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 let name = attr.name_or_empty();
198 if ["unstable", "stable", "rustc_deprecated"].contains(&name.get()) {
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");
205 // Propagate unstability. This can happen even for non-staged-api crates in case
206 // -Zforce-unstable-if-unmarked is set.
207 if let Some(stab) = self.parent_stab {
208 if stab.level.is_unstable() {
209 self.index.stab_map.insert(hir_id, stab);
213 if let Some(depr) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
214 if kind == AnnotationKind::Prohibited {
215 self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
218 // `Deprecation` is just two pointers, no need to intern it
219 let depr_entry = DeprecationEntry::local(depr, hir_id);
220 self.index.depr_map.insert(hir_id, depr_entry.clone());
222 let orig_parent_depr = replace(&mut self.parent_depr,
224 visit_children(self);
225 self.parent_depr = orig_parent_depr;
226 } else if let Some(parent_depr) = self.parent_depr.clone() {
227 self.index.depr_map.insert(hir_id, parent_depr);
228 visit_children(self);
230 visit_children(self);
236 impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
237 /// Because stability levels are scoped lexically, we want to walk
238 /// nested items in the context of the outer item, so enable
240 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
241 NestedVisitorMap::All(&self.tcx.hir())
244 fn visit_item(&mut self, i: &'tcx Item) {
245 let orig_in_trait_impl = self.in_trait_impl;
246 let mut kind = AnnotationKind::Required;
248 // Inherent impls and foreign modules serve only as containers for other items,
249 // they don't have their own stability. They still can be annotated as unstable
250 // and propagate this unstability to children, but this annotation is completely
251 // optional. They inherit stability from their parents when unannotated.
252 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {
253 self.in_trait_impl = false;
254 kind = AnnotationKind::Container;
256 hir::ItemKind::Impl(.., Some(_), _, _) => {
257 self.in_trait_impl = true;
259 hir::ItemKind::Struct(ref sd, _) => {
260 if let Some(ctor_hir_id) = sd.ctor_hir_id() {
261 self.annotate(ctor_hir_id, &i.attrs, i.span, AnnotationKind::Required, |_| {})
267 self.annotate(i.hir_id, &i.attrs, i.span, kind, |v| {
268 intravisit::walk_item(v, i)
270 self.in_trait_impl = orig_in_trait_impl;
273 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
274 self.annotate(ti.hir_id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
275 intravisit::walk_trait_item(v, ti);
279 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
280 let kind = if self.in_trait_impl {
281 AnnotationKind::Prohibited
283 AnnotationKind::Required
285 self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, |v| {
286 intravisit::walk_impl_item(v, ii);
290 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
291 self.annotate(var.node.id, &var.node.attrs, var.span, AnnotationKind::Required,
293 if let Some(ctor_hir_id) = var.node.data.ctor_hir_id() {
294 v.annotate(ctor_hir_id, &var.node.attrs, var.span, AnnotationKind::Required,
298 intravisit::walk_variant(v, var, g, item_id)
302 fn visit_struct_field(&mut self, s: &'tcx StructField) {
303 self.annotate(s.hir_id, &s.attrs, s.span, AnnotationKind::Required, |v| {
304 intravisit::walk_struct_field(v, s);
308 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
309 self.annotate(i.hir_id, &i.attrs, i.span, AnnotationKind::Required, |v| {
310 intravisit::walk_foreign_item(v, i);
314 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
315 self.annotate(md.hir_id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
319 struct MissingStabilityAnnotations<'a, 'tcx: 'a> {
320 tcx: TyCtxt<'a, 'tcx, 'tcx>,
321 access_levels: &'a AccessLevels,
324 impl<'a, 'tcx: 'a> MissingStabilityAnnotations<'a, 'tcx> {
325 fn check_missing_stability(&self, hir_id: HirId, span: Span, name: &str) {
326 let stab = self.tcx.stability().local_stability(hir_id);
327 let is_error = !self.tcx.sess.opts.test &&
329 self.access_levels.is_reachable(hir_id);
331 self.tcx.sess.span_err(
333 &format!("{} has missing stability attribute", name),
339 impl<'a, 'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'a, 'tcx> {
340 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
341 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
344 fn visit_item(&mut self, i: &'tcx Item) {
346 // Inherent impls and foreign modules serve only as containers for other items,
347 // they don't have their own stability. They still can be annotated as unstable
348 // and propagate this unstability to children, but this annotation is completely
349 // optional. They inherit stability from their parents when unannotated.
350 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {}
352 _ => self.check_missing_stability(i.hir_id, i.span, i.node.descriptive_variant())
355 intravisit::walk_item(self, i)
358 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
359 self.check_missing_stability(ti.hir_id, ti.span, "item");
360 intravisit::walk_trait_item(self, ti);
363 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
364 let impl_def_id = self.tcx.hir().local_def_id_from_hir_id(
365 self.tcx.hir().get_parent_item(ii.hir_id));
366 if self.tcx.impl_trait_ref(impl_def_id).is_none() {
367 self.check_missing_stability(ii.hir_id, ii.span, "item");
369 intravisit::walk_impl_item(self, ii);
372 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
373 self.check_missing_stability(var.node.id, var.span, "variant");
374 intravisit::walk_variant(self, var, g, item_id);
377 fn visit_struct_field(&mut self, s: &'tcx StructField) {
378 self.check_missing_stability(s.hir_id, s.span, "field");
379 intravisit::walk_struct_field(self, s);
382 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
383 self.check_missing_stability(i.hir_id, i.span, i.node.descriptive_variant());
384 intravisit::walk_foreign_item(self, i);
387 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
388 self.check_missing_stability(md.hir_id, md.span, "macro");
392 impl<'a, 'tcx> Index<'tcx> {
393 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Index<'tcx> {
395 tcx.sess.opts.debugging_opts.force_unstable_if_unmarked ||
396 tcx.features().staged_api;
397 let mut staged_api = FxHashMap::default();
398 staged_api.insert(LOCAL_CRATE, is_staged_api);
399 let mut index = Index {
401 stab_map: Default::default(),
402 depr_map: Default::default(),
403 active_features: Default::default(),
406 let active_lib_features = &tcx.features().declared_lib_features;
407 let active_lang_features = &tcx.features().declared_lang_features;
409 // Put the active features into a map for quick lookup.
410 index.active_features =
411 active_lib_features.iter().map(|&(ref s, ..)| s.clone())
412 .chain(active_lang_features.iter().map(|&(ref s, ..)| s.clone()))
416 let krate = tcx.hir().krate();
417 let mut annotator = Annotator {
422 in_trait_impl: false,
425 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
426 // a parent stability annotation which indicates that this is private
427 // with the `rustc_private` feature. This is intended for use when
428 // compiling librustc crates themselves so we can leverage crates.io
429 // while maintaining the invariant that all sysroot crates are unstable
430 // by default and are unable to be used.
431 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
432 let reason = "this crate is being loaded from the sysroot, an \
433 unstable location; did you mean to load this crate \
434 from crates.io via `Cargo.toml` instead?";
435 let stability = tcx.intern_stability(Stability {
436 level: attr::StabilityLevel::Unstable {
437 reason: Some(Symbol::intern(reason)),
440 feature: Symbol::intern("rustc_private"),
442 const_stability: None,
445 annotator.parent_stab = Some(stability);
448 annotator.annotate(hir::CRATE_HIR_ID,
451 AnnotationKind::Required,
452 |v| intravisit::walk_crate(v, krate));
457 pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
458 self.stab_map.get(&id).cloned()
461 pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
462 self.depr_map.get(&id).cloned()
466 /// Cross-references the feature names of unstable APIs with enabled
467 /// features and possibly prints errors.
468 fn check_mod_unstable_api_usage<'tcx>(tcx: TyCtxt<'_, 'tcx, 'tcx>, module_def_id: DefId) {
469 tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
472 pub fn provide(providers: &mut Providers<'_>) {
473 *providers = Providers {
474 check_mod_unstable_api_usage,
479 /// Checks whether an item marked with `deprecated(since="X")` is currently
480 /// deprecated (i.e., whether X is not greater than the current rustc version).
481 pub fn deprecation_in_effect(since: &str) -> bool {
482 fn parse_version(ver: &str) -> Vec<u32> {
483 // We ignore non-integer components of the version (e.g., "nightly").
484 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
487 if let Some(rustc) = option_env!("CFG_RELEASE") {
488 let since: Vec<u32> = parse_version(since);
489 let rustc: Vec<u32> = parse_version(rustc);
490 // We simply treat invalid `since` attributes as relating to a previous
491 // Rust version, thus always displaying the warning.
492 if since.len() != 3 {
497 // By default, a deprecation warning applies to
498 // the current version of the compiler.
503 struct Checker<'a, 'tcx: 'a> {
504 tcx: TyCtxt<'a, 'tcx, 'tcx>,
507 /// Result of `TyCtxt::eval_stability`.
508 pub enum EvalResult {
509 /// We can use the item because it is stable or we provided the
510 /// corresponding feature gate.
512 /// We cannot use the item because it is unstable and we did not provide the
513 /// corresponding feature gate.
516 reason: Option<Symbol>,
519 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
523 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
525 fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
526 // Check if `def_id` is a trait method.
527 match self.describe_def(def_id) {
528 Some(Def::Method(_)) |
529 Some(Def::AssociatedTy(_)) |
530 Some(Def::AssociatedConst(_)) => {
531 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
532 // Trait methods do not declare visibility (even
533 // for visibility info in cstore). Use containing
534 // trait instead, so methods of `pub` traits are
535 // themselves considered `pub`.
536 def_id = trait_def_id;
542 let visibility = self.visibility(def_id);
545 // Must check stability for `pub` items.
546 ty::Visibility::Public => false,
548 // These are not visible outside crate; therefore
549 // stability markers are irrelevant, if even present.
550 ty::Visibility::Restricted(..) |
551 ty::Visibility::Invisible => true,
555 /// Evaluates the stability of an item.
557 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
558 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
559 /// unstable feature otherwise.
561 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
562 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
564 pub fn eval_stability(self, def_id: DefId, id: Option<HirId>, span: Span) -> EvalResult {
565 let lint_deprecated = |def_id: DefId,
567 note: Option<Symbol>,
568 suggestion: Option<Symbol>,
570 lint: &'static Lint| {
571 if in_derive_expansion(span) {
574 let msg = if let Some(note) = note {
575 format!("{}: {}", message, note)
577 format!("{}", message)
580 let mut diag = self.struct_span_lint_hir(lint, id, span, &msg);
581 if let Some(suggestion) = suggestion {
582 if let hir::Node::Expr(_) = self.hir().get_by_hir_id(id) {
583 diag.span_suggestion(
585 "replace the use of the deprecated item",
586 suggestion.to_string(),
587 Applicability::MachineApplicable,
592 if id == hir::DUMMY_HIR_ID {
593 span_bug!(span, "emitted a {} lint with dummy HIR id: {:?}", lint.name, def_id);
597 // Deprecated attributes apply in-crate and cross-crate.
598 if let Some(id) = id {
599 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
600 let parent_def_id = self.hir().local_def_id_from_hir_id(
601 self.hir().get_parent_item(id));
602 let skip = self.lookup_deprecation_entry(parent_def_id)
603 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
606 let path = self.def_path_str(def_id);
607 let message = format!("use of deprecated item '{}'", path);
608 lint_deprecated(def_id,
610 depr_entry.attr.note,
613 lint::builtin::DEPRECATED);
618 let is_staged_api = self.lookup_stability(DefId {
619 index: CRATE_DEF_INDEX,
623 return EvalResult::Allow;
626 let stability = self.lookup_stability(def_id);
628 inspecting def_id={:?} span={:?} of stability={:?}", def_id, span, stability);
630 if let Some(id) = id {
631 if let Some(stability) = stability {
632 if let Some(depr) = &stability.rustc_depr {
633 let path = self.def_path_str(def_id);
634 if deprecation_in_effect(&depr.since.as_str()) {
635 let message = format!("use of deprecated item '{}'", path);
636 lint_deprecated(def_id,
641 lint::builtin::DEPRECATED);
643 let message = format!("use of item '{}' \
644 that will be deprecated in future version {}",
647 lint_deprecated(def_id,
652 lint::builtin::DEPRECATED_IN_FUTURE);
658 // Only the cross-crate scenario matters when checking unstable APIs
659 let cross_crate = !def_id.is_local();
661 return EvalResult::Allow;
664 // Issue #38412: private items lack stability markers.
665 if self.skip_stability_check_due_to_privacy(def_id) {
666 return EvalResult::Allow;
670 Some(&Stability { level: attr::Unstable { reason, issue }, feature, .. }) => {
671 if span.allows_unstable(&feature.as_str()) {
672 debug!("stability: skipping span={:?} since it is internal", span);
673 return EvalResult::Allow;
675 if self.stability().active_features.contains(&feature) {
676 return EvalResult::Allow;
679 // When we're compiling the compiler itself we may pull in
680 // crates from crates.io, but those crates may depend on other
681 // crates also pulled in from crates.io. We want to ideally be
682 // able to compile everything without requiring upstream
683 // modifications, so in the case that this looks like a
684 // `rustc_private` crate (e.g., a compiler crate) and we also have
685 // the `-Z force-unstable-if-unmarked` flag present (we're
686 // compiling a compiler crate), then let this missing feature
688 if feature == "rustc_private" && issue == 27812 {
689 if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
690 return EvalResult::Allow;
694 EvalResult::Deny { feature, reason, issue }
697 // Stable APIs are always ok to call and deprecated APIs are
698 // handled by the lint emitting logic above.
707 /// Checks if an item is stable or error out.
709 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
710 /// exist, emits an error.
712 /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
713 /// not `None`, a deprecated lint attached to `id` will be emitted.
714 pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) {
715 match self.eval_stability(def_id, id, span) {
716 EvalResult::Allow => {}
717 EvalResult::Deny { feature, reason, issue } => {
718 let msg = match reason {
719 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
720 None => format!("use of unstable library feature '{}'", &feature)
723 let msp: MultiSpan = span.into();
724 let cm = &self.sess.parse_sess.source_map();
725 let span_key = msp.primary_span().and_then(|sp: Span|
727 let file = cm.lookup_char_pos(sp.lo()).file;
728 if file.name.is_macros() {
738 let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
739 let fresh = self.sess.one_time_diagnostics.borrow_mut().insert(error_id);
741 emit_feature_err(&self.sess.parse_sess, &feature.as_str(), span,
742 GateIssue::Library(Some(issue)), &msg);
745 EvalResult::Unmarked => {
746 // The API could be uncallable for other reasons, for example when a private module
748 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
754 impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
755 /// Because stability levels are scoped lexically, we want to walk
756 /// nested items in the context of the outer item, so enable
758 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
759 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
762 fn visit_item(&mut self, item: &'tcx hir::Item) {
764 hir::ItemKind::ExternCrate(_) => {
765 // compiler-generated `extern crate` items have a dummy span.
766 if item.span.is_dummy() { return }
768 let def_id = self.tcx.hir().local_def_id_from_hir_id(item.hir_id);
769 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
773 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
774 self.tcx.check_stability(def_id, Some(item.hir_id), item.span);
777 // For implementations of traits, check the stability of each item
778 // individually as it's possible to have a stable trait with unstable
780 hir::ItemKind::Impl(.., Some(ref t), _, ref impl_item_refs) => {
781 if let Def::Trait(trait_did) = t.path.def {
782 for impl_item_ref in impl_item_refs {
783 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
784 let trait_item_def_id = self.tcx.associated_items(trait_did)
785 .find(|item| item.ident.name == impl_item.ident.name)
786 .map(|item| item.def_id);
787 if let Some(def_id) = trait_item_def_id {
788 // Pass `None` to skip deprecation warnings.
789 self.tcx.check_stability(def_id, None, impl_item.span);
795 // There's no good place to insert stability check for non-Copy unions,
796 // so semi-randomly perform it here in stability.rs
797 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
798 let def_id = self.tcx.hir().local_def_id_from_hir_id(item.hir_id);
799 let adt_def = self.tcx.adt_def(def_id);
800 let ty = self.tcx.type_of(def_id);
802 if adt_def.has_dtor(self.tcx) {
803 emit_feature_err(&self.tcx.sess.parse_sess,
804 "untagged_unions", item.span, GateIssue::Language,
805 "unions with `Drop` implementations are unstable");
807 let param_env = self.tcx.param_env(def_id);
808 if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
809 emit_feature_err(&self.tcx.sess.parse_sess,
810 "untagged_unions", item.span, GateIssue::Language,
811 "unions with non-`Copy` fields are unstable");
818 intravisit::walk_item(self, item);
821 fn visit_path(&mut self, path: &'tcx hir::Path, id: hir::HirId) {
822 if let Some(def_id) = path.def.opt_def_id() {
823 self.tcx.check_stability(def_id, Some(id), path.span)
825 intravisit::walk_path(self, path)
829 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
830 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
831 self.lookup_deprecation_entry(id).map(|depr| depr.attr)
835 /// Given the list of enabled features that were not language features (i.e., that
836 /// were expected to be library features), and the list of features used from
837 /// libraries, identify activated features that don't exist and error about them.
838 pub fn check_unused_or_stable_features<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
839 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
841 if tcx.stability().staged_api[&LOCAL_CRATE] {
842 let krate = tcx.hir().krate();
843 let mut missing = MissingStabilityAnnotations {
847 missing.check_missing_stability(hir::CRATE_HIR_ID, krate.span, "crate");
848 intravisit::walk_crate(&mut missing, krate);
849 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
852 let declared_lang_features = &tcx.features().declared_lang_features;
853 let mut lang_features = FxHashSet::default();
854 for &(feature, span, since) in declared_lang_features {
855 if let Some(since) = since {
856 // Warn if the user has enabled an already-stable lang feature.
857 unnecessary_stable_feature_lint(tcx, span, feature, since);
859 if lang_features.contains(&feature) {
860 // Warn if the user enables a lang feature multiple times.
861 duplicate_feature_err(tcx.sess, span, feature);
863 lang_features.insert(feature);
866 let declared_lib_features = &tcx.features().declared_lib_features;
867 let mut remaining_lib_features = FxHashMap::default();
868 for (feature, span) in declared_lib_features {
869 if remaining_lib_features.contains_key(&feature) {
870 // Warn if the user enables a lib feature multiple times.
871 duplicate_feature_err(tcx.sess, *span, *feature);
873 remaining_lib_features.insert(feature, span.clone());
875 // `stdbuild` has special handling for `libc`, so we need to
876 // recognise the feature when building std.
877 // Likewise, libtest is handled specially, so `test` isn't
878 // available as we'd like it to be.
879 // FIXME: only remove `libc` when `stdbuild` is active.
880 // FIXME: remove special casing for `test`.
881 remaining_lib_features.remove(&Symbol::intern("libc"));
882 remaining_lib_features.remove(&Symbol::intern("test"));
885 |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &Vec<_>| {
886 for &(feature, since) in defined_features {
887 if let Some(since) = since {
888 if let Some(span) = remaining_lib_features.get(&feature) {
889 // Warn if the user has enabled an already-stable lib feature.
890 unnecessary_stable_feature_lint(tcx, *span, feature, since);
893 remaining_lib_features.remove(&feature);
894 if remaining_lib_features.is_empty() {
900 // We always collect the lib features declared in the current crate, even if there are
901 // no unknown features, because the collection also does feature attribute validation.
902 let local_defined_features = tcx.lib_features().to_vec();
903 if !remaining_lib_features.is_empty() {
904 check_features(&mut remaining_lib_features, &local_defined_features);
906 for &cnum in &*tcx.crates() {
907 if remaining_lib_features.is_empty() {
910 check_features(&mut remaining_lib_features, &tcx.defined_lib_features(cnum));
914 for (feature, span) in remaining_lib_features {
915 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
918 // FIXME(#44232): the `used_features` table no longer exists, so we
919 // don't lint about unused features. We should reenable this one day!
922 fn unnecessary_stable_feature_lint<'a, 'tcx>(
923 tcx: TyCtxt<'a, 'tcx, 'tcx>,
928 tcx.lint_hir(lint::builtin::STABLE_FEATURES,
931 &format!("the feature `{}` has been stable since {} and no longer requires \
932 an attribute to enable", feature, since));
935 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
936 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)