| //! A pass that annotates every item and method with its stability level, |
| //! propagating default levels lexically from parent to children ast nodes. |
| |
| use std::mem::replace; |
| use std::num::NonZero; |
| |
| use rustc_ast_lowering::stability::extern_abi_stability; |
| use rustc_attr_data_structures::{ |
| self as attrs, AttributeKind, ConstStability, DeprecatedSince, PartialConstStability, |
| Stability, StabilityLevel, StableSince, UnstableReason, VERSION_PLACEHOLDER, find_attr, |
| }; |
| use rustc_data_structures::fx::FxIndexMap; |
| use rustc_data_structures::unord::{ExtendUnord, UnordMap, UnordSet}; |
| use rustc_feature::{ACCEPTED_LANG_FEATURES, EnabledLangFeature, EnabledLibFeature}; |
| use rustc_hir::def::{DefKind, Res}; |
| use rustc_hir::def_id::{CRATE_DEF_ID, LOCAL_CRATE, LocalDefId, LocalModDefId}; |
| use rustc_hir::hir_id::CRATE_HIR_ID; |
| use rustc_hir::intravisit::{self, Visitor, VisitorExt}; |
| use rustc_hir::{self as hir, AmbigArg, FieldDef, Item, ItemKind, TraitRef, Ty, TyKind, Variant}; |
| use rustc_middle::hir::nested_filter; |
| use rustc_middle::middle::lib_features::{FeatureStability, LibFeatures}; |
| use rustc_middle::middle::privacy::EffectiveVisibilities; |
| use rustc_middle::middle::stability::{ |
| AllowUnstable, Deprecated, DeprecationEntry, EvalResult, Index, |
| }; |
| use rustc_middle::query::Providers; |
| use rustc_middle::ty::TyCtxt; |
| use rustc_middle::ty::print::with_no_trimmed_paths; |
| use rustc_session::lint; |
| use rustc_session::lint::builtin::{ |
| DEPRECATED, INEFFECTIVE_UNSTABLE_TRAIT_IMPL, USELESS_DEPRECATED, |
| }; |
| use rustc_span::{Span, Symbol, sym}; |
| use tracing::{debug, info}; |
| |
| use crate::errors; |
| |
| #[derive(PartialEq)] |
| enum AnnotationKind { |
| /// Annotation is required if not inherited from unstable parents. |
| Required, |
| /// Annotation is useless, reject it. |
| Prohibited, |
| /// Deprecation annotation is useless, reject it. (Stability attribute is still required.) |
| DeprecationProhibited, |
| /// Annotation itself is useless, but it can be propagated to children. |
| Container, |
| } |
| |
| /// Whether to inherit deprecation flags for nested items. In most cases, we do want to inherit |
| /// deprecation, because nested items rarely have individual deprecation attributes, and so |
| /// should be treated as deprecated if their parent is. However, default generic parameters |
| /// have separate deprecation attributes from their parents, so we do not wish to inherit |
| /// deprecation in this case. For example, inheriting deprecation for `T` in `Foo<T>` |
| /// would cause a duplicate warning arising from both `Foo` and `T` being deprecated. |
| #[derive(Clone)] |
| enum InheritDeprecation { |
| Yes, |
| No, |
| } |
| |
| impl InheritDeprecation { |
| fn yes(&self) -> bool { |
| matches!(self, InheritDeprecation::Yes) |
| } |
| } |
| |
| /// Whether to inherit const stability flags for nested items. In most cases, we do not want to |
| /// inherit const stability: just because an enclosing `fn` is const-stable does not mean |
| /// all `extern` imports declared in it should be const-stable! However, trait methods |
| /// inherit const stability attributes from their parent and do not have their own. |
| enum InheritConstStability { |
| Yes, |
| No, |
| } |
| |
| impl InheritConstStability { |
| fn yes(&self) -> bool { |
| matches!(self, InheritConstStability::Yes) |
| } |
| } |
| |
| enum InheritStability { |
| Yes, |
| No, |
| } |
| |
| impl InheritStability { |
| fn yes(&self) -> bool { |
| matches!(self, InheritStability::Yes) |
| } |
| } |
| |
| /// A private tree-walker for producing an `Index`. |
| struct Annotator<'a, 'tcx> { |
| tcx: TyCtxt<'tcx>, |
| index: &'a mut Index, |
| parent_stab: Option<Stability>, |
| parent_const_stab: Option<ConstStability>, |
| parent_depr: Option<DeprecationEntry>, |
| in_trait_impl: bool, |
| } |
| |
| impl<'a, 'tcx> Annotator<'a, 'tcx> { |
| /// Determine the stability for a node based on its attributes and inherited stability. The |
| /// stability is recorded in the index and used as the parent. If the node is a function, |
| /// `fn_sig` is its signature. |
| fn annotate<F>( |
| &mut self, |
| def_id: LocalDefId, |
| item_sp: Span, |
| fn_sig: Option<&'tcx hir::FnSig<'tcx>>, |
| kind: AnnotationKind, |
| inherit_deprecation: InheritDeprecation, |
| inherit_const_stability: InheritConstStability, |
| inherit_from_parent: InheritStability, |
| visit_children: F, |
| ) where |
| F: FnOnce(&mut Self), |
| { |
| let attrs = self.tcx.hir_attrs(self.tcx.local_def_id_to_hir_id(def_id)); |
| debug!("annotate(id = {:?}, attrs = {:?})", def_id, attrs); |
| |
| let depr = attrs::find_attr!(attrs, AttributeKind::Deprecation{deprecation, span} => (*deprecation, *span)); |
| let const_stability_indirect = find_attr!(attrs, AttributeKind::ConstStabilityIndirect); |
| |
| let mut is_deprecated = false; |
| if let Some((depr, span)) = &depr { |
| is_deprecated = true; |
| |
| if matches!(kind, AnnotationKind::Prohibited | AnnotationKind::DeprecationProhibited) { |
| let hir_id = self.tcx.local_def_id_to_hir_id(def_id); |
| self.tcx.emit_node_span_lint( |
| USELESS_DEPRECATED, |
| hir_id, |
| *span, |
| errors::DeprecatedAnnotationHasNoEffect { span: *span }, |
| ); |
| } |
| |
| // `Deprecation` is just two pointers, no need to intern it |
| let depr_entry = DeprecationEntry::local(*depr, def_id); |
| self.index.depr_map.insert(def_id, depr_entry); |
| } else if let Some(parent_depr) = self.parent_depr { |
| if inherit_deprecation.yes() { |
| is_deprecated = true; |
| info!("tagging child {:?} as deprecated from parent", def_id); |
| self.index.depr_map.insert(def_id, parent_depr); |
| } |
| } |
| |
| if !self.tcx.features().staged_api() { |
| // Propagate unstability. This can happen even for non-staged-api crates in case |
| // -Zforce-unstable-if-unmarked is set. |
| if let Some(stab) = self.parent_stab { |
| if inherit_deprecation.yes() && stab.is_unstable() { |
| self.index.stab_map.insert(def_id, stab); |
| if fn_sig.is_some_and(|s| s.header.is_const()) { |
| self.index.const_stab_map.insert( |
| def_id, |
| ConstStability::unmarked(const_stability_indirect, stab), |
| ); |
| } |
| } |
| } |
| |
| self.recurse_with_stability_attrs( |
| depr.map(|(d, _)| DeprecationEntry::local(d, def_id)), |
| None, |
| None, |
| visit_children, |
| ); |
| return; |
| } |
| |
| // # Regular and body stability |
| let stab = attrs::find_attr!(attrs, AttributeKind::Stability { stability, span } => (*stability, *span)); |
| let body_stab = |
| attrs::find_attr!(attrs, AttributeKind::BodyStability { stability, .. } => *stability); |
| |
| if let Some((depr, span)) = &depr |
| && depr.is_since_rustc_version() |
| && stab.is_none() |
| { |
| self.tcx.dcx().emit_err(errors::DeprecatedAttribute { span: *span }); |
| } |
| |
| if let Some(body_stab) = body_stab { |
| // FIXME: check that this item can have body stability |
| |
| self.index.default_body_stab_map.insert(def_id, body_stab); |
| debug!(?self.index.default_body_stab_map); |
| } |
| |
| let stab = stab.map(|(stab, span)| { |
| // Error if prohibited, or can't inherit anything from a container. |
| if kind == AnnotationKind::Prohibited |
| || (kind == AnnotationKind::Container && stab.level.is_stable() && is_deprecated) |
| { |
| self.tcx.dcx().emit_err(errors::UselessStability { span, item_sp }); |
| } |
| |
| debug!("annotate: found {:?}", stab); |
| |
| // Check if deprecated_since < stable_since. If it is, |
| // this is *almost surely* an accident. |
| if let ( |
| &Some(DeprecatedSince::RustcVersion(dep_since)), |
| &attrs::StabilityLevel::Stable { since: stab_since, .. }, |
| ) = (&depr.as_ref().map(|(d, _)| d.since), &stab.level) |
| { |
| match stab_since { |
| StableSince::Current => { |
| self.tcx |
| .dcx() |
| .emit_err(errors::CannotStabilizeDeprecated { span, item_sp }); |
| } |
| StableSince::Version(stab_since) => { |
| if dep_since < stab_since { |
| self.tcx |
| .dcx() |
| .emit_err(errors::CannotStabilizeDeprecated { span, item_sp }); |
| } |
| } |
| StableSince::Err => { |
| // An error already reported. Assume the unparseable stabilization |
| // version is older than the deprecation version. |
| } |
| } |
| } |
| |
| // Stable *language* features shouldn't be used as unstable library features. |
| // (Not doing this for stable library features is checked by tidy.) |
| if let Stability { level: StabilityLevel::Unstable { .. }, feature } = stab { |
| if ACCEPTED_LANG_FEATURES.iter().find(|f| f.name == feature).is_some() { |
| self.tcx |
| .dcx() |
| .emit_err(errors::UnstableAttrForAlreadyStableFeature { span, item_sp }); |
| } |
| } |
| if let Stability { |
| level: StabilityLevel::Unstable { implied_by: Some(implied_by), .. }, |
| feature, |
| } = stab |
| { |
| self.index.implications.insert(implied_by, feature); |
| } |
| |
| self.index.stab_map.insert(def_id, stab); |
| stab |
| }); |
| |
| if stab.is_none() { |
| debug!("annotate: stab not found, parent = {:?}", self.parent_stab); |
| if let Some(stab) = self.parent_stab { |
| if inherit_deprecation.yes() && stab.is_unstable() || inherit_from_parent.yes() { |
| self.index.stab_map.insert(def_id, stab); |
| } |
| } |
| } |
| |
| let final_stab = self.index.stab_map.get(&def_id); |
| |
| // # Const stability |
| |
| let const_stab = attrs::find_attr!(attrs, AttributeKind::ConstStability { stability, span } => (*stability, *span)); |
| |
| // If the current node is a function with const stability attributes (directly given or |
| // implied), check if the function/method is const or the parent impl block is const. |
| if let Some(fn_sig) = fn_sig |
| && !fn_sig.header.is_const() |
| && const_stab.is_some() |
| { |
| self.tcx.dcx().emit_err(errors::MissingConstErr { fn_sig_span: fn_sig.span }); |
| } |
| |
| // If this is marked const *stable*, it must also be regular-stable. |
| if let Some((const_stab, const_span)) = const_stab |
| && let Some(fn_sig) = fn_sig |
| && const_stab.is_const_stable() |
| && !stab.is_some_and(|s| s.is_stable()) |
| { |
| self.tcx |
| .dcx() |
| .emit_err(errors::ConstStableNotStable { fn_sig_span: fn_sig.span, const_span }); |
| } |
| |
| // Stable *language* features shouldn't be used as unstable library features. |
| // (Not doing this for stable library features is checked by tidy.) |
| if let Some(( |
| PartialConstStability { level: StabilityLevel::Unstable { .. }, feature, .. }, |
| const_span, |
| )) = const_stab |
| { |
| if ACCEPTED_LANG_FEATURES.iter().find(|f| f.name == feature).is_some() { |
| self.tcx.dcx().emit_err(errors::UnstableAttrForAlreadyStableFeature { |
| span: const_span, |
| item_sp, |
| }); |
| } |
| } |
| |
| if let Some((stab, span)) = &const_stab |
| && stab.is_const_stable() |
| && const_stability_indirect |
| { |
| self.tcx.dcx().emit_err(errors::RustcConstStableIndirectPairing { span: *span }); |
| } |
| |
| // After checking the immediate attributes, get rid of the span and compute implied |
| // const stability: inherit feature gate from regular stability. |
| let mut const_stab = const_stab |
| .map(|(stab, _span)| ConstStability::from_partial(stab, const_stability_indirect)); |
| |
| // If this is a const fn but not annotated with stability markers, see if we can inherit regular stability. |
| if fn_sig.is_some_and(|s| s.header.is_const()) && const_stab.is_none() && |
| // We only ever inherit unstable features. |
| let Some(inherit_regular_stab) = |
| final_stab.filter(|s| s.is_unstable()) |
| { |
| const_stab = Some(ConstStability { |
| // We subject these implicitly-const functions to recursive const stability. |
| const_stable_indirect: true, |
| promotable: false, |
| level: inherit_regular_stab.level, |
| feature: inherit_regular_stab.feature, |
| }); |
| } |
| |
| // Now that everything is computed, insert it into the table. |
| const_stab.inspect(|const_stab| { |
| self.index.const_stab_map.insert(def_id, *const_stab); |
| }); |
| |
| if let Some(ConstStability { |
| level: StabilityLevel::Unstable { implied_by: Some(implied_by), .. }, |
| feature, |
| .. |
| }) = const_stab |
| { |
| self.index.implications.insert(implied_by, feature); |
| } |
| |
| // `impl const Trait for Type` items forward their const stability to their |
| // immediate children. |
| // FIXME(const_trait_impl): how is this supposed to interact with `#[rustc_const_stable_indirect]`? |
| // Currently, once that is set, we do not inherit anything from the parent any more. |
| if const_stab.is_none() { |
| debug!("annotate: const_stab not found, parent = {:?}", self.parent_const_stab); |
| if let Some(parent) = self.parent_const_stab { |
| if parent.is_const_unstable() { |
| self.index.const_stab_map.insert(def_id, parent); |
| } |
| } |
| } |
| |
| self.recurse_with_stability_attrs( |
| depr.map(|(d, _)| DeprecationEntry::local(d, def_id)), |
| stab, |
| inherit_const_stability.yes().then_some(const_stab).flatten(), |
| visit_children, |
| ); |
| } |
| |
| fn recurse_with_stability_attrs( |
| &mut self, |
| depr: Option<DeprecationEntry>, |
| stab: Option<Stability>, |
| const_stab: Option<ConstStability>, |
| f: impl FnOnce(&mut Self), |
| ) { |
| // These will be `Some` if this item changes the corresponding stability attribute. |
| let mut replaced_parent_depr = None; |
| let mut replaced_parent_stab = None; |
| let mut replaced_parent_const_stab = None; |
| |
| if let Some(depr) = depr { |
| replaced_parent_depr = Some(replace(&mut self.parent_depr, Some(depr))); |
| } |
| if let Some(stab) = stab { |
| replaced_parent_stab = Some(replace(&mut self.parent_stab, Some(stab))); |
| } |
| if let Some(const_stab) = const_stab { |
| replaced_parent_const_stab = |
| Some(replace(&mut self.parent_const_stab, Some(const_stab))); |
| } |
| |
| f(self); |
| |
| if let Some(orig_parent_depr) = replaced_parent_depr { |
| self.parent_depr = orig_parent_depr; |
| } |
| if let Some(orig_parent_stab) = replaced_parent_stab { |
| self.parent_stab = orig_parent_stab; |
| } |
| if let Some(orig_parent_const_stab) = replaced_parent_const_stab { |
| self.parent_const_stab = orig_parent_const_stab; |
| } |
| } |
| } |
| |
| impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> { |
| /// Because stability levels are scoped lexically, we want to walk |
| /// nested items in the context of the outer item, so enable |
| /// deep-walking. |
| type NestedFilter = nested_filter::All; |
| |
| fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt { |
| self.tcx |
| } |
| |
| fn visit_item(&mut self, i: &'tcx Item<'tcx>) { |
| let orig_in_trait_impl = self.in_trait_impl; |
| let mut kind = AnnotationKind::Required; |
| let mut const_stab_inherit = InheritConstStability::No; |
| let mut fn_sig = None; |
| |
| match i.kind { |
| // Inherent impls and foreign modules serve only as containers for other items, |
| // they don't have their own stability. They still can be annotated as unstable |
| // and propagate this instability to children, but this annotation is completely |
| // optional. They inherit stability from their parents when unannotated. |
| hir::ItemKind::Impl(hir::Impl { of_trait: None, .. }) |
| | hir::ItemKind::ForeignMod { .. } => { |
| self.in_trait_impl = false; |
| kind = AnnotationKind::Container; |
| } |
| hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) => { |
| self.in_trait_impl = true; |
| kind = AnnotationKind::DeprecationProhibited; |
| const_stab_inherit = InheritConstStability::Yes; |
| } |
| hir::ItemKind::Struct(_, _, ref sd) => { |
| if let Some(ctor_def_id) = sd.ctor_def_id() { |
| self.annotate( |
| ctor_def_id, |
| i.span, |
| None, |
| AnnotationKind::Required, |
| InheritDeprecation::Yes, |
| InheritConstStability::No, |
| InheritStability::Yes, |
| |_| {}, |
| ) |
| } |
| } |
| hir::ItemKind::Fn { sig: ref item_fn_sig, .. } => { |
| fn_sig = Some(item_fn_sig); |
| } |
| _ => {} |
| } |
| |
| self.annotate( |
| i.owner_id.def_id, |
| i.span, |
| fn_sig, |
| kind, |
| InheritDeprecation::Yes, |
| const_stab_inherit, |
| InheritStability::No, |
| |v| intravisit::walk_item(v, i), |
| ); |
| self.in_trait_impl = orig_in_trait_impl; |
| } |
| |
| fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem<'tcx>) { |
| let fn_sig = match ti.kind { |
| hir::TraitItemKind::Fn(ref fn_sig, _) => Some(fn_sig), |
| _ => None, |
| }; |
| |
| self.annotate( |
| ti.owner_id.def_id, |
| ti.span, |
| fn_sig, |
| AnnotationKind::Required, |
| InheritDeprecation::Yes, |
| InheritConstStability::No, |
| InheritStability::No, |
| |v| { |
| intravisit::walk_trait_item(v, ti); |
| }, |
| ); |
| } |
| |
| fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem<'tcx>) { |
| let kind = |
| if self.in_trait_impl { AnnotationKind::Prohibited } else { AnnotationKind::Required }; |
| |
| let fn_sig = match ii.kind { |
| hir::ImplItemKind::Fn(ref fn_sig, _) => Some(fn_sig), |
| _ => None, |
| }; |
| |
| self.annotate( |
| ii.owner_id.def_id, |
| ii.span, |
| fn_sig, |
| kind, |
| InheritDeprecation::Yes, |
| InheritConstStability::No, |
| InheritStability::No, |
| |v| { |
| intravisit::walk_impl_item(v, ii); |
| }, |
| ); |
| } |
| |
| fn visit_variant(&mut self, var: &'tcx Variant<'tcx>) { |
| self.annotate( |
| var.def_id, |
| var.span, |
| None, |
| AnnotationKind::Required, |
| InheritDeprecation::Yes, |
| InheritConstStability::No, |
| InheritStability::Yes, |
| |v| { |
| if let Some(ctor_def_id) = var.data.ctor_def_id() { |
| v.annotate( |
| ctor_def_id, |
| var.span, |
| None, |
| AnnotationKind::Required, |
| InheritDeprecation::Yes, |
| InheritConstStability::No, |
| InheritStability::Yes, |
| |_| {}, |
| ); |
| } |
| |
| intravisit::walk_variant(v, var) |
| }, |
| ) |
| } |
| |
| fn visit_field_def(&mut self, s: &'tcx FieldDef<'tcx>) { |
| self.annotate( |
| s.def_id, |
| s.span, |
| None, |
| AnnotationKind::Required, |
| InheritDeprecation::Yes, |
| InheritConstStability::No, |
| InheritStability::Yes, |
| |v| { |
| intravisit::walk_field_def(v, s); |
| }, |
| ); |
| } |
| |
| fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) { |
| let fn_sig = match &i.kind { |
| rustc_hir::ForeignItemKind::Fn(fn_sig, ..) => Some(fn_sig), |
| _ => None, |
| }; |
| self.annotate( |
| i.owner_id.def_id, |
| i.span, |
| fn_sig, |
| AnnotationKind::Required, |
| InheritDeprecation::Yes, |
| InheritConstStability::No, |
| InheritStability::No, |
| |v| { |
| intravisit::walk_foreign_item(v, i); |
| }, |
| ); |
| } |
| |
| fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) { |
| let kind = match &p.kind { |
| // Allow stability attributes on default generic arguments. |
| hir::GenericParamKind::Type { default: Some(_), .. } |
| | hir::GenericParamKind::Const { default: Some(_), .. } => AnnotationKind::Container, |
| _ => AnnotationKind::Prohibited, |
| }; |
| |
| self.annotate( |
| p.def_id, |
| p.span, |
| None, |
| kind, |
| InheritDeprecation::No, |
| InheritConstStability::No, |
| InheritStability::No, |
| |v| { |
| intravisit::walk_generic_param(v, p); |
| }, |
| ); |
| } |
| } |
| |
| struct MissingStabilityAnnotations<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| effective_visibilities: &'tcx EffectiveVisibilities, |
| } |
| |
| impl<'tcx> MissingStabilityAnnotations<'tcx> { |
| fn check_missing_stability(&self, def_id: LocalDefId, span: Span) { |
| let stab = self.tcx.stability().local_stability(def_id); |
| if !self.tcx.sess.is_test_crate() |
| && stab.is_none() |
| && self.effective_visibilities.is_reachable(def_id) |
| { |
| let descr = self.tcx.def_descr(def_id.to_def_id()); |
| self.tcx.dcx().emit_err(errors::MissingStabilityAttr { span, descr }); |
| } |
| } |
| |
| fn check_missing_const_stability(&self, def_id: LocalDefId, span: Span) { |
| let is_const = self.tcx.is_const_fn(def_id.to_def_id()) |
| || (self.tcx.def_kind(def_id.to_def_id()) == DefKind::Trait |
| && self.tcx.is_const_trait(def_id.to_def_id())); |
| |
| // Reachable const fn/trait must have a stability attribute. |
| if is_const |
| && self.effective_visibilities.is_reachable(def_id) |
| && self.tcx.lookup_const_stability(def_id).is_none() |
| { |
| let descr = self.tcx.def_descr(def_id.to_def_id()); |
| self.tcx.dcx().emit_err(errors::MissingConstStabAttr { span, descr }); |
| } |
| } |
| } |
| |
| impl<'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'tcx> { |
| type NestedFilter = nested_filter::OnlyBodies; |
| |
| fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt { |
| self.tcx |
| } |
| |
| fn visit_item(&mut self, i: &'tcx Item<'tcx>) { |
| // Inherent impls and foreign modules serve only as containers for other items, |
| // they don't have their own stability. They still can be annotated as unstable |
| // and propagate this instability to children, but this annotation is completely |
| // optional. They inherit stability from their parents when unannotated. |
| if !matches!( |
| i.kind, |
| hir::ItemKind::Impl(hir::Impl { of_trait: None, .. }) |
| | hir::ItemKind::ForeignMod { .. } |
| ) { |
| self.check_missing_stability(i.owner_id.def_id, i.span); |
| } |
| |
| // Ensure stable `const fn` have a const stability attribute. |
| self.check_missing_const_stability(i.owner_id.def_id, i.span); |
| |
| intravisit::walk_item(self, i) |
| } |
| |
| fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem<'tcx>) { |
| self.check_missing_stability(ti.owner_id.def_id, ti.span); |
| intravisit::walk_trait_item(self, ti); |
| } |
| |
| fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem<'tcx>) { |
| let impl_def_id = self.tcx.hir_get_parent_item(ii.hir_id()); |
| if self.tcx.impl_trait_ref(impl_def_id).is_none() { |
| self.check_missing_stability(ii.owner_id.def_id, ii.span); |
| self.check_missing_const_stability(ii.owner_id.def_id, ii.span); |
| } |
| intravisit::walk_impl_item(self, ii); |
| } |
| |
| fn visit_variant(&mut self, var: &'tcx Variant<'tcx>) { |
| self.check_missing_stability(var.def_id, var.span); |
| if let Some(ctor_def_id) = var.data.ctor_def_id() { |
| self.check_missing_stability(ctor_def_id, var.span); |
| } |
| intravisit::walk_variant(self, var); |
| } |
| |
| fn visit_field_def(&mut self, s: &'tcx FieldDef<'tcx>) { |
| self.check_missing_stability(s.def_id, s.span); |
| intravisit::walk_field_def(self, s); |
| } |
| |
| fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) { |
| self.check_missing_stability(i.owner_id.def_id, i.span); |
| intravisit::walk_foreign_item(self, i); |
| } |
| // Note that we don't need to `check_missing_stability` for default generic parameters, |
| // as we assume that any default generic parameters without attributes are automatically |
| // stable (assuming they have not inherited instability from their parent). |
| } |
| |
| fn stability_index(tcx: TyCtxt<'_>, (): ()) -> Index { |
| let mut index = Index { |
| stab_map: Default::default(), |
| const_stab_map: Default::default(), |
| default_body_stab_map: Default::default(), |
| depr_map: Default::default(), |
| implications: Default::default(), |
| }; |
| |
| { |
| let mut annotator = Annotator { |
| tcx, |
| index: &mut index, |
| parent_stab: None, |
| parent_const_stab: None, |
| parent_depr: None, |
| in_trait_impl: false, |
| }; |
| |
| // If the `-Z force-unstable-if-unmarked` flag is passed then we provide |
| // a parent stability annotation which indicates that this is private |
| // with the `rustc_private` feature. This is intended for use when |
| // compiling `librustc_*` crates themselves so we can leverage crates.io |
| // while maintaining the invariant that all sysroot crates are unstable |
| // by default and are unable to be used. |
| if tcx.sess.opts.unstable_opts.force_unstable_if_unmarked { |
| let stability = Stability { |
| level: attrs::StabilityLevel::Unstable { |
| reason: UnstableReason::Default, |
| issue: NonZero::new(27812), |
| is_soft: false, |
| implied_by: None, |
| old_name: None, |
| }, |
| feature: sym::rustc_private, |
| }; |
| annotator.parent_stab = Some(stability); |
| } |
| |
| annotator.annotate( |
| CRATE_DEF_ID, |
| tcx.hir_span(CRATE_HIR_ID), |
| None, |
| AnnotationKind::Required, |
| InheritDeprecation::Yes, |
| InheritConstStability::No, |
| InheritStability::No, |
| |v| tcx.hir_walk_toplevel_module(v), |
| ); |
| } |
| index |
| } |
| |
| /// Cross-references the feature names of unstable APIs with enabled |
| /// features and possibly prints errors. |
| fn check_mod_unstable_api_usage(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) { |
| tcx.hir_visit_item_likes_in_module(module_def_id, &mut Checker { tcx }); |
| } |
| |
| pub(crate) fn provide(providers: &mut Providers) { |
| *providers = Providers { |
| check_mod_unstable_api_usage, |
| stability_index, |
| stability_implications: |tcx, _| tcx.stability().implications.clone(), |
| lookup_stability: |tcx, id| tcx.stability().local_stability(id), |
| lookup_const_stability: |tcx, id| tcx.stability().local_const_stability(id), |
| lookup_default_body_stability: |tcx, id| tcx.stability().local_default_body_stability(id), |
| lookup_deprecation_entry: |tcx, id| tcx.stability().local_deprecation_entry(id), |
| ..*providers |
| }; |
| } |
| |
| struct Checker<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| } |
| |
| impl<'tcx> Visitor<'tcx> for Checker<'tcx> { |
| type NestedFilter = nested_filter::OnlyBodies; |
| |
| /// Because stability levels are scoped lexically, we want to walk |
| /// nested items in the context of the outer item, so enable |
| /// deep-walking. |
| fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt { |
| self.tcx |
| } |
| |
| fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) { |
| match item.kind { |
| hir::ItemKind::ExternCrate(_, ident) => { |
| // compiler-generated `extern crate` items have a dummy span. |
| // `std` is still checked for the `restricted-std` feature. |
| if item.span.is_dummy() && ident.name != sym::std { |
| return; |
| } |
| |
| let Some(cnum) = self.tcx.extern_mod_stmt_cnum(item.owner_id.def_id) else { |
| return; |
| }; |
| let def_id = cnum.as_def_id(); |
| self.tcx.check_stability(def_id, Some(item.hir_id()), item.span, None); |
| } |
| |
| // For implementations of traits, check the stability of each item |
| // individually as it's possible to have a stable trait with unstable |
| // items. |
| hir::ItemKind::Impl(hir::Impl { |
| of_trait: Some(t), self_ty, items, constness, .. |
| }) => { |
| let features = self.tcx.features(); |
| if features.staged_api() { |
| let attrs = self.tcx.hir_attrs(item.hir_id()); |
| let stab = attrs::find_attr!(attrs, AttributeKind::Stability{stability, span} => (*stability, *span)); |
| |
| // FIXME(jdonszelmann): make it impossible to miss the or_else in the typesystem |
| let const_stab = attrs::find_attr!(attrs, AttributeKind::ConstStability{stability, ..} => *stability); |
| |
| let unstable_feature_stab = |
| find_attr!(attrs, AttributeKind::UnstableFeatureBound(i) => i) |
| .map(|i| i.as_slice()) |
| .unwrap_or_default(); |
| |
| // If this impl block has an #[unstable] attribute, give an |
| // error if all involved types and traits are stable, because |
| // it will have no effect. |
| // See: https://github.com/rust-lang/rust/issues/55436 |
| // |
| // The exception is when there are both #[unstable_feature_bound(..)] and |
| // #![unstable(feature = "..", issue = "..")] that have the same symbol because |
| // that can effectively mark an impl as unstable. |
| // |
| // For example: |
| // ``` |
| // #[unstable_feature_bound(feat_foo)] |
| // #[unstable(feature = "feat_foo", issue = "none")] |
| // impl Foo for Bar {} |
| // ``` |
| if let Some(( |
| Stability { level: attrs::StabilityLevel::Unstable { .. }, feature }, |
| span, |
| )) = stab |
| { |
| let mut c = CheckTraitImplStable { tcx: self.tcx, fully_stable: true }; |
| c.visit_ty_unambig(self_ty); |
| c.visit_trait_ref(t); |
| |
| // Skip the lint if the impl is marked as unstable using |
| // #[unstable_feature_bound(..)] |
| let mut unstable_feature_bound_in_effect = false; |
| for (unstable_bound_feat_name, _) in unstable_feature_stab { |
| if *unstable_bound_feat_name == feature { |
| unstable_feature_bound_in_effect = true; |
| } |
| } |
| |
| // do not lint when the trait isn't resolved, since resolution error should |
| // be fixed first |
| if t.path.res != Res::Err |
| && c.fully_stable |
| && !unstable_feature_bound_in_effect |
| { |
| self.tcx.emit_node_span_lint( |
| INEFFECTIVE_UNSTABLE_TRAIT_IMPL, |
| item.hir_id(), |
| span, |
| errors::IneffectiveUnstableImpl, |
| ); |
| } |
| } |
| |
| if features.const_trait_impl() |
| && let hir::Constness::Const = constness |
| { |
| let stable_or_implied_stable = match const_stab { |
| None => true, |
| Some(stab) if stab.is_const_stable() => { |
| // `#![feature(const_trait_impl)]` is unstable, so any impl declared stable |
| // needs to have an error emitted. |
| // Note: Remove this error once `const_trait_impl` is stabilized |
| self.tcx |
| .dcx() |
| .emit_err(errors::TraitImplConstStable { span: item.span }); |
| true |
| } |
| Some(_) => false, |
| }; |
| |
| if let Some(trait_id) = t.trait_def_id() |
| && let Some(const_stab) = self.tcx.lookup_const_stability(trait_id) |
| { |
| // the const stability of a trait impl must match the const stability on the trait. |
| if const_stab.is_const_stable() != stable_or_implied_stable { |
| let trait_span = self.tcx.def_ident_span(trait_id).unwrap(); |
| |
| let impl_stability = if stable_or_implied_stable { |
| errors::ImplConstStability::Stable { span: item.span } |
| } else { |
| errors::ImplConstStability::Unstable { span: item.span } |
| }; |
| let trait_stability = if const_stab.is_const_stable() { |
| errors::TraitConstStability::Stable { span: trait_span } |
| } else { |
| errors::TraitConstStability::Unstable { span: trait_span } |
| }; |
| |
| self.tcx.dcx().emit_err(errors::TraitImplConstStabilityMismatch { |
| span: item.span, |
| impl_stability, |
| trait_stability, |
| }); |
| } |
| } |
| } |
| } |
| |
| if let hir::Constness::Const = constness |
| && let Some(def_id) = t.trait_def_id() |
| { |
| // FIXME(const_trait_impl): Improve the span here. |
| self.tcx.check_const_stability(def_id, t.path.span, t.path.span); |
| } |
| |
| for impl_item_ref in *items { |
| let impl_item = self.tcx.associated_item(impl_item_ref.owner_id); |
| |
| if let Some(def_id) = impl_item.trait_item_def_id { |
| // Pass `None` to skip deprecation warnings. |
| self.tcx.check_stability( |
| def_id, |
| None, |
| self.tcx.def_span(impl_item_ref.owner_id), |
| None, |
| ); |
| } |
| } |
| } |
| |
| _ => (/* pass */), |
| } |
| intravisit::walk_item(self, item); |
| } |
| |
| fn visit_poly_trait_ref(&mut self, t: &'tcx hir::PolyTraitRef<'tcx>) { |
| match t.modifiers.constness { |
| hir::BoundConstness::Always(span) | hir::BoundConstness::Maybe(span) => { |
| if let Some(def_id) = t.trait_ref.trait_def_id() { |
| self.tcx.check_const_stability(def_id, t.trait_ref.path.span, span); |
| } |
| } |
| hir::BoundConstness::Never => {} |
| } |
| intravisit::walk_poly_trait_ref(self, t); |
| } |
| |
| fn visit_path(&mut self, path: &hir::Path<'tcx>, id: hir::HirId) { |
| if let Some(def_id) = path.res.opt_def_id() { |
| let method_span = path.segments.last().map(|s| s.ident.span); |
| let item_is_allowed = self.tcx.check_stability_allow_unstable( |
| def_id, |
| Some(id), |
| path.span, |
| method_span, |
| if is_unstable_reexport(self.tcx, id) { |
| AllowUnstable::Yes |
| } else { |
| AllowUnstable::No |
| }, |
| ); |
| |
| if item_is_allowed { |
| // The item itself is allowed; check whether the path there is also allowed. |
| let is_allowed_through_unstable_modules: Option<Symbol> = |
| self.tcx.lookup_stability(def_id).and_then(|stab| match stab.level { |
| StabilityLevel::Stable { allowed_through_unstable_modules, .. } => { |
| allowed_through_unstable_modules |
| } |
| _ => None, |
| }); |
| |
| // Check parent modules stability as well if the item the path refers to is itself |
| // stable. We only emit errors for unstable path segments if the item is stable |
| // or allowed because stability is often inherited, so the most common case is that |
| // both the segments and the item are unstable behind the same feature flag. |
| // |
| // We check here rather than in `visit_path_segment` to prevent visiting the last |
| // path segment twice |
| // |
| // We include special cases via #[rustc_allowed_through_unstable_modules] for items |
| // that were accidentally stabilized through unstable paths before this check was |
| // added, such as `core::intrinsics::transmute` |
| let parents = path.segments.iter().rev().skip(1); |
| for path_segment in parents { |
| if let Some(def_id) = path_segment.res.opt_def_id() { |
| match is_allowed_through_unstable_modules { |
| None => { |
| // Emit a hard stability error if this path is not stable. |
| |
| // use `None` for id to prevent deprecation check |
| self.tcx.check_stability_allow_unstable( |
| def_id, |
| None, |
| path.span, |
| None, |
| if is_unstable_reexport(self.tcx, id) { |
| AllowUnstable::Yes |
| } else { |
| AllowUnstable::No |
| }, |
| ); |
| } |
| Some(deprecation) => { |
| // Call the stability check directly so that we can control which |
| // diagnostic is emitted. |
| let eval_result = self.tcx.eval_stability_allow_unstable( |
| def_id, |
| None, |
| path.span, |
| None, |
| if is_unstable_reexport(self.tcx, id) { |
| AllowUnstable::Yes |
| } else { |
| AllowUnstable::No |
| }, |
| ); |
| let is_allowed = matches!(eval_result, EvalResult::Allow); |
| if !is_allowed { |
| // Calculating message for lint involves calling `self.def_path_str`, |
| // which will by default invoke the expensive `visible_parent_map` query. |
| // Skip all that work if the lint is allowed anyway. |
| if self.tcx.lint_level_at_node(DEPRECATED, id).level |
| == lint::Level::Allow |
| { |
| return; |
| } |
| // Show a deprecation message. |
| let def_path = |
| with_no_trimmed_paths!(self.tcx.def_path_str(def_id)); |
| let def_kind = self.tcx.def_descr(def_id); |
| let diag = Deprecated { |
| sub: None, |
| kind: def_kind.to_owned(), |
| path: def_path, |
| note: Some(deprecation), |
| since_kind: lint::DeprecatedSinceKind::InEffect, |
| }; |
| self.tcx.emit_node_span_lint( |
| DEPRECATED, |
| id, |
| method_span.unwrap_or(path.span), |
| diag, |
| ); |
| } |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| intravisit::walk_path(self, path) |
| } |
| } |
| |
| /// Check whether a path is a `use` item that has been marked as unstable. |
| /// |
| /// See issue #94972 for details on why this is a special case |
| fn is_unstable_reexport(tcx: TyCtxt<'_>, id: hir::HirId) -> bool { |
| // Get the LocalDefId so we can lookup the item to check the kind. |
| let Some(owner) = id.as_owner() else { |
| return false; |
| }; |
| let def_id = owner.def_id; |
| |
| let Some(stab) = tcx.stability().local_stability(def_id) else { |
| return false; |
| }; |
| |
| if stab.level.is_stable() { |
| // The re-export is not marked as unstable, don't override |
| return false; |
| } |
| |
| // If this is a path that isn't a use, we don't need to do anything special |
| if !matches!(tcx.hir_expect_item(def_id).kind, ItemKind::Use(..)) { |
| return false; |
| } |
| |
| true |
| } |
| |
| struct CheckTraitImplStable<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| fully_stable: bool, |
| } |
| |
| impl<'tcx> Visitor<'tcx> for CheckTraitImplStable<'tcx> { |
| fn visit_path(&mut self, path: &hir::Path<'tcx>, _id: hir::HirId) { |
| if let Some(def_id) = path.res.opt_def_id() { |
| if let Some(stab) = self.tcx.lookup_stability(def_id) { |
| self.fully_stable &= stab.level.is_stable(); |
| } |
| } |
| intravisit::walk_path(self, path) |
| } |
| |
| fn visit_trait_ref(&mut self, t: &'tcx TraitRef<'tcx>) { |
| if let Res::Def(DefKind::Trait, trait_did) = t.path.res { |
| if let Some(stab) = self.tcx.lookup_stability(trait_did) { |
| self.fully_stable &= stab.level.is_stable(); |
| } |
| } |
| intravisit::walk_trait_ref(self, t) |
| } |
| |
| fn visit_ty(&mut self, t: &'tcx Ty<'tcx, AmbigArg>) { |
| if let TyKind::Never = t.kind { |
| self.fully_stable = false; |
| } |
| if let TyKind::FnPtr(function) = t.kind { |
| if extern_abi_stability(function.abi).is_err() { |
| self.fully_stable = false; |
| } |
| } |
| intravisit::walk_ty(self, t) |
| } |
| |
| fn visit_fn_decl(&mut self, fd: &'tcx hir::FnDecl<'tcx>) { |
| for ty in fd.inputs { |
| self.visit_ty_unambig(ty) |
| } |
| if let hir::FnRetTy::Return(output_ty) = fd.output { |
| match output_ty.kind { |
| TyKind::Never => {} // `-> !` is stable |
| _ => self.visit_ty_unambig(output_ty), |
| } |
| } |
| } |
| } |
| |
| /// Given the list of enabled features that were not language features (i.e., that |
| /// were expected to be library features), and the list of features used from |
| /// libraries, identify activated features that don't exist and error about them. |
| pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) { |
| let is_staged_api = |
| tcx.sess.opts.unstable_opts.force_unstable_if_unmarked || tcx.features().staged_api(); |
| if is_staged_api { |
| let effective_visibilities = &tcx.effective_visibilities(()); |
| let mut missing = MissingStabilityAnnotations { tcx, effective_visibilities }; |
| missing.check_missing_stability(CRATE_DEF_ID, tcx.hir_span(CRATE_HIR_ID)); |
| tcx.hir_walk_toplevel_module(&mut missing); |
| tcx.hir_visit_all_item_likes_in_crate(&mut missing); |
| } |
| |
| let enabled_lang_features = tcx.features().enabled_lang_features(); |
| let mut lang_features = UnordSet::default(); |
| for EnabledLangFeature { gate_name, attr_sp, stable_since } in enabled_lang_features { |
| if let Some(version) = stable_since { |
| // Warn if the user has enabled an already-stable lang feature. |
| unnecessary_stable_feature_lint(tcx, *attr_sp, *gate_name, *version); |
| } |
| if !lang_features.insert(gate_name) { |
| // Warn if the user enables a lang feature multiple times. |
| tcx.dcx().emit_err(errors::DuplicateFeatureErr { span: *attr_sp, feature: *gate_name }); |
| } |
| } |
| |
| let enabled_lib_features = tcx.features().enabled_lib_features(); |
| let mut remaining_lib_features = FxIndexMap::default(); |
| for EnabledLibFeature { gate_name, attr_sp } in enabled_lib_features { |
| if remaining_lib_features.contains_key(gate_name) { |
| // Warn if the user enables a lib feature multiple times. |
| tcx.dcx().emit_err(errors::DuplicateFeatureErr { span: *attr_sp, feature: *gate_name }); |
| } |
| remaining_lib_features.insert(*gate_name, *attr_sp); |
| } |
| // `stdbuild` has special handling for `libc`, so we need to |
| // recognise the feature when building std. |
| // Likewise, libtest is handled specially, so `test` isn't |
| // available as we'd like it to be. |
| // FIXME: only remove `libc` when `stdbuild` is enabled. |
| // FIXME: remove special casing for `test`. |
| // FIXME(#120456) - is `swap_remove` correct? |
| remaining_lib_features.swap_remove(&sym::libc); |
| remaining_lib_features.swap_remove(&sym::test); |
| |
| /// For each feature in `defined_features`.. |
| /// |
| /// - If it is in `remaining_lib_features` (those features with `#![feature(..)]` attributes in |
| /// the current crate), check if it is stable (or partially stable) and thus an unnecessary |
| /// attribute. |
| /// - If it is in `remaining_implications` (a feature that is referenced by an `implied_by` |
| /// from the current crate), then remove it from the remaining implications. |
| /// |
| /// Once this function has been invoked for every feature (local crate and all extern crates), |
| /// then.. |
| /// |
| /// - If features remain in `remaining_lib_features`, then the user has enabled a feature that |
| /// does not exist. |
| /// - If features remain in `remaining_implications`, the `implied_by` refers to a feature that |
| /// does not exist. |
| /// |
| /// By structuring the code in this way: checking the features defined from each crate one at a |
| /// time, less loading from metadata is performed and thus compiler performance is improved. |
| fn check_features<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| remaining_lib_features: &mut FxIndexMap<Symbol, Span>, |
| remaining_implications: &mut UnordMap<Symbol, Symbol>, |
| defined_features: &LibFeatures, |
| all_implications: &UnordMap<Symbol, Symbol>, |
| ) { |
| for (feature, stability) in defined_features.to_sorted_vec() { |
| if let FeatureStability::AcceptedSince(since) = stability |
| && let Some(span) = remaining_lib_features.get(&feature) |
| { |
| // Warn if the user has enabled an already-stable lib feature. |
| if let Some(implies) = all_implications.get(&feature) { |
| unnecessary_partially_stable_feature_lint(tcx, *span, feature, *implies, since); |
| } else { |
| unnecessary_stable_feature_lint(tcx, *span, feature, since); |
| } |
| } |
| // FIXME(#120456) - is `swap_remove` correct? |
| remaining_lib_features.swap_remove(&feature); |
| |
| // `feature` is the feature doing the implying, but `implied_by` is the feature with |
| // the attribute that establishes this relationship. `implied_by` is guaranteed to be a |
| // feature defined in the local crate because `remaining_implications` is only the |
| // implications from this crate. |
| remaining_implications.remove(&feature); |
| |
| if let FeatureStability::Unstable { old_name: Some(alias) } = stability { |
| if let Some(span) = remaining_lib_features.swap_remove(&alias) { |
| tcx.dcx().emit_err(errors::RenamedFeature { span, feature, alias }); |
| } |
| } |
| |
| if remaining_lib_features.is_empty() && remaining_implications.is_empty() { |
| break; |
| } |
| } |
| } |
| |
| // All local crate implications need to have the feature that implies it confirmed to exist. |
| let mut remaining_implications = tcx.stability_implications(LOCAL_CRATE).clone(); |
| |
| // We always collect the lib features enabled in the current crate, even if there are |
| // no unknown features, because the collection also does feature attribute validation. |
| let local_defined_features = tcx.lib_features(LOCAL_CRATE); |
| if !remaining_lib_features.is_empty() || !remaining_implications.is_empty() { |
| // Loading the implications of all crates is unavoidable to be able to emit the partial |
| // stabilization diagnostic, but it can be avoided when there are no |
| // `remaining_lib_features`. |
| let mut all_implications = remaining_implications.clone(); |
| for &cnum in tcx.crates(()) { |
| all_implications |
| .extend_unord(tcx.stability_implications(cnum).items().map(|(k, v)| (*k, *v))); |
| } |
| |
| check_features( |
| tcx, |
| &mut remaining_lib_features, |
| &mut remaining_implications, |
| local_defined_features, |
| &all_implications, |
| ); |
| |
| for &cnum in tcx.crates(()) { |
| if remaining_lib_features.is_empty() && remaining_implications.is_empty() { |
| break; |
| } |
| check_features( |
| tcx, |
| &mut remaining_lib_features, |
| &mut remaining_implications, |
| tcx.lib_features(cnum), |
| &all_implications, |
| ); |
| } |
| } |
| |
| for (feature, span) in remaining_lib_features { |
| tcx.dcx().emit_err(errors::UnknownFeature { span, feature }); |
| } |
| |
| for (&implied_by, &feature) in remaining_implications.to_sorted_stable_ord() { |
| let local_defined_features = tcx.lib_features(LOCAL_CRATE); |
| let span = local_defined_features |
| .stability |
| .get(&feature) |
| .expect("feature that implied another does not exist") |
| .1; |
| tcx.dcx().emit_err(errors::ImpliedFeatureNotExist { span, feature, implied_by }); |
| } |
| |
| // FIXME(#44232): the `used_features` table no longer exists, so we |
| // don't lint about unused features. We should re-enable this one day! |
| } |
| |
| fn unnecessary_partially_stable_feature_lint( |
| tcx: TyCtxt<'_>, |
| span: Span, |
| feature: Symbol, |
| implies: Symbol, |
| since: Symbol, |
| ) { |
| tcx.emit_node_span_lint( |
| lint::builtin::STABLE_FEATURES, |
| hir::CRATE_HIR_ID, |
| span, |
| errors::UnnecessaryPartialStableFeature { |
| span, |
| line: tcx.sess.source_map().span_extend_to_line(span), |
| feature, |
| since, |
| implies, |
| }, |
| ); |
| } |
| |
| fn unnecessary_stable_feature_lint( |
| tcx: TyCtxt<'_>, |
| span: Span, |
| feature: Symbol, |
| mut since: Symbol, |
| ) { |
| if since.as_str() == VERSION_PLACEHOLDER { |
| since = sym::env_CFG_RELEASE; |
| } |
| tcx.emit_node_span_lint( |
| lint::builtin::STABLE_FEATURES, |
| hir::CRATE_HIR_ID, |
| span, |
| errors::UnnecessaryStableFeature { feature, since }, |
| ); |
| } |
