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 rustc_feature::GateIssue;
17 use syntax::symbol::{Symbol, sym};
18 use syntax_pos::{Span, MultiSpan};
19 use syntax::ast::{Attribute, CRATE_NODE_ID};
20 use syntax::errors::Applicability;
21 use syntax::feature_gate::{feature_err, feature_err_issue};
22 use syntax::attr::{self, Stability, Deprecation, RustcDeprecation, ConstStability};
23 use crate::ty::{self, TyCtxt};
24 use crate::util::nodemap::{FxHashSet, FxHashMap};
26 use std::cmp::Ordering;
27 use std::mem::replace;
28 use std::num::NonZeroU32;
30 use rustc_error_codes::*;
33 #[derive(PartialEq, Clone, Copy, Debug)]
34 pub enum StabilityLevel {
40 pub fn from_attr_level(level: &attr::StabilityLevel) -> Self {
41 if level.is_stable() { Stable } else { Unstable }
47 // Annotation is required if not inherited from unstable parents
49 // Annotation is useless, reject it
51 // Annotation itself is useless, but it can be propagated to children
55 /// An entry in the `depr_map`.
56 #[derive(Clone, HashStable)]
57 pub struct DeprecationEntry {
58 /// The metadata of the attribute associated with this entry.
59 pub attr: Deprecation,
60 /// The `DefId` where the attr was originally attached. `None` for non-local
62 origin: Option<HirId>,
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.
90 pub struct Index<'tcx> {
91 /// This is mostly a cache, except the stabilities of local items
92 /// are filled by the annotator.
93 stab_map: FxHashMap<HirId, &'tcx Stability>,
94 const_stab_map: FxHashMap<HirId, &'tcx ConstStability>,
95 depr_map: FxHashMap<HirId, DeprecationEntry>,
97 /// Maps for each crate whether it is part of the staged API.
98 staged_api: FxHashMap<CrateNum, bool>,
100 /// Features enabled for this crate.
101 active_features: FxHashSet<Symbol>,
104 // A private tree-walker for producing an Index.
105 struct Annotator<'a, 'tcx> {
107 index: &'a mut Index<'tcx>,
108 parent_stab: Option<&'tcx Stability>,
109 parent_depr: Option<DeprecationEntry>,
113 impl<'a, 'tcx> Annotator<'a, 'tcx> {
114 // Determine the stability for a node based on its attributes and inherited
115 // stability. The stability is recorded in the index and used as the parent.
116 fn annotate<F>(&mut self, hir_id: HirId, attrs: &[Attribute],
117 item_sp: Span, kind: AnnotationKind, visit_children: F)
118 where F: FnOnce(&mut Self)
120 if self.tcx.features().staged_api {
121 // This crate explicitly wants staged API.
122 debug!("annotate(id = {:?}, attrs = {:?})", hir_id, attrs);
123 if let Some(..) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
124 self.tcx.sess.span_err(item_sp, "`#[deprecated]` cannot be used in staged API; \
125 use `#[rustc_deprecated]` instead");
127 let (stab, const_stab) = attr::find_stability(
128 &self.tcx.sess.parse_sess, attrs, item_sp,
130 if let Some(const_stab) = const_stab {
131 let const_stab = self.tcx.intern_const_stability(const_stab);
132 self.index.const_stab_map.insert(hir_id, const_stab);
134 if let Some(mut stab) = stab {
135 // Error if prohibited, or can't inherit anything from a container.
136 if kind == AnnotationKind::Prohibited ||
137 (kind == AnnotationKind::Container &&
138 stab.level.is_stable() &&
139 stab.rustc_depr.is_none()) {
140 self.tcx.sess.span_err(item_sp, "This stability annotation is useless");
143 debug!("annotate: found {:?}", stab);
144 // If parent is deprecated and we're not, inherit this by merging
145 // deprecated_since and its reason.
146 if let Some(parent_stab) = self.parent_stab {
147 if parent_stab.rustc_depr.is_some() && stab.rustc_depr.is_none() {
148 stab.rustc_depr = parent_stab.rustc_depr.clone()
152 let stab = self.tcx.intern_stability(stab);
154 // Check if deprecated_since < stable_since. If it is,
155 // this is *almost surely* an accident.
156 if let (&Some(attr::RustcDeprecation {since: dep_since, ..}),
157 &attr::Stable {since: stab_since}) = (&stab.rustc_depr, &stab.level) {
158 // Explicit version of iter::order::lt to handle parse errors properly
159 for (dep_v, stab_v) in dep_since.as_str()
161 .zip(stab_since.as_str().split('.'))
163 if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
164 match dep_v.cmp(&stab_v) {
166 self.tcx.sess.span_err(item_sp, "An API can't be stabilized \
167 after it is deprecated");
170 Ordering::Equal => continue,
171 Ordering::Greater => break,
174 // Act like it isn't less because the question is now nonsensical,
175 // and this makes us not do anything else interesting.
176 self.tcx.sess.span_err(item_sp, "Invalid stability or deprecation \
183 self.index.stab_map.insert(hir_id, stab);
185 let orig_parent_stab = replace(&mut self.parent_stab, Some(stab));
186 visit_children(self);
187 self.parent_stab = orig_parent_stab;
189 debug!("annotate: not found, parent = {:?}", self.parent_stab);
190 if let Some(stab) = self.parent_stab {
191 if stab.level.is_unstable() {
192 self.index.stab_map.insert(hir_id, stab);
195 visit_children(self);
198 // Emit errors for non-staged-api crates.
199 let unstable_attrs = [
200 sym::unstable, sym::stable,
201 sym::rustc_deprecated,
202 sym::rustc_const_unstable,
203 sym::rustc_const_stable,
206 let name = attr.name_or_empty();
207 if unstable_attrs.contains(&name) {
208 attr::mark_used(attr);
213 "stability attributes may not be used outside of the standard library",
218 // Propagate unstability. This can happen even for non-staged-api crates in case
219 // -Zforce-unstable-if-unmarked is set.
220 if let Some(stab) = self.parent_stab {
221 if stab.level.is_unstable() {
222 self.index.stab_map.insert(hir_id, stab);
226 if let Some(depr) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
227 if kind == AnnotationKind::Prohibited {
228 self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
231 // `Deprecation` is just two pointers, no need to intern it
232 let depr_entry = DeprecationEntry::local(depr, hir_id);
233 self.index.depr_map.insert(hir_id, depr_entry.clone());
235 let orig_parent_depr = replace(&mut self.parent_depr,
237 visit_children(self);
238 self.parent_depr = orig_parent_depr;
239 } else if let Some(parent_depr) = self.parent_depr.clone() {
240 self.index.depr_map.insert(hir_id, parent_depr);
241 visit_children(self);
243 visit_children(self);
249 impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
250 /// Because stability levels are scoped lexically, we want to walk
251 /// nested items in the context of the outer item, so enable
253 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
254 NestedVisitorMap::All(&self.tcx.hir())
257 fn visit_item(&mut self, i: &'tcx Item<'tcx>) {
258 let orig_in_trait_impl = self.in_trait_impl;
259 let mut kind = AnnotationKind::Required;
261 // Inherent impls and foreign modules serve only as containers for other items,
262 // they don't have their own stability. They still can be annotated as unstable
263 // and propagate this unstability to children, but this annotation is completely
264 // optional. They inherit stability from their parents when unannotated.
265 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {
266 self.in_trait_impl = false;
267 kind = AnnotationKind::Container;
269 hir::ItemKind::Impl(.., Some(_), _, _) => {
270 self.in_trait_impl = true;
272 hir::ItemKind::Struct(ref sd, _) => {
273 if let Some(ctor_hir_id) = sd.ctor_hir_id() {
274 self.annotate(ctor_hir_id, &i.attrs, i.span, AnnotationKind::Required, |_| {})
280 self.annotate(i.hir_id, &i.attrs, i.span, kind, |v| {
281 intravisit::walk_item(v, i)
283 self.in_trait_impl = orig_in_trait_impl;
286 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem<'tcx>) {
287 self.annotate(ti.hir_id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
288 intravisit::walk_trait_item(v, ti);
292 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem<'tcx>) {
293 let kind = if self.in_trait_impl {
294 AnnotationKind::Prohibited
296 AnnotationKind::Required
298 self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, |v| {
299 intravisit::walk_impl_item(v, ii);
303 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
304 self.annotate(var.id, &var.attrs, var.span, AnnotationKind::Required,
306 if let Some(ctor_hir_id) = var.data.ctor_hir_id() {
307 v.annotate(ctor_hir_id, &var.attrs, var.span, AnnotationKind::Required,
311 intravisit::walk_variant(v, var, g, item_id)
315 fn visit_struct_field(&mut self, s: &'tcx StructField) {
316 self.annotate(s.hir_id, &s.attrs, s.span, AnnotationKind::Required, |v| {
317 intravisit::walk_struct_field(v, s);
321 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) {
322 self.annotate(i.hir_id, &i.attrs, i.span, AnnotationKind::Required, |v| {
323 intravisit::walk_foreign_item(v, i);
327 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef<'tcx>) {
328 self.annotate(md.hir_id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
332 struct MissingStabilityAnnotations<'a, 'tcx> {
334 access_levels: &'a AccessLevels,
337 impl<'a, 'tcx> MissingStabilityAnnotations<'a, 'tcx> {
338 fn check_missing_stability(&self, hir_id: HirId, span: Span, name: &str) {
339 let stab = self.tcx.stability().local_stability(hir_id);
340 let is_error = !self.tcx.sess.opts.test &&
342 self.access_levels.is_reachable(hir_id);
344 self.tcx.sess.span_err(
346 &format!("{} has missing stability attribute", name),
352 impl<'a, 'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'a, 'tcx> {
353 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
354 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
357 fn visit_item(&mut self, i: &'tcx Item<'tcx>) {
359 // Inherent impls and foreign modules serve only as containers for other items,
360 // they don't have their own stability. They still can be annotated as unstable
361 // and propagate this unstability to children, but this annotation is completely
362 // optional. They inherit stability from their parents when unannotated.
363 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {}
365 _ => self.check_missing_stability(i.hir_id, i.span, i.kind.descriptive_variant())
368 intravisit::walk_item(self, i)
371 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem<'tcx>) {
372 self.check_missing_stability(ti.hir_id, ti.span, "item");
373 intravisit::walk_trait_item(self, ti);
376 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem<'tcx>) {
377 let impl_def_id = self.tcx.hir().local_def_id(
378 self.tcx.hir().get_parent_item(ii.hir_id));
379 if self.tcx.impl_trait_ref(impl_def_id).is_none() {
380 self.check_missing_stability(ii.hir_id, ii.span, "item");
382 intravisit::walk_impl_item(self, ii);
385 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: HirId) {
386 self.check_missing_stability(var.id, var.span, "variant");
387 intravisit::walk_variant(self, var, g, item_id);
390 fn visit_struct_field(&mut self, s: &'tcx StructField) {
391 self.check_missing_stability(s.hir_id, s.span, "field");
392 intravisit::walk_struct_field(self, s);
395 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) {
396 self.check_missing_stability(i.hir_id, i.span, i.kind.descriptive_variant());
397 intravisit::walk_foreign_item(self, i);
400 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef<'tcx>) {
401 self.check_missing_stability(md.hir_id, md.span, "macro");
405 impl<'tcx> Index<'tcx> {
406 pub fn new(tcx: TyCtxt<'tcx>) -> Index<'tcx> {
408 tcx.sess.opts.debugging_opts.force_unstable_if_unmarked ||
409 tcx.features().staged_api;
410 let mut staged_api = FxHashMap::default();
411 staged_api.insert(LOCAL_CRATE, is_staged_api);
412 let mut index = Index {
414 stab_map: Default::default(),
415 const_stab_map: Default::default(),
416 depr_map: Default::default(),
417 active_features: Default::default(),
420 let active_lib_features = &tcx.features().declared_lib_features;
421 let active_lang_features = &tcx.features().declared_lang_features;
423 // Put the active features into a map for quick lookup.
424 index.active_features =
425 active_lib_features.iter().map(|&(ref s, ..)| s.clone())
426 .chain(active_lang_features.iter().map(|&(ref s, ..)| s.clone()))
430 let krate = tcx.hir().krate();
431 let mut annotator = Annotator {
436 in_trait_impl: false,
439 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
440 // a parent stability annotation which indicates that this is private
441 // with the `rustc_private` feature. This is intended for use when
442 // compiling librustc crates themselves so we can leverage crates.io
443 // while maintaining the invariant that all sysroot crates are unstable
444 // by default and are unable to be used.
445 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
446 let reason = "this crate is being loaded from the sysroot, an \
447 unstable location; did you mean to load this crate \
448 from crates.io via `Cargo.toml` instead?";
449 let stability = tcx.intern_stability(Stability {
450 level: attr::StabilityLevel::Unstable {
451 reason: Some(Symbol::intern(reason)),
452 issue: NonZeroU32::new(27812),
455 feature: sym::rustc_private,
458 annotator.parent_stab = Some(stability);
461 annotator.annotate(hir::CRATE_HIR_ID,
464 AnnotationKind::Required,
465 |v| intravisit::walk_crate(v, krate));
470 pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
471 self.stab_map.get(&id).cloned()
474 pub fn local_const_stability(&self, id: HirId) -> Option<&'tcx ConstStability> {
475 self.const_stab_map.get(&id).cloned()
478 pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
479 self.depr_map.get(&id).cloned()
483 /// Cross-references the feature names of unstable APIs with enabled
484 /// features and possibly prints errors.
485 fn check_mod_unstable_api_usage(tcx: TyCtxt<'_>, module_def_id: DefId) {
486 tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
489 pub fn provide(providers: &mut Providers<'_>) {
490 *providers = Providers {
491 check_mod_unstable_api_usage,
496 pub fn report_unstable(
499 reason: Option<Symbol>,
500 issue: Option<NonZeroU32>,
503 soft_handler: impl FnOnce(&'static lint::Lint, Span, &str),
505 let msg = match reason {
506 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
507 None => format!("use of unstable library feature '{}'", &feature)
510 let msp: MultiSpan = span.into();
511 let cm = &sess.parse_sess.source_map();
512 let span_key = msp.primary_span().and_then(|sp: Span|
514 let file = cm.lookup_char_pos(sp.lo()).file;
515 if file.name.is_macros() {
525 let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
526 let fresh = sess.one_time_diagnostics.borrow_mut().insert(error_id);
529 soft_handler(lint::builtin::SOFT_UNSTABLE, span, &msg)
531 feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg)
537 /// Checks whether an item marked with `deprecated(since="X")` is currently
538 /// deprecated (i.e., whether X is not greater than the current rustc version).
539 pub fn deprecation_in_effect(since: &str) -> bool {
540 fn parse_version(ver: &str) -> Vec<u32> {
541 // We ignore non-integer components of the version (e.g., "nightly").
542 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
545 if let Some(rustc) = option_env!("CFG_RELEASE") {
546 let since: Vec<u32> = parse_version(since);
547 let rustc: Vec<u32> = parse_version(rustc);
548 // We simply treat invalid `since` attributes as relating to a previous
549 // Rust version, thus always displaying the warning.
550 if since.len() != 3 {
555 // By default, a deprecation warning applies to
556 // the current version of the compiler.
561 pub fn deprecation_suggestion(
562 diag: &mut DiagnosticBuilder<'_>, suggestion: Option<Symbol>, span: Span
564 if let Some(suggestion) = suggestion {
565 diag.span_suggestion(
567 "replace the use of the deprecated item",
568 suggestion.to_string(),
569 Applicability::MachineApplicable,
574 fn deprecation_message_common(message: String, reason: Option<Symbol>) -> String {
576 Some(reason) => format!("{}: {}", message, reason),
581 pub fn deprecation_message(depr: &Deprecation, path: &str) -> (String, &'static Lint) {
582 let message = format!("use of deprecated item '{}'", path);
583 (deprecation_message_common(message, depr.note), lint::builtin::DEPRECATED)
586 pub fn rustc_deprecation_message(depr: &RustcDeprecation, path: &str) -> (String, &'static Lint) {
587 let (message, lint) = if deprecation_in_effect(&depr.since.as_str()) {
588 (format!("use of deprecated item '{}'", path), lint::builtin::DEPRECATED)
590 (format!("use of item '{}' that will be deprecated in future version {}", path, depr.since),
591 lint::builtin::DEPRECATED_IN_FUTURE)
593 (deprecation_message_common(message, Some(depr.reason)), lint)
596 pub fn early_report_deprecation(
597 lint_buffer: &'a mut lint::LintBuffer,
599 suggestion: Option<Symbol>,
603 if in_derive_expansion(span) {
607 let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span);
608 lint_buffer.buffer_lint_with_diagnostic(lint, CRATE_NODE_ID, span, message, diag);
611 fn late_report_deprecation(
614 suggestion: Option<Symbol>,
620 if in_derive_expansion(span) {
624 let mut diag = tcx.struct_span_lint_hir(lint, hir_id, span, message);
625 if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
626 deprecation_suggestion(&mut diag, suggestion, span);
629 if hir_id == hir::DUMMY_HIR_ID {
630 span_bug!(span, "emitted a {} lint with dummy HIR id: {:?}", lint.name, def_id);
634 struct Checker<'tcx> {
638 /// Result of `TyCtxt::eval_stability`.
639 pub enum EvalResult {
640 /// We can use the item because it is stable or we provided the
641 /// corresponding feature gate.
643 /// We cannot use the item because it is unstable and we did not provide the
644 /// corresponding feature gate.
647 reason: Option<Symbol>,
648 issue: Option<NonZeroU32>,
651 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
655 impl<'tcx> TyCtxt<'tcx> {
657 fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
658 // Check if `def_id` is a trait method.
659 match self.def_kind(def_id) {
660 Some(DefKind::Method) |
661 Some(DefKind::AssocTy) |
662 Some(DefKind::AssocConst) => {
663 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
664 // Trait methods do not declare visibility (even
665 // for visibility info in cstore). Use containing
666 // trait instead, so methods of `pub` traits are
667 // themselves considered `pub`.
668 def_id = trait_def_id;
674 let visibility = self.visibility(def_id);
677 // Must check stability for `pub` items.
678 ty::Visibility::Public => false,
680 // These are not visible outside crate; therefore
681 // stability markers are irrelevant, if even present.
682 ty::Visibility::Restricted(..) |
683 ty::Visibility::Invisible => true,
687 /// Evaluates the stability of an item.
689 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
690 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
691 /// unstable feature otherwise.
693 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
694 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
696 pub fn eval_stability(self, def_id: DefId, id: Option<HirId>, span: Span) -> EvalResult {
697 // Deprecated attributes apply in-crate and cross-crate.
698 if let Some(id) = id {
699 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
700 let parent_def_id = self.hir().local_def_id(
701 self.hir().get_parent_item(id));
702 let skip = self.lookup_deprecation_entry(parent_def_id)
703 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
706 let (message, lint) =
707 deprecation_message(&depr_entry.attr, &self.def_path_str(def_id));
708 late_report_deprecation(self, &message, None, lint, span, def_id, id);
713 let is_staged_api = self.lookup_stability(DefId {
714 index: CRATE_DEF_INDEX,
718 return EvalResult::Allow;
721 let stability = self.lookup_stability(def_id);
723 inspecting def_id={:?} span={:?} of stability={:?}", def_id, span, stability);
725 if let Some(id) = id {
726 if let Some(stability) = stability {
727 if let Some(depr) = &stability.rustc_depr {
728 let (message, lint) =
729 rustc_deprecation_message(depr, &self.def_path_str(def_id));
730 late_report_deprecation(
731 self, &message, depr.suggestion, lint, span, def_id, id
737 // Only the cross-crate scenario matters when checking unstable APIs
738 let cross_crate = !def_id.is_local();
740 return EvalResult::Allow;
743 // Issue #38412: private items lack stability markers.
744 if self.skip_stability_check_due_to_privacy(def_id) {
745 return EvalResult::Allow;
750 level: attr::Unstable { reason, issue, is_soft }, feature, ..
752 if span.allows_unstable(feature) {
753 debug!("stability: skipping span={:?} since it is internal", span);
754 return EvalResult::Allow;
756 if self.stability().active_features.contains(&feature) {
757 return EvalResult::Allow;
760 // When we're compiling the compiler itself we may pull in
761 // crates from crates.io, but those crates may depend on other
762 // crates also pulled in from crates.io. We want to ideally be
763 // able to compile everything without requiring upstream
764 // modifications, so in the case that this looks like a
765 // `rustc_private` crate (e.g., a compiler crate) and we also have
766 // the `-Z force-unstable-if-unmarked` flag present (we're
767 // compiling a compiler crate), then let this missing feature
769 if feature == sym::rustc_private && issue == NonZeroU32::new(27812) {
770 if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
771 return EvalResult::Allow;
775 EvalResult::Deny { feature, reason, issue, is_soft }
778 // Stable APIs are always ok to call and deprecated APIs are
779 // handled by the lint emitting logic above.
788 /// Checks if an item is stable or error out.
790 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
791 /// exist, emits an error.
793 /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
794 /// not `None`, a deprecated lint attached to `id` will be emitted.
795 pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) {
797 |lint, span, msg: &_| self.lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, msg);
798 match self.eval_stability(def_id, id, span) {
799 EvalResult::Allow => {}
800 EvalResult::Deny { feature, reason, issue, is_soft } =>
801 report_unstable(self.sess, feature, reason, issue, is_soft, span, soft_handler),
802 EvalResult::Unmarked => {
803 // The API could be uncallable for other reasons, for example when a private module
805 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
811 impl Visitor<'tcx> for Checker<'tcx> {
812 /// Because stability levels are scoped lexically, we want to walk
813 /// nested items in the context of the outer item, so enable
815 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
816 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
819 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
821 hir::ItemKind::ExternCrate(_) => {
822 // compiler-generated `extern crate` items have a dummy span.
823 if item.span.is_dummy() { return }
825 let def_id = self.tcx.hir().local_def_id(item.hir_id);
826 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
830 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
831 self.tcx.check_stability(def_id, Some(item.hir_id), item.span);
834 // For implementations of traits, check the stability of each item
835 // individually as it's possible to have a stable trait with unstable
837 hir::ItemKind::Impl(.., Some(ref t), _, impl_item_refs) => {
838 if let Res::Def(DefKind::Trait, trait_did) = t.path.res {
839 for impl_item_ref in impl_item_refs {
840 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
841 let trait_item_def_id = self.tcx.associated_items(trait_did)
842 .find(|item| item.ident.name == impl_item.ident.name)
843 .map(|item| item.def_id);
844 if let Some(def_id) = trait_item_def_id {
845 // Pass `None` to skip deprecation warnings.
846 self.tcx.check_stability(def_id, None, impl_item.span);
852 // There's no good place to insert stability check for non-Copy unions,
853 // so semi-randomly perform it here in stability.rs
854 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
855 let def_id = self.tcx.hir().local_def_id(item.hir_id);
856 let adt_def = self.tcx.adt_def(def_id);
857 let ty = self.tcx.type_of(def_id);
859 if adt_def.has_dtor(self.tcx) {
861 &self.tcx.sess.parse_sess, sym::untagged_unions, item.span,
862 "unions with `Drop` implementations are unstable"
866 let param_env = self.tcx.param_env(def_id);
867 if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
869 &self.tcx.sess.parse_sess, sym::untagged_unions, item.span,
870 "unions with non-`Copy` fields are unstable"
879 intravisit::walk_item(self, item);
882 fn visit_path(&mut self, path: &'tcx hir::Path, id: hir::HirId) {
883 if let Some(def_id) = path.res.opt_def_id() {
884 self.tcx.check_stability(def_id, Some(id), path.span)
886 intravisit::walk_path(self, path)
890 impl<'tcx> TyCtxt<'tcx> {
891 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
892 self.lookup_deprecation_entry(id).map(|depr| depr.attr)
896 /// Given the list of enabled features that were not language features (i.e., that
897 /// were expected to be library features), and the list of features used from
898 /// libraries, identify activated features that don't exist and error about them.
899 pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
900 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
902 if tcx.stability().staged_api[&LOCAL_CRATE] {
903 let krate = tcx.hir().krate();
904 let mut missing = MissingStabilityAnnotations {
908 missing.check_missing_stability(hir::CRATE_HIR_ID, krate.span, "crate");
909 intravisit::walk_crate(&mut missing, krate);
910 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
913 let declared_lang_features = &tcx.features().declared_lang_features;
914 let mut lang_features = FxHashSet::default();
915 for &(feature, span, since) in declared_lang_features {
916 if let Some(since) = since {
917 // Warn if the user has enabled an already-stable lang feature.
918 unnecessary_stable_feature_lint(tcx, span, feature, since);
920 if !lang_features.insert(feature) {
921 // Warn if the user enables a lang feature multiple times.
922 duplicate_feature_err(tcx.sess, span, feature);
926 let declared_lib_features = &tcx.features().declared_lib_features;
927 let mut remaining_lib_features = FxHashMap::default();
928 for (feature, span) in declared_lib_features {
929 if remaining_lib_features.contains_key(&feature) {
930 // Warn if the user enables a lib feature multiple times.
931 duplicate_feature_err(tcx.sess, *span, *feature);
933 remaining_lib_features.insert(feature, span.clone());
935 // `stdbuild` has special handling for `libc`, so we need to
936 // recognise the feature when building std.
937 // Likewise, libtest is handled specially, so `test` isn't
938 // available as we'd like it to be.
939 // FIXME: only remove `libc` when `stdbuild` is active.
940 // FIXME: remove special casing for `test`.
941 remaining_lib_features.remove(&Symbol::intern("libc"));
942 remaining_lib_features.remove(&sym::test);
945 |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &[_]| {
946 for &(feature, since) in defined_features {
947 if let Some(since) = since {
948 if let Some(span) = remaining_lib_features.get(&feature) {
949 // Warn if the user has enabled an already-stable lib feature.
950 unnecessary_stable_feature_lint(tcx, *span, feature, since);
953 remaining_lib_features.remove(&feature);
954 if remaining_lib_features.is_empty() {
960 // We always collect the lib features declared in the current crate, even if there are
961 // no unknown features, because the collection also does feature attribute validation.
962 let local_defined_features = tcx.lib_features().to_vec();
963 if !remaining_lib_features.is_empty() {
964 check_features(&mut remaining_lib_features, &local_defined_features);
966 for &cnum in &*tcx.crates() {
967 if remaining_lib_features.is_empty() {
970 check_features(&mut remaining_lib_features, tcx.defined_lib_features(cnum));
974 for (feature, span) in remaining_lib_features {
975 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
978 // FIXME(#44232): the `used_features` table no longer exists, so we
979 // don't lint about unused features. We should reenable this one day!
982 fn unnecessary_stable_feature_lint(
988 tcx.lint_hir(lint::builtin::STABLE_FEATURES,
991 &format!("the feature `{}` has been stable since {} and no longer requires \
992 an attribute to enable", feature, since));
995 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
996 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)