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::lint::builtin::BuiltinLintDiagnostics;
8 use crate::hir::{self, Item, Generics, StructField, Variant, HirId};
9 use crate::hir::def::{Res, DefKind};
10 use crate::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId, LOCAL_CRATE};
11 use crate::hir::intravisit::{self, Visitor, NestedVisitorMap};
12 use crate::ty::query::Providers;
13 use crate::middle::privacy::AccessLevels;
14 use crate::session::{DiagnosticMessageId, Session};
15 use errors::DiagnosticBuilder;
16 use syntax::symbol::{Symbol, sym};
17 use syntax_pos::{Span, MultiSpan};
18 use syntax::ast::{Attribute, CRATE_NODE_ID};
19 use syntax::errors::Applicability;
20 use syntax::feature_gate::{GateIssue, emit_feature_err};
21 use syntax::attr::{self, Stability, Deprecation, RustcDeprecation};
22 use crate::ty::{self, TyCtxt};
23 use crate::util::nodemap::{FxHashSet, FxHashMap};
25 use std::mem::replace;
26 use std::cmp::Ordering;
28 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Copy, Debug, Eq, Hash)]
29 pub enum StabilityLevel {
35 pub fn from_attr_level(level: &attr::StabilityLevel) -> Self {
36 if level.is_stable() { Stable } else { Unstable }
42 // Annotation is required if not inherited from unstable parents
44 // Annotation is useless, reject it
46 // Annotation itself is useless, but it can be propagated to children
50 /// An entry in the `depr_map`.
52 pub struct DeprecationEntry {
53 /// The metadata of the attribute associated with this entry.
54 pub attr: Deprecation,
55 /// The `DefId` where the attr was originally attached. `None` for non-local
57 origin: Option<HirId>,
60 impl_stable_hash_for!(struct self::DeprecationEntry {
65 impl DeprecationEntry {
66 fn local(attr: Deprecation, id: HirId) -> DeprecationEntry {
73 pub fn external(attr: Deprecation) -> DeprecationEntry {
80 pub fn same_origin(&self, other: &DeprecationEntry) -> bool {
81 match (self.origin, other.origin) {
82 (Some(o1), Some(o2)) => o1 == o2,
88 /// A stability index, giving the stability level for items and methods.
89 pub struct Index<'tcx> {
90 /// This is mostly a cache, except the stabilities of local items
91 /// are filled by the annotator.
92 stab_map: FxHashMap<HirId, &'tcx Stability>,
93 depr_map: FxHashMap<HirId, DeprecationEntry>,
95 /// Maps for each crate whether it is part of the staged API.
96 staged_api: FxHashMap<CrateNum, bool>,
98 /// Features enabled for this crate.
99 active_features: FxHashSet<Symbol>,
102 impl_stable_hash_for!(struct self::Index<'tcx> {
109 // A private tree-walker for producing an Index.
110 struct Annotator<'a, 'tcx> {
112 index: &'a mut Index<'tcx>,
113 parent_stab: Option<&'tcx Stability>,
114 parent_depr: Option<DeprecationEntry>,
118 impl<'a, 'tcx> Annotator<'a, 'tcx> {
119 // Determine the stability for a node based on its attributes and inherited
120 // stability. The stability is recorded in the index and used as the parent.
121 fn annotate<F>(&mut self, hir_id: HirId, attrs: &[Attribute],
122 item_sp: Span, kind: AnnotationKind, visit_children: F)
123 where F: FnOnce(&mut Self)
125 if self.tcx.features().staged_api {
126 // This crate explicitly wants staged API.
127 debug!("annotate(id = {:?}, attrs = {:?})", hir_id, attrs);
128 if let Some(..) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
129 self.tcx.sess.span_err(item_sp, "`#[deprecated]` cannot be used in staged API; \
130 use `#[rustc_deprecated]` instead");
132 if let Some(mut stab) = attr::find_stability(&self.tcx.sess.parse_sess,
134 // Error if prohibited, or can't inherit anything from a container.
135 if kind == AnnotationKind::Prohibited ||
136 (kind == AnnotationKind::Container &&
137 stab.level.is_stable() &&
138 stab.rustc_depr.is_none()) {
139 self.tcx.sess.span_err(item_sp, "This stability annotation is useless");
142 debug!("annotate: found {:?}", stab);
143 // If parent is deprecated and we're not, inherit this by merging
144 // deprecated_since and its reason.
145 if let Some(parent_stab) = self.parent_stab {
146 if parent_stab.rustc_depr.is_some() && stab.rustc_depr.is_none() {
147 stab.rustc_depr = parent_stab.rustc_depr.clone()
151 let stab = self.tcx.intern_stability(stab);
153 // Check if deprecated_since < stable_since. If it is,
154 // this is *almost surely* an accident.
155 if let (&Some(attr::RustcDeprecation {since: dep_since, ..}),
156 &attr::Stable {since: stab_since}) = (&stab.rustc_depr, &stab.level) {
157 // Explicit version of iter::order::lt to handle parse errors properly
158 for (dep_v, stab_v) in dep_since.as_str()
160 .zip(stab_since.as_str().split('.'))
162 if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
163 match dep_v.cmp(&stab_v) {
165 self.tcx.sess.span_err(item_sp, "An API can't be stabilized \
166 after it is deprecated");
169 Ordering::Equal => continue,
170 Ordering::Greater => break,
173 // Act like it isn't less because the question is now nonsensical,
174 // and this makes us not do anything else interesting.
175 self.tcx.sess.span_err(item_sp, "Invalid stability or deprecation \
182 self.index.stab_map.insert(hir_id, stab);
184 let orig_parent_stab = replace(&mut self.parent_stab, Some(stab));
185 visit_children(self);
186 self.parent_stab = orig_parent_stab;
188 debug!("annotate: not found, parent = {:?}", self.parent_stab);
189 if let Some(stab) = self.parent_stab {
190 if stab.level.is_unstable() {
191 self.index.stab_map.insert(hir_id, stab);
194 visit_children(self);
197 // Emit errors for non-staged-api crates.
199 let name = attr.name_or_empty();
200 if [sym::unstable, sym::stable, sym::rustc_deprecated].contains(&name) {
201 attr::mark_used(attr);
202 self.tcx.sess.span_err(attr.span, "stability attributes may not be used \
203 outside of the standard library");
207 // Propagate unstability. This can happen even for non-staged-api crates in case
208 // -Zforce-unstable-if-unmarked is set.
209 if let Some(stab) = self.parent_stab {
210 if stab.level.is_unstable() {
211 self.index.stab_map.insert(hir_id, stab);
215 if let Some(depr) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
216 if kind == AnnotationKind::Prohibited {
217 self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
220 // `Deprecation` is just two pointers, no need to intern it
221 let depr_entry = DeprecationEntry::local(depr, hir_id);
222 self.index.depr_map.insert(hir_id, depr_entry.clone());
224 let orig_parent_depr = replace(&mut self.parent_depr,
226 visit_children(self);
227 self.parent_depr = orig_parent_depr;
228 } else if let Some(parent_depr) = self.parent_depr.clone() {
229 self.index.depr_map.insert(hir_id, parent_depr);
230 visit_children(self);
232 visit_children(self);
238 impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
239 /// Because stability levels are scoped lexically, we want to walk
240 /// nested items in the context of the outer item, so enable
242 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
243 NestedVisitorMap::All(&self.tcx.hir())
246 fn visit_item(&mut self, i: &'tcx Item) {
247 let orig_in_trait_impl = self.in_trait_impl;
248 let mut kind = AnnotationKind::Required;
250 // Inherent impls and foreign modules serve only as containers for other items,
251 // they don't have their own stability. They still can be annotated as unstable
252 // and propagate this unstability to children, but this annotation is completely
253 // optional. They inherit stability from their parents when unannotated.
254 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {
255 self.in_trait_impl = false;
256 kind = AnnotationKind::Container;
258 hir::ItemKind::Impl(.., Some(_), _, _) => {
259 self.in_trait_impl = true;
261 hir::ItemKind::Struct(ref sd, _) => {
262 if let Some(ctor_hir_id) = sd.ctor_hir_id() {
263 self.annotate(ctor_hir_id, &i.attrs, i.span, AnnotationKind::Required, |_| {})
269 self.annotate(i.hir_id, &i.attrs, i.span, kind, |v| {
270 intravisit::walk_item(v, i)
272 self.in_trait_impl = orig_in_trait_impl;
275 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
276 self.annotate(ti.hir_id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
277 intravisit::walk_trait_item(v, ti);
281 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
282 let kind = if self.in_trait_impl {
283 AnnotationKind::Prohibited
285 AnnotationKind::Required
287 self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, |v| {
288 intravisit::walk_impl_item(v, ii);
292 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
293 self.annotate(var.id, &var.attrs, var.span, AnnotationKind::Required,
295 if let Some(ctor_hir_id) = var.data.ctor_hir_id() {
296 v.annotate(ctor_hir_id, &var.attrs, var.span, AnnotationKind::Required,
300 intravisit::walk_variant(v, var, g, item_id)
304 fn visit_struct_field(&mut self, s: &'tcx StructField) {
305 self.annotate(s.hir_id, &s.attrs, s.span, AnnotationKind::Required, |v| {
306 intravisit::walk_struct_field(v, s);
310 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
311 self.annotate(i.hir_id, &i.attrs, i.span, AnnotationKind::Required, |v| {
312 intravisit::walk_foreign_item(v, i);
316 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
317 self.annotate(md.hir_id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
321 struct MissingStabilityAnnotations<'a, 'tcx> {
323 access_levels: &'a AccessLevels,
326 impl<'a, 'tcx> MissingStabilityAnnotations<'a, 'tcx> {
327 fn check_missing_stability(&self, hir_id: HirId, span: Span, name: &str) {
328 let stab = self.tcx.stability().local_stability(hir_id);
329 let is_error = !self.tcx.sess.opts.test &&
331 self.access_levels.is_reachable(hir_id);
333 self.tcx.sess.span_err(
335 &format!("{} has missing stability attribute", name),
341 impl<'a, 'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'a, 'tcx> {
342 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
343 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
346 fn visit_item(&mut self, i: &'tcx Item) {
348 // Inherent impls and foreign modules serve only as containers for other items,
349 // they don't have their own stability. They still can be annotated as unstable
350 // and propagate this unstability to children, but this annotation is completely
351 // optional. They inherit stability from their parents when unannotated.
352 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {}
354 _ => self.check_missing_stability(i.hir_id, i.span, i.node.descriptive_variant())
357 intravisit::walk_item(self, i)
360 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
361 self.check_missing_stability(ti.hir_id, ti.span, "item");
362 intravisit::walk_trait_item(self, ti);
365 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
366 let impl_def_id = self.tcx.hir().local_def_id(
367 self.tcx.hir().get_parent_item(ii.hir_id));
368 if self.tcx.impl_trait_ref(impl_def_id).is_none() {
369 self.check_missing_stability(ii.hir_id, ii.span, "item");
371 intravisit::walk_impl_item(self, ii);
374 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
375 self.check_missing_stability(var.id, var.span, "variant");
376 intravisit::walk_variant(self, var, g, item_id);
379 fn visit_struct_field(&mut self, s: &'tcx StructField) {
380 self.check_missing_stability(s.hir_id, s.span, "field");
381 intravisit::walk_struct_field(self, s);
384 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
385 self.check_missing_stability(i.hir_id, i.span, i.node.descriptive_variant());
386 intravisit::walk_foreign_item(self, i);
389 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
390 self.check_missing_stability(md.hir_id, md.span, "macro");
394 impl<'tcx> Index<'tcx> {
395 pub fn new(tcx: TyCtxt<'tcx>) -> Index<'tcx> {
397 tcx.sess.opts.debugging_opts.force_unstable_if_unmarked ||
398 tcx.features().staged_api;
399 let mut staged_api = FxHashMap::default();
400 staged_api.insert(LOCAL_CRATE, is_staged_api);
401 let mut index = Index {
403 stab_map: Default::default(),
404 depr_map: Default::default(),
405 active_features: Default::default(),
408 let active_lib_features = &tcx.features().declared_lib_features;
409 let active_lang_features = &tcx.features().declared_lang_features;
411 // Put the active features into a map for quick lookup.
412 index.active_features =
413 active_lib_features.iter().map(|&(ref s, ..)| s.clone())
414 .chain(active_lang_features.iter().map(|&(ref s, ..)| s.clone()))
418 let krate = tcx.hir().krate();
419 let mut annotator = Annotator {
424 in_trait_impl: false,
427 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
428 // a parent stability annotation which indicates that this is private
429 // with the `rustc_private` feature. This is intended for use when
430 // compiling librustc crates themselves so we can leverage crates.io
431 // while maintaining the invariant that all sysroot crates are unstable
432 // by default and are unable to be used.
433 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
434 let reason = "this crate is being loaded from the sysroot, an \
435 unstable location; did you mean to load this crate \
436 from crates.io via `Cargo.toml` instead?";
437 let stability = tcx.intern_stability(Stability {
438 level: attr::StabilityLevel::Unstable {
439 reason: Some(Symbol::intern(reason)),
443 feature: sym::rustc_private,
445 const_stability: None,
447 allow_const_fn_ptr: false,
449 annotator.parent_stab = Some(stability);
452 annotator.annotate(hir::CRATE_HIR_ID,
455 AnnotationKind::Required,
456 |v| intravisit::walk_crate(v, krate));
461 pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
462 self.stab_map.get(&id).cloned()
465 pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
466 self.depr_map.get(&id).cloned()
470 /// Cross-references the feature names of unstable APIs with enabled
471 /// features and possibly prints errors.
472 fn check_mod_unstable_api_usage(tcx: TyCtxt<'_>, module_def_id: DefId) {
473 tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
476 pub fn provide(providers: &mut Providers<'_>) {
477 *providers = Providers {
478 check_mod_unstable_api_usage,
483 pub fn report_unstable(
484 sess: &Session, feature: Symbol, reason: Option<Symbol>, issue: u32, is_soft: bool, span: Span
486 let msg = match reason {
487 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
488 None => format!("use of unstable library feature '{}'", &feature)
491 let msp: MultiSpan = span.into();
492 let cm = &sess.parse_sess.source_map();
493 let span_key = msp.primary_span().and_then(|sp: Span|
495 let file = cm.lookup_char_pos(sp.lo()).file;
496 if file.name.is_macros() {
506 let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
507 let fresh = sess.one_time_diagnostics.borrow_mut().insert(error_id);
510 sess.buffer_lint(lint::builtin::SOFT_UNSTABLE, CRATE_NODE_ID, span, &msg);
513 &sess.parse_sess, feature, span, GateIssue::Library(Some(issue)), &msg
519 /// Checks whether an item marked with `deprecated(since="X")` is currently
520 /// deprecated (i.e., whether X is not greater than the current rustc version).
521 pub fn deprecation_in_effect(since: &str) -> bool {
522 fn parse_version(ver: &str) -> Vec<u32> {
523 // We ignore non-integer components of the version (e.g., "nightly").
524 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
527 if let Some(rustc) = option_env!("CFG_RELEASE") {
528 let since: Vec<u32> = parse_version(since);
529 let rustc: Vec<u32> = parse_version(rustc);
530 // We simply treat invalid `since` attributes as relating to a previous
531 // Rust version, thus always displaying the warning.
532 if since.len() != 3 {
537 // By default, a deprecation warning applies to
538 // the current version of the compiler.
543 pub fn deprecation_suggestion(
544 diag: &mut DiagnosticBuilder<'_>, suggestion: Option<Symbol>, span: Span
546 if let Some(suggestion) = suggestion {
547 diag.span_suggestion(
549 "replace the use of the deprecated item",
550 suggestion.to_string(),
551 Applicability::MachineApplicable,
556 fn deprecation_message_common(message: String, reason: Option<Symbol>) -> String {
558 Some(reason) => format!("{}: {}", message, reason),
563 pub fn deprecation_message(depr: &Deprecation, path: &str) -> (String, &'static Lint) {
564 let message = format!("use of deprecated item '{}'", path);
565 (deprecation_message_common(message, depr.note), lint::builtin::DEPRECATED)
568 pub fn rustc_deprecation_message(depr: &RustcDeprecation, path: &str) -> (String, &'static Lint) {
569 let (message, lint) = if deprecation_in_effect(&depr.since.as_str()) {
570 (format!("use of deprecated item '{}'", path), lint::builtin::DEPRECATED)
572 (format!("use of item '{}' that will be deprecated in future version {}", path, depr.since),
573 lint::builtin::DEPRECATED_IN_FUTURE)
575 (deprecation_message_common(message, Some(depr.reason)), lint)
578 pub fn early_report_deprecation(
581 suggestion: Option<Symbol>,
585 if in_derive_expansion(span) {
589 let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span);
590 sess.buffer_lint_with_diagnostic(lint, CRATE_NODE_ID, span, message, diag);
593 fn late_report_deprecation(
596 suggestion: Option<Symbol>,
602 if in_derive_expansion(span) {
606 let mut diag = tcx.struct_span_lint_hir(lint, hir_id, span, message);
607 if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
608 deprecation_suggestion(&mut diag, suggestion, span);
611 if hir_id == hir::DUMMY_HIR_ID {
612 span_bug!(span, "emitted a {} lint with dummy HIR id: {:?}", lint.name, def_id);
616 struct Checker<'tcx> {
620 /// Result of `TyCtxt::eval_stability`.
621 pub enum EvalResult {
622 /// We can use the item because it is stable or we provided the
623 /// corresponding feature gate.
625 /// We cannot use the item because it is unstable and we did not provide the
626 /// corresponding feature gate.
629 reason: Option<Symbol>,
633 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
637 impl<'tcx> TyCtxt<'tcx> {
639 fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
640 // Check if `def_id` is a trait method.
641 match self.def_kind(def_id) {
642 Some(DefKind::Method) |
643 Some(DefKind::AssocTy) |
644 Some(DefKind::AssocConst) => {
645 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
646 // Trait methods do not declare visibility (even
647 // for visibility info in cstore). Use containing
648 // trait instead, so methods of `pub` traits are
649 // themselves considered `pub`.
650 def_id = trait_def_id;
656 let visibility = self.visibility(def_id);
659 // Must check stability for `pub` items.
660 ty::Visibility::Public => false,
662 // These are not visible outside crate; therefore
663 // stability markers are irrelevant, if even present.
664 ty::Visibility::Restricted(..) |
665 ty::Visibility::Invisible => true,
669 /// Evaluates the stability of an item.
671 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
672 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
673 /// unstable feature otherwise.
675 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
676 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
678 pub fn eval_stability(self, def_id: DefId, id: Option<HirId>, span: Span) -> EvalResult {
679 // Deprecated attributes apply in-crate and cross-crate.
680 if let Some(id) = id {
681 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
682 let parent_def_id = self.hir().local_def_id(
683 self.hir().get_parent_item(id));
684 let skip = self.lookup_deprecation_entry(parent_def_id)
685 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
688 let (message, lint) =
689 deprecation_message(&depr_entry.attr, &self.def_path_str(def_id));
690 late_report_deprecation(self, &message, None, lint, span, def_id, id);
695 let is_staged_api = self.lookup_stability(DefId {
696 index: CRATE_DEF_INDEX,
700 return EvalResult::Allow;
703 let stability = self.lookup_stability(def_id);
705 inspecting def_id={:?} span={:?} of stability={:?}", def_id, span, stability);
707 if let Some(id) = id {
708 if let Some(stability) = stability {
709 if let Some(depr) = &stability.rustc_depr {
710 let (message, lint) =
711 rustc_deprecation_message(depr, &self.def_path_str(def_id));
712 late_report_deprecation(
713 self, &message, depr.suggestion, lint, span, def_id, id
719 // Only the cross-crate scenario matters when checking unstable APIs
720 let cross_crate = !def_id.is_local();
722 return EvalResult::Allow;
725 // Issue #38412: private items lack stability markers.
726 if self.skip_stability_check_due_to_privacy(def_id) {
727 return EvalResult::Allow;
732 level: attr::Unstable { reason, issue, is_soft }, feature, ..
734 if span.allows_unstable(feature) {
735 debug!("stability: skipping span={:?} since it is internal", span);
736 return EvalResult::Allow;
738 if self.stability().active_features.contains(&feature) {
739 return EvalResult::Allow;
742 // When we're compiling the compiler itself we may pull in
743 // crates from crates.io, but those crates may depend on other
744 // crates also pulled in from crates.io. We want to ideally be
745 // able to compile everything without requiring upstream
746 // modifications, so in the case that this looks like a
747 // `rustc_private` crate (e.g., a compiler crate) and we also have
748 // the `-Z force-unstable-if-unmarked` flag present (we're
749 // compiling a compiler crate), then let this missing feature
751 if feature == sym::rustc_private && issue == 27812 {
752 if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
753 return EvalResult::Allow;
757 EvalResult::Deny { feature, reason, issue, is_soft }
760 // Stable APIs are always ok to call and deprecated APIs are
761 // handled by the lint emitting logic above.
770 /// Checks if an item is stable or error out.
772 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
773 /// exist, emits an error.
775 /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
776 /// not `None`, a deprecated lint attached to `id` will be emitted.
777 pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) {
778 match self.eval_stability(def_id, id, span) {
779 EvalResult::Allow => {}
780 EvalResult::Deny { feature, reason, issue, is_soft } =>
781 report_unstable(self.sess, feature, reason, issue, is_soft, span),
782 EvalResult::Unmarked => {
783 // The API could be uncallable for other reasons, for example when a private module
785 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
791 impl Visitor<'tcx> for Checker<'tcx> {
792 /// Because stability levels are scoped lexically, we want to walk
793 /// nested items in the context of the outer item, so enable
795 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
796 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
799 fn visit_item(&mut self, item: &'tcx hir::Item) {
801 hir::ItemKind::ExternCrate(_) => {
802 // compiler-generated `extern crate` items have a dummy span.
803 if item.span.is_dummy() { return }
805 let def_id = self.tcx.hir().local_def_id(item.hir_id);
806 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
810 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
811 self.tcx.check_stability(def_id, Some(item.hir_id), item.span);
814 // For implementations of traits, check the stability of each item
815 // individually as it's possible to have a stable trait with unstable
817 hir::ItemKind::Impl(.., Some(ref t), _, ref impl_item_refs) => {
818 if let Res::Def(DefKind::Trait, trait_did) = t.path.res {
819 for impl_item_ref in impl_item_refs {
820 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
821 let trait_item_def_id = self.tcx.associated_items(trait_did)
822 .find(|item| item.ident.name == impl_item.ident.name)
823 .map(|item| item.def_id);
824 if let Some(def_id) = trait_item_def_id {
825 // Pass `None` to skip deprecation warnings.
826 self.tcx.check_stability(def_id, None, impl_item.span);
832 // There's no good place to insert stability check for non-Copy unions,
833 // so semi-randomly perform it here in stability.rs
834 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
835 let def_id = self.tcx.hir().local_def_id(item.hir_id);
836 let adt_def = self.tcx.adt_def(def_id);
837 let ty = self.tcx.type_of(def_id);
839 if adt_def.has_dtor(self.tcx) {
840 emit_feature_err(&self.tcx.sess.parse_sess,
841 sym::untagged_unions, item.span, GateIssue::Language,
842 "unions with `Drop` implementations are unstable");
844 let param_env = self.tcx.param_env(def_id);
845 if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
846 emit_feature_err(&self.tcx.sess.parse_sess,
847 sym::untagged_unions, item.span, GateIssue::Language,
848 "unions with non-`Copy` fields are unstable");
855 intravisit::walk_item(self, item);
858 fn visit_path(&mut self, path: &'tcx hir::Path, id: hir::HirId) {
859 if let Some(def_id) = path.res.opt_def_id() {
860 self.tcx.check_stability(def_id, Some(id), path.span)
862 intravisit::walk_path(self, path)
866 impl<'tcx> TyCtxt<'tcx> {
867 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
868 self.lookup_deprecation_entry(id).map(|depr| depr.attr)
872 /// Given the list of enabled features that were not language features (i.e., that
873 /// were expected to be library features), and the list of features used from
874 /// libraries, identify activated features that don't exist and error about them.
875 pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
876 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
878 if tcx.stability().staged_api[&LOCAL_CRATE] {
879 let krate = tcx.hir().krate();
880 let mut missing = MissingStabilityAnnotations {
884 missing.check_missing_stability(hir::CRATE_HIR_ID, krate.span, "crate");
885 intravisit::walk_crate(&mut missing, krate);
886 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
889 let declared_lang_features = &tcx.features().declared_lang_features;
890 let mut lang_features = FxHashSet::default();
891 for &(feature, span, since) in declared_lang_features {
892 if let Some(since) = since {
893 // Warn if the user has enabled an already-stable lang feature.
894 unnecessary_stable_feature_lint(tcx, span, feature, since);
896 if lang_features.contains(&feature) {
897 // Warn if the user enables a lang feature multiple times.
898 duplicate_feature_err(tcx.sess, span, feature);
900 lang_features.insert(feature);
903 let declared_lib_features = &tcx.features().declared_lib_features;
904 let mut remaining_lib_features = FxHashMap::default();
905 for (feature, span) in declared_lib_features {
906 if remaining_lib_features.contains_key(&feature) {
907 // Warn if the user enables a lib feature multiple times.
908 duplicate_feature_err(tcx.sess, *span, *feature);
910 remaining_lib_features.insert(feature, span.clone());
912 // `stdbuild` has special handling for `libc`, so we need to
913 // recognise the feature when building std.
914 // Likewise, libtest is handled specially, so `test` isn't
915 // available as we'd like it to be.
916 // FIXME: only remove `libc` when `stdbuild` is active.
917 // FIXME: remove special casing for `test`.
918 remaining_lib_features.remove(&Symbol::intern("libc"));
919 remaining_lib_features.remove(&sym::test);
922 |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &[_]| {
923 for &(feature, since) in defined_features {
924 if let Some(since) = since {
925 if let Some(span) = remaining_lib_features.get(&feature) {
926 // Warn if the user has enabled an already-stable lib feature.
927 unnecessary_stable_feature_lint(tcx, *span, feature, since);
930 remaining_lib_features.remove(&feature);
931 if remaining_lib_features.is_empty() {
937 // We always collect the lib features declared in the current crate, even if there are
938 // no unknown features, because the collection also does feature attribute validation.
939 let local_defined_features = tcx.lib_features().to_vec();
940 if !remaining_lib_features.is_empty() {
941 check_features(&mut remaining_lib_features, &local_defined_features);
943 for &cnum in &*tcx.crates() {
944 if remaining_lib_features.is_empty() {
947 check_features(&mut remaining_lib_features, tcx.defined_lib_features(cnum));
951 for (feature, span) in remaining_lib_features {
952 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
955 // FIXME(#44232): the `used_features` table no longer exists, so we
956 // don't lint about unused features. We should reenable this one day!
959 fn unnecessary_stable_feature_lint(
965 tcx.lint_hir(lint::builtin::STABLE_FEATURES,
968 &format!("the feature `{}` has been stable since {} and no longer requires \
969 an attribute to enable", feature, since));
972 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
973 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)