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 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
6 use rustc::middle::privacy::AccessLevels;
7 use rustc::middle::stability::{DeprecationEntry, Index};
8 use rustc::session::Session;
9 use rustc::traits::misc::can_type_implement_copy;
10 use rustc::ty::query::Providers;
11 use rustc::ty::TyCtxt;
12 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
14 use rustc_hir::def::{DefKind, Res};
15 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
16 use rustc_hir::{Generics, HirId, Item, StructField, Variant};
17 use rustc_span::symbol::{sym, Symbol};
19 use syntax::ast::Attribute;
20 use syntax::attr::{self, Stability};
21 use syntax::feature_gate::feature_err;
23 use std::cmp::Ordering;
24 use std::mem::replace;
25 use std::num::NonZeroU32;
27 use rustc_error_codes::*;
31 // Annotation is required if not inherited from unstable parents
33 // Annotation is useless, reject it
35 // Annotation itself is useless, but it can be propagated to children
39 // A private tree-walker for producing an Index.
40 struct Annotator<'a, 'tcx> {
42 index: &'a mut Index<'tcx>,
43 parent_stab: Option<&'tcx Stability>,
44 parent_depr: Option<DeprecationEntry>,
48 impl<'a, 'tcx> Annotator<'a, 'tcx> {
49 // Determine the stability for a node based on its attributes and inherited
50 // stability. The stability is recorded in the index and used as the parent.
61 if self.tcx.features().staged_api {
62 // This crate explicitly wants staged API.
63 debug!("annotate(id = {:?}, attrs = {:?})", hir_id, attrs);
64 if let Some(..) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
65 self.tcx.sess.span_err(
67 "`#[deprecated]` cannot be used in staged API; \
68 use `#[rustc_deprecated]` instead",
71 let (stab, const_stab) =
72 attr::find_stability(&self.tcx.sess.parse_sess, attrs, item_sp);
73 if let Some(const_stab) = const_stab {
74 let const_stab = self.tcx.intern_const_stability(const_stab);
75 self.index.const_stab_map.insert(hir_id, const_stab);
77 if let Some(mut stab) = stab {
78 // Error if prohibited, or can't inherit anything from a container.
79 if kind == AnnotationKind::Prohibited
80 || (kind == AnnotationKind::Container
81 && stab.level.is_stable()
82 && stab.rustc_depr.is_none())
84 self.tcx.sess.span_err(item_sp, "This stability annotation is useless");
87 debug!("annotate: found {:?}", stab);
88 // If parent is deprecated and we're not, inherit this by merging
89 // deprecated_since and its reason.
90 if let Some(parent_stab) = self.parent_stab {
91 if parent_stab.rustc_depr.is_some() && stab.rustc_depr.is_none() {
92 stab.rustc_depr = parent_stab.rustc_depr.clone()
96 let stab = self.tcx.intern_stability(stab);
98 // Check if deprecated_since < stable_since. If it is,
99 // this is *almost surely* an accident.
101 &Some(attr::RustcDeprecation { since: dep_since, .. }),
102 &attr::Stable { since: stab_since },
103 ) = (&stab.rustc_depr, &stab.level)
105 // Explicit version of iter::order::lt to handle parse errors properly
106 for (dep_v, stab_v) in
107 dep_since.as_str().split('.').zip(stab_since.as_str().split('.'))
109 if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
110 match dep_v.cmp(&stab_v) {
112 self.tcx.sess.span_err(
114 "An API can't be stabilized \
115 after it is deprecated",
119 Ordering::Equal => continue,
120 Ordering::Greater => break,
123 // Act like it isn't less because the question is now nonsensical,
124 // and this makes us not do anything else interesting.
125 self.tcx.sess.span_err(
127 "Invalid stability or deprecation \
135 self.index.stab_map.insert(hir_id, stab);
137 let orig_parent_stab = replace(&mut self.parent_stab, Some(stab));
138 visit_children(self);
139 self.parent_stab = orig_parent_stab;
141 debug!("annotate: not found, parent = {:?}", self.parent_stab);
142 if let Some(stab) = self.parent_stab {
143 if stab.level.is_unstable() {
144 self.index.stab_map.insert(hir_id, stab);
147 visit_children(self);
150 // Emit errors for non-staged-api crates.
151 let unstable_attrs = [
154 sym::rustc_deprecated,
155 sym::rustc_const_unstable,
156 sym::rustc_const_stable,
159 let name = attr.name_or_empty();
160 if unstable_attrs.contains(&name) {
161 attr::mark_used(attr);
166 "stability attributes may not be used outside of the standard library",
172 // Propagate unstability. This can happen even for non-staged-api crates in case
173 // -Zforce-unstable-if-unmarked is set.
174 if let Some(stab) = self.parent_stab {
175 if stab.level.is_unstable() {
176 self.index.stab_map.insert(hir_id, stab);
180 if let Some(depr) = attr::find_deprecation(&self.tcx.sess.parse_sess, attrs, item_sp) {
181 if kind == AnnotationKind::Prohibited {
182 self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
185 // `Deprecation` is just two pointers, no need to intern it
186 let depr_entry = DeprecationEntry::local(depr, hir_id);
187 self.index.depr_map.insert(hir_id, depr_entry.clone());
189 let orig_parent_depr = replace(&mut self.parent_depr, Some(depr_entry));
190 visit_children(self);
191 self.parent_depr = orig_parent_depr;
192 } else if let Some(parent_depr) = self.parent_depr.clone() {
193 self.index.depr_map.insert(hir_id, parent_depr);
194 visit_children(self);
196 visit_children(self);
202 impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
203 /// Because stability levels are scoped lexically, we want to walk
204 /// nested items in the context of the outer item, so enable
206 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
207 NestedVisitorMap::All(&self.tcx.hir())
210 fn visit_item(&mut self, i: &'tcx Item<'tcx>) {
211 let orig_in_trait_impl = self.in_trait_impl;
212 let mut kind = AnnotationKind::Required;
214 // Inherent impls and foreign modules serve only as containers for other items,
215 // they don't have their own stability. They still can be annotated as unstable
216 // and propagate this unstability to children, but this annotation is completely
217 // optional. They inherit stability from their parents when unannotated.
218 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {
219 self.in_trait_impl = false;
220 kind = AnnotationKind::Container;
222 hir::ItemKind::Impl(.., Some(_), _, _) => {
223 self.in_trait_impl = true;
225 hir::ItemKind::Struct(ref sd, _) => {
226 if let Some(ctor_hir_id) = sd.ctor_hir_id() {
227 self.annotate(ctor_hir_id, &i.attrs, i.span, AnnotationKind::Required, |_| {})
233 self.annotate(i.hir_id, &i.attrs, i.span, kind, |v| intravisit::walk_item(v, i));
234 self.in_trait_impl = orig_in_trait_impl;
237 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem<'tcx>) {
238 self.annotate(ti.hir_id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
239 intravisit::walk_trait_item(v, ti);
243 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem<'tcx>) {
245 if self.in_trait_impl { AnnotationKind::Prohibited } else { AnnotationKind::Required };
246 self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, |v| {
247 intravisit::walk_impl_item(v, ii);
251 fn visit_variant(&mut self, var: &'tcx Variant<'tcx>, g: &'tcx Generics<'tcx>, item_id: HirId) {
252 self.annotate(var.id, &var.attrs, var.span, AnnotationKind::Required, |v| {
253 if let Some(ctor_hir_id) = var.data.ctor_hir_id() {
254 v.annotate(ctor_hir_id, &var.attrs, var.span, AnnotationKind::Required, |_| {});
257 intravisit::walk_variant(v, var, g, item_id)
261 fn visit_struct_field(&mut self, s: &'tcx StructField<'tcx>) {
262 self.annotate(s.hir_id, &s.attrs, s.span, AnnotationKind::Required, |v| {
263 intravisit::walk_struct_field(v, s);
267 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) {
268 self.annotate(i.hir_id, &i.attrs, i.span, AnnotationKind::Required, |v| {
269 intravisit::walk_foreign_item(v, i);
273 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef<'tcx>) {
274 self.annotate(md.hir_id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
278 struct MissingStabilityAnnotations<'a, 'tcx> {
280 access_levels: &'a AccessLevels,
283 impl<'a, 'tcx> MissingStabilityAnnotations<'a, 'tcx> {
284 fn check_missing_stability(&self, hir_id: HirId, span: Span, name: &str) {
285 let stab = self.tcx.stability().local_stability(hir_id);
287 !self.tcx.sess.opts.test && stab.is_none() && self.access_levels.is_reachable(hir_id);
289 self.tcx.sess.span_err(span, &format!("{} has missing stability attribute", name));
294 impl<'a, 'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'a, 'tcx> {
295 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
296 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
299 fn visit_item(&mut self, i: &'tcx Item<'tcx>) {
301 // Inherent impls and foreign modules serve only as containers for other items,
302 // they don't have their own stability. They still can be annotated as unstable
303 // and propagate this unstability to children, but this annotation is completely
304 // optional. They inherit stability from their parents when unannotated.
305 hir::ItemKind::Impl(.., None, _, _) | hir::ItemKind::ForeignMod(..) => {}
307 _ => self.check_missing_stability(i.hir_id, i.span, i.kind.descriptive_variant()),
310 intravisit::walk_item(self, i)
313 fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem<'tcx>) {
314 self.check_missing_stability(ti.hir_id, ti.span, "item");
315 intravisit::walk_trait_item(self, ti);
318 fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem<'tcx>) {
319 let impl_def_id = self.tcx.hir().local_def_id(self.tcx.hir().get_parent_item(ii.hir_id));
320 if self.tcx.impl_trait_ref(impl_def_id).is_none() {
321 self.check_missing_stability(ii.hir_id, ii.span, "item");
323 intravisit::walk_impl_item(self, ii);
326 fn visit_variant(&mut self, var: &'tcx Variant<'tcx>, g: &'tcx Generics<'tcx>, item_id: HirId) {
327 self.check_missing_stability(var.id, var.span, "variant");
328 intravisit::walk_variant(self, var, g, item_id);
331 fn visit_struct_field(&mut self, s: &'tcx StructField<'tcx>) {
332 self.check_missing_stability(s.hir_id, s.span, "field");
333 intravisit::walk_struct_field(self, s);
336 fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) {
337 self.check_missing_stability(i.hir_id, i.span, i.kind.descriptive_variant());
338 intravisit::walk_foreign_item(self, i);
341 fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef<'tcx>) {
342 self.check_missing_stability(md.hir_id, md.span, "macro");
346 fn new_index(tcx: TyCtxt<'tcx>) -> Index<'tcx> {
348 tcx.sess.opts.debugging_opts.force_unstable_if_unmarked || tcx.features().staged_api;
349 let mut staged_api = FxHashMap::default();
350 staged_api.insert(LOCAL_CRATE, is_staged_api);
351 let mut index = Index {
353 stab_map: Default::default(),
354 const_stab_map: Default::default(),
355 depr_map: Default::default(),
356 active_features: Default::default(),
359 let active_lib_features = &tcx.features().declared_lib_features;
360 let active_lang_features = &tcx.features().declared_lang_features;
362 // Put the active features into a map for quick lookup.
363 index.active_features = active_lib_features
365 .map(|&(ref s, ..)| s.clone())
366 .chain(active_lang_features.iter().map(|&(ref s, ..)| s.clone()))
370 let krate = tcx.hir().krate();
371 let mut annotator = Annotator {
376 in_trait_impl: false,
379 // If the `-Z force-unstable-if-unmarked` flag is passed then we provide
380 // a parent stability annotation which indicates that this is private
381 // with the `rustc_private` feature. This is intended for use when
382 // compiling librustc crates themselves so we can leverage crates.io
383 // while maintaining the invariant that all sysroot crates are unstable
384 // by default and are unable to be used.
385 if tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
386 let reason = "this crate is being loaded from the sysroot, an \
387 unstable location; did you mean to load this crate \
388 from crates.io via `Cargo.toml` instead?";
389 let stability = tcx.intern_stability(Stability {
390 level: attr::StabilityLevel::Unstable {
391 reason: Some(Symbol::intern(reason)),
392 issue: NonZeroU32::new(27812),
395 feature: sym::rustc_private,
398 annotator.parent_stab = Some(stability);
405 AnnotationKind::Required,
406 |v| intravisit::walk_crate(v, krate),
412 /// Cross-references the feature names of unstable APIs with enabled
413 /// features and possibly prints errors.
414 fn check_mod_unstable_api_usage(tcx: TyCtxt<'_>, module_def_id: DefId) {
415 tcx.hir().visit_item_likes_in_module(module_def_id, &mut Checker { tcx }.as_deep_visitor());
418 pub(crate) fn provide(providers: &mut Providers<'_>) {
419 *providers = Providers { check_mod_unstable_api_usage, ..*providers };
420 providers.stability_index = |tcx, cnum| {
421 assert_eq!(cnum, LOCAL_CRATE);
422 tcx.arena.alloc(new_index(tcx))
426 struct Checker<'tcx> {
430 impl Visitor<'tcx> for Checker<'tcx> {
431 /// Because stability levels are scoped lexically, we want to walk
432 /// nested items in the context of the outer item, so enable
434 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
435 NestedVisitorMap::OnlyBodies(&self.tcx.hir())
438 fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
440 hir::ItemKind::ExternCrate(_) => {
441 // compiler-generated `extern crate` items have a dummy span.
442 if item.span.is_dummy() {
446 let def_id = self.tcx.hir().local_def_id(item.hir_id);
447 let cnum = match self.tcx.extern_mod_stmt_cnum(def_id) {
451 let def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
452 self.tcx.check_stability(def_id, Some(item.hir_id), item.span);
455 // For implementations of traits, check the stability of each item
456 // individually as it's possible to have a stable trait with unstable
458 hir::ItemKind::Impl(.., Some(ref t), _, impl_item_refs) => {
459 if let Res::Def(DefKind::Trait, trait_did) = t.path.res {
460 for impl_item_ref in impl_item_refs {
461 let impl_item = self.tcx.hir().impl_item(impl_item_ref.id);
462 let trait_item_def_id = self
464 .associated_items(trait_did)
465 .find(|item| item.ident.name == impl_item.ident.name)
466 .map(|item| item.def_id);
467 if let Some(def_id) = trait_item_def_id {
468 // Pass `None` to skip deprecation warnings.
469 self.tcx.check_stability(def_id, None, impl_item.span);
475 // There's no good place to insert stability check for non-Copy unions,
476 // so semi-randomly perform it here in stability.rs
477 hir::ItemKind::Union(..) if !self.tcx.features().untagged_unions => {
478 let def_id = self.tcx.hir().local_def_id(item.hir_id);
479 let adt_def = self.tcx.adt_def(def_id);
480 let ty = self.tcx.type_of(def_id);
482 if adt_def.has_dtor(self.tcx) {
484 &self.tcx.sess.parse_sess,
485 sym::untagged_unions,
487 "unions with `Drop` implementations are unstable",
491 let param_env = self.tcx.param_env(def_id);
492 if !can_type_implement_copy(self.tcx, param_env, ty).is_ok() {
494 &self.tcx.sess.parse_sess,
495 sym::untagged_unions,
497 "unions with non-`Copy` fields are unstable",
506 intravisit::walk_item(self, item);
509 fn visit_path(&mut self, path: &'tcx hir::Path<'tcx>, id: hir::HirId) {
510 if let Some(def_id) = path.res.opt_def_id() {
511 self.tcx.check_stability(def_id, Some(id), path.span)
513 intravisit::walk_path(self, path)
517 /// Given the list of enabled features that were not language features (i.e., that
518 /// were expected to be library features), and the list of features used from
519 /// libraries, identify activated features that don't exist and error about them.
520 pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
521 let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
523 if tcx.stability().staged_api[&LOCAL_CRATE] {
524 let krate = tcx.hir().krate();
525 let mut missing = MissingStabilityAnnotations { tcx, access_levels };
526 missing.check_missing_stability(hir::CRATE_HIR_ID, krate.span, "crate");
527 intravisit::walk_crate(&mut missing, krate);
528 krate.visit_all_item_likes(&mut missing.as_deep_visitor());
531 let declared_lang_features = &tcx.features().declared_lang_features;
532 let mut lang_features = FxHashSet::default();
533 for &(feature, span, since) in declared_lang_features {
534 if let Some(since) = since {
535 // Warn if the user has enabled an already-stable lang feature.
536 unnecessary_stable_feature_lint(tcx, span, feature, since);
538 if !lang_features.insert(feature) {
539 // Warn if the user enables a lang feature multiple times.
540 duplicate_feature_err(tcx.sess, span, feature);
544 let declared_lib_features = &tcx.features().declared_lib_features;
545 let mut remaining_lib_features = FxHashMap::default();
546 for (feature, span) in declared_lib_features {
547 if remaining_lib_features.contains_key(&feature) {
548 // Warn if the user enables a lib feature multiple times.
549 duplicate_feature_err(tcx.sess, *span, *feature);
551 remaining_lib_features.insert(feature, span.clone());
553 // `stdbuild` has special handling for `libc`, so we need to
554 // recognise the feature when building std.
555 // Likewise, libtest is handled specially, so `test` isn't
556 // available as we'd like it to be.
557 // FIXME: only remove `libc` when `stdbuild` is active.
558 // FIXME: remove special casing for `test`.
559 remaining_lib_features.remove(&Symbol::intern("libc"));
560 remaining_lib_features.remove(&sym::test);
562 let check_features = |remaining_lib_features: &mut FxHashMap<_, _>, defined_features: &[_]| {
563 for &(feature, since) in defined_features {
564 if let Some(since) = since {
565 if let Some(span) = remaining_lib_features.get(&feature) {
566 // Warn if the user has enabled an already-stable lib feature.
567 unnecessary_stable_feature_lint(tcx, *span, feature, since);
570 remaining_lib_features.remove(&feature);
571 if remaining_lib_features.is_empty() {
577 // We always collect the lib features declared in the current crate, even if there are
578 // no unknown features, because the collection also does feature attribute validation.
579 let local_defined_features = tcx.lib_features().to_vec();
580 if !remaining_lib_features.is_empty() {
581 check_features(&mut remaining_lib_features, &local_defined_features);
583 for &cnum in &*tcx.crates() {
584 if remaining_lib_features.is_empty() {
587 check_features(&mut remaining_lib_features, tcx.defined_lib_features(cnum));
591 for (feature, span) in remaining_lib_features {
592 struct_span_err!(tcx.sess, span, E0635, "unknown feature `{}`", feature).emit();
595 // FIXME(#44232): the `used_features` table no longer exists, so we
596 // don't lint about unused features. We should reenable this one day!
599 fn unnecessary_stable_feature_lint(tcx: TyCtxt<'_>, span: Span, feature: Symbol, since: Symbol) {
601 lint::builtin::STABLE_FEATURES,
605 "the feature `{}` has been stable since {} and no longer requires \
606 an attribute to enable",
612 fn duplicate_feature_err(sess: &Session, span: Span, feature: Symbol) {
613 struct_span_err!(sess, span, E0636, "the feature `{}` has already been declared", feature)