opt_ty(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1392 Target::Struct => true,
1394 self.tcx.sess.emit_err(errors::RustcLintOptTy { attr_span: attr.span, span });
1400 /// Checks that the `#[rustc_lint_opt_deny_field_access]` attribute is only applied to a field.
1401 fn check_rustc_lint_opt_deny_field_access(
1408 Target::Field => true,
1412 .emit_err(errors::RustcLintOptDenyFieldAccess { attr_span: attr.span, span });
1418 /// Checks that the dep-graph debugging attributes are only present when the query-dep-graph
1419 /// option is passed to the compiler.
1420 fn check_rustc_dirty_clean(&self, attr: &Attribute) -> bool {
1421 if self.tcx.sess.opts.unstable_opts.query_dep_graph {
1424 self.tcx.sess.emit_err(errors::RustcDirtyClean { span: attr.span });
1429 /// Checks if `#[link_section]` is applied to a function or static.
1430 fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1432 Target::Static | Target::Fn | Target::Method(..) => {}
1433 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1434 // `#[link_section]` attribute with just a lint, because we previously
1435 // erroneously allowed it and some crates used it accidentally, to to be compatible
1436 // with crates depending on them, we can't throw an error here.
1437 Target::Field | Target::Arm | Target::MacroDef => {
1438 self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_section");
1441 // FIXME: #[link_section] was previously allowed on non-functions/statics and some
1442 // crates used this, so only emit a warning.
1443 self.tcx.emit_spanned_lint(
1447 errors::LinkSection { span },
1453 /// Checks if `#[no_mangle]` is applied to a function or static.
1454 fn check_no_mangle(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1456 Target::Static | Target::Fn => {}
1457 Target::Method(..) if self.is_impl_item(hir_id) => {}
1458 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1459 // `#[no_mangle]` attribute with just a lint, because we previously
1460 // erroneously allowed it and some crates used it accidentally, to to be compatible
1461 // with crates depending on them, we can't throw an error here.
1462 Target::Field | Target::Arm | Target::MacroDef => {
1463 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_mangle");
1465 // FIXME: #[no_mangle] was previously allowed on non-functions/statics, this should be an error
1466 // The error should specify that the item that is wrong is specifically a *foreign* fn/static
1467 // otherwise the error seems odd
1468 Target::ForeignFn | Target::ForeignStatic => {
1469 let foreign_item_kind = match target {
1470 Target::ForeignFn => "function",
1471 Target::ForeignStatic => "static",
1472 _ => unreachable!(),
1474 self.tcx.emit_spanned_lint(
1478 errors::NoMangleForeign { span, attr_span: attr.span, foreign_item_kind },
1482 // FIXME: #[no_mangle] was previously allowed on non-functions/statics and some
1483 // crates used this, so only emit a warning.
1484 self.tcx.emit_spanned_lint(
1488 errors::NoMangle { span },
1494 /// Checks if the `#[repr]` attributes on `item` are valid.
1497 attrs: &[Attribute],
1500 item: Option<ItemLike<'_>>,
1503 // Extract the names of all repr hints, e.g., [foo, bar, align] for:
1506 // #[repr(bar, align(8))]
1508 let hints: Vec<_> = attrs
1510 .filter(|attr| attr.has_name(sym::repr))
1511 .filter_map(|attr| attr.meta_item_list())
1515 let mut int_reprs = 0;
1516 let mut is_c = false;
1517 let mut is_simd = false;
1518 let mut is_transparent = false;
1520 for hint in &hints {
1521 if !hint.is_meta_item() {
1522 self.tcx.sess.emit_err(errors::ReprIdent { span: hint.span() });
1526 let (article, allowed_targets) = match hint.name_or_empty() {
1530 Target::Struct | Target::Union | Target::Enum => continue,
1531 _ => ("a", "struct, enum, or union"),
1535 if let (Target::Fn, false) = (target, self.tcx.features().fn_align) {
1537 &self.tcx.sess.parse_sess,
1540 "`repr(align)` attributes on functions are unstable",
1546 Target::Struct | Target::Union | Target::Enum | Target::Fn => continue,
1547 _ => ("a", "struct, enum, function, or union"),
1551 if target != Target::Struct && target != Target::Union {
1552 ("a", "struct or union")
1559 if target != Target::Struct {
1565 sym::transparent => {
1566 is_transparent = true;
1568 Target::Struct | Target::Union | Target::Enum => continue,
1569 _ => ("a", "struct, enum, or union"),
1585 if target != Target::Enum {
1596 "unrecognized representation hint"
1609 &format!("attribute should be applied to {article} {allowed_targets}")
1611 .span_label(span, &format!("not {article} {allowed_targets}"))
1615 // Just point at all repr hints if there are any incompatibilities.
1616 // This is not ideal, but tracking precisely which ones are at fault is a huge hassle.
1617 let hint_spans = hints.iter().map(|hint| hint.span());
1619 // Error on repr(transparent, <anything else>).
1620 if is_transparent && hints.len() > 1 {
1621 let hint_spans: Vec<_> = hint_spans.clone().collect();
1626 "transparent {} cannot have other repr hints",
1631 // Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8)
1633 || (is_simd && is_c)
1636 && item.map_or(false, |item| {
1637 if let ItemLike::Item(item) = item {
1638 return is_c_like_enum(item);
1643 self.tcx.emit_spanned_lint(
1644 CONFLICTING_REPR_HINTS,
1646 hint_spans.collect::<Vec<Span>>(),
1647 errors::ReprConflicting,
1652 fn check_used(&self, attrs: &[Attribute], target: Target) {
1653 let mut used_linker_span = None;
1654 let mut used_compiler_span = None;
1655 for attr in attrs.iter().filter(|attr| attr.has_name(sym::used)) {
1656 if target != Target::Static {
1657 self.tcx.sess.emit_err(errors::UsedStatic { span: attr.span });
1659 let inner = attr.meta_item_list();
1660 match inner.as_deref() {
1661 Some([item]) if item.has_name(sym::linker) => {
1662 if used_linker_span.is_none() {
1663 used_linker_span = Some(attr.span);
1666 Some([item]) if item.has_name(sym::compiler) => {
1667 if used_compiler_span.is_none() {
1668 used_compiler_span = Some(attr.span);
1672 // This error case is handled in rustc_typeck::collect.
1675 // Default case (compiler) when arg isn't defined.
1676 if used_compiler_span.is_none() {
1677 used_compiler_span = Some(attr.span);
1682 if let (Some(linker_span), Some(compiler_span)) = (used_linker_span, used_compiler_span) {
1685 .emit_err(errors::UsedCompilerLinker { spans: vec![linker_span, compiler_span] });
1689 /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
1690 /// (Allows proc_macro functions)
1691 fn check_allow_internal_unstable(
1697 attrs: &[Attribute],
1699 debug!("Checking target: {:?}", target);
1703 if self.tcx.sess.is_proc_macro_attr(attr) {
1704 debug!("Is proc macro attr");
1708 debug!("Is not proc macro attr");
1711 Target::MacroDef => true,
1712 // FIXME(#80564): We permit struct fields and match arms to have an
1713 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
1714 // erroneously allowed it and some crates used it accidentally, to to be compatible
1715 // with crates depending on them, we can't throw an error here.
1716 Target::Field | Target::Arm => {
1717 self.inline_attr_str_error_without_macro_def(
1720 "allow_internal_unstable",
1727 .emit_err(errors::AllowInternalUnstable { attr_span: attr.span, span });
1733 /// Checks if the items on the `#[debugger_visualizer]` attribute are valid.
1734 fn check_debugger_visualizer(&self, attr: &Attribute, target: Target) -> bool {
1738 self.tcx.sess.emit_err(errors::DebugVisualizerPlacement { span: attr.span });
1743 let Some(hints) = attr.meta_item_list() else {
1744 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1748 let hint = match hints.len() {
1751 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1756 let Some(meta_item) = hint.meta_item() else {
1757 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1761 let visualizer_path = match (meta_item.name_or_empty(), meta_item.value_str()) {
1762 (sym::natvis_file, Some(value)) => value,
1763 (sym::gdb_script_file, Some(value)) => value,
1765 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: meta_item.span });
1771 match resolve_path(&self.tcx.sess.parse_sess, visualizer_path.as_str(), attr.span) {
1779 match std::fs::File::open(&file) {
1786 &format!("couldn't read {}: {}", file.display(), err),
1794 /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
1795 /// (Allows proc_macro functions)
1796 fn check_rustc_allow_const_fn_unstable(
1804 Target::Fn | Target::Method(_)
1805 if self.tcx.is_const_fn_raw(self.tcx.hir().local_def_id(hir_id).to_def_id()) =>
1809 // FIXME(#80564): We permit struct fields and match arms to have an
1810 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
1811 // erroneously allowed it and some crates used it accidentally, to to be compatible
1812 // with crates depending on them, we can't throw an error here.
1813 Target::Field | Target::Arm | Target::MacroDef => {
1814 self.inline_attr_str_error_with_macro_def(hir_id, attr, "allow_internal_unstable");
1820 .emit_err(errors::RustcAllowConstFnUnstable { attr_span: attr.span, span });
1826 fn check_rustc_std_internal_symbol(
1833 Target::Fn | Target::Static => true,
1837 .emit_err(errors::RustcStdInternalSymbol { attr_span: attr.span, span });
1843 /// `#[const_trait]` only applies to traits.
1844 fn check_const_trait(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1846 Target::Trait => true,
1848 self.tcx.sess.emit_err(errors::ConstTrait { attr_span: attr.span });
1854 fn check_stability_promotable(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1856 Target::Expression => {
1857 self.tcx.sess.emit_err(errors::StabilityPromotable { attr_span: attr.span });
1864 fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) {
1866 Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
1867 self.tcx.emit_spanned_lint(
1878 fn check_macro_use(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1879 let name = attr.name_or_empty();
1881 Target::ExternCrate | Target::Mod => {}
1883 self.tcx.emit_spanned_lint(
1887 errors::MacroUse { name },
1893 fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1894 if target != Target::MacroDef {
1895 self.tcx.emit_spanned_lint(UNUSED_ATTRIBUTES, hir_id, attr.span, errors::MacroExport);
1899 fn check_plugin_registrar(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1900 if target != Target::Fn {
1901 self.tcx.emit_spanned_lint(
1905 errors::PluginRegistrar,
1910 fn check_unused_attribute(&self, hir_id: HirId, attr: &Attribute) {
1911 // Warn on useless empty attributes.
1912 let note = if matches!(
1913 attr.name_or_empty(),
1922 | sym::target_feature
1923 ) && attr.meta_item_list().map_or(false, |list| list.is_empty())
1925 errors::UnusedNote::EmptyList { name: attr.name_or_empty() }
1927 attr.name_or_empty(),
1928 sym::allow | sym::warn | sym::deny | sym::forbid | sym::expect
1929 ) && let Some(meta) = attr.meta_item_list()
1931 && let Some(item) = meta[0].meta_item()
1932 && let MetaItemKind::NameValue(_) = &item.kind
1933 && item.path == sym::reason
1935 errors::UnusedNote::NoLints { name: attr.name_or_empty() }
1936 } else if attr.name_or_empty() == sym::default_method_body_is_const {
1937 errors::UnusedNote::DefaultMethodBodyConst
1942 self.tcx.emit_spanned_lint(
1946 errors::Unused { attr_span: attr.span, note },
1951 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
1952 type NestedFilter = nested_filter::OnlyBodies;
1954 fn nested_visit_map(&mut self) -> Self::Map {
1958 fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
1959 // Historically we've run more checks on non-exported than exported macros,
1960 // so this lets us continue to run them while maintaining backwards compatibility.
1961 // In the long run, the checks should be harmonized.
1962 if let ItemKind::Macro(ref macro_def, _) = item.kind {
1963 let def_id = item.def_id.to_def_id();
1964 if macro_def.macro_rules && !self.tcx.has_attr(def_id, sym::macro_export) {
1965 check_non_exported_macro_for_invalid_attrs(self.tcx, item);
1969 let target = Target::from_item(item);
1970 self.check_attributes(item.hir_id(), item.span, target, Some(ItemLike::Item(item)));
1971 intravisit::walk_item(self, item)
1974 fn visit_generic_param(&mut self, generic_param: &'tcx hir::GenericParam<'tcx>) {
1975 let target = Target::from_generic_param(generic_param);
1976 self.check_attributes(generic_param.hir_id, generic_param.span, target, None);
1977 intravisit::walk_generic_param(self, generic_param)
1980 fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>) {
1981 let target = Target::from_trait_item(trait_item);
1982 self.check_attributes(trait_item.hir_id(), trait_item.span, target, None);
1983 intravisit::walk_trait_item(self, trait_item)
1986 fn visit_field_def(&mut self, struct_field: &'tcx hir::FieldDef<'tcx>) {
1987 self.check_attributes(struct_field.hir_id, struct_field.span, Target::Field, None);
1988 intravisit::walk_field_def(self, struct_field);
1991 fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
1992 self.check_attributes(arm.hir_id, arm.span, Target::Arm, None);
1993 intravisit::walk_arm(self, arm);
1996 fn visit_foreign_item(&mut self, f_item: &'tcx ForeignItem<'tcx>) {
1997 let target = Target::from_foreign_item(f_item);
1998 self.check_attributes(
2002 Some(ItemLike::ForeignItem(f_item)),
2004 intravisit::walk_foreign_item(self, f_item)
2007 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
2008 let target = target_from_impl_item(self.tcx, impl_item);
2009 self.check_attributes(impl_item.hir_id(), impl_item.span, target, None);
2010 intravisit::walk_impl_item(self, impl_item)
2013 fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
2014 // When checking statements ignore expressions, they will be checked later.
2015 if let hir::StmtKind::Local(ref l) = stmt.kind {
2016 self.check_attributes(l.hir_id, stmt.span, Target::Statement, None);
2018 intravisit::walk_stmt(self, stmt)
2021 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
2022 let target = match expr.kind {
2023 hir::ExprKind::Closure { .. } => Target::Closure,
2024 _ => Target::Expression,
2027 self.check_attributes(expr.hir_id, expr.span, target, None);
2028 intravisit::walk_expr(self, expr)
2033 variant: &'tcx hir::Variant<'tcx>,
2034 generics: &'tcx hir::Generics<'tcx>,
2037 self.check_attributes(variant.id, variant.span, Target::Variant, None);
2038 intravisit::walk_variant(self, variant, generics, item_id)
2041 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
2042 self.check_attributes(param.hir_id, param.span, Target::Param, None);
2044 intravisit::walk_param(self, param);
2048 fn is_c_like_enum(item: &Item<'_>) -> bool {
2049 if let ItemKind::Enum(ref def, _) = item.kind {
2050 for variant in def.variants {
2051 match variant.data {
2052 hir::VariantData::Unit(..) => { /* continue */ }
2062 // FIXME: Fix "Cannot determine resolution" error and remove built-in macros
2064 fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
2065 // Check for builtin attributes at the crate level
2066 // which were unsuccessfully resolved due to cannot determine
2067 // resolution for the attribute macro error.
2068 const ATTRS_TO_CHECK: &[Symbol] = &[
2072 sym::automatically_derived,
2078 sym::global_allocator,
2083 // This function should only be called with crate attributes
2084 // which are inner attributes always but lets check to make sure
2085 if attr.style == AttrStyle::Inner {
2086 for attr_to_check in ATTRS_TO_CHECK {
2087 if attr.has_name(*attr_to_check) {
2088 let mut err = tcx.sess.struct_span_err(
2091 "`{}` attribute cannot be used at crate level",
2092 attr_to_check.to_ident_string()
2095 // Only emit an error with a suggestion if we can create a
2096 // string out of the attribute span
2097 if let Ok(src) = tcx.sess.source_map().span_to_snippet(attr.span) {
2098 let replacement = src.replace("#!", "#");
2099 err.span_suggestion_verbose(
2101 "perhaps you meant to use an outer attribute",
2103 rustc_errors::Applicability::MachineApplicable,
2113 fn check_non_exported_macro_for_invalid_attrs(tcx: TyCtxt<'_>, item: &Item<'_>) {
2114 let attrs = tcx.hir().attrs(item.hir_id());
2117 if attr.has_name(sym::inline) {
2118 tcx.sess.emit_err(errors::NonExportedMacroInvalidAttrs { attr_span: attr.span });
2123 fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
2124 let check_attr_visitor = &mut CheckAttrVisitor { tcx };
2125 tcx.hir().visit_item_likes_in_module(module_def_id, check_attr_visitor);
2126 if module_def_id.is_top_level_module() {
2127 check_attr_visitor.check_attributes(CRATE_HIR_ID, DUMMY_SP, Target::Mod, None);
2128 check_invalid_crate_level_attr(tcx, tcx.hir().krate_attrs());
2132 pub(crate) fn provide(providers: &mut Providers) {
2133 *providers = Providers { check_mod_attrs, ..*providers };
2136 fn check_duplicates(
2140 duplicates: AttributeDuplicates,
2141 seen: &mut FxHashMap<Symbol, Span>,
2143 use AttributeDuplicates::*;
2144 if matches!(duplicates, WarnFollowingWordOnly) && !attr.is_word() {
2149 WarnFollowing | FutureWarnFollowing | WarnFollowingWordOnly | FutureWarnPreceding => {
2150 match seen.entry(attr.name_or_empty()) {
2151 Entry::Occupied(mut entry) => {
2152 let (this, other) = if matches!(duplicates, FutureWarnPreceding) {
2153 let to_remove = entry.insert(attr.span);
2154 (to_remove, attr.span)
2156 (attr.span, *entry.get())
2158 tcx.emit_spanned_lint(
2162 errors::UnusedDuplicate {
2167 FutureWarnFollowing | FutureWarnPreceding
2173 Entry::Vacant(entry) => {
2174 entry.insert(attr.span);
2178 ErrorFollowing | ErrorPreceding => match seen.entry(attr.name_or_empty()) {
2179 Entry::Occupied(mut entry) => {
2180 let (this, other) = if matches!(duplicates, ErrorPreceding) {
2181 let to_remove = entry.insert(attr.span);
2182 (to_remove, attr.span)
2184 (attr.span, *entry.get())
2186 tcx.sess.emit_err(errors::UnusedMultiple {
2189 name: attr.name_or_empty(),
2192 Entry::Vacant(entry) => {
2193 entry.insert(attr.span);