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::hir::def::{DefKind, Res};
7 use crate::hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
8 use crate::hir::intravisit::{self, NestedVisitorMap, Visitor};
9 use crate::hir::{self, Generics, HirId, Item, StructField, Variant};
10 use crate::lint::builtin::BuiltinLintDiagnostics;
11 use crate::lint::{self, in_derive_expansion, Lint};
12 use crate::middle::privacy::AccessLevels;
13 use crate::session::{DiagnosticMessageId, Session};
14 use crate::ty::query::Providers;
15 use crate::ty::{self, TyCtxt};
16 use crate::util::nodemap::{FxHashMap, FxHashSet};
17 use errors::DiagnosticBuilder;
18 use rustc_feature::GateIssue;
19 use syntax::ast::{Attribute, CRATE_NODE_ID};
20 use syntax::attr::{self, ConstStability, Deprecation, RustcDeprecation, Stability};
21 use syntax::errors::Applicability;
22 use syntax::feature_gate::{feature_err, feature_err_issue};
23 use syntax::symbol::{sym, Symbol};
24 use syntax_pos::{MultiSpan, Span};
26 use std::cmp::Ordering;
27 use std::mem::replace;
28 use std::num::NonZeroU32;
30 use rustc_error_codes::*;
32 #[derive(PartialEq, Clone, Copy, Debug)]
33 pub enum StabilityLevel {
39 pub fn from_attr_level(level: &attr::StabilityLevel) -> Self {
40 if level.is_stable() { Stable } else { Unstable }
46 // Annotation is required if not inherited from unstable parents
48 // Annotation is useless, reject it
50 // Annotation itself is useless, but it can be propagated to children
54 /// An entry in the `depr_map`.
55 #[derive(Clone, HashStable)]
56 pub struct DeprecationEntry {
57 /// The metadata of the attribute associated with this entry.
58 pub attr: Deprecation,
59 /// The `DefId` where the attr was originally attached. `None` for non-local
61 origin: Option<HirId>,
64 impl DeprecationEntry {
65 fn local(attr: Deprecation, id: HirId) -> DeprecationEntry {
66 DeprecationEntry { attr, origin: Some(id) }
69 pub fn external(attr: Deprecation) -> DeprecationEntry {
70 DeprecationEntry { attr, origin: None }
73 pub fn same_origin(&self, other: &DeprecationEntry) -> bool {
74 match (self.origin, other.origin) {
75 (Some(o1), Some(o2)) => o1 == o2,
81 /// A stability index, giving the stability level for items and methods.
83 pub struct Index<'tcx> {
84 /// This is mostly a cache, except the stabilities of local items
85 /// are filled by the annotator.
86 stab_map: FxHashMap<HirId, &'tcx Stability>,
87 const_stab_map: FxHashMap<HirId, &'tcx ConstStability>,
88 depr_map: FxHashMap<HirId, DeprecationEntry>,
90 /// Maps for each crate whether it is part of the staged API.
91 staged_api: FxHashMap<CrateNum, bool>,
93 /// Features enabled for this crate.
94 active_features: FxHashSet<Symbol>,
97 // A private tree-walker for producing an Index.
98 struct Annotator<'a, 'tcx> {
100 index: &'a mut Index<'tcx>,
101 parent_stab: Option<&'tcx Stability>,
102 parent_depr: Option<DeprecationEntry>,
106 impl<'a, 'tcx> Annotator<'a, 'tcx> {
107 // Determine the stability for a node based on its attributes and inherited
108 // stability. The stability is recorded in the index and used as the parent.
114 kind: AnnotationKind,
117 F: FnOnce(&mut Self),
119 if self.tcx.features().staged_api {
120 // This crate explicitly wants staged API.
121 debug!("annotate(id = {:?}, attrs = {:?})", hir_id, attrs);
122 if let Some(..) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
123 self.tcx.sess.span_err(
125 "`#[deprecated]` cannot be used in staged API; \
126 use `#[rustc_deprecated]` instead",
129 let (stab, const_stab) =
130 attr::find_stability(&self.tcx.sess.parse_sess, attrs, item_sp);
131 if let Some(const_stab) = const_stab {
132 let const_stab = self.tcx.intern_const_stability(const_stab);
133 self.index.const_stab_map.insert(hir_id, const_stab);
135 if let Some(mut stab) = stab {
136 // Error if prohibited, or can't inherit anything from a container.
137 if kind == AnnotationKind::Prohibited
138 || (kind == AnnotationKind::Container
139 && stab.level.is_stable()
140 && stab.rustc_depr.is_none())
142 self.tcx.sess.span_err(item_sp, "This stability annotation is useless");
145 debug!("annotate: found {:?}", stab);
146 // If parent is deprecated and we're not, inherit this by merging
147 // deprecated_since and its reason.
148 if let Some(parent_stab) = self.parent_stab {
149 if parent_stab.rustc_depr.is_some() && stab.rustc_depr.is_none() {
150 stab.rustc_depr = parent_stab.rustc_depr.clone()
154 let stab = self.tcx.intern_stability(stab);
156 // Check if deprecated_since < stable_since. If it is,
157 // this is *almost surely* an accident.
159 &Some(attr::RustcDeprecation { since: dep_since, .. }),
160 &attr::Stable { since: stab_since },
161 ) = (&stab.rustc_depr, &stab.level)
163 // Explicit version of iter::order::lt to handle parse errors properly
164 for (dep_v, stab_v) in
165 dep_since.as_str().split('.').zip(stab_since.as_str().split('.'))
167 if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
168 match dep_v.cmp(&stab_v) {
170 self.tcx.sess.span_err(
172 "An API can't be stabilized \
173 after it is deprecated",
177 Ordering::Equal => continue,
178 Ordering::Greater => break,
181 // Act like it isn't less because the question is now nonsensical,
182 // and this makes us not do anything else interesting.
183 self.tcx.sess.span_err(
185 "Invalid stability or deprecation \
193 self.index.stab_map.insert(hir_id, stab);
195 let orig_parent_stab = replace(&mut self.parent_stab, Some(stab));
196 visit_children(self);
197 self.parent_stab = orig_parent_stab;
199 debug!("annotate: not found, parent = {:?}", self.parent_stab);
200 if let Some(stab) = self.parent_stab {
201 if stab.level.is_unstable() {
202 self.index.stab_map.insert(hir_id, stab);
205 visit_children(self);
208 // Emit errors for non-staged-api crates.
209 let unstable_attrs = [
212 sym::rustc_deprecated,
213 sym::rustc_const_unstable,
214 sym::rustc_const_stable,
217 let name = attr.name_or_empty();
218 if unstable_attrs.contains(&name) {
219 attr::mark_used(attr);
224 "stability attributes may not be used outside of the standard library",
230 // Propagate unstability. This can happen even for non-staged-api crates in case
231 // -Zforce-unstable-if-unmarked is set.
232 if let Some(stab) = self.parent_stab {
233 if stab.level.is_unstable() {
234 self.index.stab_map.insert(hir_id, stab);
238 if let Some(depr) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
239 if kind == AnnotationKind::Prohibited {
240 self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
243 // `Deprecation` is just two pointers, no need to intern it
244 let depr_entry = DeprecationEntry::local(depr, hir_id);
245 self.index.depr_map.insert(hir_id, depr_entry.clone());
247 let orig_parent_depr = replace(&mut self.parent_depr, Some(depr_entry));
248 visit_children(self);
249 self.parent_depr = orig_parent_depr;
250 } else if let Some(parent_depr) = self.parent_depr.clone() {
251 self.index.depr_map.insert(hir_id, parent_depr);
252 visit_children(self);
254 visit_children(self);
260 impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
261 /// Because stability levels are scoped lexically, we want to walk
262 /// nested items in the context of the outer item, so enable
264 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
265 NestedVisitorMap::All(&self.tcx.hir())
268 fn visit_item(&mut self, i: &'tcx Item<'tcx>) {
269 let orig_in_trait_impl = self.in_trait_impl;
270 let mut kind = AnnotationKind::Required;
272 // Inherent impls and foreign modules serve only as containers for other items,
273 // they don't have their own stability. They still can be annotated as unstable
274 // and propagate this unstability to children, but this annotation is completely
275 // optional. They inherit stability from their parents when unannotated.
276 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {
277 self.in_trait_impl = false;
278 kind = AnnotationKind::Container;
280 hir::ItemKind::Impl(.., Some(_), _, _) => {
281 self.in_trait_impl = true;
283 hir::ItemKind::Struct(ref sd, _) => {
284 if let Some(ctor_hir_id) = sd.ctor_hir_id() {
285 self.annotate(ctor_hir_id, &i.attrs, i.span, AnnotationKind::Required, |_| {})
291 self.annotate(i.hir_id, &i.attrs, i.span, kind, |v| intravisit::walk_item(v, i));
292 self.in_trait_impl = orig_in_trait_impl;
295 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem<'tcx>) {
296 self.annotate(ti.hir_id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
297 intravisit::walk_trait_item(v, ti);
301 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem<'tcx>) {
303 if self.in_trait_impl { AnnotationKind::Prohibited } else { AnnotationKind::Required };
304 self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, |v| {
305 intravisit::walk_impl_item(v, ii);
309 fn visit_variant(&mut self, var: &'tcx Variant<'tcx>, g: &'tcx Generics, item_id: HirId) {
310 self.annotate(var.id, &var.attrs, var.span, AnnotationKind::Required, |v| {
311 if let Some(ctor_hir_id) = var.data.ctor_hir_id() {
312 v.annotate(ctor_hir_id, &var.attrs, var.span, AnnotationKind::Required, |_| {});
315 intravisit::walk_variant(v, var, g, item_id)
319 fn visit_struct_field(&mut self, s: &'tcx StructField<'tcx>) {
320 self.annotate(s.hir_id, &s.attrs, s.span, AnnotationKind::Required, |v| {
321 intravisit::walk_struct_field(v, s);
325 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) {
326 self.annotate(i.hir_id, &i.attrs, i.span, AnnotationKind::Required, |v| {
327 intravisit::walk_foreign_item(v, i);
331 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef<'tcx>) {
332 self.annotate(md.hir_id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
336 struct MissingStabilityAnnotations<'a, 'tcx> {
338 access_levels: &'a AccessLevels,
341 impl<'a, 'tcx> MissingStabilityAnnotations<'a, 'tcx> {
342 fn check_missing_stability(&self, hir_id: HirId, span: Span, name: &str) {
343 let stab = self.tcx.stability().local_stability(hir_id);
345 !self.tcx.sess.opts.test && stab.is_none() && self.access_levels.is_reachable(hir_id);
347 self.tcx.sess.span_err(span, &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(self.tcx.hir().get_parent_item(ii.hir_id));
378 if self.tcx.impl_trait_ref(impl_def_id).is_none() {
379 self.check_missing_stability(ii.hir_id, ii.span, "item");
381 intravisit::walk_impl_item(self, ii);
384 fn visit_variant(&mut self, var: &'tcx Variant<'tcx>, g: &'tcx Generics, item_id: HirId) {
385 self.check_missing_stability(var.id, var.span, "variant");
386 intravisit::walk_variant(self, var, g, item_id);
389 fn visit_struct_field(&mut self, s: &'tcx StructField<'tcx>) {
390 self.check_missing_stability(s.hir_id, s.span, "field");
391 intravisit::walk_struct_field(self, s);
394 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) {
395 self.check_missing_stability(i.hir_id, i.span, i.kind.descriptive_variant());
396 intravisit::walk_foreign_item(self, i);
399 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef<'tcx>) {
400 self.check_missing_stability(md.hir_id, md.span, "macro");
404 impl<'tcx> Index<'tcx> {
405 pub fn new(tcx: TyCtxt<'tcx>) -> Index<'tcx> {
407 tcx.sess.opts.debugging_opts.force_unstable_if_unmarked || tcx.features().staged_api;
408 let mut staged_api = FxHashMap::default();
409 staged_api.insert(LOCAL_CRATE, is_staged_api);
410 let mut index = Index {
412 stab_map: Default::default(),
413 const_stab_map: Default::default(),
414 depr_map: Default::default(),
415 active_features: Default::default(),
418 let active_lib_features = &tcx.features().declared_lib_features;
419 let active_lang_features = &tcx.features().declared_lang_features;
421 // Put the active features into a map for quick lookup.
422 index.active_features = active_lib_features
424 .map(|&(ref s, ..)| s.clone())
425 .chain(active_lang_features.iter().map(|&(ref s, ..)| s.clone()))
429 let krate = tcx.hir().krate();
430 let mut annotator = Annotator {
435 in_trait_impl: false,
438 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
439 // a parent stability annotation which indicates that this is private
440 // with the `rustc_private` feature. This is intended for use when
441 // compiling librustc crates themselves so we can leverage crates.io
442 // while maintaining the invariant that all sysroot crates are unstable
443 // by default and are unable to be used.
444 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
445 let reason = "this crate is being loaded from the sysroot, an \
446 unstable location; did you mean to load this crate \
447 from crates.io via `Cargo.toml` instead?";
448 let stability = tcx.intern_stability(Stability {
449 level: attr::StabilityLevel::Unstable {
450 reason: Some(Symbol::intern(reason)),
451 issue: NonZeroU32::new(27812),
454 feature: sym::rustc_private,
457 annotator.parent_stab = Some(stability);
464 AnnotationKind::Required,
465 |v| intravisit::walk_crate(v, krate),
471 pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
472 self.stab_map.get(&id).cloned()
475 pub fn local_const_stability(&self, id: HirId) -> Option<&'tcx ConstStability> {
476 self.const_stab_map.get(&id).cloned()
479 pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
480 self.depr_map.get(&id).cloned()
484 /// Cross-references the feature names of unstable APIs with enabled
485 /// features and possibly prints errors.
486 fn check_mod_unstable_api_usage(tcx: TyCtxt<'_>, module_def_id: DefId) {
487 tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
490 pub fn provide(providers: &mut Providers<'_>) {
491 *providers = Providers { check_mod_unstable_api_usage, ..*providers };
494 pub fn report_unstable(
497 reason: Option<Symbol>,
498 issue: Option<NonZeroU32>,
501 soft_handler: impl FnOnce(&'static lint::Lint, Span, &str),
503 let msg = match reason {
504 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
505 None => format!("use of unstable library feature '{}'", &feature),
508 let msp: MultiSpan = span.into();
509 let cm = &sess.parse_sess.source_map();
510 let span_key = msp.primary_span().and_then(|sp: Span| {
512 let file = cm.lookup_char_pos(sp.lo()).file;
513 if file.name.is_macros() { None } else { Some(span) }
519 let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
520 let fresh = sess.one_time_diagnostics.borrow_mut().insert(error_id);
523 soft_handler(lint::builtin::SOFT_UNSTABLE, span, &msg)
525 feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg)
531 /// Checks whether an item marked with `deprecated(since="X")` is currently
532 /// deprecated (i.e., whether X is not greater than the current rustc version).
533 pub fn deprecation_in_effect(since: &str) -> bool {
534 fn parse_version(ver: &str) -> Vec<u32> {
535 // We ignore non-integer components of the version (e.g., "nightly").
536 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
539 if let Some(rustc) = option_env!("CFG_RELEASE") {
540 let since: Vec<u32> = parse_version(since);
541 let rustc: Vec<u32> = parse_version(rustc);
542 // We simply treat invalid `since` attributes as relating to a previous
543 // Rust version, thus always displaying the warning.
544 if since.len() != 3 {
549 // By default, a deprecation warning applies to
550 // the current version of the compiler.
555 pub fn deprecation_suggestion(
556 diag: &mut DiagnosticBuilder<'_>,
557 suggestion: Option<Symbol>,
560 if let Some(suggestion) = suggestion {
561 diag.span_suggestion(
563 "replace the use of the deprecated item",
564 suggestion.to_string(),
565 Applicability::MachineApplicable,
570 fn deprecation_message_common(message: String, reason: Option<Symbol>) -> String {
572 Some(reason) => format!("{}: {}", message, reason),
577 pub fn deprecation_message(depr: &Deprecation, path: &str) -> (String, &'static Lint) {
578 let message = format!("use of deprecated item '{}'", path);
579 (deprecation_message_common(message, depr.note), lint::builtin::DEPRECATED)
582 pub fn rustc_deprecation_message(depr: &RustcDeprecation, path: &str) -> (String, &'static Lint) {
583 let (message, lint) = if deprecation_in_effect(&depr.since.as_str()) {
584 (format!("use of deprecated item '{}'", path), lint::builtin::DEPRECATED)
588 "use of item '{}' that will be deprecated in future version {}",
591 lint::builtin::DEPRECATED_IN_FUTURE,
594 (deprecation_message_common(message, Some(depr.reason)), lint)
597 pub fn early_report_deprecation(
598 lint_buffer: &'a mut lint::LintBuffer,
600 suggestion: Option<Symbol>,
604 if in_derive_expansion(span) {
608 let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span);
609 lint_buffer.buffer_lint_with_diagnostic(lint, CRATE_NODE_ID, span, message, diag);
612 fn late_report_deprecation(
615 suggestion: Option<Symbol>,
621 if in_derive_expansion(span) {
625 let mut diag = tcx.struct_span_lint_hir(lint, hir_id, span, message);
626 if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
627 deprecation_suggestion(&mut diag, suggestion, span);
630 if hir_id == hir::DUMMY_HIR_ID {
631 span_bug!(span, "emitted a {} lint with dummy HIR id: {:?}", lint.name, def_id);
635 struct Checker<'tcx> {
639 /// Result of `TyCtxt::eval_stability`.
640 pub enum EvalResult {
641 /// We can use the item because it is stable or we provided the
642 /// corresponding feature gate.
644 /// We cannot use the item because it is unstable and we did not provide the
645 /// corresponding feature gate.
646 Deny { feature: Symbol, reason: Option<Symbol>, issue: Option<NonZeroU32>, is_soft: bool },
647 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
651 impl<'tcx> TyCtxt<'tcx> {
653 fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
654 // Check if `def_id` is a trait method.
655 match self.def_kind(def_id) {
656 Some(DefKind::Method) | Some(DefKind::AssocTy) | Some(DefKind::AssocConst) => {
657 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
658 // Trait methods do not declare visibility (even
659 // for visibility info in cstore). Use containing
660 // trait instead, so methods of `pub` traits are
661 // themselves considered `pub`.
662 def_id = trait_def_id;
668 let visibility = self.visibility(def_id);
671 // Must check stability for `pub` items.
672 ty::Visibility::Public => false,
674 // These are not visible outside crate; therefore
675 // stability markers are irrelevant, if even present.
676 ty::Visibility::Restricted(..) | ty::Visibility::Invisible => true,
680 /// Evaluates the stability of an item.
682 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
683 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
684 /// unstable feature otherwise.
686 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
687 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
689 pub fn eval_stability(self, def_id: DefId, id: Option<HirId>, span: Span) -> EvalResult {
690 // Deprecated attributes apply in-crate and cross-crate.
691 if let Some(id) = id {
692 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
693 let parent_def_id = self.hir().local_def_id(self.hir().get_parent_item(id));
695 .lookup_deprecation_entry(parent_def_id)
696 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
699 let (message, lint) =
700 deprecation_message(&depr_entry.attr, &self.def_path_str(def_id));
701 late_report_deprecation(self, &message, None, lint, span, def_id, id);
707 self.lookup_stability(DefId { index: CRATE_DEF_INDEX, ..def_id }).is_some();
709 return EvalResult::Allow;
712 let stability = self.lookup_stability(def_id);
715 inspecting def_id={:?} span={:?} of stability={:?}",
716 def_id, span, stability
719 if let Some(id) = id {
720 if let Some(stability) = stability {
721 if let Some(depr) = &stability.rustc_depr {
722 let (message, lint) =
723 rustc_deprecation_message(depr, &self.def_path_str(def_id));
724 late_report_deprecation(
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.
782 None => EvalResult::Unmarked,
786 /// Checks if an item is stable or error out.
788 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
789 /// exist, emits an error.
791 /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
792 /// not `None`, a deprecated lint attached to `id` will be emitted.
793 pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) {
795 |lint, span, msg: &_| self.lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, msg);
796 match self.eval_stability(def_id, id, span) {
797 EvalResult::Allow => {}
798 EvalResult::Deny { feature, reason, issue, is_soft } => {
799 report_unstable(self.sess, feature, reason, issue, is_soft, span, soft_handler)
801 EvalResult::Unmarked => {
802 // The API could be uncallable for other reasons, for example when a private module
804 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
810 impl Visitor<'tcx> for Checker<'tcx> {
811 /// Because stability levels are scoped lexically, we want to walk
812 /// nested items in the context of the outer item, so enable
814 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
815 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
818 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
820 hir::ItemKind::ExternCrate(_) => {
821 // compiler-generated `extern crate` items have a dummy span.
822 if item.span.is_dummy() {
826 let def_id = self.tcx.hir().local_def_id(item.hir_id);
827 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
831 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
832 self.tcx.check_stability(def_id, Some(item.hir_id), item.span);
835 // For implementations of traits, check the stability of each item
836 // individually as it's possible to have a stable trait with unstable
838 hir::ItemKind::Impl(.., Some(ref t), _, impl_item_refs) => {
839 if let Res::Def(DefKind::Trait, trait_did) = t.path.res {
840 for impl_item_ref in impl_item_refs {
841 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
842 let trait_item_def_id = self
844 .associated_items(trait_did)
845 .find(|item| item.ident.name == impl_item.ident.name)
846 .map(|item| item.def_id);
847 if let Some(def_id) = trait_item_def_id {
848 // Pass `None` to skip deprecation warnings.
849 self.tcx.check_stability(def_id, None, impl_item.span);
855 // There's no good place to insert stability check for non-Copy unions,
856 // so semi-randomly perform it here in stability.rs
857 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
858 let def_id = self.tcx.hir().local_def_id(item.hir_id);
859 let adt_def = self.tcx.adt_def(def_id);
860 let ty = self.tcx.type_of(def_id);
862 if adt_def.has_dtor(self.tcx) {
864 &self.tcx.sess.parse_sess,
865 sym::untagged_unions,
867 "unions with `Drop` implementations are unstable",
871 let param_env = self.tcx.param_env(def_id);
872 if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
874 &self.tcx.sess.parse_sess,
875 sym::untagged_unions,
877 "unions with non-`Copy` fields are unstable",
886 intravisit::walk_item(self, item);
889 fn visit_path(&mut self, path: &'tcx hir::Path, id: hir::HirId) {
890 if let Some(def_id) = path.res.opt_def_id() {
891 self.tcx.check_stability(def_id, Some(id), path.span)
893 intravisit::walk_path(self, path)
897 impl<'tcx> TyCtxt<'tcx> {
898 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
899 self.lookup_deprecation_entry(id).map(|depr| depr.attr)
903 /// Given the list of enabled features that were not language features (i.e., that
904 /// were expected to be library features), and the list of features used from
905 /// libraries, identify activated features that don't exist and error about them.
906 pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
907 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
909 if tcx.stability().staged_api[&LOCAL_CRATE] {
910 let krate = tcx.hir().krate();
911 let mut missing = MissingStabilityAnnotations { tcx, access_levels };
912 missing.check_missing_stability(hir::CRATE_HIR_ID, krate.span, "crate");
913 intravisit::walk_crate(&mut missing, krate);
914 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
917 let declared_lang_features = &tcx.features().declared_lang_features;
918 let mut lang_features = FxHashSet::default();
919 for &(feature, span, since) in declared_lang_features {
920 if let Some(since) = since {
921 // Warn if the user has enabled an already-stable lang feature.
922 unnecessary_stable_feature_lint(tcx, span, feature, since);
924 if !lang_features.insert(feature) {
925 // Warn if the user enables a lang feature multiple times.
926 duplicate_feature_err(tcx.sess, span, feature);
930 let declared_lib_features = &tcx.features().declared_lib_features;
931 let mut remaining_lib_features = FxHashMap::default();
932 for (feature, span) in declared_lib_features {
933 if remaining_lib_features.contains_key(&feature) {
934 // Warn if the user enables a lib feature multiple times.
935 duplicate_feature_err(tcx.sess, *span, *feature);
937 remaining_lib_features.insert(feature, span.clone());
939 // `stdbuild` has special handling for `libc`, so we need to
940 // recognise the feature when building std.
941 // Likewise, libtest is handled specially, so `test` isn't
942 // available as we'd like it to be.
943 // FIXME: only remove `libc` when `stdbuild` is active.
944 // FIXME: remove special casing for `test`.
945 remaining_lib_features.remove(&Symbol::intern("libc"));
946 remaining_lib_features.remove(&sym::test);
948 let check_features = |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &[_]| {
949 for &(feature, since) in defined_features {
950 if let Some(since) = since {
951 if let Some(span) = remaining_lib_features.get(&feature) {
952 // Warn if the user has enabled an already-stable lib feature.
953 unnecessary_stable_feature_lint(tcx, *span, feature, since);
956 remaining_lib_features.remove(&feature);
957 if remaining_lib_features.is_empty() {
963 // We always collect the lib features declared in the current crate, even if there are
964 // no unknown features, because the collection also does feature attribute validation.
965 let local_defined_features = tcx.lib_features().to_vec();
966 if !remaining_lib_features.is_empty() {
967 check_features(&mut remaining_lib_features, &local_defined_features);
969 for &cnum in &*tcx.crates() {
970 if remaining_lib_features.is_empty() {
973 check_features(&mut remaining_lib_features, tcx.defined_lib_features(cnum));
977 for (feature, span) in remaining_lib_features {
978 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
981 // FIXME(#44232): the `used_features` table no longer exists, so we
982 // don't lint about unused features. We should reenable this one day!
985 fn unnecessary_stable_feature_lint(tcx: TyCtxt<'_>, span: Span, feature: Symbol, since: Symbol) {
987 lint::builtin::STABLE_FEATURES,
991 "the feature `{}` has been stable since {} and no longer requires \
992 an attribute to enable",
998 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
999 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)