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(PartialEq, Clone, Copy, Debug)]
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);
206 "stability attributes may not be used outside of the standard library",
211 // Propagate unstability. This can happen even for non-staged-api crates in case
212 // -Zforce-unstable-if-unmarked is set.
213 if let Some(stab) = self.parent_stab {
214 if stab.level.is_unstable() {
215 self.index.stab_map.insert(hir_id, stab);
219 if let Some(depr) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
220 if kind == AnnotationKind::Prohibited {
221 self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
224 // `Deprecation` is just two pointers, no need to intern it
225 let depr_entry = DeprecationEntry::local(depr, hir_id);
226 self.index.depr_map.insert(hir_id, depr_entry.clone());
228 let orig_parent_depr = replace(&mut self.parent_depr,
230 visit_children(self);
231 self.parent_depr = orig_parent_depr;
232 } else if let Some(parent_depr) = self.parent_depr.clone() {
233 self.index.depr_map.insert(hir_id, parent_depr);
234 visit_children(self);
236 visit_children(self);
242 impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
243 /// Because stability levels are scoped lexically, we want to walk
244 /// nested items in the context of the outer item, so enable
246 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
247 NestedVisitorMap::All(&self.tcx.hir())
250 fn visit_item(&mut self, i: &'tcx Item) {
251 let orig_in_trait_impl = self.in_trait_impl;
252 let mut kind = AnnotationKind::Required;
254 // Inherent impls and foreign modules serve only as containers for other items,
255 // they don't have their own stability. They still can be annotated as unstable
256 // and propagate this unstability to children, but this annotation is completely
257 // optional. They inherit stability from their parents when unannotated.
258 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {
259 self.in_trait_impl = false;
260 kind = AnnotationKind::Container;
262 hir::ItemKind::Impl(.., Some(_), _, _) => {
263 self.in_trait_impl = true;
265 hir::ItemKind::Struct(ref sd, _) => {
266 if let Some(ctor_hir_id) = sd.ctor_hir_id() {
267 self.annotate(ctor_hir_id, &i.attrs, i.span, AnnotationKind::Required, |_| {})
273 self.annotate(i.hir_id, &i.attrs, i.span, kind, |v| {
274 intravisit::walk_item(v, i)
276 self.in_trait_impl = orig_in_trait_impl;
279 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
280 self.annotate(ti.hir_id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
281 intravisit::walk_trait_item(v, ti);
285 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
286 let kind = if self.in_trait_impl {
287 AnnotationKind::Prohibited
289 AnnotationKind::Required
291 self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, |v| {
292 intravisit::walk_impl_item(v, ii);
296 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
297 self.annotate(var.id, &var.attrs, var.span, AnnotationKind::Required,
299 if let Some(ctor_hir_id) = var.data.ctor_hir_id() {
300 v.annotate(ctor_hir_id, &var.attrs, var.span, AnnotationKind::Required,
304 intravisit::walk_variant(v, var, g, item_id)
308 fn visit_struct_field(&mut self, s: &'tcx StructField) {
309 self.annotate(s.hir_id, &s.attrs, s.span, AnnotationKind::Required, |v| {
310 intravisit::walk_struct_field(v, s);
314 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
315 self.annotate(i.hir_id, &i.attrs, i.span, AnnotationKind::Required, |v| {
316 intravisit::walk_foreign_item(v, i);
320 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
321 self.annotate(md.hir_id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
325 struct MissingStabilityAnnotations<'a, 'tcx> {
327 access_levels: &'a AccessLevels,
330 impl<'a, 'tcx> MissingStabilityAnnotations<'a, 'tcx> {
331 fn check_missing_stability(&self, hir_id: HirId, span: Span, name: &str) {
332 let stab = self.tcx.stability().local_stability(hir_id);
333 let is_error = !self.tcx.sess.opts.test &&
335 self.access_levels.is_reachable(hir_id);
337 self.tcx.sess.span_err(
339 &format!("{} has missing stability attribute", name),
345 impl<'a, 'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'a, 'tcx> {
346 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
347 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
350 fn visit_item(&mut self, i: &'tcx Item) {
352 // Inherent impls and foreign modules serve only as containers for other items,
353 // they don't have their own stability. They still can be annotated as unstable
354 // and propagate this unstability to children, but this annotation is completely
355 // optional. They inherit stability from their parents when unannotated.
356 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {}
358 _ => self.check_missing_stability(i.hir_id, i.span, i.kind.descriptive_variant())
361 intravisit::walk_item(self, i)
364 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
365 self.check_missing_stability(ti.hir_id, ti.span, "item");
366 intravisit::walk_trait_item(self, ti);
369 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
370 let impl_def_id = self.tcx.hir().local_def_id(
371 self.tcx.hir().get_parent_item(ii.hir_id));
372 if self.tcx.impl_trait_ref(impl_def_id).is_none() {
373 self.check_missing_stability(ii.hir_id, ii.span, "item");
375 intravisit::walk_impl_item(self, ii);
378 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
379 self.check_missing_stability(var.id, var.span, "variant");
380 intravisit::walk_variant(self, var, g, item_id);
383 fn visit_struct_field(&mut self, s: &'tcx StructField) {
384 self.check_missing_stability(s.hir_id, s.span, "field");
385 intravisit::walk_struct_field(self, s);
388 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
389 self.check_missing_stability(i.hir_id, i.span, i.kind.descriptive_variant());
390 intravisit::walk_foreign_item(self, i);
393 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
394 self.check_missing_stability(md.hir_id, md.span, "macro");
398 impl<'tcx> Index<'tcx> {
399 pub fn new(tcx: TyCtxt<'tcx>) -> Index<'tcx> {
401 tcx.sess.opts.debugging_opts.force_unstable_if_unmarked ||
402 tcx.features().staged_api;
403 let mut staged_api = FxHashMap::default();
404 staged_api.insert(LOCAL_CRATE, is_staged_api);
405 let mut index = Index {
407 stab_map: Default::default(),
408 depr_map: Default::default(),
409 active_features: Default::default(),
412 let active_lib_features = &tcx.features().declared_lib_features;
413 let active_lang_features = &tcx.features().declared_lang_features;
415 // Put the active features into a map for quick lookup.
416 index.active_features =
417 active_lib_features.iter().map(|&(ref s, ..)| s.clone())
418 .chain(active_lang_features.iter().map(|&(ref s, ..)| s.clone()))
422 let krate = tcx.hir().krate();
423 let mut annotator = Annotator {
428 in_trait_impl: false,
431 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
432 // a parent stability annotation which indicates that this is private
433 // with the `rustc_private` feature. This is intended for use when
434 // compiling librustc crates themselves so we can leverage crates.io
435 // while maintaining the invariant that all sysroot crates are unstable
436 // by default and are unable to be used.
437 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
438 let reason = "this crate is being loaded from the sysroot, an \
439 unstable location; did you mean to load this crate \
440 from crates.io via `Cargo.toml` instead?";
441 let stability = tcx.intern_stability(Stability {
442 level: attr::StabilityLevel::Unstable {
443 reason: Some(Symbol::intern(reason)),
447 feature: sym::rustc_private,
449 const_stability: None,
451 allow_const_fn_ptr: false,
453 annotator.parent_stab = Some(stability);
456 annotator.annotate(hir::CRATE_HIR_ID,
459 AnnotationKind::Required,
460 |v| intravisit::walk_crate(v, krate));
465 pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
466 self.stab_map.get(&id).cloned()
469 pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
470 self.depr_map.get(&id).cloned()
474 /// Cross-references the feature names of unstable APIs with enabled
475 /// features and possibly prints errors.
476 fn check_mod_unstable_api_usage(tcx: TyCtxt<'_>, module_def_id: DefId) {
477 tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
480 pub fn provide(providers: &mut Providers<'_>) {
481 *providers = Providers {
482 check_mod_unstable_api_usage,
487 pub fn report_unstable(
490 reason: Option<Symbol>,
494 soft_handler: impl FnOnce(&'static lint::Lint, Span, &str),
496 let msg = match reason {
497 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
498 None => format!("use of unstable library feature '{}'", &feature)
501 let msp: MultiSpan = span.into();
502 let cm = &sess.parse_sess.source_map();
503 let span_key = msp.primary_span().and_then(|sp: Span|
505 let file = cm.lookup_char_pos(sp.lo()).file;
506 if file.name.is_macros() {
516 let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
517 let fresh = sess.one_time_diagnostics.borrow_mut().insert(error_id);
520 soft_handler(lint::builtin::SOFT_UNSTABLE, span, &msg)
523 &sess.parse_sess, feature, span, GateIssue::Library(Some(issue)), &msg
529 /// Checks whether an item marked with `deprecated(since="X")` is currently
530 /// deprecated (i.e., whether X is not greater than the current rustc version).
531 pub fn deprecation_in_effect(since: &str) -> bool {
532 fn parse_version(ver: &str) -> Vec<u32> {
533 // We ignore non-integer components of the version (e.g., "nightly").
534 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
537 if let Some(rustc) = option_env!("CFG_RELEASE") {
538 let since: Vec<u32> = parse_version(since);
539 let rustc: Vec<u32> = parse_version(rustc);
540 // We simply treat invalid `since` attributes as relating to a previous
541 // Rust version, thus always displaying the warning.
542 if since.len() != 3 {
547 // By default, a deprecation warning applies to
548 // the current version of the compiler.
553 pub fn deprecation_suggestion(
554 diag: &mut DiagnosticBuilder<'_>, suggestion: Option<Symbol>, span: Span
556 if let Some(suggestion) = suggestion {
557 diag.span_suggestion(
559 "replace the use of the deprecated item",
560 suggestion.to_string(),
561 Applicability::MachineApplicable,
566 fn deprecation_message_common(message: String, reason: Option<Symbol>) -> String {
568 Some(reason) => format!("{}: {}", message, reason),
573 pub fn deprecation_message(depr: &Deprecation, path: &str) -> (String, &'static Lint) {
574 let message = format!("use of deprecated item '{}'", path);
575 (deprecation_message_common(message, depr.note), lint::builtin::DEPRECATED)
578 pub fn rustc_deprecation_message(depr: &RustcDeprecation, path: &str) -> (String, &'static Lint) {
579 let (message, lint) = if deprecation_in_effect(&depr.since.as_str()) {
580 (format!("use of deprecated item '{}'", path), lint::builtin::DEPRECATED)
582 (format!("use of item '{}' that will be deprecated in future version {}", path, depr.since),
583 lint::builtin::DEPRECATED_IN_FUTURE)
585 (deprecation_message_common(message, Some(depr.reason)), lint)
588 pub fn early_report_deprecation(
589 lint_buffer: &'a mut lint::LintBuffer,
591 suggestion: Option<Symbol>,
595 if in_derive_expansion(span) {
599 let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span);
600 lint_buffer.buffer_lint_with_diagnostic(lint, CRATE_NODE_ID, span, message, diag);
603 fn late_report_deprecation(
606 suggestion: Option<Symbol>,
612 if in_derive_expansion(span) {
616 let mut diag = tcx.struct_span_lint_hir(lint, hir_id, span, message);
617 if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
618 deprecation_suggestion(&mut diag, suggestion, span);
621 if hir_id == hir::DUMMY_HIR_ID {
622 span_bug!(span, "emitted a {} lint with dummy HIR id: {:?}", lint.name, def_id);
626 struct Checker<'tcx> {
630 /// Result of `TyCtxt::eval_stability`.
631 pub enum EvalResult {
632 /// We can use the item because it is stable or we provided the
633 /// corresponding feature gate.
635 /// We cannot use the item because it is unstable and we did not provide the
636 /// corresponding feature gate.
639 reason: Option<Symbol>,
643 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
647 impl<'tcx> TyCtxt<'tcx> {
649 fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
650 // Check if `def_id` is a trait method.
651 match self.def_kind(def_id) {
652 Some(DefKind::Method) |
653 Some(DefKind::AssocTy) |
654 Some(DefKind::AssocConst) => {
655 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
656 // Trait methods do not declare visibility (even
657 // for visibility info in cstore). Use containing
658 // trait instead, so methods of `pub` traits are
659 // themselves considered `pub`.
660 def_id = trait_def_id;
666 let visibility = self.visibility(def_id);
669 // Must check stability for `pub` items.
670 ty::Visibility::Public => false,
672 // These are not visible outside crate; therefore
673 // stability markers are irrelevant, if even present.
674 ty::Visibility::Restricted(..) |
675 ty::Visibility::Invisible => true,
679 /// Evaluates the stability of an item.
681 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
682 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
683 /// unstable feature otherwise.
685 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
686 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
688 pub fn eval_stability(self, def_id: DefId, id: Option<HirId>, span: Span) -> EvalResult {
689 // Deprecated attributes apply in-crate and cross-crate.
690 if let Some(id) = id {
691 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
692 let parent_def_id = self.hir().local_def_id(
693 self.hir().get_parent_item(id));
694 let skip = self.lookup_deprecation_entry(parent_def_id)
695 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
698 let (message, lint) =
699 deprecation_message(&depr_entry.attr, &self.def_path_str(def_id));
700 late_report_deprecation(self, &message, None, lint, span, def_id, id);
705 let is_staged_api = self.lookup_stability(DefId {
706 index: CRATE_DEF_INDEX,
710 return EvalResult::Allow;
713 let stability = self.lookup_stability(def_id);
715 inspecting def_id={:?} span={:?} of stability={:?}", def_id, span, stability);
717 if let Some(id) = id {
718 if let Some(stability) = stability {
719 if let Some(depr) = &stability.rustc_depr {
720 let (message, lint) =
721 rustc_deprecation_message(depr, &self.def_path_str(def_id));
722 late_report_deprecation(
723 self, &message, depr.suggestion, lint, span, def_id, id
729 // Only the cross-crate scenario matters when checking unstable APIs
730 let cross_crate = !def_id.is_local();
732 return EvalResult::Allow;
735 // Issue #38412: private items lack stability markers.
736 if self.skip_stability_check_due_to_privacy(def_id) {
737 return EvalResult::Allow;
742 level: attr::Unstable { reason, issue, is_soft }, feature, ..
744 if span.allows_unstable(feature) {
745 debug!("stability: skipping span={:?} since it is internal", span);
746 return EvalResult::Allow;
748 if self.stability().active_features.contains(&feature) {
749 return EvalResult::Allow;
752 // When we're compiling the compiler itself we may pull in
753 // crates from crates.io, but those crates may depend on other
754 // crates also pulled in from crates.io. We want to ideally be
755 // able to compile everything without requiring upstream
756 // modifications, so in the case that this looks like a
757 // `rustc_private` crate (e.g., a compiler crate) and we also have
758 // the `-Z force-unstable-if-unmarked` flag present (we're
759 // compiling a compiler crate), then let this missing feature
761 if feature == sym::rustc_private && issue == 27812 {
762 if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
763 return EvalResult::Allow;
767 EvalResult::Deny { feature, reason, issue, is_soft }
770 // Stable APIs are always ok to call and deprecated APIs are
771 // handled by the lint emitting logic above.
780 /// Checks if an item is stable or error out.
782 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
783 /// exist, emits an error.
785 /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
786 /// not `None`, a deprecated lint attached to `id` will be emitted.
787 pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) {
789 |lint, span, msg: &_| self.lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, msg);
790 match self.eval_stability(def_id, id, span) {
791 EvalResult::Allow => {}
792 EvalResult::Deny { feature, reason, issue, is_soft } =>
793 report_unstable(self.sess, feature, reason, issue, is_soft, span, soft_handler),
794 EvalResult::Unmarked => {
795 // The API could be uncallable for other reasons, for example when a private module
797 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
803 impl Visitor<'tcx> for Checker<'tcx> {
804 /// Because stability levels are scoped lexically, we want to walk
805 /// nested items in the context of the outer item, so enable
807 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
808 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
811 fn visit_item(&mut self, item: &'tcx hir::Item) {
813 hir::ItemKind::ExternCrate(_) => {
814 // compiler-generated `extern crate` items have a dummy span.
815 if item.span.is_dummy() { return }
817 let def_id = self.tcx.hir().local_def_id(item.hir_id);
818 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
822 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
823 self.tcx.check_stability(def_id, Some(item.hir_id), item.span);
826 // For implementations of traits, check the stability of each item
827 // individually as it's possible to have a stable trait with unstable
829 hir::ItemKind::Impl(.., Some(ref t), _, ref impl_item_refs) => {
830 if let Res::Def(DefKind::Trait, trait_did) = t.path.res {
831 for impl_item_ref in impl_item_refs {
832 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
833 let trait_item_def_id = self.tcx.associated_items(trait_did)
834 .find(|item| item.ident.name == impl_item.ident.name)
835 .map(|item| item.def_id);
836 if let Some(def_id) = trait_item_def_id {
837 // Pass `None` to skip deprecation warnings.
838 self.tcx.check_stability(def_id, None, impl_item.span);
844 // There's no good place to insert stability check for non-Copy unions,
845 // so semi-randomly perform it here in stability.rs
846 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
847 let def_id = self.tcx.hir().local_def_id(item.hir_id);
848 let adt_def = self.tcx.adt_def(def_id);
849 let ty = self.tcx.type_of(def_id);
851 if adt_def.has_dtor(self.tcx) {
852 emit_feature_err(&self.tcx.sess.parse_sess,
853 sym::untagged_unions, item.span, GateIssue::Language,
854 "unions with `Drop` implementations are unstable");
856 let param_env = self.tcx.param_env(def_id);
857 if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
858 emit_feature_err(&self.tcx.sess.parse_sess,
859 sym::untagged_unions, item.span, GateIssue::Language,
860 "unions with non-`Copy` fields are unstable");
867 intravisit::walk_item(self, item);
870 fn visit_path(&mut self, path: &'tcx hir::Path, id: hir::HirId) {
871 if let Some(def_id) = path.res.opt_def_id() {
872 self.tcx.check_stability(def_id, Some(id), path.span)
874 intravisit::walk_path(self, path)
878 impl<'tcx> TyCtxt<'tcx> {
879 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
880 self.lookup_deprecation_entry(id).map(|depr| depr.attr)
884 /// Given the list of enabled features that were not language features (i.e., that
885 /// were expected to be library features), and the list of features used from
886 /// libraries, identify activated features that don't exist and error about them.
887 pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
888 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
890 if tcx.stability().staged_api[&LOCAL_CRATE] {
891 let krate = tcx.hir().krate();
892 let mut missing = MissingStabilityAnnotations {
896 missing.check_missing_stability(hir::CRATE_HIR_ID, krate.span, "crate");
897 intravisit::walk_crate(&mut missing, krate);
898 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
901 let declared_lang_features = &tcx.features().declared_lang_features;
902 let mut lang_features = FxHashSet::default();
903 for &(feature, span, since) in declared_lang_features {
904 if let Some(since) = since {
905 // Warn if the user has enabled an already-stable lang feature.
906 unnecessary_stable_feature_lint(tcx, span, feature, since);
908 if !lang_features.insert(feature) {
909 // Warn if the user enables a lang feature multiple times.
910 duplicate_feature_err(tcx.sess, span, feature);
914 let declared_lib_features = &tcx.features().declared_lib_features;
915 let mut remaining_lib_features = FxHashMap::default();
916 for (feature, span) in declared_lib_features {
917 if remaining_lib_features.contains_key(&feature) {
918 // Warn if the user enables a lib feature multiple times.
919 duplicate_feature_err(tcx.sess, *span, *feature);
921 remaining_lib_features.insert(feature, span.clone());
923 // `stdbuild` has special handling for `libc`, so we need to
924 // recognise the feature when building std.
925 // Likewise, libtest is handled specially, so `test` isn't
926 // available as we'd like it to be.
927 // FIXME: only remove `libc` when `stdbuild` is active.
928 // FIXME: remove special casing for `test`.
929 remaining_lib_features.remove(&Symbol::intern("libc"));
930 remaining_lib_features.remove(&sym::test);
933 |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &[_]| {
934 for &(feature, since) in defined_features {
935 if let Some(since) = since {
936 if let Some(span) = remaining_lib_features.get(&feature) {
937 // Warn if the user has enabled an already-stable lib feature.
938 unnecessary_stable_feature_lint(tcx, *span, feature, since);
941 remaining_lib_features.remove(&feature);
942 if remaining_lib_features.is_empty() {
948 // We always collect the lib features declared in the current crate, even if there are
949 // no unknown features, because the collection also does feature attribute validation.
950 let local_defined_features = tcx.lib_features().to_vec();
951 if !remaining_lib_features.is_empty() {
952 check_features(&mut remaining_lib_features, &local_defined_features);
954 for &cnum in &*tcx.crates() {
955 if remaining_lib_features.is_empty() {
958 check_features(&mut remaining_lib_features, tcx.defined_lib_features(cnum));
962 for (feature, span) in remaining_lib_features {
963 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
966 // FIXME(#44232): the `used_features` table no longer exists, so we
967 // don't lint about unused features. We should reenable this one day!
970 fn unnecessary_stable_feature_lint(
976 tcx.lint_hir(lint::builtin::STABLE_FEATURES,
979 &format!("the feature `{}` has been stable since {} and no longer requires \
980 an attribute to enable", feature, since));
983 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
984 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)