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),
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.
218 | Target::ForeignStatic
220 self.tcx.ensure().codegen_fn_attrs(self.tcx.hir().local_def_id(hir_id));
223 self.check_repr(attrs, span, target, item, hir_id);
224 self.check_used(attrs, target);
227 fn inline_attr_str_error_with_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
228 self.tcx.emit_spanned_lint(
232 errors::IgnoredAttrWithMacro { sym },
236 fn inline_attr_str_error_without_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
237 self.tcx.emit_spanned_lint(
241 errors::IgnoredAttr { sym },
245 /// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid.
246 fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
250 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
251 Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
252 self.tcx.emit_spanned_lint(
256 errors::IgnoredInlineAttrFnProto,
260 // FIXME(#65833): We permit associated consts to have an `#[inline]` attribute with
261 // just a lint, because we previously erroneously allowed it and some crates used it
262 // accidentally, to to be compatible with crates depending on them, we can't throw an
264 Target::AssocConst => {
265 self.tcx.emit_spanned_lint(
269 errors::IgnoredInlineAttrConstants,
273 // FIXME(#80564): Same for fields, arms, and macro defs
274 Target::Field | Target::Arm | Target::MacroDef => {
275 self.inline_attr_str_error_with_macro_def(hir_id, attr, "inline");
279 self.tcx.sess.emit_err(errors::InlineNotFnOrClosure {
280 attr_span: attr.span,
288 /// Checks if a `#[no_coverage]` is applied directly to a function
289 fn check_no_coverage(
297 // no_coverage on function is fine
300 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
302 // function prototypes can't be covered
303 Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
304 self.tcx.emit_spanned_lint(
308 errors::IgnoredNoCoverageFnProto,
313 Target::Mod | Target::ForeignMod | Target::Impl | Target::Trait => {
314 self.tcx.emit_spanned_lint(
318 errors::IgnoredNoCoveragePropagate,
323 Target::Expression | Target::Statement | Target::Arm => {
324 self.tcx.emit_spanned_lint(
328 errors::IgnoredNoCoverageFnDefn,
334 self.tcx.sess.emit_err(errors::IgnoredNoCoverageNotCoverable {
335 attr_span: attr.span,
343 fn check_generic_attr(
348 allowed_targets: &[Target],
350 if !allowed_targets.iter().any(|t| t == &target) {
351 let name = attr.name_or_empty();
352 let mut i = allowed_targets.iter();
354 let b = i.next().map_or_else(String::new, |t| t.to_string() + "s");
355 let supported_names = i.enumerate().fold(b, |mut b, (i, allowed_target)| {
356 if allowed_targets.len() > 2 && i == allowed_targets.len() - 2 {
357 b.push_str(", and ");
358 } else if allowed_targets.len() == 2 && i == allowed_targets.len() - 2 {
364 b.push_str(&(allowed_target.to_string() + "s"));
367 self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
368 lint.build(&format!("`#[{name}]` only has an effect on {}", supported_names))
374 /// Checks if `#[naked]` is applied to a function definition.
375 fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
378 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
379 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
380 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
381 // erroneously allowed it and some crates used it accidentally, to to be compatible
382 // with crates depending on them, we can't throw an error here.
383 Target::Field | Target::Arm | Target::MacroDef => {
384 self.inline_attr_str_error_with_macro_def(hir_id, attr, "naked");
388 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
389 attr_span: attr.span,
397 /// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition.
398 fn check_cmse_nonsecure_entry(&self, attr: &Attribute, span: Span, target: Target) -> bool {
401 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
403 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
404 attr_span: attr.span,
412 /// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid.
413 fn check_track_caller(
422 _ if attrs.iter().any(|attr| attr.has_name(sym::naked)) => {
423 self.tcx.sess.emit_err(errors::NakedTrackedCaller { attr_span });
426 Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => true,
427 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
428 // `#[track_caller]` attribute with just a lint, because we previously
429 // erroneously allowed it and some crates used it accidentally, to to be compatible
430 // with crates depending on them, we can't throw an error here.
431 Target::Field | Target::Arm | Target::MacroDef => {
433 self.inline_attr_str_error_with_macro_def(hir_id, attr, "track_caller");
440 .emit_err(errors::TrackedCallerWrongLocation { attr_span, defn_span: span });
446 /// Checks if the `#[non_exhaustive]` attribute on an `item` is valid. Returns `true` if valid.
447 fn check_non_exhaustive(
455 Target::Struct | Target::Enum | Target::Variant => true,
456 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
457 // `#[non_exhaustive]` attribute with just a lint, because we previously
458 // erroneously allowed it and some crates used it accidentally, to to be compatible
459 // with crates depending on them, we can't throw an error here.
460 Target::Field | Target::Arm | Target::MacroDef => {
461 self.inline_attr_str_error_with_macro_def(hir_id, attr, "non_exhaustive");
465 self.tcx.sess.emit_err(errors::NonExhaustiveWrongLocation {
466 attr_span: attr.span,
474 /// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid.
475 fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
477 Target::Trait => true,
478 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
479 // `#[marker]` attribute with just a lint, because we previously
480 // erroneously allowed it and some crates used it accidentally, to to be compatible
481 // with crates depending on them, we can't throw an error here.
482 Target::Field | Target::Arm | Target::MacroDef => {
483 self.inline_attr_str_error_with_macro_def(hir_id, attr, "marker");
487 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
488 attr_span: attr.span,
496 /// Checks if the `#[rustc_must_implement_one_of]` attribute on a `target` is valid. Returns `true` if valid.
497 fn check_rustc_must_implement_one_of(
504 Target::Trait => true,
506 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
507 attr_span: attr.span,
515 /// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid.
516 fn check_target_feature(
525 | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
526 // FIXME: #[target_feature] was previously erroneously allowed on statements and some
527 // crates used this, so only emit a warning.
528 Target::Statement => {
529 self.tcx.emit_spanned_lint(
533 errors::TargetFeatureOnStatement,
537 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
538 // `#[target_feature]` attribute with just a lint, because we previously
539 // erroneously allowed it and some crates used it accidentally, to to be compatible
540 // with crates depending on them, we can't throw an error here.
541 Target::Field | Target::Arm | Target::MacroDef => {
542 self.inline_attr_str_error_with_macro_def(hir_id, attr, "target_feature");
546 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
547 attr_span: attr.span,
555 /// Checks if the `#[thread_local]` attribute on `item` is valid. Returns `true` if valid.
556 fn check_thread_local(&self, attr: &Attribute, span: Span, target: Target) -> bool {
558 Target::ForeignStatic | Target::Static => true,
560 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToStatic {
561 attr_span: attr.span,
569 fn doc_attr_str_error(&self, meta: &NestedMetaItem, attr_name: &str) {
570 self.tcx.sess.emit_err(errors::DocExpectStr { attr_span: meta.span(), attr_name });
573 fn check_doc_alias_value(
575 meta: &NestedMetaItem,
580 aliases: &mut FxHashMap<String, Span>,
583 let span = meta.name_value_literal_span().unwrap_or_else(|| meta.span());
585 &format!("`#[doc(alias{})]`", if is_list { "(\"...\")" } else { " = \"...\"" });
586 if doc_alias == kw::Empty {
587 tcx.sess.emit_err(errors::DocAliasEmpty { span, attr_str });
591 let doc_alias_str = doc_alias.as_str();
592 if let Some(c) = doc_alias_str
594 .find(|&c| c == '"' || c == '\'' || (c.is_whitespace() && c != ' '))
596 tcx.sess.emit_err(errors::DocAliasBadChar { span, attr_str, char_: c });
599 if doc_alias_str.starts_with(' ') || doc_alias_str.ends_with(' ') {
600 tcx.sess.emit_err(errors::DocAliasStartEnd { span, attr_str });
604 let span = meta.span();
605 if let Some(location) = match target {
607 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
608 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
609 if Target::from_item(containing_item) == Target::Impl {
610 Some("type alias in implementation block")
615 Target::AssocConst => {
616 let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
617 let containing_item = self.tcx.hir().expect_item(parent_hir_id);
618 // We can't link to trait impl's consts.
619 let err = "associated constant in trait implementation block";
620 match containing_item.kind {
621 ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) => Some(err),
625 // we check the validity of params elsewhere
626 Target::Param => return false,
632 | Target::Impl => Some(target.name()),
651 | Target::ForeignStatic
653 | Target::GenericParam(..)
654 | Target::MacroDef => None,
656 tcx.sess.emit_err(errors::DocAliasBadLocation { span, attr_str, location });
659 let item_name = self.tcx.hir().name(hir_id);
660 if item_name == doc_alias {
661 tcx.sess.emit_err(errors::DocAliasNotAnAlias { span, attr_str });
664 if let Err(entry) = aliases.try_insert(doc_alias_str.to_owned(), span) {
665 self.tcx.emit_spanned_lint(
669 errors::DocAliasDuplicated { first_defn: *entry.entry.get() },
677 meta: &NestedMetaItem,
680 aliases: &mut FxHashMap<String, Span>,
682 if let Some(values) = meta.meta_item_list() {
686 Some(l) => match l.kind {
687 LitKind::Str(s, _) => {
688 if !self.check_doc_alias_value(v, s, hir_id, target, true, aliases) {
695 .emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
700 self.tcx.sess.emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
706 } else if let Some(doc_alias) = meta.value_str() {
707 self.check_doc_alias_value(meta, doc_alias, hir_id, target, false, aliases)
709 self.tcx.sess.emit_err(errors::DocAliasMalformed { span: meta.span() });
714 fn check_doc_keyword(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
715 let doc_keyword = meta.value_str().unwrap_or(kw::Empty);
716 if doc_keyword == kw::Empty {
717 self.doc_attr_str_error(meta, "keyword");
720 match self.tcx.hir().find(hir_id).and_then(|node| match node {
721 hir::Node::Item(item) => Some(&item.kind),
724 Some(ItemKind::Mod(ref module)) => {
725 if !module.item_ids.is_empty() {
726 self.tcx.sess.emit_err(errors::DocKeywordEmptyMod { span: meta.span() });
731 self.tcx.sess.emit_err(errors::DocKeywordNotMod { span: meta.span() });
735 if !rustc_lexer::is_ident(doc_keyword.as_str()) {
736 self.tcx.sess.emit_err(errors::DocKeywordInvalidIdent {
737 span: meta.name_value_literal_span().unwrap_or_else(|| meta.span()),
745 fn check_doc_fake_variadic(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
746 match self.tcx.hir().find(hir_id).and_then(|node| match node {
747 hir::Node::Item(item) => Some(&item.kind),
750 Some(ItemKind::Impl(ref i)) => {
751 let is_valid = matches!(&i.self_ty.kind, hir::TyKind::Tup([_]))
752 || if let hir::TyKind::BareFn(bare_fn_ty) = &i.self_ty.kind {
753 bare_fn_ty.decl.inputs.len() == 1
758 self.tcx.sess.emit_err(errors::DocFakeVariadicNotValid { span: meta.span() });
763 self.tcx.sess.emit_err(errors::DocKeywordOnlyImpl { span: meta.span() });
770 /// Checks `#[doc(inline)]`/`#[doc(no_inline)]` attributes. Returns `true` if valid.
772 /// A doc inlining attribute is invalid if it is applied to a non-`use` item, or
773 /// if there are conflicting attributes for one item.
775 /// `specified_inline` is used to keep track of whether we have
776 /// already seen an inlining attribute for this item.
777 /// If so, `specified_inline` holds the value and the span of
778 /// the first `inline`/`no_inline` attribute.
782 meta: &NestedMetaItem,
785 specified_inline: &mut Option<(bool, Span)>,
787 if target == Target::Use || target == Target::ExternCrate {
788 let do_inline = meta.name_or_empty() == sym::inline;
789 if let Some((prev_inline, prev_span)) = *specified_inline {
790 if do_inline != prev_inline {
791 let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]);
792 spans.push_span_label(prev_span, fluent::passes::doc_inline_conflict_first);
793 spans.push_span_label(meta.span(), fluent::passes::doc_inline_conflict_second);
794 self.tcx.sess.emit_err(errors::DocKeywordConflict { spans });
799 *specified_inline = Some((do_inline, meta.span()));
803 self.tcx.emit_spanned_lint(
804 INVALID_DOC_ATTRIBUTES,
807 errors::DocInlineOnlyUse {
808 attr_span: meta.span(),
809 item_span: (attr.style == AttrStyle::Outer)
810 .then(|| self.tcx.hir().span(hir_id)),
817 /// Checks that an attribute is *not* used at the crate level. Returns `true` if valid.
818 fn check_attr_not_crate_level(
820 meta: &NestedMetaItem,
824 if CRATE_HIR_ID == hir_id {
825 self.tcx.sess.emit_err(errors::DocAttrNotCrateLevel { span: meta.span(), attr_name });
831 /// Checks that an attribute is used at the crate level. Returns `true` if valid.
832 fn check_attr_crate_level(
835 meta: &NestedMetaItem,
838 if hir_id != CRATE_HIR_ID {
839 self.tcx.struct_span_lint_hir(INVALID_DOC_ATTRIBUTES, hir_id, meta.span(), |lint| {
840 let mut err = lint.build(fluent::passes::attr_crate_level);
841 if attr.style == AttrStyle::Outer
842 && self.tcx.hir().get_parent_item(hir_id) == CRATE_DEF_ID
844 if let Ok(mut src) = self.tcx.sess.source_map().span_to_snippet(attr.span) {
846 err.span_suggestion_verbose(
848 fluent::passes::suggestion,
850 Applicability::MaybeIncorrect,
853 err.span_help(attr.span, fluent::passes::help);
856 err.note(fluent::passes::note).emit();
863 /// Checks that `doc(test(...))` attribute contains only valid attributes. Returns `true` if
865 fn check_test_attr(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
866 let mut is_valid = true;
867 if let Some(metas) = meta.meta_item_list() {
868 for i_meta in metas {
869 match i_meta.name_or_empty() {
870 sym::attr | sym::no_crate_inject => {}
872 self.tcx.emit_spanned_lint(
873 INVALID_DOC_ATTRIBUTES,
876 errors::DocTestUnknown {
877 path: rustc_ast_pretty::pprust::path_to_string(
878 &i_meta.meta_item().unwrap().path,
887 self.tcx.emit_spanned_lint(
888 INVALID_DOC_ATTRIBUTES,
891 errors::DocTestTakesList,
898 /// Runs various checks on `#[doc]` attributes. Returns `true` if valid.
900 /// `specified_inline` should be initialized to `None` and kept for the scope
901 /// of one item. Read the documentation of [`check_doc_inline`] for more information.
903 /// [`check_doc_inline`]: Self::check_doc_inline
909 specified_inline: &mut Option<(bool, Span)>,
910 aliases: &mut FxHashMap<String, Span>,
912 let mut is_valid = true;
914 if let Some(mi) = attr.meta() && let Some(list) = mi.meta_item_list() {
916 if let Some(i_meta) = meta.meta_item() {
917 match i_meta.name_or_empty() {
919 if !self.check_attr_not_crate_level(meta, hir_id, "alias")
920 || !self.check_doc_alias(meta, hir_id, target, aliases) =>
926 if !self.check_attr_not_crate_level(meta, hir_id, "keyword")
927 || !self.check_doc_keyword(meta, hir_id) =>
933 if !self.check_attr_not_crate_level(meta, hir_id, "fake_variadic")
934 || !self.check_doc_fake_variadic(meta, hir_id) =>
939 sym::html_favicon_url
941 | sym::html_playground_url
942 | sym::issue_tracker_base_url
944 | sym::html_no_source
946 if !self.check_attr_crate_level(attr, meta, hir_id) =>
951 sym::inline | sym::no_inline
952 if !self.check_doc_inline(
963 // no_default_passes: deprecated
964 // passes: deprecated
965 // plugins: removed, but rustdoc warns about it itself
970 | sym::html_favicon_url
972 | sym::html_no_source
973 | sym::html_playground_url
976 | sym::issue_tracker_base_url
979 | sym::no_default_passes
984 | sym::fake_variadic => {}
987 if !self.check_test_attr(meta, hir_id) {
993 if !self.tcx.features().rustdoc_internals {
994 self.tcx.emit_spanned_lint(
995 INVALID_DOC_ATTRIBUTES,
998 errors::DocPrimitive,
1004 let path = rustc_ast_pretty::pprust::path_to_string(&i_meta.path);
1005 if i_meta.has_name(sym::spotlight) {
1006 self.tcx.emit_spanned_lint(
1007 INVALID_DOC_ATTRIBUTES,
1010 errors::DocTestUnknownSpotlight {
1015 } else if i_meta.has_name(sym::include) &&
1016 let Some(value) = i_meta.value_str() {
1017 let applicability = if list.len() == 1 {
1018 Applicability::MachineApplicable
1020 Applicability::MaybeIncorrect
1022 // If there are multiple attributes, the suggestion would suggest
1023 // deleting all of them, which is incorrect.
1024 self.tcx.emit_spanned_lint(
1025 INVALID_DOC_ATTRIBUTES,
1028 errors::DocTestUnknownInclude {
1030 value: value.to_string(),
1031 inner: (attr.style == AttrStyle::Inner)
1034 sugg: (attr.meta().unwrap().span, applicability),
1038 self.tcx.emit_spanned_lint(
1039 INVALID_DOC_ATTRIBUTES,
1042 errors::DocTestUnknownAny { path }
1049 self.tcx.emit_spanned_lint(
1050 INVALID_DOC_ATTRIBUTES,
1063 /// Warns against some misuses of `#[pass_by_value]`
1064 fn check_pass_by_value(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1066 Target::Struct | Target::Enum | Target::TyAlias => true,
1068 self.tcx.sess.emit_err(errors::PassByValue { attr_span: attr.span, span });
1074 fn check_allow_incoherent_impl(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1076 Target::Method(MethodKind::Inherent) => true,
1078 self.tcx.sess.emit_err(errors::AllowIncoherentImpl { attr_span: attr.span, span });
1084 fn check_has_incoherent_inherent_impls(
1091 Target::Trait | Target::Struct | Target::Enum | Target::Union | Target::ForeignTy => {
1097 .emit_err(errors::HasIncoherentInherentImpl { attr_span: attr.span, span });
1103 /// Warns against some misuses of `#[must_use]`
1104 fn check_must_use(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
1105 let node = self.tcx.hir().get(hir_id);
1106 if let Some(kind) = node.fn_kind() && let rustc_hir::IsAsync::Async = kind.asyncness() {
1107 self.tcx.emit_spanned_lint(
1111 errors::MustUseAsync { span }
1123 // `impl Trait` in return position can trip
1124 // `unused_must_use` if `Trait` is marked as
1128 let article = match target {
1133 | Target::Expression
1135 | Target::AssocConst
1136 | Target::AssocTy => "an",
1140 self.tcx.emit_spanned_lint(
1144 errors::MustUseNoEffect { article, target },
1148 // For now, its always valid
1152 /// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid.
1153 fn check_must_not_suspend(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1155 Target::Struct | Target::Enum | Target::Union | Target::Trait => true,
1157 self.tcx.sess.emit_err(errors::MustNotSuspend { attr_span: attr.span, span });
1163 /// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid.
1164 fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1166 Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {}
1167 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1168 // `#[cold]` attribute with just a lint, because we previously
1169 // erroneously allowed it and some crates used it accidentally, to to be compatible
1170 // with crates depending on them, we can't throw an error here.
1171 Target::Field | Target::Arm | Target::MacroDef => {
1172 self.inline_attr_str_error_with_macro_def(hir_id, attr, "cold");
1175 // FIXME: #[cold] was previously allowed on non-functions and some crates used
1176 // this, so only emit a warning.
1177 self.tcx.emit_spanned_lint(
1181 errors::Cold { span },
1187 /// Checks if `#[link]` is applied to an item other than a foreign module.
1188 fn check_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1189 if target == Target::ForeignMod
1190 && let hir::Node::Item(item) = self.tcx.hir().get(hir_id)
1191 && let Item { kind: ItemKind::ForeignMod { abi, .. }, .. } = item
1192 && !matches!(abi, Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic)
1197 self.tcx.emit_spanned_lint(
1201 errors::Link { span: (target != Target::ForeignMod).then_some(span) },
1205 /// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
1206 fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1208 Target::ForeignFn | Target::ForeignStatic => {}
1209 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1210 // `#[link_name]` attribute with just a lint, because we previously
1211 // erroneously allowed it and some crates used it accidentally, to to be compatible
1212 // with crates depending on them, we can't throw an error here.
1213 Target::Field | Target::Arm | Target::MacroDef => {
1214 self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_name");
1217 // FIXME: #[cold] was previously allowed on non-functions/statics and some crates
1218 // used this, so only emit a warning.
1219 let attr_span = matches!(target, Target::ForeignMod).then_some(attr.span);
1220 if let Some(s) = attr.value_str() {
1221 self.tcx.emit_spanned_lint(
1225 errors::LinkName { span, attr_span, value: s.as_str() },
1228 self.tcx.emit_spanned_lint(
1232 errors::LinkName { span, attr_span, value: "..." },
1239 /// Checks if `#[no_link]` is applied to an `extern crate`. Returns `true` if valid.
1240 fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
1242 Target::ExternCrate => true,
1243 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1244 // `#[no_link]` attribute with just a lint, because we previously
1245 // erroneously allowed it and some crates used it accidentally, to to be compatible
1246 // with crates depending on them, we can't throw an error here.
1247 Target::Field | Target::Arm | Target::MacroDef => {
1248 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_link");
1252 self.tcx.sess.emit_err(errors::NoLink { attr_span: attr.span, span });
1258 fn is_impl_item(&self, hir_id: HirId) -> bool {
1259 matches!(self.tcx.hir().get(hir_id), hir::Node::ImplItem(..))
1262 /// Checks if `#[export_name]` is applied to a function or static. Returns `true` if valid.
1263 fn check_export_name(
1271 Target::Static | Target::Fn => true,
1272 Target::Method(..) if self.is_impl_item(hir_id) => true,
1273 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1274 // `#[export_name]` attribute with just a lint, because we previously
1275 // erroneously allowed it and some crates used it accidentally, to to be compatible
1276 // with crates depending on them, we can't throw an error here.
1277 Target::Field | Target::Arm | Target::MacroDef => {
1278 self.inline_attr_str_error_with_macro_def(hir_id, attr, "export_name");
1282 self.tcx.sess.emit_err(errors::ExportName { attr_span: attr.span, span });
1288 fn check_rustc_layout_scalar_valid_range(
1294 if target != Target::Struct {
1295 self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeNotStruct {
1296 attr_span: attr.span,
1302 let Some(list) = attr.meta_item_list() else {
1306 if matches!(&list[..], &[NestedMetaItem::Literal(Lit { kind: LitKind::Int(..), .. })]) {
1309 self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeArg { attr_span: attr.span });
1314 /// Checks if `#[rustc_legacy_const_generics]` is applied to a function and has a valid argument.
1315 fn check_rustc_legacy_const_generics(
1320 item: Option<ItemLike<'_>>,
1322 let is_function = matches!(target, Target::Fn);
1324 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
1325 attr_span: attr.span,
1331 let Some(list) = attr.meta_item_list() else {
1332 // The attribute form is validated on AST.
1336 let Some(ItemLike::Item(Item {
1337 kind: ItemKind::Fn(FnSig { decl, .. }, generics, _),
1340 bug!("should be a function item");
1343 for param in generics.params {
1345 hir::GenericParamKind::Const { .. } => {}
1347 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsOnly {
1348 attr_span: attr.span,
1349 param_span: param.span,
1356 if list.len() != generics.params.len() {
1357 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndex {
1358 attr_span: attr.span,
1359 generics_span: generics.span,
1364 let arg_count = decl.inputs.len() as u128 + generics.params.len() as u128;
1365 let mut invalid_args = vec![];
1367 if let Some(LitKind::Int(val, _)) = meta.literal().map(|lit| &lit.kind) {
1368 if *val >= arg_count {
1369 let span = meta.span();
1370 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexExceed {
1372 arg_count: arg_count as usize,
1377 invalid_args.push(meta.span());
1381 if !invalid_args.is_empty() {
1382 self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexNegative { invalid_args });
1389 /// Helper function for checking that the provided attribute is only applied to a function or
1391 fn check_applied_to_fn_or_method(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1392 let is_function = matches!(target, Target::Fn | Target::Method(..));
1394 self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
1395 attr_span: attr.span,
1404 /// Checks that the `#[rustc_lint_query_instability]` attribute is only applied to a function
1406 fn check_rustc_lint_query_instability(
1412 self.check_applied_to_fn_or_method(attr, span, target)
1415 /// Checks that the `#[rustc_lint_diagnostics]` attribute is only applied to a function or
1417 fn check_rustc_lint_diagnostics(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1418 self.check_applied_to_fn_or_method(attr, span, target)
1421 /// Checks that the `#[rustc_lint_opt_ty]` attribute is only applied to a struct.
1422 fn check_rustc_lint_opt_ty(&self, attr: &Attribute, span: Span, target: Target) -> bool {
1424 Target::Struct => true,
1426 self.tcx.sess.emit_err(errors::RustcLintOptTy { attr_span: attr.span, span });
1432 /// Checks that the `#[rustc_lint_opt_deny_field_access]` attribute is only applied to a field.
1433 fn check_rustc_lint_opt_deny_field_access(
1440 Target::Field => true,
1444 .emit_err(errors::RustcLintOptDenyFieldAccess { attr_span: attr.span, span });
1450 /// Checks that the dep-graph debugging attributes are only present when the query-dep-graph
1451 /// option is passed to the compiler.
1452 fn check_rustc_dirty_clean(&self, attr: &Attribute) -> bool {
1453 if self.tcx.sess.opts.unstable_opts.query_dep_graph {
1456 self.tcx.sess.emit_err(errors::RustcDirtyClean { span: attr.span });
1461 /// Checks if `#[link_section]` is applied to a function or static.
1462 fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1464 Target::Static | Target::Fn | Target::Method(..) => {}
1465 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1466 // `#[link_section]` attribute with just a lint, because we previously
1467 // erroneously allowed it and some crates used it accidentally, to to be compatible
1468 // with crates depending on them, we can't throw an error here.
1469 Target::Field | Target::Arm | Target::MacroDef => {
1470 self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_section");
1473 // FIXME: #[link_section] was previously allowed on non-functions/statics and some
1474 // crates used this, so only emit a warning.
1475 self.tcx.emit_spanned_lint(
1479 errors::LinkSection { span },
1485 /// Checks if `#[no_mangle]` is applied to a function or static.
1486 fn check_no_mangle(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
1488 Target::Static | Target::Fn => {}
1489 Target::Method(..) if self.is_impl_item(hir_id) => {}
1490 // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
1491 // `#[no_mangle]` attribute with just a lint, because we previously
1492 // erroneously allowed it and some crates used it accidentally, to to be compatible
1493 // with crates depending on them, we can't throw an error here.
1494 Target::Field | Target::Arm | Target::MacroDef => {
1495 self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_mangle");
1497 // FIXME: #[no_mangle] was previously allowed on non-functions/statics, this should be an error
1498 // The error should specify that the item that is wrong is specifically a *foreign* fn/static
1499 // otherwise the error seems odd
1500 Target::ForeignFn | Target::ForeignStatic => {
1501 let foreign_item_kind = match target {
1502 Target::ForeignFn => "function",
1503 Target::ForeignStatic => "static",
1504 _ => unreachable!(),
1506 self.tcx.emit_spanned_lint(
1510 errors::NoMangleForeign { span, attr_span: attr.span, foreign_item_kind },
1514 // FIXME: #[no_mangle] was previously allowed on non-functions/statics and some
1515 // crates used this, so only emit a warning.
1516 self.tcx.emit_spanned_lint(
1520 errors::NoMangle { span },
1526 /// Checks if the `#[repr]` attributes on `item` are valid.
1529 attrs: &[Attribute],
1532 item: Option<ItemLike<'_>>,
1535 // Extract the names of all repr hints, e.g., [foo, bar, align] for:
1538 // #[repr(bar, align(8))]
1540 let hints: Vec<_> = attrs
1542 .filter(|attr| attr.has_name(sym::repr))
1543 .filter_map(|attr| attr.meta_item_list())
1547 let mut int_reprs = 0;
1548 let mut is_c = false;
1549 let mut is_simd = false;
1550 let mut is_transparent = false;
1552 for hint in &hints {
1553 if !hint.is_meta_item() {
1554 self.tcx.sess.emit_err(errors::ReprIdent { span: hint.span() });
1558 let (article, allowed_targets) = match hint.name_or_empty() {
1562 Target::Struct | Target::Union | Target::Enum => continue,
1563 _ => ("a", "struct, enum, or union"),
1567 if let (Target::Fn, false) = (target, self.tcx.features().fn_align) {
1569 &self.tcx.sess.parse_sess,
1572 "`repr(align)` attributes on functions are unstable",
1578 Target::Struct | Target::Union | Target::Enum | Target::Fn => continue,
1579 _ => ("a", "struct, enum, function, or union"),
1583 if target != Target::Struct && target != Target::Union {
1584 ("a", "struct or union")
1591 if target != Target::Struct {
1597 sym::transparent => {
1598 is_transparent = true;
1600 Target::Struct | Target::Union | Target::Enum => continue,
1601 _ => ("a", "struct, enum, or union"),
1617 if target != Target::Enum {
1628 "unrecognized representation hint"
1641 &format!("attribute should be applied to {article} {allowed_targets}")
1643 .span_label(span, &format!("not {article} {allowed_targets}"))
1647 // Just point at all repr hints if there are any incompatibilities.
1648 // This is not ideal, but tracking precisely which ones are at fault is a huge hassle.
1649 let hint_spans = hints.iter().map(|hint| hint.span());
1651 // Error on repr(transparent, <anything else>).
1652 if is_transparent && hints.len() > 1 {
1653 let hint_spans: Vec<_> = hint_spans.clone().collect();
1658 "transparent {} cannot have other repr hints",
1663 // Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8)
1665 || (is_simd && is_c)
1668 && item.map_or(false, |item| {
1669 if let ItemLike::Item(item) = item {
1670 return is_c_like_enum(item);
1675 self.tcx.emit_spanned_lint(
1676 CONFLICTING_REPR_HINTS,
1678 hint_spans.collect::<Vec<Span>>(),
1679 errors::ReprConflicting,
1684 fn check_used(&self, attrs: &[Attribute], target: Target) {
1685 let mut used_linker_span = None;
1686 let mut used_compiler_span = None;
1687 for attr in attrs.iter().filter(|attr| attr.has_name(sym::used)) {
1688 if target != Target::Static {
1689 self.tcx.sess.emit_err(errors::UsedStatic { span: attr.span });
1691 let inner = attr.meta_item_list();
1692 match inner.as_deref() {
1693 Some([item]) if item.has_name(sym::linker) => {
1694 if used_linker_span.is_none() {
1695 used_linker_span = Some(attr.span);
1698 Some([item]) if item.has_name(sym::compiler) => {
1699 if used_compiler_span.is_none() {
1700 used_compiler_span = Some(attr.span);
1704 // This error case is handled in rustc_typeck::collect.
1707 // Default case (compiler) when arg isn't defined.
1708 if used_compiler_span.is_none() {
1709 used_compiler_span = Some(attr.span);
1714 if let (Some(linker_span), Some(compiler_span)) = (used_linker_span, used_compiler_span) {
1717 .emit_err(errors::UsedCompilerLinker { spans: vec![linker_span, compiler_span] });
1721 /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
1722 /// (Allows proc_macro functions)
1723 fn check_allow_internal_unstable(
1729 attrs: &[Attribute],
1731 debug!("Checking target: {:?}", target);
1735 if self.tcx.sess.is_proc_macro_attr(attr) {
1736 debug!("Is proc macro attr");
1740 debug!("Is not proc macro attr");
1743 Target::MacroDef => true,
1744 // FIXME(#80564): We permit struct fields and match arms to have an
1745 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
1746 // erroneously allowed it and some crates used it accidentally, to to be compatible
1747 // with crates depending on them, we can't throw an error here.
1748 Target::Field | Target::Arm => {
1749 self.inline_attr_str_error_without_macro_def(
1752 "allow_internal_unstable",
1759 .emit_err(errors::AllowInternalUnstable { attr_span: attr.span, span });
1765 /// Checks if the items on the `#[debugger_visualizer]` attribute are valid.
1766 fn check_debugger_visualizer(&self, attr: &Attribute, target: Target) -> bool {
1770 self.tcx.sess.emit_err(errors::DebugVisualizerPlacement { span: attr.span });
1775 let Some(hints) = attr.meta_item_list() else {
1776 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1780 let hint = match hints.len() {
1783 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1788 let Some(meta_item) = hint.meta_item() else {
1789 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
1793 let visualizer_path = match (meta_item.name_or_empty(), meta_item.value_str()) {
1794 (sym::natvis_file, Some(value)) => value,
1795 (sym::gdb_script_file, Some(value)) => value,
1797 self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: meta_item.span });
1803 match resolve_path(&self.tcx.sess.parse_sess, visualizer_path.as_str(), attr.span) {
1811 match std::fs::File::open(&file) {
1818 &format!("couldn't read {}: {}", file.display(), err),
1826 /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
1827 /// (Allows proc_macro functions)
1828 fn check_rustc_allow_const_fn_unstable(
1836 Target::Fn | Target::Method(_)
1837 if self.tcx.is_const_fn_raw(self.tcx.hir().local_def_id(hir_id).to_def_id()) =>
1841 // FIXME(#80564): We permit struct fields and match arms to have an
1842 // `#[allow_internal_unstable]` attribute with just a lint, because we previously
1843 // erroneously allowed it and some crates used it accidentally, to to be compatible
1844 // with crates depending on them, we can't throw an error here.
1845 Target::Field | Target::Arm | Target::MacroDef => {
1846 self.inline_attr_str_error_with_macro_def(hir_id, attr, "allow_internal_unstable");
1852 .emit_err(errors::RustcAllowConstFnUnstable { attr_span: attr.span, span });
1858 fn check_rustc_std_internal_symbol(
1865 Target::Fn | Target::Static => true,
1869 .emit_err(errors::RustcStdInternalSymbol { attr_span: attr.span, span });
1875 /// `#[const_trait]` only applies to traits.
1876 fn check_const_trait(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1878 Target::Trait => true,
1880 self.tcx.sess.emit_err(errors::ConstTrait { attr_span: attr.span });
1886 fn check_stability_promotable(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
1888 Target::Expression => {
1889 self.tcx.sess.emit_err(errors::StabilityPromotable { attr_span: attr.span });
1896 fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) {
1898 Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
1899 self.tcx.emit_spanned_lint(
1910 fn check_macro_use(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1911 let name = attr.name_or_empty();
1913 Target::ExternCrate | Target::Mod => {}
1915 self.tcx.emit_spanned_lint(
1919 errors::MacroUse { name },
1925 fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1926 if target != Target::MacroDef {
1927 self.tcx.emit_spanned_lint(UNUSED_ATTRIBUTES, hir_id, attr.span, errors::MacroExport);
1931 fn check_plugin_registrar(&self, hir_id: HirId, attr: &Attribute, target: Target) {
1932 if target != Target::Fn {
1933 self.tcx.emit_spanned_lint(
1937 errors::PluginRegistrar,
1942 fn check_unused_attribute(&self, hir_id: HirId, attr: &Attribute) {
1943 // Warn on useless empty attributes.
1944 let note = if matches!(
1945 attr.name_or_empty(),
1954 | sym::target_feature
1955 ) && attr.meta_item_list().map_or(false, |list| list.is_empty())
1957 errors::UnusedNote::EmptyList { name: attr.name_or_empty() }
1959 attr.name_or_empty(),
1960 sym::allow | sym::warn | sym::deny | sym::forbid | sym::expect
1961 ) && let Some(meta) = attr.meta_item_list()
1963 && let Some(item) = meta[0].meta_item()
1964 && let MetaItemKind::NameValue(_) = &item.kind
1965 && item.path == sym::reason
1967 errors::UnusedNote::NoLints { name: attr.name_or_empty() }
1968 } else if attr.name_or_empty() == sym::default_method_body_is_const {
1969 errors::UnusedNote::DefaultMethodBodyConst
1974 self.tcx.emit_spanned_lint(
1978 errors::Unused { attr_span: attr.span, note },
1983 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
1984 type NestedFilter = nested_filter::OnlyBodies;
1986 fn nested_visit_map(&mut self) -> Self::Map {
1990 fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
1991 // Historically we've run more checks on non-exported than exported macros,
1992 // so this lets us continue to run them while maintaining backwards compatibility.
1993 // In the long run, the checks should be harmonized.
1994 if let ItemKind::Macro(ref macro_def, _) = item.kind {
1995 let def_id = item.def_id.to_def_id();
1996 if macro_def.macro_rules && !self.tcx.has_attr(def_id, sym::macro_export) {
1997 check_non_exported_macro_for_invalid_attrs(self.tcx, item);
2001 let target = Target::from_item(item);
2002 self.check_attributes(item.hir_id(), item.span, target, Some(ItemLike::Item(item)));
2003 intravisit::walk_item(self, item)
2006 fn visit_generic_param(&mut self, generic_param: &'tcx hir::GenericParam<'tcx>) {
2007 let target = Target::from_generic_param(generic_param);
2008 self.check_attributes(generic_param.hir_id, generic_param.span, target, None);
2009 intravisit::walk_generic_param(self, generic_param)
2012 fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>) {
2013 let target = Target::from_trait_item(trait_item);
2014 self.check_attributes(trait_item.hir_id(), trait_item.span, target, None);
2015 intravisit::walk_trait_item(self, trait_item)
2018 fn visit_field_def(&mut self, struct_field: &'tcx hir::FieldDef<'tcx>) {
2019 self.check_attributes(struct_field.hir_id, struct_field.span, Target::Field, None);
2020 intravisit::walk_field_def(self, struct_field);
2023 fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
2024 self.check_attributes(arm.hir_id, arm.span, Target::Arm, None);
2025 intravisit::walk_arm(self, arm);
2028 fn visit_foreign_item(&mut self, f_item: &'tcx ForeignItem<'tcx>) {
2029 let target = Target::from_foreign_item(f_item);
2030 self.check_attributes(f_item.hir_id(), f_item.span, target, Some(ItemLike::ForeignItem));
2031 intravisit::walk_foreign_item(self, f_item)
2034 fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
2035 let target = target_from_impl_item(self.tcx, impl_item);
2036 self.check_attributes(impl_item.hir_id(), impl_item.span, target, None);
2037 intravisit::walk_impl_item(self, impl_item)
2040 fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
2041 // When checking statements ignore expressions, they will be checked later.
2042 if let hir::StmtKind::Local(ref l) = stmt.kind {
2043 self.check_attributes(l.hir_id, stmt.span, Target::Statement, None);
2045 intravisit::walk_stmt(self, stmt)
2048 fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
2049 let target = match expr.kind {
2050 hir::ExprKind::Closure { .. } => Target::Closure,
2051 _ => Target::Expression,
2054 self.check_attributes(expr.hir_id, expr.span, target, None);
2055 intravisit::walk_expr(self, expr)
2060 variant: &'tcx hir::Variant<'tcx>,
2061 generics: &'tcx hir::Generics<'tcx>,
2064 self.check_attributes(variant.id, variant.span, Target::Variant, None);
2065 intravisit::walk_variant(self, variant, generics, item_id)
2068 fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
2069 self.check_attributes(param.hir_id, param.span, Target::Param, None);
2071 intravisit::walk_param(self, param);
2075 fn is_c_like_enum(item: &Item<'_>) -> bool {
2076 if let ItemKind::Enum(ref def, _) = item.kind {
2077 for variant in def.variants {
2078 match variant.data {
2079 hir::VariantData::Unit(..) => { /* continue */ }
2089 // FIXME: Fix "Cannot determine resolution" error and remove built-in macros
2091 fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
2092 // Check for builtin attributes at the crate level
2093 // which were unsuccessfully resolved due to cannot determine
2094 // resolution for the attribute macro error.
2095 const ATTRS_TO_CHECK: &[Symbol] = &[
2099 sym::automatically_derived,
2105 sym::global_allocator,
2110 // This function should only be called with crate attributes
2111 // which are inner attributes always but lets check to make sure
2112 if attr.style == AttrStyle::Inner {
2113 for attr_to_check in ATTRS_TO_CHECK {
2114 if attr.has_name(*attr_to_check) {
2115 let mut err = tcx.sess.struct_span_err(
2118 "`{}` attribute cannot be used at crate level",
2119 attr_to_check.to_ident_string()
2122 // Only emit an error with a suggestion if we can create a
2123 // string out of the attribute span
2124 if let Ok(src) = tcx.sess.source_map().span_to_snippet(attr.span) {
2125 let replacement = src.replace("#!", "#");
2126 err.span_suggestion_verbose(
2128 "perhaps you meant to use an outer attribute",
2130 rustc_errors::Applicability::MachineApplicable,
2140 fn check_non_exported_macro_for_invalid_attrs(tcx: TyCtxt<'_>, item: &Item<'_>) {
2141 let attrs = tcx.hir().attrs(item.hir_id());
2144 if attr.has_name(sym::inline) {
2145 tcx.sess.emit_err(errors::NonExportedMacroInvalidAttrs { attr_span: attr.span });
2150 fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
2151 let check_attr_visitor = &mut CheckAttrVisitor { tcx };
2152 tcx.hir().visit_item_likes_in_module(module_def_id, check_attr_visitor);
2153 if module_def_id.is_top_level_module() {
2154 check_attr_visitor.check_attributes(CRATE_HIR_ID, DUMMY_SP, Target::Mod, None);
2155 check_invalid_crate_level_attr(tcx, tcx.hir().krate_attrs());
2159 pub(crate) fn provide(providers: &mut Providers) {
2160 *providers = Providers { check_mod_attrs, ..*providers };
2163 fn check_duplicates(
2167 duplicates: AttributeDuplicates,
2168 seen: &mut FxHashMap<Symbol, Span>,
2170 use AttributeDuplicates::*;
2171 if matches!(duplicates, WarnFollowingWordOnly) && !attr.is_word() {
2176 WarnFollowing | FutureWarnFollowing | WarnFollowingWordOnly | FutureWarnPreceding => {
2177 match seen.entry(attr.name_or_empty()) {
2178 Entry::Occupied(mut entry) => {
2179 let (this, other) = if matches!(duplicates, FutureWarnPreceding) {
2180 let to_remove = entry.insert(attr.span);
2181 (to_remove, attr.span)
2183 (attr.span, *entry.get())
2185 tcx.emit_spanned_lint(
2189 errors::UnusedDuplicate {
2194 FutureWarnFollowing | FutureWarnPreceding
2200 Entry::Vacant(entry) => {
2201 entry.insert(attr.span);
2205 ErrorFollowing | ErrorPreceding => match seen.entry(attr.name_or_empty()) {
2206 Entry::Occupied(mut entry) => {
2207 let (this, other) = if matches!(duplicates, ErrorPreceding) {
2208 let to_remove = entry.insert(attr.span);
2209 (to_remove, attr.span)
2211 (attr.span, *entry.get())
2213 tcx.sess.emit_err(errors::UnusedMultiple {
2216 name: attr.name_or_empty(),
2219 Entry::Vacant(entry) => {
2220 entry.insert(attr.span);