1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! A pass that annotates every item and method with its stability level,
12 //! propagating default levels lexically from parent to children ast nodes.
14 pub use self::StabilityLevel::*;
17 use hir::{self, Item, Generics, StructField, Variant, HirId};
19 use hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId, LOCAL_CRATE};
20 use hir::intravisit::{self, Visitor, NestedVisitorMap};
21 use middle::privacy::AccessLevels;
22 use session::{DiagnosticMessageId, Session};
23 use syntax::symbol::Symbol;
24 use syntax_pos::{Span, MultiSpan};
26 use syntax::ast::{NodeId, Attribute};
27 use syntax::feature_gate::{GateIssue, emit_feature_err};
28 use syntax::attr::{self, Stability, Deprecation};
29 use ty::{self, TyCtxt};
30 use util::nodemap::{FxHashSet, FxHashMap};
32 use std::mem::replace;
33 use std::cmp::Ordering;
35 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Copy, Debug, Eq, Hash)]
36 pub enum StabilityLevel {
42 pub fn from_attr_level(level: &attr::StabilityLevel) -> Self {
43 if level.is_stable() { Stable } else { Unstable }
49 // Annotation is required if not inherited from unstable parents
51 // Annotation is useless, reject it
53 // Annotation itself is useless, but it can be propagated to children
57 /// An entry in the `depr_map`.
59 pub struct DeprecationEntry {
60 /// The metadata of the attribute associated with this entry.
61 pub attr: Deprecation,
62 /// The def id where the attr was originally attached. `None` for non-local
64 origin: Option<HirId>,
67 impl_stable_hash_for!(struct self::DeprecationEntry {
72 impl DeprecationEntry {
73 fn local(attr: Deprecation, id: HirId) -> DeprecationEntry {
80 pub fn external(attr: Deprecation) -> DeprecationEntry {
87 pub fn same_origin(&self, other: &DeprecationEntry) -> bool {
88 match (self.origin, other.origin) {
89 (Some(o1), Some(o2)) => o1 == o2,
95 /// A stability index, giving the stability level for items and methods.
96 pub struct Index<'tcx> {
97 /// This is mostly a cache, except the stabilities of local items
98 /// are filled by the annotator.
99 stab_map: FxHashMap<HirId, &'tcx Stability>,
100 depr_map: FxHashMap<HirId, DeprecationEntry>,
102 /// Maps for each crate whether it is part of the staged API.
103 staged_api: FxHashMap<CrateNum, bool>,
105 /// Features enabled for this crate.
106 active_features: FxHashSet<Symbol>,
109 impl_stable_hash_for!(struct self::Index<'tcx> {
116 // A private tree-walker for producing an Index.
117 struct Annotator<'a, 'tcx: 'a> {
118 tcx: TyCtxt<'a, 'tcx, 'tcx>,
119 index: &'a mut Index<'tcx>,
120 parent_stab: Option<&'tcx Stability>,
121 parent_depr: Option<DeprecationEntry>,
125 impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
126 // Determine the stability for a node based on its attributes and inherited
127 // stability. The stability is recorded in the index and used as the parent.
128 fn annotate<F>(&mut self, id: NodeId, attrs: &[Attribute],
129 item_sp: Span, kind: AnnotationKind, visit_children: F)
130 where F: FnOnce(&mut Self)
132 if self.tcx.features().staged_api {
133 // This crate explicitly wants staged API.
134 debug!("annotate(id = {:?}, attrs = {:?})", id, attrs);
135 if let Some(..) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
136 self.tcx.sess.span_err(item_sp, "`#[deprecated]` cannot be used in staged api, \
137 use `#[rustc_deprecated]` instead");
139 if let Some(mut stab) = attr::find_stability(&self.tcx.sess.parse_sess,
141 // Error if prohibited, or can't inherit anything from a container
142 if kind == AnnotationKind::Prohibited ||
143 (kind == AnnotationKind::Container &&
144 stab.level.is_stable() &&
145 stab.rustc_depr.is_none()) {
146 self.tcx.sess.span_err(item_sp, "This stability annotation is useless");
149 debug!("annotate: found {:?}", stab);
150 // If parent is deprecated and we're not, inherit this by merging
151 // deprecated_since and its reason.
152 if let Some(parent_stab) = self.parent_stab {
153 if parent_stab.rustc_depr.is_some() && stab.rustc_depr.is_none() {
154 stab.rustc_depr = parent_stab.rustc_depr.clone()
158 let stab = self.tcx.intern_stability(stab);
160 // Check if deprecated_since < stable_since. If it is,
161 // this is *almost surely* an accident.
162 if let (&Some(attr::RustcDeprecation {since: dep_since, ..}),
163 &attr::Stable {since: stab_since}) = (&stab.rustc_depr, &stab.level) {
164 // Explicit version of iter::order::lt to handle parse errors properly
165 for (dep_v, stab_v) in dep_since.as_str()
167 .zip(stab_since.as_str().split('.'))
169 if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
170 match dep_v.cmp(&stab_v) {
172 self.tcx.sess.span_err(item_sp, "An API can't be stabilized \
173 after it is deprecated");
176 Ordering::Equal => continue,
177 Ordering::Greater => break,
180 // Act like it isn't less because the question is now nonsensical,
181 // and this makes us not do anything else interesting.
182 self.tcx.sess.span_err(item_sp, "Invalid stability or deprecation \
189 let hir_id = self.tcx.hir().node_to_hir_id(id);
190 self.index.stab_map.insert(hir_id, stab);
192 let orig_parent_stab = replace(&mut self.parent_stab, Some(stab));
193 visit_children(self);
194 self.parent_stab = orig_parent_stab;
196 debug!("annotate: not found, parent = {:?}", self.parent_stab);
197 if let Some(stab) = self.parent_stab {
198 if stab.level.is_unstable() {
199 let hir_id = self.tcx.hir().node_to_hir_id(id);
200 self.index.stab_map.insert(hir_id, stab);
203 visit_children(self);
206 // Emit errors for non-staged-api crates.
208 let tag = attr.name();
209 if tag == "unstable" || tag == "stable" || tag == "rustc_deprecated" {
210 attr::mark_used(attr);
211 self.tcx.sess.span_err(attr.span(), "stability attributes may not be used \
212 outside of the standard library");
216 // Propagate unstability. This can happen even for non-staged-api crates in case
217 // -Zforce-unstable-if-unmarked is set.
218 if let Some(stab) = self.parent_stab {
219 if stab.level.is_unstable() {
220 let hir_id = self.tcx.hir().node_to_hir_id(id);
221 self.index.stab_map.insert(hir_id, stab);
225 if let Some(depr) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
226 if kind == AnnotationKind::Prohibited {
227 self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
230 // `Deprecation` is just two pointers, no need to intern it
231 let hir_id = self.tcx.hir().node_to_hir_id(id);
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 let hir_id = self.tcx.hir().node_to_hir_id(id);
241 self.index.depr_map.insert(hir_id, parent_depr);
242 visit_children(self);
244 visit_children(self);
250 impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
251 /// Because stability levels are scoped lexically, we want to walk
252 /// nested items in the context of the outer item, so enable
254 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
255 NestedVisitorMap::All(&self.tcx.hir())
258 fn visit_item(&mut self, i: &'tcx Item) {
259 let orig_in_trait_impl = self.in_trait_impl;
260 let mut kind = AnnotationKind::Required;
262 // Inherent impls and foreign modules serve only as containers for other items,
263 // they don't have their own stability. They still can be annotated as unstable
264 // and propagate this unstability to children, but this annotation is completely
265 // optional. They inherit stability from their parents when unannotated.
266 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {
267 self.in_trait_impl = false;
268 kind = AnnotationKind::Container;
270 hir::ItemKind::Impl(.., Some(_), _, _) => {
271 self.in_trait_impl = true;
273 hir::ItemKind::Struct(ref sd, _) => {
275 self.annotate(sd.id(), &i.attrs, i.span, AnnotationKind::Required, |_| {})
281 self.annotate(i.id, &i.attrs, i.span, kind, |v| {
282 intravisit::walk_item(v, i)
284 self.in_trait_impl = orig_in_trait_impl;
287 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
288 self.annotate(ti.id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
289 intravisit::walk_trait_item(v, ti);
293 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem) {
294 let kind = if self.in_trait_impl {
295 AnnotationKind::Prohibited
297 AnnotationKind::Required
299 self.annotate(ii.id, &ii.attrs, ii.span, kind, |v| {
300 intravisit::walk_impl_item(v, ii);
304 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: NodeId) {
305 self.annotate(var.node.data.id(), &var.node.attrs, var.span, AnnotationKind::Required, |v| {
306 intravisit::walk_variant(v, var, g, item_id);
310 fn visit_struct_field(&mut self, s: &'tcx StructField) {
311 self.annotate(s.id, &s.attrs, s.span, AnnotationKind::Required, |v| {
312 intravisit::walk_struct_field(v, s);
316 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
317 self.annotate(i.id, &i.attrs, i.span, AnnotationKind::Required, |v| {
318 intravisit::walk_foreign_item(v, i);
322 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
323 self.annotate(md.id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
327 struct MissingStabilityAnnotations<'a, 'tcx: 'a> {
328 tcx: TyCtxt<'a, 'tcx, 'tcx>,
329 access_levels: &'a AccessLevels,
332 impl<'a, 'tcx: 'a> MissingStabilityAnnotations<'a, 'tcx> {
333 fn check_missing_stability(&self, id: NodeId, span: Span) {
334 let hir_id = self.tcx.hir().node_to_hir_id(id);
335 let stab = self.tcx.stability().local_stability(hir_id);
336 let is_error = !self.tcx.sess.opts.test &&
338 self.access_levels.is_reachable(id);
340 self.tcx.sess.span_err(span, "This node does not have a stability attribute");
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.id, i.span)
361 intravisit::walk_item(self, i)
364 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem) {
365 self.check_missing_stability(ti.id, ti.span);
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(self.tcx.hir().get_parent(ii.id));
371 if self.tcx.impl_trait_ref(impl_def_id).is_none() {
372 self.check_missing_stability(ii.id, ii.span);
374 intravisit::walk_impl_item(self, ii);
377 fn visit_variant(&mut self, var: &'tcx Variant, g: &'tcx Generics, item_id: NodeId) {
378 self.check_missing_stability(var.node.data.id(), var.span);
379 intravisit::walk_variant(self, var, g, item_id);
382 fn visit_struct_field(&mut self, s: &'tcx StructField) {
383 self.check_missing_stability(s.id, s.span);
384 intravisit::walk_struct_field(self, s);
387 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem) {
388 self.check_missing_stability(i.id, i.span);
389 intravisit::walk_foreign_item(self, i);
392 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef) {
393 self.check_missing_stability(md.id, md.span);
397 impl<'a, 'tcx> Index<'tcx> {
398 pub fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Index<'tcx> {
400 tcx.sess.opts.debugging_opts.force_unstable_if_unmarked ||
401 tcx.features().staged_api;
402 let mut staged_api = FxHashMap::default();
403 staged_api.insert(LOCAL_CRATE, is_staged_api);
404 let mut index = Index {
406 stab_map: Default::default(),
407 depr_map: Default::default(),
408 active_features: Default::default(),
411 let ref active_lib_features = tcx.features().declared_lib_features;
413 // Put the active features into a map for quick lookup
414 index.active_features = active_lib_features.iter().map(|&(ref s, _)| s.clone()).collect();
417 let krate = tcx.hir().krate();
418 let mut annotator = Annotator {
423 in_trait_impl: false,
426 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
427 // a parent stability annotation which indicates that this is private
428 // with the `rustc_private` feature. This is intended for use when
429 // compiling librustc crates themselves so we can leverage crates.io
430 // while maintaining the invariant that all sysroot crates are unstable
431 // by default and are unable to be used.
432 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
433 let reason = "this crate is being loaded from the sysroot, an \
434 unstable location; did you mean to load this crate \
435 from crates.io via `Cargo.toml` instead?";
436 let stability = tcx.intern_stability(Stability {
437 level: attr::StabilityLevel::Unstable {
438 reason: Some(Symbol::intern(reason)),
441 feature: Symbol::intern("rustc_private"),
443 const_stability: None,
446 annotator.parent_stab = Some(stability);
449 annotator.annotate(ast::CRATE_NODE_ID,
452 AnnotationKind::Required,
453 |v| intravisit::walk_crate(v, krate));
458 pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
459 self.stab_map.get(&id).cloned()
462 pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
463 self.depr_map.get(&id).cloned()
467 /// Cross-references the feature names of unstable APIs with enabled
468 /// features and possibly prints errors.
469 pub fn check_unstable_api_usage<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
470 let mut checker = Checker { tcx };
471 tcx.hir().krate().visit_all_item_likes(&mut checker.as_deep_visitor());
474 /// Check whether an item marked with `deprecated(since="X")` is currently
475 /// deprecated (i.e., whether X is not greater than the current rustc version).
476 pub fn deprecation_in_effect(since: &str) -> bool {
477 fn parse_version(ver: &str) -> Vec<u32> {
478 // We ignore non-integer components of the version (e.g., "nightly").
479 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
482 if let Some(rustc) = option_env!("CFG_RELEASE") {
483 let since: Vec<u32> = parse_version(since);
484 let rustc: Vec<u32> = parse_version(rustc);
485 // We simply treat invalid `since` attributes as relating to a previous
486 // Rust version, thus always displaying the warning.
487 if since.len() != 3 {
492 // By default, a deprecation warning applies to
493 // the current version of the compiler.
498 struct Checker<'a, 'tcx: 'a> {
499 tcx: TyCtxt<'a, 'tcx, 'tcx>,
502 /// Result of `TyCtxt::eval_stability`.
503 pub enum EvalResult {
504 /// We can use the item because it is stable or we provided the
505 /// corresponding feature gate.
507 /// We cannot use the item because it is unstable and we did not provide the
508 /// corresponding feature gate.
511 reason: Option<Symbol>,
514 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
518 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
520 fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
521 // Check if `def_id` is a trait method.
522 match self.describe_def(def_id) {
523 Some(Def::Method(_)) |
524 Some(Def::AssociatedTy(_)) |
525 Some(Def::AssociatedConst(_)) => {
526 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
527 // Trait methods do not declare visibility (even
528 // for visibility info in cstore). Use containing
529 // trait instead, so methods of `pub` traits are
530 // themselves considered `pub`.
531 def_id = trait_def_id;
537 let visibility = self.visibility(def_id);
540 // Must check stability for `pub` items.
541 ty::Visibility::Public => false,
543 // These are not visible outside crate; therefore
544 // stability markers are irrelevant, if even present.
545 ty::Visibility::Restricted(..) |
546 ty::Visibility::Invisible => true,
550 /// Evaluates the stability of an item.
552 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
553 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
554 /// unstable feature otherwise.
556 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
557 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
559 pub fn eval_stability(self, def_id: DefId, id: Option<NodeId>, span: Span) -> EvalResult {
560 if span.allows_unstable() {
561 debug!("stability: skipping span={:?} since it is internal", span);
562 return EvalResult::Allow;
565 let lint_deprecated = |def_id: DefId, id: NodeId, note: Option<Symbol>| {
566 let path = self.item_path_str(def_id);
568 let msg = if let Some(note) = note {
569 format!("use of deprecated item '{}': {}", path, note)
571 format!("use of deprecated item '{}'", path)
574 self.lint_node(lint::builtin::DEPRECATED, id, span, &msg);
575 if id == ast::DUMMY_NODE_ID {
576 span_bug!(span, "emitted a deprecated lint with dummy node id: {:?}", def_id);
580 // Deprecated attributes apply in-crate and cross-crate.
581 if let Some(id) = id {
582 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
583 // If the deprecation is scheduled for a future Rust
584 // version, then we should display no warning message.
585 let deprecated_in_future_version = if let Some(sym) = depr_entry.attr.since {
586 let since = sym.as_str();
587 !deprecation_in_effect(&since)
592 let parent_def_id = self.hir().local_def_id(self.hir().get_parent(id));
593 let skip = deprecated_in_future_version ||
594 self.lookup_deprecation_entry(parent_def_id)
595 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
597 lint_deprecated(def_id, id, depr_entry.attr.note);
602 let is_staged_api = self.lookup_stability(DefId {
603 index: CRATE_DEF_INDEX,
607 return EvalResult::Allow;
610 let stability = self.lookup_stability(def_id);
612 inspecting def_id={:?} span={:?} of stability={:?}", def_id, span, stability);
614 if let Some(&Stability{rustc_depr: Some(attr::RustcDeprecation { reason, since }), ..})
616 if let Some(id) = id {
617 if deprecation_in_effect(&since.as_str()) {
618 lint_deprecated(def_id, id, Some(reason));
623 // Only the cross-crate scenario matters when checking unstable APIs
624 let cross_crate = !def_id.is_local();
626 return EvalResult::Allow;
629 // Issue #38412: private items lack stability markers.
630 if self.skip_stability_check_due_to_privacy(def_id) {
631 return EvalResult::Allow;
635 Some(&Stability { level: attr::Unstable { reason, issue }, feature, .. }) => {
636 if self.stability().active_features.contains(&feature) {
637 return EvalResult::Allow;
640 // When we're compiling the compiler itself we may pull in
641 // crates from crates.io, but those crates may depend on other
642 // crates also pulled in from crates.io. We want to ideally be
643 // able to compile everything without requiring upstream
644 // modifications, so in the case that this looks like a
645 // `rustc_private` crate (e.g., a compiler crate) and we also have
646 // the `-Z force-unstable-if-unmarked` flag present (we're
647 // compiling a compiler crate), then let this missing feature
649 if feature == "rustc_private" && issue == 27812 {
650 if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
651 return EvalResult::Allow;
655 EvalResult::Deny { feature, reason, issue }
658 // Stable APIs are always ok to call and deprecated APIs are
659 // handled by the lint emitting logic above.
668 /// Checks if an item is stable or error out.
670 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
671 /// exist, emits an error.
673 /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
674 /// not `None`, a deprecated lint attached to `id` will be emitted.
675 pub fn check_stability(self, def_id: DefId, id: Option<NodeId>, span: Span) {
676 match self.eval_stability(def_id, id, span) {
677 EvalResult::Allow => {}
678 EvalResult::Deny { feature, reason, issue } => {
679 let msg = match reason {
680 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
681 None => format!("use of unstable library feature '{}'", &feature)
684 let msp: MultiSpan = span.into();
685 let cm = &self.sess.parse_sess.source_map();
686 let span_key = msp.primary_span().and_then(|sp: Span|
688 let file = cm.lookup_char_pos(sp.lo()).file;
689 if file.name.is_macros() {
699 let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
700 let fresh = self.sess.one_time_diagnostics.borrow_mut().insert(error_id);
702 emit_feature_err(&self.sess.parse_sess, &feature.as_str(), span,
703 GateIssue::Library(Some(issue)), &msg);
706 EvalResult::Unmarked => {
707 span_bug!(span, "encountered unmarked API: {:?}", def_id);
713 impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
714 /// Because stability levels are scoped lexically, we want to walk
715 /// nested items in the context of the outer item, so enable
717 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
718 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
721 fn visit_item(&mut self, item: &'tcx hir::Item) {
723 hir::ItemKind::ExternCrate(_) => {
724 // compiler-generated `extern crate` items have a dummy span.
725 if item.span.is_dummy() { return }
727 let def_id = self.tcx.hir().local_def_id(item.id);
728 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
732 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
733 self.tcx.check_stability(def_id, Some(item.id), item.span);
736 // For implementations of traits, check the stability of each item
737 // individually as it's possible to have a stable trait with unstable
739 hir::ItemKind::Impl(.., Some(ref t), _, ref impl_item_refs) => {
740 if let Def::Trait(trait_did) = t.path.def {
741 for impl_item_ref in impl_item_refs {
742 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
743 let trait_item_def_id = self.tcx.associated_items(trait_did)
744 .find(|item| item.ident.name == impl_item.ident.name)
745 .map(|item| item.def_id);
746 if let Some(def_id) = trait_item_def_id {
747 // Pass `None` to skip deprecation warnings.
748 self.tcx.check_stability(def_id, None, impl_item.span);
754 // There's no good place to insert stability check for non-Copy unions,
755 // so semi-randomly perform it here in stability.rs
756 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
757 let def_id = self.tcx.hir().local_def_id(item.id);
758 let adt_def = self.tcx.adt_def(def_id);
759 let ty = self.tcx.type_of(def_id);
761 if adt_def.has_dtor(self.tcx) {
762 emit_feature_err(&self.tcx.sess.parse_sess,
763 "untagged_unions", item.span, GateIssue::Language,
764 "unions with `Drop` implementations are unstable");
766 let param_env = self.tcx.param_env(def_id);
767 if !param_env.can_type_implement_copy(self.tcx, ty).is_ok() {
768 emit_feature_err(&self.tcx.sess.parse_sess,
769 "untagged_unions", item.span, GateIssue::Language,
770 "unions with non-`Copy` fields are unstable");
777 intravisit::walk_item(self, item);
780 fn visit_path(&mut self, path: &'tcx hir::Path, id: hir::HirId) {
781 let id = self.tcx.hir().hir_to_node_id(id);
782 if let Some(def_id) = path.def.opt_def_id() {
783 self.tcx.check_stability(def_id, Some(id), path.span)
785 intravisit::walk_path(self, path)
789 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
790 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
791 self.lookup_deprecation_entry(id).map(|depr| depr.attr)
795 /// Given the list of enabled features that were not language features (i.e., that
796 /// were expected to be library features), and the list of features used from
797 /// libraries, identify activated features that don't exist and error about them.
798 pub fn check_unused_or_stable_features<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
799 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
801 if tcx.stability().staged_api[&LOCAL_CRATE] {
802 let krate = tcx.hir().krate();
803 let mut missing = MissingStabilityAnnotations {
807 missing.check_missing_stability(ast::CRATE_NODE_ID, krate.span);
808 intravisit::walk_crate(&mut missing, krate);
809 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
812 let declared_lang_features = &tcx.features().declared_lang_features;
813 let mut lang_features = FxHashSet::default();
814 for &(feature, span, since) in declared_lang_features {
815 if let Some(since) = since {
816 // Warn if the user has enabled an already-stable lang feature.
817 unnecessary_stable_feature_lint(tcx, span, feature, since);
819 if lang_features.contains(&feature) {
820 // Warn if the user enables a lang feature multiple times.
821 duplicate_feature_err(tcx.sess, span, feature);
823 lang_features.insert(feature);
826 let declared_lib_features = &tcx.features().declared_lib_features;
827 let mut remaining_lib_features = FxHashMap::default();
828 for (feature, span) in declared_lib_features {
829 if remaining_lib_features.contains_key(&feature) {
830 // Warn if the user enables a lib feature multiple times.
831 duplicate_feature_err(tcx.sess, *span, *feature);
833 remaining_lib_features.insert(feature, span.clone());
835 // `stdbuild` has special handling for `libc`, so we need to
836 // recognise the feature when building std.
837 // Likewise, libtest is handled specially, so `test` isn't
838 // available as we'd like it to be.
839 // FIXME: only remove `libc` when `stdbuild` is active.
840 // FIXME: remove special casing for `test`.
841 remaining_lib_features.remove(&Symbol::intern("libc"));
842 remaining_lib_features.remove(&Symbol::intern("test"));
845 |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &Vec<_>| {
846 for &(feature, since) in defined_features {
847 if let Some(since) = since {
848 if let Some(span) = remaining_lib_features.get(&feature) {
849 // Warn if the user has enabled an already-stable lib feature.
850 unnecessary_stable_feature_lint(tcx, *span, feature, since);
853 remaining_lib_features.remove(&feature);
854 if remaining_lib_features.is_empty() {
860 // We always collect the lib features declared in the current crate, even if there are
861 // no unknown features, because the collection also does feature attribute validation.
862 let local_defined_features = tcx.lib_features().to_vec();
863 if !remaining_lib_features.is_empty() {
864 check_features(&mut remaining_lib_features, &local_defined_features);
866 for &cnum in &*tcx.crates() {
867 if remaining_lib_features.is_empty() {
870 check_features(&mut remaining_lib_features, &tcx.defined_lib_features(cnum));
874 for (feature, span) in remaining_lib_features {
875 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
878 // FIXME(#44232): the `used_features` table no longer exists, so we
879 // don't lint about unused features. We should reenable this one day!
882 fn unnecessary_stable_feature_lint<'a, 'tcx>(
883 tcx: TyCtxt<'a, 'tcx, 'tcx>,
888 tcx.lint_node(lint::builtin::STABLE_FEATURES,
891 &format!("the feature `{}` has been stable since {} and no longer requires \
892 an attribute to enable", feature, since));
895 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
896 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)