1 //! A pass that annotates every item and method with its stability level,
2 //! propagating default levels lexically from parent to children ast nodes.
4 pub use self::StabilityLevel::*;
6 use crate::lint::{self, Lint};
7 use crate::hir::{self, Item, Generics, StructField, Variant, HirId};
8 use crate::hir::def::Def;
9 use crate::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId, LOCAL_CRATE};
10 use crate::hir::intravisit::{self, Visitor, NestedVisitorMap};
11 use crate::ty::query::Providers;
12 use crate::middle::privacy::AccessLevels;
13 use crate::session::{DiagnosticMessageId, Session};
14 use syntax::symbol::Symbol;
15 use syntax_pos::{Span, MultiSpan};
17 use syntax::ast::{NodeId, Attribute};
18 use syntax::errors::Applicability;
19 use syntax::feature_gate::{GateIssue, emit_feature_err};
20 use syntax::attr::{self, Stability, Deprecation};
21 use crate::ty::{self, TyCtxt};
22 use crate::util::nodemap::{FxHashSet, FxHashMap};
24 use std::mem::replace;
25 use std::cmp::Ordering;
27 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Copy, Debug, Eq, Hash)]
28 pub enum StabilityLevel {
34 pub fn from_attr_level(level: &attr::StabilityLevel) -> Self {
35 if level.is_stable() { Stable } else { Unstable }
41 // Annotation is required if not inherited from unstable parents
43 // Annotation is useless, reject it
45 // Annotation itself is useless, but it can be propagated to children
49 /// An entry in the `depr_map`.
51 pub struct DeprecationEntry {
52 /// The metadata of the attribute associated with this entry.
53 pub attr: Deprecation,
54 /// The `DefId` where the attr was originally attached. `None` for non-local
56 origin: Option<HirId>,
59 impl_stable_hash_for!(struct self::DeprecationEntry {
64 impl DeprecationEntry {
65 fn local(attr: Deprecation, id: HirId) -> DeprecationEntry {
72 pub fn external(attr: Deprecation) -> DeprecationEntry {
79 pub fn same_origin(&self, other: &DeprecationEntry) -> bool {
80 match (self.origin, other.origin) {
81 (Some(o1), Some(o2)) => o1 == o2,
87 /// A stability index, giving the stability level for items and methods.
88 pub struct Index<'tcx> {
89 /// This is mostly a cache, except the stabilities of local items
90 /// are filled by the annotator.
91 stab_map: FxHashMap<HirId, &'tcx Stability>,
92 depr_map: FxHashMap<HirId, DeprecationEntry>,
94 /// Maps for each crate whether it is part of the staged API.
95 staged_api: FxHashMap<CrateNum, bool>,
97 /// Features enabled for this crate.
98 active_features: FxHashSet<Symbol>,
101 impl_stable_hash_for!(struct self::Index<'tcx> {
108 // A private tree-walker for producing an Index.
109 struct Annotator<'a, 'tcx: 'a> {
110 tcx: TyCtxt<'a, 'tcx, 'tcx>,
111 index: &'a mut Index<'tcx>,
112 parent_stab: Option<&'tcx Stability>,
113 parent_depr: Option<DeprecationEntry>,
117 impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
118 // Determine the stability for a node based on its attributes and inherited
119 // stability. The stability is recorded in the index and used as the parent.
120 fn annotate<F>(&mut self, hir_id: HirId, attrs: &[Attribute],
121 item_sp: Span, kind: AnnotationKind, visit_children: F)
122 where F: FnOnce(&mut Self)
124 if self.tcx.features().staged_api {
125 // This crate explicitly wants staged API.
126 debug!("annotate(id = {:?}, attrs = {:?})", hir_id, attrs);
127 if let Some(..) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
128 self.tcx.sess.span_err(item_sp, "`#[deprecated]` cannot be used in staged api, \
129 use `#[rustc_deprecated]` instead");
131 if let Some(mut stab) = attr::find_stability(&self.tcx.sess.parse_sess,
133 // Error if prohibited, or can't inherit anything from a container
134 if kind == AnnotationKind::Prohibited ||
135 (kind == AnnotationKind::Container &&
136 stab.level.is_stable() &&
137 stab.rustc_depr.is_none()) {
138 self.tcx.sess.span_err(item_sp, "This stability annotation is useless");
141 debug!("annotate: found {:?}", stab);
142 // If parent is deprecated and we're not, inherit this by merging
143 // deprecated_since and its reason.
144 if let Some(parent_stab) = self.parent_stab {
145 if parent_stab.rustc_depr.is_some() && stab.rustc_depr.is_none() {
146 stab.rustc_depr = parent_stab.rustc_depr.clone()
150 let stab = self.tcx.intern_stability(stab);
152 // Check if deprecated_since < stable_since. If it is,
153 // this is *almost surely* an accident.
154 if let (&Some(attr::RustcDeprecation {since: dep_since, ..}),
155 &attr::Stable {since: stab_since}) = (&stab.rustc_depr, &stab.level) {
156 // Explicit version of iter::order::lt to handle parse errors properly
157 for (dep_v, stab_v) in dep_since.as_str()
159 .zip(stab_since.as_str().split('.'))
161 if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
162 match dep_v.cmp(&stab_v) {
164 self.tcx.sess.span_err(item_sp, "An API can't be stabilized \
165 after it is deprecated");
168 Ordering::Equal => continue,
169 Ordering::Greater => break,
172 // Act like it isn't less because the question is now nonsensical,
173 // and this makes us not do anything else interesting.
174 self.tcx.sess.span_err(item_sp, "Invalid stability or deprecation \
181 self.index.stab_map.insert(hir_id, stab);
183 let orig_parent_stab = replace(&mut self.parent_stab, Some(stab));
184 visit_children(self);
185 self.parent_stab = orig_parent_stab;
187 debug!("annotate: not found, parent = {:?}", self.parent_stab);
188 if let Some(stab) = self.parent_stab {
189 if stab.level.is_unstable() {
190 self.index.stab_map.insert(hir_id, stab);
193 visit_children(self);
196 // Emit errors for non-staged-api crates.
198 let tag = attr.name();
199 if tag == "unstable" || tag == "stable" || tag == "rustc_deprecated" {
200 attr::mark_used(attr);
201 self.tcx.sess.span_err(attr.span(), "stability attributes may not be used \
202 outside of the standard library");
206 // Propagate unstability. This can happen even for non-staged-api crates in case
207 // -Zforce-unstable-if-unmarked is set.
208 if let Some(stab) = self.parent_stab {
209 if stab.level.is_unstable() {
210 self.index.stab_map.insert(hir_id, stab);
214 if let Some(depr) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
215 if kind == AnnotationKind::Prohibited {
216 self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
219 // `Deprecation` is just two pointers, no need to intern it
220 let depr_entry = DeprecationEntry::local(depr, hir_id);
221 self.index.depr_map.insert(hir_id, depr_entry.clone());
223 let orig_parent_depr = replace(&mut self.parent_depr,
225 visit_children(self);
226 self.parent_depr = orig_parent_depr;
227 } else if let Some(parent_depr) = self.parent_depr.clone() {
228 self.index.depr_map.insert(hir_id, parent_depr);
229 visit_children(self);
231 visit_children(self);
237 impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
238 /// Because stability levels are scoped lexically, we want to walk
239 /// nested items in the context of the outer item, so enable
241 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
242 NestedVisitorMap::All(&self.tcx.hir())
245 fn visit_item(&mut self, i: &'tcx Item) {
246 let orig_in_trait_impl = self.in_trait_impl;
247 let mut kind = AnnotationKind::Required;
249 // Inherent impls and foreign modules serve only as containers for other items,
250 // they don't have their own stability. They still can be annotated as unstable
251 // and propagate this unstability to children, but this annotation is completely
252 // optional. They inherit stability from their parents when unannotated.
253 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {
254 self.in_trait_impl = false;
255 kind = AnnotationKind::Container;
257 hir::ItemKind::Impl(.., Some(_), _, _) => {
258 self.in_trait_impl = true;
260 hir::ItemKind::Struct(ref sd, _) => {
262 self.annotate(sd.hir_id(), &i.attrs, i.span, AnnotationKind::Required, |_| {})
268 self.annotate(i.hir_id, &i.attrs, i.span, kind, |v| {
269 intravisit::walk_item(v, i)
271 self.in_trait_impl = orig_in_trait_impl;
274 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
275 self.annotate(ti.hir_id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
276 intravisit::walk_trait_item(v, ti);
280 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
281 let kind = if self.in_trait_impl {
282 AnnotationKind::Prohibited
284 AnnotationKind::Required
286 self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, |v| {
287 intravisit::walk_impl_item(v, ii);
291 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
292 self.annotate(var.node.data.hir_id(), &var.node.attrs, var.span, AnnotationKind::Required,
293 |v| { intravisit::walk_variant(v, var, g, item_id) })
296 fn visit_struct_field(&mut self, s: &'tcx StructField) {
297 self.annotate(s.hir_id, &s.attrs, s.span, AnnotationKind::Required, |v| {
298 intravisit::walk_struct_field(v, s);
302 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
303 self.annotate(i.hir_id, &i.attrs, i.span, AnnotationKind::Required, |v| {
304 intravisit::walk_foreign_item(v, i);
308 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
309 self.annotate(md.hir_id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
313 struct MissingStabilityAnnotations<'a, 'tcx: 'a> {
314 tcx: TyCtxt<'a, 'tcx, 'tcx>,
315 access_levels: &'a AccessLevels,
318 impl<'a, 'tcx: 'a> MissingStabilityAnnotations<'a, 'tcx> {
319 fn check_missing_stability(&self, hir_id: HirId, span: Span, name: &str) {
320 let stab = self.tcx.stability().local_stability(hir_id);
321 let node_id = self.tcx.hir().hir_to_node_id(hir_id);
322 let is_error = !self.tcx.sess.opts.test &&
324 self.access_levels.is_reachable(node_id);
326 self.tcx.sess.span_err(
328 &format!("{} has missing stability attribute", name),
334 impl<'a, 'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'a, 'tcx> {
335 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
336 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
339 fn visit_item(&mut self, i: &'tcx Item) {
341 // Inherent impls and foreign modules serve only as containers for other items,
342 // they don't have their own stability. They still can be annotated as unstable
343 // and propagate this unstability to children, but this annotation is completely
344 // optional. They inherit stability from their parents when unannotated.
345 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {}
347 _ => self.check_missing_stability(i.hir_id, i.span, i.node.descriptive_variant())
350 intravisit::walk_item(self, i)
353 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
354 self.check_missing_stability(ti.hir_id, ti.span, "item");
355 intravisit::walk_trait_item(self, ti);
358 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
359 let impl_def_id = self.tcx.hir().local_def_id(self.tcx.hir().get_parent(ii.id));
360 if self.tcx.impl_trait_ref(impl_def_id).is_none() {
361 self.check_missing_stability(ii.hir_id, ii.span, "item");
363 intravisit::walk_impl_item(self, ii);
366 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
367 self.check_missing_stability(var.node.data.hir_id(), var.span, "variant");
368 intravisit::walk_variant(self, var, g, item_id);
371 fn visit_struct_field(&mut self, s: &'tcx StructField) {
372 self.check_missing_stability(s.hir_id, s.span, "field");
373 intravisit::walk_struct_field(self, s);
376 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
377 self.check_missing_stability(i.hir_id, i.span, i.node.descriptive_variant());
378 intravisit::walk_foreign_item(self, i);
381 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
382 self.check_missing_stability(md.hir_id, md.span, "macro");
386 impl<'a, 'tcx> Index<'tcx> {
387 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Index<'tcx> {
389 tcx.sess.opts.debugging_opts.force_unstable_if_unmarked ||
390 tcx.features().staged_api;
391 let mut staged_api = FxHashMap::default();
392 staged_api.insert(LOCAL_CRATE, is_staged_api);
393 let mut index = Index {
395 stab_map: Default::default(),
396 depr_map: Default::default(),
397 active_features: Default::default(),
400 let ref active_lib_features = tcx.features().declared_lib_features;
402 // Put the active features into a map for quick lookup
403 index.active_features = active_lib_features.iter().map(|&(ref s, _)| s.clone()).collect();
406 let krate = tcx.hir().krate();
407 let mut annotator = Annotator {
412 in_trait_impl: false,
415 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
416 // a parent stability annotation which indicates that this is private
417 // with the `rustc_private` feature. This is intended for use when
418 // compiling librustc crates themselves so we can leverage crates.io
419 // while maintaining the invariant that all sysroot crates are unstable
420 // by default and are unable to be used.
421 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
422 let reason = "this crate is being loaded from the sysroot, an \
423 unstable location; did you mean to load this crate \
424 from crates.io via `Cargo.toml` instead?";
425 let stability = tcx.intern_stability(Stability {
426 level: attr::StabilityLevel::Unstable {
427 reason: Some(Symbol::intern(reason)),
430 feature: Symbol::intern("rustc_private"),
432 const_stability: None,
435 annotator.parent_stab = Some(stability);
438 annotator.annotate(hir::CRATE_HIR_ID,
441 AnnotationKind::Required,
442 |v| intravisit::walk_crate(v, krate));
447 pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
448 self.stab_map.get(&id).cloned()
451 pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
452 self.depr_map.get(&id).cloned()
456 pub fn check_unstable_api_usage<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
457 for &module in tcx.hir().krate().modules.keys() {
458 tcx.ensure().check_mod_unstable_api_usage(tcx.hir().local_def_id(module));
462 /// Cross-references the feature names of unstable APIs with enabled
463 /// features and possibly prints errors.
464 fn check_mod_unstable_api_usage<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
465 tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
468 pub fn provide(providers: &mut Providers<'_>) {
469 *providers = Providers {
470 check_mod_unstable_api_usage,
475 /// Checks whether an item marked with `deprecated(since="X")` is currently
476 /// deprecated (i.e., whether X is not greater than the current rustc version).
477 pub fn deprecation_in_effect(since: &str) -> bool {
478 fn parse_version(ver: &str) -> Vec<u32> {
479 // We ignore non-integer components of the version (e.g., "nightly").
480 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
483 if let Some(rustc) = option_env!("CFG_RELEASE") {
484 let since: Vec<u32> = parse_version(since);
485 let rustc: Vec<u32> = parse_version(rustc);
486 // We simply treat invalid `since` attributes as relating to a previous
487 // Rust version, thus always displaying the warning.
488 if since.len() != 3 {
493 // By default, a deprecation warning applies to
494 // the current version of the compiler.
499 struct Checker<'a, 'tcx: 'a> {
500 tcx: TyCtxt<'a, 'tcx, 'tcx>,
503 /// Result of `TyCtxt::eval_stability`.
504 pub enum EvalResult {
505 /// We can use the item because it is stable or we provided the
506 /// corresponding feature gate.
508 /// We cannot use the item because it is unstable and we did not provide the
509 /// corresponding feature gate.
512 reason: Option<Symbol>,
515 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
519 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
521 fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
522 // Check if `def_id` is a trait method.
523 match self.describe_def(def_id) {
524 Some(Def::Method(_)) |
525 Some(Def::AssociatedTy(_)) |
526 Some(Def::AssociatedConst(_)) => {
527 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
528 // Trait methods do not declare visibility (even
529 // for visibility info in cstore). Use containing
530 // trait instead, so methods of `pub` traits are
531 // themselves considered `pub`.
532 def_id = trait_def_id;
538 let visibility = self.visibility(def_id);
541 // Must check stability for `pub` items.
542 ty::Visibility::Public => false,
544 // These are not visible outside crate; therefore
545 // stability markers are irrelevant, if even present.
546 ty::Visibility::Restricted(..) |
547 ty::Visibility::Invisible => true,
551 /// Evaluates the stability of an item.
553 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
554 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
555 /// unstable feature otherwise.
557 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
558 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
560 pub fn eval_stability(self, def_id: DefId, id: Option<NodeId>, span: Span) -> EvalResult {
561 let lint_deprecated = |def_id: DefId,
563 note: Option<Symbol>,
564 suggestion: Option<Symbol>,
566 lint: &'static Lint| {
567 let msg = if let Some(note) = note {
568 format!("{}: {}", message, note)
570 format!("{}", message)
573 let mut diag = self.struct_span_lint_node(lint, id, span, &msg);
574 if let Some(suggestion) = suggestion {
575 if let hir::Node::Expr(_) = self.hir().get(id) {
576 diag.span_suggestion(
579 suggestion.to_string(),
580 Applicability::MachineApplicable,
585 if id == ast::DUMMY_NODE_ID {
586 span_bug!(span, "emitted a {} lint with dummy node id: {:?}", lint.name, def_id);
590 // Deprecated attributes apply in-crate and cross-crate.
591 if let Some(id) = id {
592 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
593 let parent_def_id = self.hir().local_def_id(self.hir().get_parent(id));
594 let skip = self.lookup_deprecation_entry(parent_def_id)
595 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
598 let path = self.item_path_str(def_id);
599 let message = format!("use of deprecated item '{}'", path);
600 lint_deprecated(def_id,
602 depr_entry.attr.note,
605 lint::builtin::DEPRECATED);
610 let is_staged_api = self.lookup_stability(DefId {
611 index: CRATE_DEF_INDEX,
615 return EvalResult::Allow;
618 let stability = self.lookup_stability(def_id);
620 inspecting def_id={:?} span={:?} of stability={:?}", def_id, span, stability);
622 if let Some(id) = id {
623 if let Some(stability) = stability {
624 if let Some(depr) = &stability.rustc_depr {
625 let path = self.item_path_str(def_id);
626 if deprecation_in_effect(&depr.since.as_str()) {
627 let message = format!("use of deprecated item '{}'", path);
628 lint_deprecated(def_id,
633 lint::builtin::DEPRECATED);
635 let message = format!("use of item '{}' \
636 that will be deprecated in future version {}",
639 lint_deprecated(def_id,
644 lint::builtin::DEPRECATED_IN_FUTURE);
650 // Only the cross-crate scenario matters when checking unstable APIs
651 let cross_crate = !def_id.is_local();
653 return EvalResult::Allow;
656 // Issue #38412: private items lack stability markers.
657 if self.skip_stability_check_due_to_privacy(def_id) {
658 return EvalResult::Allow;
662 Some(&Stability { level: attr::Unstable { reason, issue }, feature, .. }) => {
663 if span.allows_unstable(&feature.as_str()) {
664 debug!("stability: skipping span={:?} since it is internal", span);
665 return EvalResult::Allow;
667 if self.stability().active_features.contains(&feature) {
668 return EvalResult::Allow;
671 // When we're compiling the compiler itself we may pull in
672 // crates from crates.io, but those crates may depend on other
673 // crates also pulled in from crates.io. We want to ideally be
674 // able to compile everything without requiring upstream
675 // modifications, so in the case that this looks like a
676 // `rustc_private` crate (e.g., a compiler crate) and we also have
677 // the `-Z force-unstable-if-unmarked` flag present (we're
678 // compiling a compiler crate), then let this missing feature
680 if feature == "rustc_private" && issue == 27812 {
681 if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
682 return EvalResult::Allow;
686 EvalResult::Deny { feature, reason, issue }
689 // Stable APIs are always ok to call and deprecated APIs are
690 // handled by the lint emitting logic above.
699 /// Checks if an item is stable or error out.
701 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
702 /// exist, emits an error.
704 /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
705 /// not `None`, a deprecated lint attached to `id` will be emitted.
706 pub fn check_stability(self, def_id: DefId, id: Option<NodeId>, span: Span) {
707 match self.eval_stability(def_id, id, span) {
708 EvalResult::Allow => {}
709 EvalResult::Deny { feature, reason, issue } => {
710 let msg = match reason {
711 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
712 None => format!("use of unstable library feature '{}'", &feature)
715 let msp: MultiSpan = span.into();
716 let cm = &self.sess.parse_sess.source_map();
717 let span_key = msp.primary_span().and_then(|sp: Span|
719 let file = cm.lookup_char_pos(sp.lo()).file;
720 if file.name.is_macros() {
730 let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
731 let fresh = self.sess.one_time_diagnostics.borrow_mut().insert(error_id);
733 emit_feature_err(&self.sess.parse_sess, &feature.as_str(), span,
734 GateIssue::Library(Some(issue)), &msg);
737 EvalResult::Unmarked => {
738 // The API could be uncallable for other reasons, for example when a private module
740 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
746 impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
747 /// Because stability levels are scoped lexically, we want to walk
748 /// nested items in the context of the outer item, so enable
750 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
751 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
754 fn visit_item(&mut self, item: &'tcx hir::Item) {
756 hir::ItemKind::ExternCrate(_) => {
757 // compiler-generated `extern crate` items have a dummy span.
758 if item.span.is_dummy() { return }
760 let def_id = self.tcx.hir().local_def_id(item.id);
761 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
765 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
766 self.tcx.check_stability(def_id, Some(item.id), item.span);
769 // For implementations of traits, check the stability of each item
770 // individually as it's possible to have a stable trait with unstable
772 hir::ItemKind::Impl(.., Some(ref t), _, ref impl_item_refs) => {
773 if let Def::Trait(trait_did) = t.path.def {
774 for impl_item_ref in impl_item_refs {
775 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
776 let trait_item_def_id = self.tcx.associated_items(trait_did)
777 .find(|item| item.ident.name == impl_item.ident.name)
778 .map(|item| item.def_id);
779 if let Some(def_id) = trait_item_def_id {
780 // Pass `None` to skip deprecation warnings.
781 self.tcx.check_stability(def_id, None, impl_item.span);
787 // There's no good place to insert stability check for non-Copy unions,
788 // so semi-randomly perform it here in stability.rs
789 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
790 let def_id = self.tcx.hir().local_def_id(item.id);
791 let adt_def = self.tcx.adt_def(def_id);
792 let ty = self.tcx.type_of(def_id);
794 if adt_def.has_dtor(self.tcx) {
795 emit_feature_err(&self.tcx.sess.parse_sess,
796 "untagged_unions", item.span, GateIssue::Language,
797 "unions with `Drop` implementations are unstable");
799 let param_env = self.tcx.param_env(def_id);
800 if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
801 emit_feature_err(&self.tcx.sess.parse_sess,
802 "untagged_unions", item.span, GateIssue::Language,
803 "unions with non-`Copy` fields are unstable");
810 intravisit::walk_item(self, item);
813 fn visit_path(&mut self, path: &'tcx hir::Path, id: hir::HirId) {
814 let id = self.tcx.hir().hir_to_node_id(id);
815 if let Some(def_id) = path.def.opt_def_id() {
816 self.tcx.check_stability(def_id, Some(id), path.span)
818 intravisit::walk_path(self, path)
822 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
823 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
824 self.lookup_deprecation_entry(id).map(|depr| depr.attr)
828 /// Given the list of enabled features that were not language features (i.e., that
829 /// were expected to be library features), and the list of features used from
830 /// libraries, identify activated features that don't exist and error about them.
831 pub fn check_unused_or_stable_features<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
832 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
834 if tcx.stability().staged_api[&LOCAL_CRATE] {
835 let krate = tcx.hir().krate();
836 let mut missing = MissingStabilityAnnotations {
840 missing.check_missing_stability(hir::CRATE_HIR_ID, krate.span, "crate");
841 intravisit::walk_crate(&mut missing, krate);
842 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
845 let declared_lang_features = &tcx.features().declared_lang_features;
846 let mut lang_features = FxHashSet::default();
847 for &(feature, span, since) in declared_lang_features {
848 if let Some(since) = since {
849 // Warn if the user has enabled an already-stable lang feature.
850 unnecessary_stable_feature_lint(tcx, span, feature, since);
852 if lang_features.contains(&feature) {
853 // Warn if the user enables a lang feature multiple times.
854 duplicate_feature_err(tcx.sess, span, feature);
856 lang_features.insert(feature);
859 let declared_lib_features = &tcx.features().declared_lib_features;
860 let mut remaining_lib_features = FxHashMap::default();
861 for (feature, span) in declared_lib_features {
862 if remaining_lib_features.contains_key(&feature) {
863 // Warn if the user enables a lib feature multiple times.
864 duplicate_feature_err(tcx.sess, *span, *feature);
866 remaining_lib_features.insert(feature, span.clone());
868 // `stdbuild` has special handling for `libc`, so we need to
869 // recognise the feature when building std.
870 // Likewise, libtest is handled specially, so `test` isn't
871 // available as we'd like it to be.
872 // FIXME: only remove `libc` when `stdbuild` is active.
873 // FIXME: remove special casing for `test`.
874 remaining_lib_features.remove(&Symbol::intern("libc"));
875 remaining_lib_features.remove(&Symbol::intern("test"));
878 |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &Vec<_>| {
879 for &(feature, since) in defined_features {
880 if let Some(since) = since {
881 if let Some(span) = remaining_lib_features.get(&feature) {
882 // Warn if the user has enabled an already-stable lib feature.
883 unnecessary_stable_feature_lint(tcx, *span, feature, since);
886 remaining_lib_features.remove(&feature);
887 if remaining_lib_features.is_empty() {
893 // We always collect the lib features declared in the current crate, even if there are
894 // no unknown features, because the collection also does feature attribute validation.
895 let local_defined_features = tcx.lib_features().to_vec();
896 if !remaining_lib_features.is_empty() {
897 check_features(&mut remaining_lib_features, &local_defined_features);
899 for &cnum in &*tcx.crates() {
900 if remaining_lib_features.is_empty() {
903 check_features(&mut remaining_lib_features, &tcx.defined_lib_features(cnum));
907 for (feature, span) in remaining_lib_features {
908 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
911 // FIXME(#44232): the `used_features` table no longer exists, so we
912 // don't lint about unused features. We should reenable this one day!
915 fn unnecessary_stable_feature_lint<'a, 'tcx>(
916 tcx: TyCtxt<'a, 'tcx, 'tcx>,
921 tcx.lint_node(lint::builtin::STABLE_FEATURES,
924 &format!("the feature `{}` has been stable since {} and no longer requires \
925 an attribute to enable", feature, since));
928 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
929 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)