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, in_derive_expansion};
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};
16 use syntax::ast::Attribute;
17 use syntax::errors::Applicability;
18 use syntax::feature_gate::{GateIssue, emit_feature_err};
19 use syntax::attr::{self, Stability, Deprecation};
20 use crate::ty::{self, TyCtxt};
21 use crate::util::nodemap::{FxHashSet, FxHashMap};
23 use std::mem::replace;
24 use std::cmp::Ordering;
26 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Copy, Debug, Eq, Hash)]
27 pub enum StabilityLevel {
33 pub fn from_attr_level(level: &attr::StabilityLevel) -> Self {
34 if level.is_stable() { Stable } else { Unstable }
40 // Annotation is required if not inherited from unstable parents
42 // Annotation is useless, reject it
44 // Annotation itself is useless, but it can be propagated to children
48 /// An entry in the `depr_map`.
50 pub struct DeprecationEntry {
51 /// The metadata of the attribute associated with this entry.
52 pub attr: Deprecation,
53 /// The `DefId` where the attr was originally attached. `None` for non-local
55 origin: Option<HirId>,
58 impl_stable_hash_for!(struct self::DeprecationEntry {
63 impl DeprecationEntry {
64 fn local(attr: Deprecation, id: HirId) -> DeprecationEntry {
71 pub fn external(attr: Deprecation) -> DeprecationEntry {
78 pub fn same_origin(&self, other: &DeprecationEntry) -> bool {
79 match (self.origin, other.origin) {
80 (Some(o1), Some(o2)) => o1 == o2,
86 /// A stability index, giving the stability level for items and methods.
87 pub struct Index<'tcx> {
88 /// This is mostly a cache, except the stabilities of local items
89 /// are filled by the annotator.
90 stab_map: FxHashMap<HirId, &'tcx Stability>,
91 depr_map: FxHashMap<HirId, DeprecationEntry>,
93 /// Maps for each crate whether it is part of the staged API.
94 staged_api: FxHashMap<CrateNum, bool>,
96 /// Features enabled for this crate.
97 active_features: FxHashSet<Symbol>,
100 impl_stable_hash_for!(struct self::Index<'tcx> {
107 // A private tree-walker for producing an Index.
108 struct Annotator<'a, 'tcx: 'a> {
109 tcx: TyCtxt<'a, 'tcx, 'tcx>,
110 index: &'a mut Index<'tcx>,
111 parent_stab: Option<&'tcx Stability>,
112 parent_depr: Option<DeprecationEntry>,
116 impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
117 // Determine the stability for a node based on its attributes and inherited
118 // stability. The stability is recorded in the index and used as the parent.
119 fn annotate<F>(&mut self, hir_id: HirId, attrs: &[Attribute],
120 item_sp: Span, kind: AnnotationKind, visit_children: F)
121 where F: FnOnce(&mut Self)
123 if self.tcx.features().staged_api {
124 // This crate explicitly wants staged API.
125 debug!("annotate(id = {:?}, attrs = {:?})", hir_id, attrs);
126 if let Some(..) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
127 self.tcx.sess.span_err(item_sp, "`#[deprecated]` cannot be used in staged api, \
128 use `#[rustc_deprecated]` instead");
130 if let Some(mut stab) = attr::find_stability(&self.tcx.sess.parse_sess,
132 // Error if prohibited, or can't inherit anything from a container
133 if kind == AnnotationKind::Prohibited ||
134 (kind == AnnotationKind::Container &&
135 stab.level.is_stable() &&
136 stab.rustc_depr.is_none()) {
137 self.tcx.sess.span_err(item_sp, "This stability annotation is useless");
140 debug!("annotate: found {:?}", stab);
141 // If parent is deprecated and we're not, inherit this by merging
142 // deprecated_since and its reason.
143 if let Some(parent_stab) = self.parent_stab {
144 if parent_stab.rustc_depr.is_some() && stab.rustc_depr.is_none() {
145 stab.rustc_depr = parent_stab.rustc_depr.clone()
149 let stab = self.tcx.intern_stability(stab);
151 // Check if deprecated_since < stable_since. If it is,
152 // this is *almost surely* an accident.
153 if let (&Some(attr::RustcDeprecation {since: dep_since, ..}),
154 &attr::Stable {since: stab_since}) = (&stab.rustc_depr, &stab.level) {
155 // Explicit version of iter::order::lt to handle parse errors properly
156 for (dep_v, stab_v) in dep_since.as_str()
158 .zip(stab_since.as_str().split('.'))
160 if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
161 match dep_v.cmp(&stab_v) {
163 self.tcx.sess.span_err(item_sp, "An API can't be stabilized \
164 after it is deprecated");
167 Ordering::Equal => continue,
168 Ordering::Greater => break,
171 // Act like it isn't less because the question is now nonsensical,
172 // and this makes us not do anything else interesting.
173 self.tcx.sess.span_err(item_sp, "Invalid stability or deprecation \
180 self.index.stab_map.insert(hir_id, stab);
182 let orig_parent_stab = replace(&mut self.parent_stab, Some(stab));
183 visit_children(self);
184 self.parent_stab = orig_parent_stab;
186 debug!("annotate: not found, parent = {:?}", self.parent_stab);
187 if let Some(stab) = self.parent_stab {
188 if stab.level.is_unstable() {
189 self.index.stab_map.insert(hir_id, stab);
192 visit_children(self);
195 // Emit errors for non-staged-api crates.
197 if let Some(tag) = attr.ident_str() {
198 if tag == "unstable" || tag == "stable" || tag == "rustc_deprecated" {
199 attr::mark_used(attr);
200 self.tcx.sess.span_err(attr.span, "stability attributes may not be used \
201 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 is_error = !self.tcx.sess.opts.test &&
323 self.access_levels.is_reachable(hir_id);
325 self.tcx.sess.span_err(
327 &format!("{} has missing stability attribute", name),
333 impl<'a, 'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'a, 'tcx> {
334 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
335 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
338 fn visit_item(&mut self, i: &'tcx Item) {
340 // Inherent impls and foreign modules serve only as containers for other items,
341 // they don't have their own stability. They still can be annotated as unstable
342 // and propagate this unstability to children, but this annotation is completely
343 // optional. They inherit stability from their parents when unannotated.
344 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {}
346 _ => self.check_missing_stability(i.hir_id, i.span, i.node.descriptive_variant())
349 intravisit::walk_item(self, i)
352 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
353 self.check_missing_stability(ti.hir_id, ti.span, "item");
354 intravisit::walk_trait_item(self, ti);
357 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
358 let impl_def_id = self.tcx.hir().local_def_id_from_hir_id(
359 self.tcx.hir().get_parent_item(ii.hir_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 active_lib_features = &tcx.features().declared_lib_features;
401 let active_lang_features = &tcx.features().declared_lang_features;
403 // Put the active features into a map for quick lookup.
404 index.active_features =
405 active_lib_features.iter().map(|&(ref s, ..)| s.clone())
406 .chain(active_lang_features.iter().map(|&(ref s, ..)| s.clone()))
410 let krate = tcx.hir().krate();
411 let mut annotator = Annotator {
416 in_trait_impl: false,
419 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
420 // a parent stability annotation which indicates that this is private
421 // with the `rustc_private` feature. This is intended for use when
422 // compiling librustc crates themselves so we can leverage crates.io
423 // while maintaining the invariant that all sysroot crates are unstable
424 // by default and are unable to be used.
425 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
426 let reason = "this crate is being loaded from the sysroot, an \
427 unstable location; did you mean to load this crate \
428 from crates.io via `Cargo.toml` instead?";
429 let stability = tcx.intern_stability(Stability {
430 level: attr::StabilityLevel::Unstable {
431 reason: Some(Symbol::intern(reason)),
434 feature: Symbol::intern("rustc_private"),
436 const_stability: None,
439 annotator.parent_stab = Some(stability);
442 annotator.annotate(hir::CRATE_HIR_ID,
445 AnnotationKind::Required,
446 |v| intravisit::walk_crate(v, krate));
451 pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
452 self.stab_map.get(&id).cloned()
455 pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
456 self.depr_map.get(&id).cloned()
460 /// Cross-references the feature names of unstable APIs with enabled
461 /// features and possibly prints errors.
462 fn check_mod_unstable_api_usage<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
463 tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
466 pub fn provide(providers: &mut Providers<'_>) {
467 *providers = Providers {
468 check_mod_unstable_api_usage,
473 /// Checks whether an item marked with `deprecated(since="X")` is currently
474 /// deprecated (i.e., whether X is not greater than the current rustc version).
475 pub fn deprecation_in_effect(since: &str) -> bool {
476 fn parse_version(ver: &str) -> Vec<u32> {
477 // We ignore non-integer components of the version (e.g., "nightly").
478 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
481 if let Some(rustc) = option_env!("CFG_RELEASE") {
482 let since: Vec<u32> = parse_version(since);
483 let rustc: Vec<u32> = parse_version(rustc);
484 // We simply treat invalid `since` attributes as relating to a previous
485 // Rust version, thus always displaying the warning.
486 if since.len() != 3 {
491 // By default, a deprecation warning applies to
492 // the current version of the compiler.
497 struct Checker<'a, 'tcx: 'a> {
498 tcx: TyCtxt<'a, 'tcx, 'tcx>,
501 /// Result of `TyCtxt::eval_stability`.
502 pub enum EvalResult {
503 /// We can use the item because it is stable or we provided the
504 /// corresponding feature gate.
506 /// We cannot use the item because it is unstable and we did not provide the
507 /// corresponding feature gate.
510 reason: Option<Symbol>,
513 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
517 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
519 fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
520 // Check if `def_id` is a trait method.
521 match self.describe_def(def_id) {
522 Some(Def::Method(_)) |
523 Some(Def::AssociatedTy(_)) |
524 Some(Def::AssociatedConst(_)) => {
525 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
526 // Trait methods do not declare visibility (even
527 // for visibility info in cstore). Use containing
528 // trait instead, so methods of `pub` traits are
529 // themselves considered `pub`.
530 def_id = trait_def_id;
536 let visibility = self.visibility(def_id);
539 // Must check stability for `pub` items.
540 ty::Visibility::Public => false,
542 // These are not visible outside crate; therefore
543 // stability markers are irrelevant, if even present.
544 ty::Visibility::Restricted(..) |
545 ty::Visibility::Invisible => true,
549 /// Evaluates the stability of an item.
551 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
552 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
553 /// unstable feature otherwise.
555 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
556 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
558 pub fn eval_stability(self, def_id: DefId, id: Option<HirId>, span: Span) -> EvalResult {
559 let lint_deprecated = |def_id: DefId,
561 note: Option<Symbol>,
562 suggestion: Option<Symbol>,
564 lint: &'static Lint| {
565 if in_derive_expansion(span) {
568 let msg = if let Some(note) = note {
569 format!("{}: {}", message, note)
571 format!("{}", message)
574 let mut diag = self.struct_span_lint_hir(lint, id, span, &msg);
575 if let Some(suggestion) = suggestion {
576 if let hir::Node::Expr(_) = self.hir().get_by_hir_id(id) {
577 diag.span_suggestion(
580 suggestion.to_string(),
581 Applicability::MachineApplicable,
586 if id == hir::DUMMY_HIR_ID {
587 span_bug!(span, "emitted a {} lint with dummy HIR id: {:?}", lint.name, def_id);
591 // Deprecated attributes apply in-crate and cross-crate.
592 if let Some(id) = id {
593 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
594 let parent_def_id = self.hir().local_def_id_from_hir_id(
595 self.hir().get_parent_item(id));
596 let skip = self.lookup_deprecation_entry(parent_def_id)
597 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
600 let path = self.def_path_str(def_id);
601 let message = format!("use of deprecated item '{}'", path);
602 lint_deprecated(def_id,
604 depr_entry.attr.note,
607 lint::builtin::DEPRECATED);
612 let is_staged_api = self.lookup_stability(DefId {
613 index: CRATE_DEF_INDEX,
617 return EvalResult::Allow;
620 let stability = self.lookup_stability(def_id);
622 inspecting def_id={:?} span={:?} of stability={:?}", def_id, span, stability);
624 if let Some(id) = id {
625 if let Some(stability) = stability {
626 if let Some(depr) = &stability.rustc_depr {
627 let path = self.def_path_str(def_id);
628 if deprecation_in_effect(&depr.since.as_str()) {
629 let message = format!("use of deprecated item '{}'", path);
630 lint_deprecated(def_id,
635 lint::builtin::DEPRECATED);
637 let message = format!("use of item '{}' \
638 that will be deprecated in future version {}",
641 lint_deprecated(def_id,
646 lint::builtin::DEPRECATED_IN_FUTURE);
652 // Only the cross-crate scenario matters when checking unstable APIs
653 let cross_crate = !def_id.is_local();
655 return EvalResult::Allow;
658 // Issue #38412: private items lack stability markers.
659 if self.skip_stability_check_due_to_privacy(def_id) {
660 return EvalResult::Allow;
664 Some(&Stability { level: attr::Unstable { reason, issue }, feature, .. }) => {
665 if span.allows_unstable(&feature.as_str()) {
666 debug!("stability: skipping span={:?} since it is internal", span);
667 return EvalResult::Allow;
669 if self.stability().active_features.contains(&feature) {
670 return EvalResult::Allow;
673 // When we're compiling the compiler itself we may pull in
674 // crates from crates.io, but those crates may depend on other
675 // crates also pulled in from crates.io. We want to ideally be
676 // able to compile everything without requiring upstream
677 // modifications, so in the case that this looks like a
678 // `rustc_private` crate (e.g., a compiler crate) and we also have
679 // the `-Z force-unstable-if-unmarked` flag present (we're
680 // compiling a compiler crate), then let this missing feature
682 if feature == "rustc_private" && issue == 27812 {
683 if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
684 return EvalResult::Allow;
688 EvalResult::Deny { feature, reason, issue }
691 // Stable APIs are always ok to call and deprecated APIs are
692 // handled by the lint emitting logic above.
701 /// Checks if an item is stable or error out.
703 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
704 /// exist, emits an error.
706 /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
707 /// not `None`, a deprecated lint attached to `id` will be emitted.
708 pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) {
709 match self.eval_stability(def_id, id, span) {
710 EvalResult::Allow => {}
711 EvalResult::Deny { feature, reason, issue } => {
712 let msg = match reason {
713 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
714 None => format!("use of unstable library feature '{}'", &feature)
717 let msp: MultiSpan = span.into();
718 let cm = &self.sess.parse_sess.source_map();
719 let span_key = msp.primary_span().and_then(|sp: Span|
721 let file = cm.lookup_char_pos(sp.lo()).file;
722 if file.name.is_macros() {
732 let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
733 let fresh = self.sess.one_time_diagnostics.borrow_mut().insert(error_id);
735 emit_feature_err(&self.sess.parse_sess, &feature.as_str(), span,
736 GateIssue::Library(Some(issue)), &msg);
739 EvalResult::Unmarked => {
740 // The API could be uncallable for other reasons, for example when a private module
742 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
748 impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
749 /// Because stability levels are scoped lexically, we want to walk
750 /// nested items in the context of the outer item, so enable
752 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
753 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
756 fn visit_item(&mut self, item: &'tcx hir::Item) {
758 hir::ItemKind::ExternCrate(_) => {
759 // compiler-generated `extern crate` items have a dummy span.
760 if item.span.is_dummy() { return }
762 let def_id = self.tcx.hir().local_def_id_from_hir_id(item.hir_id);
763 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
767 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
768 self.tcx.check_stability(def_id, Some(item.hir_id), item.span);
771 // For implementations of traits, check the stability of each item
772 // individually as it's possible to have a stable trait with unstable
774 hir::ItemKind::Impl(.., Some(ref t), _, ref impl_item_refs) => {
775 if let Def::Trait(trait_did) = t.path.def {
776 for impl_item_ref in impl_item_refs {
777 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
778 let trait_item_def_id = self.tcx.associated_items(trait_did)
779 .find(|item| item.ident.name == impl_item.ident.name)
780 .map(|item| item.def_id);
781 if let Some(def_id) = trait_item_def_id {
782 // Pass `None` to skip deprecation warnings.
783 self.tcx.check_stability(def_id, None, impl_item.span);
789 // There's no good place to insert stability check for non-Copy unions,
790 // so semi-randomly perform it here in stability.rs
791 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
792 let def_id = self.tcx.hir().local_def_id_from_hir_id(item.hir_id);
793 let adt_def = self.tcx.adt_def(def_id);
794 let ty = self.tcx.type_of(def_id);
796 if adt_def.has_dtor(self.tcx) {
797 emit_feature_err(&self.tcx.sess.parse_sess,
798 "untagged_unions", item.span, GateIssue::Language,
799 "unions with `Drop` implementations are unstable");
801 let param_env = self.tcx.param_env(def_id);
802 if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
803 emit_feature_err(&self.tcx.sess.parse_sess,
804 "untagged_unions", item.span, GateIssue::Language,
805 "unions with non-`Copy` fields are unstable");
812 intravisit::walk_item(self, item);
815 fn visit_path(&mut self, path: &'tcx hir::Path, id: hir::HirId) {
816 if let Some(def_id) = path.def.opt_def_id() {
817 self.tcx.check_stability(def_id, Some(id), path.span)
819 intravisit::walk_path(self, path)
823 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
824 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
825 self.lookup_deprecation_entry(id).map(|depr| depr.attr)
829 /// Given the list of enabled features that were not language features (i.e., that
830 /// were expected to be library features), and the list of features used from
831 /// libraries, identify activated features that don't exist and error about them.
832 pub fn check_unused_or_stable_features<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
833 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
835 if tcx.stability().staged_api[&LOCAL_CRATE] {
836 let krate = tcx.hir().krate();
837 let mut missing = MissingStabilityAnnotations {
841 missing.check_missing_stability(hir::CRATE_HIR_ID, krate.span, "crate");
842 intravisit::walk_crate(&mut missing, krate);
843 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
846 let declared_lang_features = &tcx.features().declared_lang_features;
847 let mut lang_features = FxHashSet::default();
848 for &(feature, span, since) in declared_lang_features {
849 if let Some(since) = since {
850 // Warn if the user has enabled an already-stable lang feature.
851 unnecessary_stable_feature_lint(tcx, span, feature, since);
853 if lang_features.contains(&feature) {
854 // Warn if the user enables a lang feature multiple times.
855 duplicate_feature_err(tcx.sess, span, feature);
857 lang_features.insert(feature);
860 let declared_lib_features = &tcx.features().declared_lib_features;
861 let mut remaining_lib_features = FxHashMap::default();
862 for (feature, span) in declared_lib_features {
863 if remaining_lib_features.contains_key(&feature) {
864 // Warn if the user enables a lib feature multiple times.
865 duplicate_feature_err(tcx.sess, *span, *feature);
867 remaining_lib_features.insert(feature, span.clone());
869 // `stdbuild` has special handling for `libc`, so we need to
870 // recognise the feature when building std.
871 // Likewise, libtest is handled specially, so `test` isn't
872 // available as we'd like it to be.
873 // FIXME: only remove `libc` when `stdbuild` is active.
874 // FIXME: remove special casing for `test`.
875 remaining_lib_features.remove(&Symbol::intern("libc"));
876 remaining_lib_features.remove(&Symbol::intern("test"));
879 |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &Vec<_>| {
880 for &(feature, since) in defined_features {
881 if let Some(since) = since {
882 if let Some(span) = remaining_lib_features.get(&feature) {
883 // Warn if the user has enabled an already-stable lib feature.
884 unnecessary_stable_feature_lint(tcx, *span, feature, since);
887 remaining_lib_features.remove(&feature);
888 if remaining_lib_features.is_empty() {
894 // We always collect the lib features declared in the current crate, even if there are
895 // no unknown features, because the collection also does feature attribute validation.
896 let local_defined_features = tcx.lib_features().to_vec();
897 if !remaining_lib_features.is_empty() {
898 check_features(&mut remaining_lib_features, &local_defined_features);
900 for &cnum in &*tcx.crates() {
901 if remaining_lib_features.is_empty() {
904 check_features(&mut remaining_lib_features, &tcx.defined_lib_features(cnum));
908 for (feature, span) in remaining_lib_features {
909 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
912 // FIXME(#44232): the `used_features` table no longer exists, so we
913 // don't lint about unused features. We should reenable this one day!
916 fn unnecessary_stable_feature_lint<'a, 'tcx>(
917 tcx: TyCtxt<'a, 'tcx, 'tcx>,
922 tcx.lint_hir(lint::builtin::STABLE_FEATURES,
925 &format!("the feature `{}` has been stable since {} and no longer requires \
926 an attribute to enable", feature, since));
929 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
930 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)