| //! This module implements some validity checks for attributes. |
| //! In particular it verifies that `#[inline]` and `#[repr]` attributes are |
| //! attached to items that actually support them and if there are |
| //! conflicts between multiple such attributes attached to the same |
| //! item. |
| |
| use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, NestedMetaItem}; |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_errors::{pluralize, struct_span_err, Applicability}; |
| use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP}; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID}; |
| use rustc_hir::intravisit::{self, Visitor}; |
| use rustc_hir::{self, FnSig, ForeignItem, HirId, Item, ItemKind, TraitItem, CRATE_HIR_ID}; |
| use rustc_hir::{MethodKind, Target}; |
| use rustc_middle::hir::nested_filter; |
| use rustc_middle::ty::query::Providers; |
| use rustc_middle::ty::TyCtxt; |
| use rustc_session::lint::builtin::{ |
| CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, UNUSED_ATTRIBUTES, |
| }; |
| use rustc_session::parse::feature_err; |
| use rustc_span::symbol::{sym, Symbol}; |
| use rustc_span::{MultiSpan, Span, DUMMY_SP}; |
| use std::collections::hash_map::Entry; |
| |
| pub(crate) fn target_from_impl_item<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| impl_item: &hir::ImplItem<'_>, |
| ) -> Target { |
| match impl_item.kind { |
| hir::ImplItemKind::Const(..) => Target::AssocConst, |
| hir::ImplItemKind::Fn(..) => { |
| let parent_hir_id = tcx.hir().get_parent_item(impl_item.hir_id()); |
| let containing_item = tcx.hir().expect_item(parent_hir_id); |
| let containing_impl_is_for_trait = match &containing_item.kind { |
| hir::ItemKind::Impl(impl_) => impl_.of_trait.is_some(), |
| _ => bug!("parent of an ImplItem must be an Impl"), |
| }; |
| if containing_impl_is_for_trait { |
| Target::Method(MethodKind::Trait { body: true }) |
| } else { |
| Target::Method(MethodKind::Inherent) |
| } |
| } |
| hir::ImplItemKind::TyAlias(..) => Target::AssocTy, |
| } |
| } |
| |
| #[derive(Clone, Copy)] |
| enum ItemLike<'tcx> { |
| Item(&'tcx Item<'tcx>), |
| ForeignItem(&'tcx ForeignItem<'tcx>), |
| } |
| |
| struct CheckAttrVisitor<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| } |
| |
| impl CheckAttrVisitor<'_> { |
| /// Checks any attribute. |
| fn check_attributes( |
| &self, |
| hir_id: HirId, |
| span: Span, |
| target: Target, |
| item: Option<ItemLike<'_>>, |
| ) { |
| let mut doc_aliases = FxHashMap::default(); |
| let mut is_valid = true; |
| let mut specified_inline = None; |
| let mut seen = FxHashMap::default(); |
| let attrs = self.tcx.hir().attrs(hir_id); |
| for attr in attrs { |
| let attr_is_valid = match attr.name_or_empty() { |
| sym::inline => self.check_inline(hir_id, attr, span, target), |
| sym::non_exhaustive => self.check_non_exhaustive(hir_id, attr, span, target), |
| sym::marker => self.check_marker(hir_id, attr, span, target), |
| sym::rustc_must_implement_one_of => { |
| self.check_rustc_must_implement_one_of(attr, span, target) |
| } |
| sym::target_feature => self.check_target_feature(hir_id, attr, span, target), |
| sym::track_caller => { |
| self.check_track_caller(hir_id, attr.span, attrs, span, target) |
| } |
| sym::doc => self.check_doc_attrs( |
| attr, |
| hir_id, |
| target, |
| &mut specified_inline, |
| &mut doc_aliases, |
| ), |
| sym::no_link => self.check_no_link(hir_id, &attr, span, target), |
| sym::export_name => self.check_export_name(hir_id, &attr, span, target), |
| sym::rustc_layout_scalar_valid_range_start |
| | sym::rustc_layout_scalar_valid_range_end => { |
| self.check_rustc_layout_scalar_valid_range(&attr, span, target) |
| } |
| sym::allow_internal_unstable => { |
| self.check_allow_internal_unstable(hir_id, &attr, span, target, &attrs) |
| } |
| sym::rustc_allow_const_fn_unstable => { |
| self.check_rustc_allow_const_fn_unstable(hir_id, &attr, span, target) |
| } |
| sym::naked => self.check_naked(hir_id, attr, span, target), |
| sym::rustc_legacy_const_generics => { |
| self.check_rustc_legacy_const_generics(&attr, span, target, item) |
| } |
| sym::rustc_lint_query_instability => { |
| self.check_rustc_lint_query_instability(&attr, span, target) |
| } |
| sym::rustc_clean |
| | sym::rustc_dirty |
| | sym::rustc_if_this_changed |
| | sym::rustc_then_this_would_need => self.check_rustc_dirty_clean(&attr), |
| sym::cmse_nonsecure_entry => self.check_cmse_nonsecure_entry(attr, span, target), |
| sym::default_method_body_is_const => { |
| self.check_default_method_body_is_const(attr, span, target) |
| } |
| sym::must_not_suspend => self.check_must_not_suspend(&attr, span, target), |
| sym::must_use => self.check_must_use(hir_id, &attr, span, target), |
| sym::rustc_pass_by_value => self.check_pass_by_value(&attr, span, target), |
| sym::rustc_const_unstable |
| | sym::rustc_const_stable |
| | sym::unstable |
| | sym::stable |
| | sym::rustc_promotable => self.check_stability_promotable(&attr, span, target), |
| _ => true, |
| }; |
| is_valid &= attr_is_valid; |
| |
| // lint-only checks |
| match attr.name_or_empty() { |
| sym::cold => self.check_cold(hir_id, attr, span, target), |
| sym::link => self.check_link(hir_id, attr, span, target), |
| sym::link_name => self.check_link_name(hir_id, attr, span, target), |
| sym::link_section => self.check_link_section(hir_id, attr, span, target), |
| sym::no_mangle => self.check_no_mangle(hir_id, attr, span, target), |
| sym::deprecated | sym::rustc_deprecated => { |
| self.check_deprecated(hir_id, attr, span, target) |
| } |
| sym::macro_use | sym::macro_escape => self.check_macro_use(hir_id, attr, target), |
| sym::path => self.check_generic_attr(hir_id, attr, target, &[Target::Mod]), |
| sym::plugin_registrar => self.check_plugin_registrar(hir_id, attr, target), |
| sym::macro_export => self.check_macro_export(hir_id, attr, target), |
| sym::ignore | sym::should_panic | sym::proc_macro_derive => { |
| self.check_generic_attr(hir_id, attr, target, &[Target::Fn]) |
| } |
| sym::automatically_derived => { |
| self.check_generic_attr(hir_id, attr, target, &[Target::Impl]) |
| } |
| sym::no_implicit_prelude => { |
| self.check_generic_attr(hir_id, attr, target, &[Target::Mod]) |
| } |
| _ => {} |
| } |
| |
| let builtin = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name)); |
| |
| if hir_id != CRATE_HIR_ID { |
| if let Some(BuiltinAttribute { type_: AttributeType::CrateLevel, .. }) = |
| attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name)) |
| { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| let msg = match attr.style { |
| ast::AttrStyle::Outer => { |
| "crate-level attribute should be an inner attribute: add an exclamation \ |
| mark: `#![foo]`" |
| } |
| ast::AttrStyle::Inner => "crate-level attribute should be in the root module", |
| }; |
| lint.build(msg).emit() |
| }); |
| } |
| } |
| |
| if let Some(BuiltinAttribute { duplicates, .. }) = builtin { |
| check_duplicates(self.tcx, attr, hir_id, *duplicates, &mut seen); |
| } |
| |
| // Warn on useless empty attributes. |
| if matches!( |
| attr.name_or_empty(), |
| sym::macro_use |
| | sym::allow |
| | sym::warn |
| | sym::deny |
| | sym::forbid |
| | sym::feature |
| | sym::repr |
| | sym::target_feature |
| ) && attr.meta_item_list().map_or(false, |list| list.is_empty()) |
| { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("unused attribute") |
| .span_suggestion( |
| attr.span, |
| "remove this attribute", |
| String::new(), |
| Applicability::MachineApplicable, |
| ) |
| .note(&format!( |
| "attribute `{}` with an empty list has no effect", |
| attr.name_or_empty() |
| )) |
| .emit(); |
| }); |
| } |
| } |
| |
| if !is_valid { |
| return; |
| } |
| |
| if matches!(target, Target::Closure | Target::Fn | Target::Method(_) | Target::ForeignFn) { |
| self.tcx.ensure().codegen_fn_attrs(self.tcx.hir().local_def_id(hir_id)); |
| } |
| |
| self.check_repr(attrs, span, target, item, hir_id); |
| self.check_used(attrs, target); |
| } |
| |
| fn inline_attr_str_error_with_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build(&format!( |
| "`#[{}]` is ignored on struct fields, match arms and macro defs", |
| sym, |
| )) |
| .warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ) |
| .note( |
| "see issue #80564 <https://github.com/rust-lang/rust/issues/80564> \ |
| for more information", |
| ) |
| .emit(); |
| }); |
| } |
| |
| fn inline_attr_str_error_without_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build(&format!("`#[{}]` is ignored on struct fields and match arms", sym)) |
| .warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ) |
| .note( |
| "see issue #80564 <https://github.com/rust-lang/rust/issues/80564> \ |
| for more information", |
| ) |
| .emit(); |
| }); |
| } |
| |
| /// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid. |
| fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool { |
| match target { |
| Target::Fn |
| | Target::Closure |
| | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true, |
| Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("`#[inline]` is ignored on function prototypes").emit() |
| }); |
| true |
| } |
| // FIXME(#65833): We permit associated consts to have an `#[inline]` attribute with |
| // just a lint, because we previously erroneously allowed it and some crates used it |
| // accidentally, to to be compatible with crates depending on them, we can't throw an |
| // error here. |
| Target::AssocConst => { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("`#[inline]` is ignored on constants") |
| .warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ) |
| .note( |
| "see issue #65833 <https://github.com/rust-lang/rust/issues/65833> \ |
| for more information", |
| ) |
| .emit(); |
| }); |
| true |
| } |
| // FIXME(#80564): Same for fields, arms, and macro defs |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "inline"); |
| true |
| } |
| _ => { |
| struct_span_err!( |
| self.tcx.sess, |
| attr.span, |
| E0518, |
| "attribute should be applied to function or closure", |
| ) |
| .span_label(span, "not a function or closure") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| fn check_generic_attr( |
| &self, |
| hir_id: HirId, |
| attr: &Attribute, |
| target: Target, |
| allowed_targets: &[Target], |
| ) { |
| if !allowed_targets.iter().any(|t| t == &target) { |
| let name = attr.name_or_empty(); |
| let mut i = allowed_targets.iter(); |
| // Pluralize |
| let b = i.next().map_or_else(String::new, |t| t.to_string() + "s"); |
| let supported_names = i.enumerate().fold(b, |mut b, (i, allowed_target)| { |
| if allowed_targets.len() > 2 && i == allowed_targets.len() - 2 { |
| b.push_str(", and "); |
| } else if allowed_targets.len() == 2 && i == allowed_targets.len() - 2 { |
| b.push_str(" and "); |
| } else { |
| b.push_str(", "); |
| } |
| // Pluralize |
| b.push_str(&(allowed_target.to_string() + "s")); |
| b |
| }); |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build(&format!("`#[{name}]` only has an effect on {}", supported_names)) |
| .emit(); |
| }); |
| } |
| } |
| |
| /// Checks if `#[naked]` is applied to a function definition. |
| fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool { |
| match target { |
| Target::Fn |
| | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true, |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[allow_internal_unstable]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "naked"); |
| true |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| attr.span, |
| "attribute should be applied to a function definition", |
| ) |
| .span_label(span, "not a function definition") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition. |
| fn check_cmse_nonsecure_entry(&self, attr: &Attribute, span: Span, target: Target) -> bool { |
| match target { |
| Target::Fn |
| | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true, |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| attr.span, |
| "attribute should be applied to a function definition", |
| ) |
| .span_label(span, "not a function definition") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid. |
| fn check_track_caller( |
| &self, |
| hir_id: HirId, |
| attr_span: Span, |
| attrs: &[Attribute], |
| span: Span, |
| target: Target, |
| ) -> bool { |
| match target { |
| _ if attrs.iter().any(|attr| attr.has_name(sym::naked)) => { |
| struct_span_err!( |
| self.tcx.sess, |
| attr_span, |
| E0736, |
| "cannot use `#[track_caller]` with `#[naked]`", |
| ) |
| .emit(); |
| false |
| } |
| Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => true, |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[track_caller]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| for attr in attrs { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "track_caller"); |
| } |
| true |
| } |
| _ => { |
| struct_span_err!( |
| self.tcx.sess, |
| attr_span, |
| E0739, |
| "attribute should be applied to function" |
| ) |
| .span_label(span, "not a function") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Checks if the `#[non_exhaustive]` attribute on an `item` is valid. Returns `true` if valid. |
| fn check_non_exhaustive( |
| &self, |
| hir_id: HirId, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| ) -> bool { |
| match target { |
| Target::Struct | Target::Enum | Target::Variant => true, |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[non_exhaustive]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "non_exhaustive"); |
| true |
| } |
| _ => { |
| struct_span_err!( |
| self.tcx.sess, |
| attr.span, |
| E0701, |
| "attribute can only be applied to a struct or enum" |
| ) |
| .span_label(span, "not a struct or enum") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid. |
| fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool { |
| match target { |
| Target::Trait => true, |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[marker]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "marker"); |
| true |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute can only be applied to a trait") |
| .span_label(span, "not a trait") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Checks if the `#[rustc_must_implement_one_of]` attribute on a `target` is valid. Returns `true` if valid. |
| fn check_rustc_must_implement_one_of( |
| &self, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| ) -> bool { |
| match target { |
| Target::Trait => true, |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute can only be applied to a trait") |
| .span_label(span, "not a trait") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid. |
| fn check_target_feature( |
| &self, |
| hir_id: HirId, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| ) -> bool { |
| match target { |
| Target::Fn |
| | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true, |
| // FIXME: #[target_feature] was previously erroneously allowed on statements and some |
| // crates used this, so only emit a warning. |
| Target::Statement => { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("attribute should be applied to a function") |
| .warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ) |
| .span_label(span, "not a function") |
| .emit(); |
| }); |
| true |
| } |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[target_feature]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "target_feature"); |
| true |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute should be applied to a function") |
| .span_label(span, "not a function") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| fn doc_attr_str_error(&self, meta: &NestedMetaItem, attr_name: &str) { |
| self.tcx |
| .sess |
| .struct_span_err( |
| meta.span(), |
| &format!("doc {0} attribute expects a string: #[doc({0} = \"a\")]", attr_name), |
| ) |
| .emit(); |
| } |
| |
| fn check_doc_alias_value( |
| &self, |
| meta: &NestedMetaItem, |
| doc_alias: &str, |
| hir_id: HirId, |
| target: Target, |
| is_list: bool, |
| aliases: &mut FxHashMap<String, Span>, |
| ) -> bool { |
| let tcx = self.tcx; |
| let err_fn = move |span: Span, msg: &str| { |
| tcx.sess.span_err( |
| span, |
| &format!( |
| "`#[doc(alias{})]` {}", |
| if is_list { "(\"...\")" } else { " = \"...\"" }, |
| msg, |
| ), |
| ); |
| false |
| }; |
| if doc_alias.is_empty() { |
| return err_fn( |
| meta.name_value_literal_span().unwrap_or_else(|| meta.span()), |
| "attribute cannot have empty value", |
| ); |
| } |
| if let Some(c) = |
| doc_alias.chars().find(|&c| c == '"' || c == '\'' || (c.is_whitespace() && c != ' ')) |
| { |
| self.tcx.sess.span_err( |
| meta.name_value_literal_span().unwrap_or_else(|| meta.span()), |
| &format!( |
| "{:?} character isn't allowed in `#[doc(alias{})]`", |
| c, |
| if is_list { "(\"...\")" } else { " = \"...\"" }, |
| ), |
| ); |
| return false; |
| } |
| if doc_alias.starts_with(' ') || doc_alias.ends_with(' ') { |
| return err_fn( |
| meta.name_value_literal_span().unwrap_or_else(|| meta.span()), |
| "cannot start or end with ' '", |
| ); |
| } |
| if let Some(err) = match target { |
| Target::Impl => Some("implementation block"), |
| Target::ForeignMod => Some("extern block"), |
| Target::AssocTy => { |
| let parent_hir_id = self.tcx.hir().get_parent_item(hir_id); |
| let containing_item = self.tcx.hir().expect_item(parent_hir_id); |
| if Target::from_item(containing_item) == Target::Impl { |
| Some("type alias in implementation block") |
| } else { |
| None |
| } |
| } |
| Target::AssocConst => { |
| let parent_hir_id = self.tcx.hir().get_parent_item(hir_id); |
| let containing_item = self.tcx.hir().expect_item(parent_hir_id); |
| // We can't link to trait impl's consts. |
| let err = "associated constant in trait implementation block"; |
| match containing_item.kind { |
| ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) => Some(err), |
| _ => None, |
| } |
| } |
| // we check the validity of params elsewhere |
| Target::Param => return false, |
| _ => None, |
| } { |
| return err_fn(meta.span(), &format!("isn't allowed on {}", err)); |
| } |
| let item_name = self.tcx.hir().name(hir_id); |
| if item_name.as_str() == doc_alias { |
| return err_fn(meta.span(), "is the same as the item's name"); |
| } |
| let span = meta.span(); |
| if let Err(entry) = aliases.try_insert(doc_alias.to_owned(), span) { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, span, |lint| { |
| lint.build("doc alias is duplicated") |
| .span_label(*entry.entry.get(), "first defined here") |
| .emit(); |
| }); |
| } |
| true |
| } |
| |
| fn check_doc_alias( |
| &self, |
| meta: &NestedMetaItem, |
| hir_id: HirId, |
| target: Target, |
| aliases: &mut FxHashMap<String, Span>, |
| ) -> bool { |
| if let Some(values) = meta.meta_item_list() { |
| let mut errors = 0; |
| for v in values { |
| match v.literal() { |
| Some(l) => match l.kind { |
| LitKind::Str(s, _) => { |
| if !self.check_doc_alias_value( |
| v, |
| s.as_str(), |
| hir_id, |
| target, |
| true, |
| aliases, |
| ) { |
| errors += 1; |
| } |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| v.span(), |
| "`#[doc(alias(\"a\"))]` expects string literals", |
| ) |
| .emit(); |
| errors += 1; |
| } |
| }, |
| None => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| v.span(), |
| "`#[doc(alias(\"a\"))]` expects string literals", |
| ) |
| .emit(); |
| errors += 1; |
| } |
| } |
| } |
| errors == 0 |
| } else if let Some(doc_alias) = meta.value_str().map(|s| s.to_string()) { |
| self.check_doc_alias_value(meta, &doc_alias, hir_id, target, false, aliases) |
| } else { |
| self.tcx |
| .sess |
| .struct_span_err( |
| meta.span(), |
| "doc alias attribute expects a string `#[doc(alias = \"a\")]` or a list of \ |
| strings `#[doc(alias(\"a\", \"b\"))]`", |
| ) |
| .emit(); |
| false |
| } |
| } |
| |
| fn check_doc_keyword(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool { |
| let doc_keyword = meta.value_str().map(|s| s.to_string()).unwrap_or_else(String::new); |
| if doc_keyword.is_empty() { |
| self.doc_attr_str_error(meta, "keyword"); |
| return false; |
| } |
| match self.tcx.hir().find(hir_id).and_then(|node| match node { |
| hir::Node::Item(item) => Some(&item.kind), |
| _ => None, |
| }) { |
| Some(ItemKind::Mod(ref module)) => { |
| if !module.item_ids.is_empty() { |
| self.tcx |
| .sess |
| .struct_span_err( |
| meta.span(), |
| "`#[doc(keyword = \"...\")]` can only be used on empty modules", |
| ) |
| .emit(); |
| return false; |
| } |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| meta.span(), |
| "`#[doc(keyword = \"...\")]` can only be used on modules", |
| ) |
| .emit(); |
| return false; |
| } |
| } |
| if !rustc_lexer::is_ident(&doc_keyword) { |
| self.tcx |
| .sess |
| .struct_span_err( |
| meta.name_value_literal_span().unwrap_or_else(|| meta.span()), |
| &format!("`{}` is not a valid identifier", doc_keyword), |
| ) |
| .emit(); |
| return false; |
| } |
| true |
| } |
| |
| /// Checks `#[doc(inline)]`/`#[doc(no_inline)]` attributes. Returns `true` if valid. |
| /// |
| /// A doc inlining attribute is invalid if it is applied to a non-`use` item, or |
| /// if there are conflicting attributes for one item. |
| /// |
| /// `specified_inline` is used to keep track of whether we have |
| /// already seen an inlining attribute for this item. |
| /// If so, `specified_inline` holds the value and the span of |
| /// the first `inline`/`no_inline` attribute. |
| fn check_doc_inline( |
| &self, |
| attr: &Attribute, |
| meta: &NestedMetaItem, |
| hir_id: HirId, |
| target: Target, |
| specified_inline: &mut Option<(bool, Span)>, |
| ) -> bool { |
| if target == Target::Use || target == Target::ExternCrate { |
| let do_inline = meta.name_or_empty() == sym::inline; |
| if let Some((prev_inline, prev_span)) = *specified_inline { |
| if do_inline != prev_inline { |
| let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]); |
| spans.push_span_label(prev_span, String::from("this attribute...")); |
| spans.push_span_label( |
| meta.span(), |
| String::from("...conflicts with this attribute"), |
| ); |
| self.tcx |
| .sess |
| .struct_span_err(spans, "conflicting doc inlining attributes") |
| .help("remove one of the conflicting attributes") |
| .emit(); |
| return false; |
| } |
| true |
| } else { |
| *specified_inline = Some((do_inline, meta.span())); |
| true |
| } |
| } else { |
| self.tcx.struct_span_lint_hir( |
| INVALID_DOC_ATTRIBUTES, |
| hir_id, |
| meta.span(), |
| |lint| { |
| let mut err = lint.build( |
| "this attribute can only be applied to a `use` item", |
| ); |
| err.span_label(meta.span(), "only applicable on `use` items"); |
| if attr.style == AttrStyle::Outer { |
| err.span_label( |
| self.tcx.hir().span(hir_id), |
| "not a `use` item", |
| ); |
| } |
| err.note("read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#inline-and-no_inline for more information") |
| .emit(); |
| }, |
| ); |
| false |
| } |
| } |
| |
| /// Checks that an attribute is *not* used at the crate level. Returns `true` if valid. |
| fn check_attr_not_crate_level( |
| &self, |
| meta: &NestedMetaItem, |
| hir_id: HirId, |
| attr_name: &str, |
| ) -> bool { |
| if CRATE_HIR_ID == hir_id { |
| self.tcx |
| .sess |
| .struct_span_err( |
| meta.span(), |
| &format!( |
| "`#![doc({} = \"...\")]` isn't allowed as a crate-level attribute", |
| attr_name, |
| ), |
| ) |
| .emit(); |
| return false; |
| } |
| true |
| } |
| |
| /// Checks that an attribute is used at the crate level. Returns `true` if valid. |
| fn check_attr_crate_level( |
| &self, |
| attr: &Attribute, |
| meta: &NestedMetaItem, |
| hir_id: HirId, |
| ) -> bool { |
| if hir_id != CRATE_HIR_ID { |
| self.tcx.struct_span_lint_hir( |
| INVALID_DOC_ATTRIBUTES, |
| hir_id, |
| meta.span(), |
| |lint| { |
| let mut err = lint.build( |
| "this attribute can only be applied at the crate level", |
| ); |
| if attr.style == AttrStyle::Outer && self.tcx.hir().get_parent_item(hir_id) == CRATE_DEF_ID { |
| if let Ok(mut src) = |
| self.tcx.sess.source_map().span_to_snippet(attr.span) |
| { |
| src.insert(1, '!'); |
| err.span_suggestion_verbose( |
| attr.span, |
| "to apply to the crate, use an inner attribute", |
| src, |
| Applicability::MaybeIncorrect, |
| ); |
| } else { |
| err.span_help( |
| attr.span, |
| "to apply to the crate, use an inner attribute", |
| ); |
| } |
| } |
| err.note("read https://doc.rust-lang.org/nightly/rustdoc/the-doc-attribute.html#at-the-crate-level for more information") |
| .emit(); |
| }, |
| ); |
| return false; |
| } |
| true |
| } |
| |
| /// Checks that `doc(test(...))` attribute contains only valid attributes. Returns `true` if |
| /// valid. |
| fn check_test_attr(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool { |
| let mut is_valid = true; |
| if let Some(metas) = meta.meta_item_list() { |
| for i_meta in metas { |
| match i_meta.name_or_empty() { |
| sym::attr | sym::no_crate_inject => {} |
| _ => { |
| self.tcx.struct_span_lint_hir( |
| INVALID_DOC_ATTRIBUTES, |
| hir_id, |
| i_meta.span(), |
| |lint| { |
| lint.build(&format!( |
| "unknown `doc(test)` attribute `{}`", |
| rustc_ast_pretty::pprust::path_to_string( |
| &i_meta.meta_item().unwrap().path |
| ), |
| )) |
| .emit(); |
| }, |
| ); |
| is_valid = false; |
| } |
| } |
| } |
| } else { |
| self.tcx.struct_span_lint_hir(INVALID_DOC_ATTRIBUTES, hir_id, meta.span(), |lint| { |
| lint.build("`#[doc(test(...)]` takes a list of attributes").emit(); |
| }); |
| is_valid = false; |
| } |
| is_valid |
| } |
| |
| /// Runs various checks on `#[doc]` attributes. Returns `true` if valid. |
| /// |
| /// `specified_inline` should be initialized to `None` and kept for the scope |
| /// of one item. Read the documentation of [`check_doc_inline`] for more information. |
| /// |
| /// [`check_doc_inline`]: Self::check_doc_inline |
| fn check_doc_attrs( |
| &self, |
| attr: &Attribute, |
| hir_id: HirId, |
| target: Target, |
| specified_inline: &mut Option<(bool, Span)>, |
| aliases: &mut FxHashMap<String, Span>, |
| ) -> bool { |
| let mut is_valid = true; |
| |
| if let Some(list) = attr.meta().and_then(|mi| mi.meta_item_list().map(|l| l.to_vec())) { |
| for meta in &list { |
| if let Some(i_meta) = meta.meta_item() { |
| match i_meta.name_or_empty() { |
| sym::alias |
| if !self.check_attr_not_crate_level(&meta, hir_id, "alias") |
| || !self.check_doc_alias(&meta, hir_id, target, aliases) => |
| { |
| is_valid = false |
| } |
| |
| sym::keyword |
| if !self.check_attr_not_crate_level(&meta, hir_id, "keyword") |
| || !self.check_doc_keyword(&meta, hir_id) => |
| { |
| is_valid = false |
| } |
| |
| sym::html_favicon_url |
| | sym::html_logo_url |
| | sym::html_playground_url |
| | sym::issue_tracker_base_url |
| | sym::html_root_url |
| | sym::html_no_source |
| | sym::test |
| if !self.check_attr_crate_level(&attr, &meta, hir_id) => |
| { |
| is_valid = false; |
| } |
| |
| sym::inline | sym::no_inline |
| if !self.check_doc_inline( |
| &attr, |
| &meta, |
| hir_id, |
| target, |
| specified_inline, |
| ) => |
| { |
| is_valid = false; |
| } |
| |
| // no_default_passes: deprecated |
| // passes: deprecated |
| // plugins: removed, but rustdoc warns about it itself |
| sym::alias |
| | sym::cfg |
| | sym::cfg_hide |
| | sym::hidden |
| | sym::html_favicon_url |
| | sym::html_logo_url |
| | sym::html_no_source |
| | sym::html_playground_url |
| | sym::html_root_url |
| | sym::inline |
| | sym::issue_tracker_base_url |
| | sym::keyword |
| | sym::masked |
| | sym::no_default_passes |
| | sym::no_inline |
| | sym::notable_trait |
| | sym::passes |
| | sym::plugins => {} |
| |
| sym::test => { |
| if !self.check_test_attr(&meta, hir_id) { |
| is_valid = false; |
| } |
| } |
| |
| sym::primitive => { |
| if !self.tcx.features().rustdoc_internals { |
| self.tcx.struct_span_lint_hir( |
| INVALID_DOC_ATTRIBUTES, |
| hir_id, |
| i_meta.span, |
| |lint| { |
| let mut diag = lint.build( |
| "`doc(primitive)` should never have been stable", |
| ); |
| diag.emit(); |
| }, |
| ); |
| } |
| } |
| |
| _ => { |
| self.tcx.struct_span_lint_hir( |
| INVALID_DOC_ATTRIBUTES, |
| hir_id, |
| i_meta.span, |
| |lint| { |
| let mut diag = lint.build(&format!( |
| "unknown `doc` attribute `{}`", |
| rustc_ast_pretty::pprust::path_to_string(&i_meta.path), |
| )); |
| if i_meta.has_name(sym::spotlight) { |
| diag.note( |
| "`doc(spotlight)` was renamed to `doc(notable_trait)`", |
| ); |
| diag.span_suggestion_short( |
| i_meta.span, |
| "use `notable_trait` instead", |
| String::from("notable_trait"), |
| Applicability::MachineApplicable, |
| ); |
| diag.note("`doc(spotlight)` is now a no-op"); |
| } |
| if i_meta.has_name(sym::include) { |
| if let Some(value) = i_meta.value_str() { |
| // if there are multiple attributes, the suggestion would suggest deleting all of them, which is incorrect |
| let applicability = if list.len() == 1 { |
| Applicability::MachineApplicable |
| } else { |
| Applicability::MaybeIncorrect |
| }; |
| let inner = if attr.style == AttrStyle::Inner { |
| "!" |
| } else { |
| "" |
| }; |
| diag.span_suggestion( |
| attr.meta().unwrap().span, |
| "use `doc = include_str!` instead", |
| format!( |
| "#{}[doc = include_str!(\"{}\")]", |
| inner, value |
| ), |
| applicability, |
| ); |
| } |
| } |
| diag.emit(); |
| }, |
| ); |
| is_valid = false; |
| } |
| } |
| } else { |
| self.tcx.struct_span_lint_hir( |
| INVALID_DOC_ATTRIBUTES, |
| hir_id, |
| meta.span(), |
| |lint| { |
| lint.build(&"invalid `doc` attribute").emit(); |
| }, |
| ); |
| is_valid = false; |
| } |
| } |
| } |
| |
| is_valid |
| } |
| |
| /// Warns against some misuses of `#[pass_by_value]` |
| fn check_pass_by_value(&self, attr: &Attribute, span: Span, target: Target) -> bool { |
| match target { |
| Target::Struct | Target::Enum | Target::TyAlias => true, |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| attr.span, |
| "`pass_by_value` attribute should be applied to a struct, enum or type alias.", |
| ) |
| .span_label(span, "is not a struct, enum or type alias") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Warns against some misuses of `#[must_use]` |
| fn check_must_use(&self, hir_id: HirId, attr: &Attribute, span: Span, _target: Target) -> bool { |
| let node = self.tcx.hir().get(hir_id); |
| if let Some(fn_node) = node.fn_kind() { |
| if let rustc_hir::IsAsync::Async = fn_node.asyncness() { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build( |
| "`must_use` attribute on `async` functions \ |
| applies to the anonymous `Future` returned by the \ |
| function, not the value within", |
| ) |
| .span_label( |
| span, |
| "this attribute does nothing, the `Future`s \ |
| returned by async functions are already `must_use`", |
| ) |
| .emit(); |
| }); |
| } |
| } |
| |
| // For now, its always valid |
| true |
| } |
| |
| /// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid. |
| fn check_must_not_suspend(&self, attr: &Attribute, span: Span, target: Target) -> bool { |
| match target { |
| Target::Struct | Target::Enum | Target::Union | Target::Trait => true, |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "`must_not_suspend` attribute should be applied to a struct, enum, or trait") |
| .span_label(span, "is not a struct, enum, or trait") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid. |
| fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) { |
| match target { |
| Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {} |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[cold]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "cold"); |
| } |
| _ => { |
| // FIXME: #[cold] was previously allowed on non-functions and some crates used |
| // this, so only emit a warning. |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("attribute should be applied to a function") |
| .warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ) |
| .span_label(span, "not a function") |
| .emit(); |
| }); |
| } |
| } |
| } |
| |
| /// Checks if `#[link]` is applied to an item other than a foreign module. |
| fn check_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) { |
| match target { |
| Target::ForeignMod => {} |
| _ => { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| let mut diag = lint.build("attribute should be applied to an `extern` block"); |
| diag.warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ); |
| |
| diag.span_label(span, "not an `extern` block"); |
| diag.emit(); |
| }); |
| } |
| } |
| } |
| |
| /// Checks if `#[link_name]` is applied to an item other than a foreign function or static. |
| fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) { |
| match target { |
| Target::ForeignFn | Target::ForeignStatic => {} |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[link_name]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_name"); |
| } |
| _ => { |
| // FIXME: #[cold] was previously allowed on non-functions/statics and some crates |
| // used this, so only emit a warning. |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| let mut diag = |
| lint.build("attribute should be applied to a foreign function or static"); |
| diag.warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ); |
| |
| // See issue #47725 |
| if let Target::ForeignMod = target { |
| if let Some(value) = attr.value_str() { |
| diag.span_help( |
| attr.span, |
| &format!(r#"try `#[link(name = "{}")]` instead"#, value), |
| ); |
| } else { |
| diag.span_help(attr.span, r#"try `#[link(name = "...")]` instead"#); |
| } |
| } |
| |
| diag.span_label(span, "not a foreign function or static"); |
| diag.emit(); |
| }); |
| } |
| } |
| } |
| |
| /// Checks if `#[no_link]` is applied to an `extern crate`. Returns `true` if valid. |
| fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool { |
| match target { |
| Target::ExternCrate => true, |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[no_link]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_link"); |
| true |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| attr.span, |
| "attribute should be applied to an `extern crate` item", |
| ) |
| .span_label(span, "not an `extern crate` item") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| fn is_impl_item(&self, hir_id: HirId) -> bool { |
| matches!(self.tcx.hir().get(hir_id), hir::Node::ImplItem(..)) |
| } |
| |
| /// Checks if `#[export_name]` is applied to a function or static. Returns `true` if valid. |
| fn check_export_name( |
| &self, |
| hir_id: HirId, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| ) -> bool { |
| match target { |
| Target::Static | Target::Fn => true, |
| Target::Method(..) if self.is_impl_item(hir_id) => true, |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[export_name]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "export_name"); |
| true |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| attr.span, |
| "attribute should be applied to a free function, impl method or static", |
| ) |
| .span_label(span, "not a free function, impl method or static") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| fn check_rustc_layout_scalar_valid_range( |
| &self, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| ) -> bool { |
| if target != Target::Struct { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute should be applied to a struct") |
| .span_label(span, "not a struct") |
| .emit(); |
| return false; |
| } |
| |
| let list = match attr.meta_item_list() { |
| None => return false, |
| Some(it) => it, |
| }; |
| |
| if matches!(&list[..], &[NestedMetaItem::Literal(Lit { kind: LitKind::Int(..), .. })]) { |
| true |
| } else { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "expected exactly one integer literal argument") |
| .emit(); |
| false |
| } |
| } |
| |
| /// Checks if `#[rustc_legacy_const_generics]` is applied to a function and has a valid argument. |
| fn check_rustc_legacy_const_generics( |
| &self, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| item: Option<ItemLike<'_>>, |
| ) -> bool { |
| let is_function = matches!(target, Target::Fn | Target::Method(..)); |
| if !is_function { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute should be applied to a function") |
| .span_label(span, "not a function") |
| .emit(); |
| return false; |
| } |
| |
| let list = match attr.meta_item_list() { |
| // The attribute form is validated on AST. |
| None => return false, |
| Some(it) => it, |
| }; |
| |
| let (decl, generics) = match item { |
| Some(ItemLike::Item(Item { |
| kind: ItemKind::Fn(FnSig { decl, .. }, generics, _), |
| .. |
| })) => (decl, generics), |
| _ => bug!("should be a function item"), |
| }; |
| |
| for param in generics.params { |
| match param.kind { |
| hir::GenericParamKind::Const { .. } => {} |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| attr.span, |
| "#[rustc_legacy_const_generics] functions must \ |
| only have const generics", |
| ) |
| .span_label(param.span, "non-const generic parameter") |
| .emit(); |
| return false; |
| } |
| } |
| } |
| |
| if list.len() != generics.params.len() { |
| self.tcx |
| .sess |
| .struct_span_err( |
| attr.span, |
| "#[rustc_legacy_const_generics] must have one index for each generic parameter", |
| ) |
| .span_label(generics.span, "generic parameters") |
| .emit(); |
| return false; |
| } |
| |
| let arg_count = decl.inputs.len() as u128 + generics.params.len() as u128; |
| let mut invalid_args = vec![]; |
| for meta in list { |
| if let Some(LitKind::Int(val, _)) = meta.literal().map(|lit| &lit.kind) { |
| if *val >= arg_count { |
| let span = meta.span(); |
| self.tcx |
| .sess |
| .struct_span_err(span, "index exceeds number of arguments") |
| .span_label( |
| span, |
| format!( |
| "there {} only {} argument{}", |
| if arg_count != 1 { "are" } else { "is" }, |
| arg_count, |
| pluralize!(arg_count) |
| ), |
| ) |
| .emit(); |
| return false; |
| } |
| } else { |
| invalid_args.push(meta.span()); |
| } |
| } |
| |
| if !invalid_args.is_empty() { |
| self.tcx |
| .sess |
| .struct_span_err(invalid_args, "arguments should be non-negative integers") |
| .emit(); |
| false |
| } else { |
| true |
| } |
| } |
| |
| fn check_rustc_lint_query_instability( |
| &self, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| ) -> bool { |
| let is_function = matches!(target, Target::Fn | Target::Method(..)); |
| if !is_function { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute should be applied to a function") |
| .span_label(span, "not a function") |
| .emit(); |
| false |
| } else { |
| true |
| } |
| } |
| |
| /// Checks that the dep-graph debugging attributes are only present when the query-dep-graph |
| /// option is passed to the compiler. |
| fn check_rustc_dirty_clean(&self, attr: &Attribute) -> bool { |
| if self.tcx.sess.opts.debugging_opts.query_dep_graph { |
| true |
| } else { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute requires -Z query-dep-graph to be enabled") |
| .emit(); |
| false |
| } |
| } |
| |
| /// Checks if `#[link_section]` is applied to a function or static. |
| fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) { |
| match target { |
| Target::Static | Target::Fn | Target::Method(..) => {} |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[link_section]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_section"); |
| } |
| _ => { |
| // FIXME: #[link_section] was previously allowed on non-functions/statics and some |
| // crates used this, so only emit a warning. |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("attribute should be applied to a function or static") |
| .warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ) |
| .span_label(span, "not a function or static") |
| .emit(); |
| }); |
| } |
| } |
| } |
| |
| /// Checks if `#[no_mangle]` is applied to a function or static. |
| fn check_no_mangle(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) { |
| match target { |
| Target::Static | Target::Fn => {} |
| Target::Method(..) if self.is_impl_item(hir_id) => {} |
| // FIXME(#80564): We permit struct fields, match arms and macro defs to have an |
| // `#[no_mangle]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_mangle"); |
| } |
| // FIXME: #[no_mangle] was previously allowed on non-functions/statics, this should be an error |
| // The error should specify that the item that is wrong is specifically a *foreign* fn/static |
| // otherwise the error seems odd |
| Target::ForeignFn | Target::ForeignStatic => { |
| let foreign_item_kind = match target { |
| Target::ForeignFn => "function", |
| Target::ForeignStatic => "static", |
| _ => unreachable!(), |
| }; |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build(&format!( |
| "`#[no_mangle]` has no effect on a foreign {}", |
| foreign_item_kind |
| )) |
| .warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ) |
| .span_label(span, format!("foreign {}", foreign_item_kind)) |
| .note("symbol names in extern blocks are not mangled") |
| .span_suggestion( |
| attr.span, |
| "remove this attribute", |
| String::new(), |
| Applicability::MachineApplicable, |
| ) |
| .emit(); |
| }); |
| } |
| _ => { |
| // FIXME: #[no_mangle] was previously allowed on non-functions/statics and some |
| // crates used this, so only emit a warning. |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build( |
| "attribute should be applied to a free function, impl method or static", |
| ) |
| .warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ) |
| .span_label(span, "not a free function, impl method or static") |
| .emit(); |
| }); |
| } |
| } |
| } |
| |
| /// Checks if the `#[repr]` attributes on `item` are valid. |
| fn check_repr( |
| &self, |
| attrs: &[Attribute], |
| span: Span, |
| target: Target, |
| item: Option<ItemLike<'_>>, |
| hir_id: HirId, |
| ) { |
| // Extract the names of all repr hints, e.g., [foo, bar, align] for: |
| // ``` |
| // #[repr(foo)] |
| // #[repr(bar, align(8))] |
| // ``` |
| let hints: Vec<_> = attrs |
| .iter() |
| .filter(|attr| attr.has_name(sym::repr)) |
| .filter_map(|attr| attr.meta_item_list()) |
| .flatten() |
| .collect(); |
| |
| let mut int_reprs = 0; |
| let mut is_c = false; |
| let mut is_simd = false; |
| let mut is_transparent = false; |
| |
| for hint in &hints { |
| if !hint.is_meta_item() { |
| struct_span_err!( |
| self.tcx.sess, |
| hint.span(), |
| E0565, |
| "meta item in `repr` must be an identifier" |
| ) |
| .emit(); |
| continue; |
| } |
| |
| let (article, allowed_targets) = match hint.name_or_empty() { |
| sym::C => { |
| is_c = true; |
| match target { |
| Target::Struct | Target::Union | Target::Enum => continue, |
| _ => ("a", "struct, enum, or union"), |
| } |
| } |
| sym::align => { |
| if let (Target::Fn, true) = (target, !self.tcx.features().fn_align) { |
| feature_err( |
| &self.tcx.sess.parse_sess, |
| sym::fn_align, |
| hint.span(), |
| "`repr(align)` attributes on functions are unstable", |
| ) |
| .emit(); |
| } |
| |
| match target { |
| Target::Struct | Target::Union | Target::Enum | Target::Fn => continue, |
| _ => ("a", "struct, enum, function, or union"), |
| } |
| } |
| sym::packed => { |
| if target != Target::Struct && target != Target::Union { |
| ("a", "struct or union") |
| } else { |
| continue; |
| } |
| } |
| sym::simd => { |
| is_simd = true; |
| if target != Target::Struct { |
| ("a", "struct") |
| } else { |
| continue; |
| } |
| } |
| sym::transparent => { |
| is_transparent = true; |
| match target { |
| Target::Struct | Target::Union | Target::Enum => continue, |
| _ => ("a", "struct, enum, or union"), |
| } |
| } |
| sym::no_niche => { |
| if !self.tcx.features().enabled(sym::no_niche) { |
| feature_err( |
| &self.tcx.sess.parse_sess, |
| sym::no_niche, |
| hint.span(), |
| "the attribute `repr(no_niche)` is currently unstable", |
| ) |
| .emit(); |
| } |
| match target { |
| Target::Struct | Target::Enum => continue, |
| _ => ("a", "struct or enum"), |
| } |
| } |
| sym::i8 |
| | sym::u8 |
| | sym::i16 |
| | sym::u16 |
| | sym::i32 |
| | sym::u32 |
| | sym::i64 |
| | sym::u64 |
| | sym::i128 |
| | sym::u128 |
| | sym::isize |
| | sym::usize => { |
| int_reprs += 1; |
| if target != Target::Enum { |
| ("an", "enum") |
| } else { |
| continue; |
| } |
| } |
| _ => { |
| struct_span_err!( |
| self.tcx.sess, |
| hint.span(), |
| E0552, |
| "unrecognized representation hint" |
| ) |
| .emit(); |
| |
| continue; |
| } |
| }; |
| |
| struct_span_err!( |
| self.tcx.sess, |
| hint.span(), |
| E0517, |
| "{}", |
| &format!("attribute should be applied to {} {}", article, allowed_targets) |
| ) |
| .span_label(span, &format!("not {} {}", article, allowed_targets)) |
| .emit(); |
| } |
| |
| // Just point at all repr hints if there are any incompatibilities. |
| // This is not ideal, but tracking precisely which ones are at fault is a huge hassle. |
| let hint_spans = hints.iter().map(|hint| hint.span()); |
| |
| // Error on repr(transparent, <anything else apart from no_niche>). |
| let non_no_niche = |hint: &&NestedMetaItem| hint.name_or_empty() != sym::no_niche; |
| let non_no_niche_count = hints.iter().filter(non_no_niche).count(); |
| if is_transparent && non_no_niche_count > 1 { |
| let hint_spans: Vec<_> = hint_spans.clone().collect(); |
| struct_span_err!( |
| self.tcx.sess, |
| hint_spans, |
| E0692, |
| "transparent {} cannot have other repr hints", |
| target |
| ) |
| .emit(); |
| } |
| // Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8) |
| if (int_reprs > 1) |
| || (is_simd && is_c) |
| || (int_reprs == 1 |
| && is_c |
| && item.map_or(false, |item| { |
| if let ItemLike::Item(item) = item { |
| return is_c_like_enum(item); |
| } |
| return false; |
| })) |
| { |
| self.tcx.struct_span_lint_hir( |
| CONFLICTING_REPR_HINTS, |
| hir_id, |
| hint_spans.collect::<Vec<Span>>(), |
| |lint| { |
| lint.build("conflicting representation hints") |
| .code(rustc_errors::error_code!(E0566)) |
| .emit(); |
| }, |
| ); |
| } |
| } |
| |
| fn check_used(&self, attrs: &[Attribute], target: Target) { |
| let mut used_linker_span = None; |
| let mut used_compiler_span = None; |
| for attr in attrs { |
| if attr.has_name(sym::used) && target != Target::Static { |
| self.tcx |
| .sess |
| .span_err(attr.span, "attribute must be applied to a `static` variable"); |
| } |
| let inner = attr.meta_item_list(); |
| match inner.as_deref() { |
| Some([item]) if item.has_name(sym::linker) => { |
| if used_linker_span.is_none() { |
| used_linker_span = Some(attr.span); |
| } |
| } |
| Some([item]) if item.has_name(sym::compiler) => { |
| if used_compiler_span.is_none() { |
| used_compiler_span = Some(attr.span); |
| } |
| } |
| Some(_) => { |
| // This error case is handled in rustc_typeck::collect. |
| } |
| None => { |
| // Default case (compiler) when arg isn't defined. |
| if used_compiler_span.is_none() { |
| used_compiler_span = Some(attr.span); |
| } |
| } |
| } |
| } |
| if let (Some(linker_span), Some(compiler_span)) = (used_linker_span, used_compiler_span) { |
| let spans = vec![linker_span, compiler_span]; |
| self.tcx |
| .sess |
| .struct_span_err( |
| spans, |
| "`used(compiler)` and `used(linker)` can't be used together", |
| ) |
| .emit(); |
| } |
| } |
| |
| /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros. |
| /// (Allows proc_macro functions) |
| fn check_allow_internal_unstable( |
| &self, |
| hir_id: HirId, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| attrs: &[Attribute], |
| ) -> bool { |
| debug!("Checking target: {:?}", target); |
| match target { |
| Target::Fn => { |
| for attr in attrs { |
| if self.tcx.sess.is_proc_macro_attr(attr) { |
| debug!("Is proc macro attr"); |
| return true; |
| } |
| } |
| debug!("Is not proc macro attr"); |
| false |
| } |
| Target::MacroDef => true, |
| // FIXME(#80564): We permit struct fields and match arms to have an |
| // `#[allow_internal_unstable]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm => { |
| self.inline_attr_str_error_without_macro_def( |
| hir_id, |
| attr, |
| "allow_internal_unstable", |
| ); |
| true |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute should be applied to a macro") |
| .span_label(span, "not a macro") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros. |
| /// (Allows proc_macro functions) |
| fn check_rustc_allow_const_fn_unstable( |
| &self, |
| hir_id: HirId, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| ) -> bool { |
| match target { |
| Target::Fn | Target::Method(_) |
| if self.tcx.is_const_fn_raw(self.tcx.hir().local_def_id(hir_id)) => |
| { |
| true |
| } |
| // FIXME(#80564): We permit struct fields and match arms to have an |
| // `#[allow_internal_unstable]` attribute with just a lint, because we previously |
| // erroneously allowed it and some crates used it accidentally, to to be compatible |
| // with crates depending on them, we can't throw an error here. |
| Target::Field | Target::Arm | Target::MacroDef => { |
| self.inline_attr_str_error_with_macro_def(hir_id, attr, "allow_internal_unstable"); |
| true |
| } |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute should be applied to `const fn`") |
| .span_label(span, "not a `const fn`") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| /// default_method_body_is_const should only be applied to trait methods with default bodies. |
| fn check_default_method_body_is_const( |
| &self, |
| attr: &Attribute, |
| span: Span, |
| target: Target, |
| ) -> bool { |
| match target { |
| Target::Method(MethodKind::Trait { body: true }) => true, |
| _ => { |
| self.tcx |
| .sess |
| .struct_span_err( |
| attr.span, |
| "attribute should be applied to a trait method with body", |
| ) |
| .span_label(span, "not a trait method or missing a body") |
| .emit(); |
| false |
| } |
| } |
| } |
| |
| fn check_stability_promotable(&self, attr: &Attribute, _span: Span, target: Target) -> bool { |
| match target { |
| Target::Expression => { |
| self.tcx |
| .sess |
| .struct_span_err(attr.span, "attribute cannot be applied to an expression") |
| .emit(); |
| false |
| } |
| _ => true, |
| } |
| } |
| |
| fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) { |
| match target { |
| Target::Closure | Target::Expression | Target::Statement | Target::Arm => { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("attribute is ignored here").emit(); |
| }); |
| } |
| _ => {} |
| } |
| } |
| |
| fn check_macro_use(&self, hir_id: HirId, attr: &Attribute, target: Target) { |
| let name = attr.name_or_empty(); |
| match target { |
| Target::ExternCrate | Target::Mod => {} |
| _ => { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build(&format!( |
| "`#[{name}]` only has an effect on `extern crate` and modules" |
| )) |
| .emit(); |
| }); |
| } |
| } |
| } |
| |
| fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) { |
| if target != Target::MacroDef { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("`#[macro_export]` only has an effect on macro definitions").emit(); |
| }); |
| } |
| } |
| |
| fn check_plugin_registrar(&self, hir_id: HirId, attr: &Attribute, target: Target) { |
| if target != Target::Fn { |
| self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| { |
| lint.build("`#[plugin_registrar]` only has an effect on functions").emit(); |
| }); |
| } |
| } |
| } |
| |
| impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> { |
| type NestedFilter = nested_filter::OnlyBodies; |
| |
| fn nested_visit_map(&mut self) -> Self::Map { |
| self.tcx.hir() |
| } |
| |
| fn visit_item(&mut self, item: &'tcx Item<'tcx>) { |
| // Historically we've run more checks on non-exported than exported macros, |
| // so this lets us continue to run them while maintaining backwards compatibility. |
| // In the long run, the checks should be harmonized. |
| if let ItemKind::Macro(ref macro_def) = item.kind { |
| let def_id = item.def_id.to_def_id(); |
| if macro_def.macro_rules && !self.tcx.has_attr(def_id, sym::macro_export) { |
| check_non_exported_macro_for_invalid_attrs(self.tcx, item); |
| } |
| } |
| |
| let target = Target::from_item(item); |
| self.check_attributes(item.hir_id(), item.span, target, Some(ItemLike::Item(item))); |
| intravisit::walk_item(self, item) |
| } |
| |
| fn visit_generic_param(&mut self, generic_param: &'tcx hir::GenericParam<'tcx>) { |
| let target = Target::from_generic_param(generic_param); |
| self.check_attributes(generic_param.hir_id, generic_param.span, target, None); |
| intravisit::walk_generic_param(self, generic_param) |
| } |
| |
| fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>) { |
| let target = Target::from_trait_item(trait_item); |
| self.check_attributes(trait_item.hir_id(), trait_item.span, target, None); |
| intravisit::walk_trait_item(self, trait_item) |
| } |
| |
| fn visit_field_def(&mut self, struct_field: &'tcx hir::FieldDef<'tcx>) { |
| self.check_attributes(struct_field.hir_id, struct_field.span, Target::Field, None); |
| intravisit::walk_field_def(self, struct_field); |
| } |
| |
| fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) { |
| self.check_attributes(arm.hir_id, arm.span, Target::Arm, None); |
| intravisit::walk_arm(self, arm); |
| } |
| |
| fn visit_foreign_item(&mut self, f_item: &'tcx ForeignItem<'tcx>) { |
| let target = Target::from_foreign_item(f_item); |
| self.check_attributes( |
| f_item.hir_id(), |
| f_item.span, |
| target, |
| Some(ItemLike::ForeignItem(f_item)), |
| ); |
| intravisit::walk_foreign_item(self, f_item) |
| } |
| |
| fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) { |
| let target = target_from_impl_item(self.tcx, impl_item); |
| self.check_attributes(impl_item.hir_id(), impl_item.span, target, None); |
| intravisit::walk_impl_item(self, impl_item) |
| } |
| |
| fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) { |
| // When checking statements ignore expressions, they will be checked later. |
| if let hir::StmtKind::Local(ref l) = stmt.kind { |
| self.check_attributes(l.hir_id, stmt.span, Target::Statement, None); |
| } |
| intravisit::walk_stmt(self, stmt) |
| } |
| |
| fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) { |
| let target = match expr.kind { |
| hir::ExprKind::Closure(..) => Target::Closure, |
| _ => Target::Expression, |
| }; |
| |
| self.check_attributes(expr.hir_id, expr.span, target, None); |
| intravisit::walk_expr(self, expr) |
| } |
| |
| fn visit_variant( |
| &mut self, |
| variant: &'tcx hir::Variant<'tcx>, |
| generics: &'tcx hir::Generics<'tcx>, |
| item_id: HirId, |
| ) { |
| self.check_attributes(variant.id, variant.span, Target::Variant, None); |
| intravisit::walk_variant(self, variant, generics, item_id) |
| } |
| |
| fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) { |
| self.check_attributes(param.hir_id, param.span, Target::Param, None); |
| |
| intravisit::walk_param(self, param); |
| } |
| } |
| |
| fn is_c_like_enum(item: &Item<'_>) -> bool { |
| if let ItemKind::Enum(ref def, _) = item.kind { |
| for variant in def.variants { |
| match variant.data { |
| hir::VariantData::Unit(..) => { /* continue */ } |
| _ => return false, |
| } |
| } |
| true |
| } else { |
| false |
| } |
| } |
| |
| // FIXME: Fix "Cannot determine resolution" error and remove built-in macros |
| // from this check. |
| fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) { |
| // Check for builtin attributes at the crate level |
| // which were unsuccessfully resolved due to cannot determine |
| // resolution for the attribute macro error. |
| const ATTRS_TO_CHECK: &[Symbol] = &[ |
| sym::macro_export, |
| sym::repr, |
| sym::path, |
| sym::automatically_derived, |
| sym::start, |
| sym::rustc_main, |
| sym::derive, |
| sym::test, |
| sym::test_case, |
| sym::global_allocator, |
| sym::bench, |
| ]; |
| |
| for attr in attrs { |
| // This function should only be called with crate attributes |
| // which are inner attributes always but lets check to make sure |
| if attr.style == AttrStyle::Inner { |
| for attr_to_check in ATTRS_TO_CHECK { |
| if attr.has_name(*attr_to_check) { |
| let mut err = tcx.sess.struct_span_err( |
| attr.span, |
| &format!( |
| "`{}` attribute cannot be used at crate level", |
| attr_to_check.to_ident_string() |
| ), |
| ); |
| // Only emit an error with a suggestion if we can create a |
| // string out of the attribute span |
| if let Ok(src) = tcx.sess.source_map().span_to_snippet(attr.span) { |
| let replacement = src.replace("#!", "#"); |
| err.span_suggestion_verbose( |
| attr.span, |
| "perhaps you meant to use an outer attribute", |
| replacement, |
| rustc_errors::Applicability::MachineApplicable, |
| ); |
| } |
| err.emit() |
| } |
| } |
| } |
| } |
| } |
| |
| fn check_non_exported_macro_for_invalid_attrs(tcx: TyCtxt<'_>, item: &Item<'_>) { |
| let attrs = tcx.hir().attrs(item.hir_id()); |
| |
| for attr in attrs { |
| if attr.has_name(sym::inline) { |
| struct_span_err!( |
| tcx.sess, |
| attr.span, |
| E0518, |
| "attribute should be applied to function or closure", |
| ) |
| .span_label(attr.span, "not a function or closure") |
| .emit(); |
| } |
| } |
| } |
| |
| fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) { |
| let check_attr_visitor = &mut CheckAttrVisitor { tcx }; |
| tcx.hir().visit_item_likes_in_module(module_def_id, &mut check_attr_visitor.as_deep_visitor()); |
| if module_def_id.is_top_level_module() { |
| check_attr_visitor.check_attributes(CRATE_HIR_ID, DUMMY_SP, Target::Mod, None); |
| check_invalid_crate_level_attr(tcx, tcx.hir().krate_attrs()); |
| } |
| } |
| |
| pub(crate) fn provide(providers: &mut Providers) { |
| *providers = Providers { check_mod_attrs, ..*providers }; |
| } |
| |
| fn check_duplicates( |
| tcx: TyCtxt<'_>, |
| attr: &Attribute, |
| hir_id: HirId, |
| duplicates: AttributeDuplicates, |
| seen: &mut FxHashMap<Symbol, Span>, |
| ) { |
| use AttributeDuplicates::*; |
| if matches!(duplicates, WarnFollowingWordOnly) && !attr.is_word() { |
| return; |
| } |
| match duplicates { |
| DuplicatesOk => {} |
| WarnFollowing | FutureWarnFollowing | WarnFollowingWordOnly | FutureWarnPreceding => { |
| match seen.entry(attr.name_or_empty()) { |
| Entry::Occupied(mut entry) => { |
| let (this, other) = if matches!(duplicates, FutureWarnPreceding) { |
| let to_remove = entry.insert(attr.span); |
| (to_remove, attr.span) |
| } else { |
| (attr.span, *entry.get()) |
| }; |
| tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, this, |lint| { |
| let mut db = lint.build("unused attribute"); |
| db.span_note(other, "attribute also specified here").span_suggestion( |
| this, |
| "remove this attribute", |
| String::new(), |
| Applicability::MachineApplicable, |
| ); |
| if matches!(duplicates, FutureWarnFollowing | FutureWarnPreceding) { |
| db.warn( |
| "this was previously accepted by the compiler but is \ |
| being phased out; it will become a hard error in \ |
| a future release!", |
| ); |
| } |
| db.emit(); |
| }); |
| } |
| Entry::Vacant(entry) => { |
| entry.insert(attr.span); |
| } |
| } |
| } |
| ErrorFollowing | ErrorPreceding => match seen.entry(attr.name_or_empty()) { |
| Entry::Occupied(mut entry) => { |
| let (this, other) = if matches!(duplicates, ErrorPreceding) { |
| let to_remove = entry.insert(attr.span); |
| (to_remove, attr.span) |
| } else { |
| (attr.span, *entry.get()) |
| }; |
| tcx.sess |
| .struct_span_err( |
| this, |
| &format!("multiple `{}` attributes", attr.name_or_empty()), |
| ) |
| .span_note(other, "attribute also specified here") |
| .span_suggestion( |
| this, |
| "remove this attribute", |
| String::new(), |
| Applicability::MachineApplicable, |
| ) |
| .emit(); |
| } |
| Entry::Vacant(entry) => { |
| entry.insert(attr.span); |
| } |
| }, |
| } |
| } |
