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::ty::{self, DefIdTree, TyCtxt};
8 use rustc_attr::{self as attr, ConstStability, DefaultBodyStability, Deprecation, Stability};
9 use rustc_data_structures::fx::FxHashMap;
10 use rustc_errors::{Applicability, Diagnostic};
11 use rustc_feature::GateIssue;
12 use rustc_hir::def::DefKind;
13 use rustc_hir::def_id::{DefId, LocalDefId};
14 use rustc_hir::{self as hir, HirId};
15 use rustc_middle::ty::print::with_no_trimmed_paths;
16 use rustc_session::lint::builtin::{DEPRECATED, DEPRECATED_IN_FUTURE, SOFT_UNSTABLE};
17 use rustc_session::lint::{BuiltinLintDiagnostics, Level, Lint, LintBuffer};
18 use rustc_session::parse::feature_err_issue;
19 use rustc_session::Session;
20 use rustc_span::symbol::{sym, Symbol};
22 use std::num::NonZeroU32;
24 #[derive(PartialEq, Clone, Copy, Debug)]
25 pub enum StabilityLevel {
30 /// An entry in the `depr_map`.
31 #[derive(Copy, Clone, HashStable, Debug, Encodable, Decodable)]
32 pub struct DeprecationEntry {
33 /// The metadata of the attribute associated with this entry.
34 pub attr: Deprecation,
35 /// The `DefId` where the attr was originally attached. `None` for non-local
37 origin: Option<LocalDefId>,
40 impl DeprecationEntry {
41 pub fn local(attr: Deprecation, def_id: LocalDefId) -> DeprecationEntry {
42 DeprecationEntry { attr, origin: Some(def_id) }
45 pub fn external(attr: Deprecation) -> DeprecationEntry {
46 DeprecationEntry { attr, origin: None }
49 pub fn same_origin(&self, other: &DeprecationEntry) -> bool {
50 match (self.origin, other.origin) {
51 (Some(o1), Some(o2)) => o1 == o2,
57 /// A stability index, giving the stability level for items and methods.
58 #[derive(HashStable, Debug)]
60 /// This is mostly a cache, except the stabilities of local items
61 /// are filled by the annotator.
62 pub stab_map: FxHashMap<LocalDefId, Stability>,
63 pub const_stab_map: FxHashMap<LocalDefId, ConstStability>,
64 pub default_body_stab_map: FxHashMap<LocalDefId, DefaultBodyStability>,
65 pub depr_map: FxHashMap<LocalDefId, DeprecationEntry>,
66 /// Mapping from feature name to feature name based on the `implied_by` field of `#[unstable]`
67 /// attributes. If a `#[unstable(feature = "implier", implied_by = "impliee")]` attribute
68 /// exists, then this map will have a `impliee -> implier` entry.
70 /// This mapping is necessary unless both the `#[stable]` and `#[unstable]` attributes should
71 /// specify their implications (both `implies` and `implied_by`). If only one of the two
72 /// attributes do (as in the current implementation, `implied_by` in `#[unstable]`), then this
73 /// mapping is necessary for diagnostics. When a "unnecessary feature attribute" error is
74 /// reported, only the `#[stable]` attribute information is available, so the map is necessary
75 /// to know that the feature implies another feature. If it were reversed, and the `#[stable]`
76 /// attribute had an `implies` meta item, then a map would be necessary when avoiding a "use of
77 /// unstable feature" error for a feature that was implied.
78 pub implications: FxHashMap<Symbol, Symbol>,
82 pub fn local_stability(&self, def_id: LocalDefId) -> Option<Stability> {
83 self.stab_map.get(&def_id).copied()
86 pub fn local_const_stability(&self, def_id: LocalDefId) -> Option<ConstStability> {
87 self.const_stab_map.get(&def_id).copied()
90 pub fn local_default_body_stability(&self, def_id: LocalDefId) -> Option<DefaultBodyStability> {
91 self.default_body_stab_map.get(&def_id).copied()
94 pub fn local_deprecation_entry(&self, def_id: LocalDefId) -> Option<DeprecationEntry> {
95 self.depr_map.get(&def_id).cloned()
99 pub fn report_unstable(
102 reason: Option<Symbol>,
103 issue: Option<NonZeroU32>,
104 suggestion: Option<(Span, String, String, Applicability)>,
107 soft_handler: impl FnOnce(&'static Lint, Span, &str),
109 let msg = match reason {
110 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
111 None => format!("use of unstable library feature '{}'", &feature),
115 soft_handler(SOFT_UNSTABLE, span, &msg)
118 feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg);
119 if let Some((inner_types, ref msg, sugg, applicability)) = suggestion {
120 err.span_suggestion(inner_types, msg, sugg, applicability);
126 /// Checks whether an item marked with `deprecated(since="X")` is currently
127 /// deprecated (i.e., whether X is not greater than the current rustc version).
128 pub fn deprecation_in_effect(depr: &Deprecation) -> bool {
129 let is_since_rustc_version = depr.is_since_rustc_version;
130 let since = depr.since.as_ref().map(Symbol::as_str);
132 fn parse_version(ver: &str) -> Vec<u32> {
133 // We ignore non-integer components of the version (e.g., "nightly").
134 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
137 if !is_since_rustc_version {
138 // The `since` field doesn't have semantic purpose without `#![staged_api]`.
142 if let Some(since) = since {
147 if let Some(rustc) = option_env!("CFG_RELEASE") {
148 let since: Vec<u32> = parse_version(&since);
149 let rustc: Vec<u32> = parse_version(rustc);
150 // We simply treat invalid `since` attributes as relating to a previous
151 // Rust version, thus always displaying the warning.
152 if since.len() != 3 {
155 return since <= rustc;
159 // Assume deprecation is in effect if "since" field is missing
160 // or if we can't determine the current Rust version.
164 pub fn deprecation_suggestion(
165 diag: &mut Diagnostic,
167 suggestion: Option<Symbol>,
170 if let Some(suggestion) = suggestion {
171 diag.span_suggestion_verbose(
173 &format!("replace the use of the deprecated {}", kind),
175 Applicability::MachineApplicable,
180 fn deprecation_lint(is_in_effect: bool) -> &'static Lint {
181 if is_in_effect { DEPRECATED } else { DEPRECATED_IN_FUTURE }
184 fn deprecation_message(
186 since: Option<Symbol>,
187 note: Option<Symbol>,
191 let message = if is_in_effect {
192 format!("use of deprecated {} `{}`", kind, path)
194 let since = since.as_ref().map(Symbol::as_str);
196 if since == Some("TBD") {
197 format!("use of {} `{}` that will be deprecated in a future Rust version", kind, path)
200 "use of {} `{}` that will be deprecated in future version {}",
209 Some(reason) => format!("{}: {}", message, reason),
214 pub fn deprecation_message_and_lint(
218 ) -> (String, &'static Lint) {
219 let is_in_effect = deprecation_in_effect(depr);
221 deprecation_message(is_in_effect, depr.since, depr.note, kind, path),
222 deprecation_lint(is_in_effect),
226 pub fn early_report_deprecation<'a>(
227 lint_buffer: &'a mut LintBuffer,
229 suggestion: Option<Symbol>,
234 if span.in_derive_expansion() {
238 let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span);
239 lint_buffer.buffer_lint_with_diagnostic(lint, node_id, span, message, diag);
242 fn late_report_deprecation(
245 suggestion: Option<Symbol>,
248 method_span: Option<Span>,
252 if span.in_derive_expansion() {
255 let method_span = method_span.unwrap_or(span);
256 tcx.struct_span_lint_hir(lint, hir_id, method_span, message, |diag| {
257 if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
258 let kind = tcx.def_kind(def_id).descr(def_id);
259 deprecation_suggestion(diag, kind, suggestion, method_span);
265 /// Result of `TyCtxt::eval_stability`.
266 pub enum EvalResult {
267 /// We can use the item because it is stable or we provided the
268 /// corresponding feature gate.
270 /// We cannot use the item because it is unstable and we did not provide the
271 /// corresponding feature gate.
274 reason: Option<Symbol>,
275 issue: Option<NonZeroU32>,
276 suggestion: Option<(Span, String, String, Applicability)>,
279 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
284 fn skip_stability_check_due_to_privacy(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
285 if tcx.def_kind(def_id) == DefKind::TyParam {
286 // Have no visibility, considered public for the purpose of this check.
289 match tcx.visibility(def_id) {
290 // Must check stability for `pub` items.
291 ty::Visibility::Public => false,
293 // These are not visible outside crate; therefore
294 // stability markers are irrelevant, if even present.
295 ty::Visibility::Restricted(..) => true,
300 fn suggestion_for_allocator_api(
305 ) -> Option<(Span, String, String, Applicability)> {
306 if feature == sym::allocator_api {
307 if let Some(trait_) = tcx.opt_parent(def_id) {
308 if tcx.is_diagnostic_item(sym::Vec, trait_) {
309 let sm = tcx.sess.parse_sess.source_map();
310 let inner_types = sm.span_extend_to_prev_char(span, '<', true);
311 if let Ok(snippet) = sm.span_to_snippet(inner_types) {
314 "consider wrapping the inner types in tuple".to_string(),
315 format!("({})", snippet),
316 Applicability::MaybeIncorrect,
325 /// An override option for eval_stability.
326 pub enum AllowUnstable {
327 /// Don't emit an unstable error for the item
329 /// Handle the item normally
333 impl<'tcx> TyCtxt<'tcx> {
334 /// Evaluates the stability of an item.
336 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
337 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
338 /// unstable feature otherwise.
340 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
341 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
343 pub fn eval_stability(
348 method_span: Option<Span>,
350 self.eval_stability_allow_unstable(def_id, id, span, method_span, AllowUnstable::No)
353 /// Evaluates the stability of an item.
355 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
356 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
357 /// unstable feature otherwise.
359 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
360 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
363 /// Pass `AllowUnstable::Yes` to `allow_unstable` to force an unstable item to be allowed. Deprecation warnings will be emitted normally.
364 pub fn eval_stability_allow_unstable(
369 method_span: Option<Span>,
370 allow_unstable: AllowUnstable,
372 // Deprecated attributes apply in-crate and cross-crate.
373 if let Some(id) = id {
374 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
375 let parent_def_id = self.hir().get_parent_item(id);
377 .lookup_deprecation_entry(parent_def_id.to_def_id())
378 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
380 // #[deprecated] doesn't emit a notice if we're not on the
381 // topmost deprecation. For example, if a struct is deprecated,
382 // the use of a field won't be linted.
384 // With #![staged_api], we want to emit down the whole
386 let depr_attr = &depr_entry.attr;
387 if !skip || depr_attr.is_since_rustc_version {
388 // Calculating message for lint involves calling `self.def_path_str`.
389 // Which by default to calculate visible path will invoke expensive `visible_parent_map` query.
390 // So we skip message calculation altogether, if lint is allowed.
391 let is_in_effect = deprecation_in_effect(depr_attr);
392 let lint = deprecation_lint(is_in_effect);
393 if self.lint_level_at_node(lint, id).0 != Level::Allow {
394 let def_path = with_no_trimmed_paths!(self.def_path_str(def_id));
395 let def_kind = self.def_kind(def_id).descr(def_id);
397 late_report_deprecation(
399 &deprecation_message(
406 depr_attr.suggestion,
418 let is_staged_api = self.lookup_stability(def_id.krate.as_def_id()).is_some();
420 return EvalResult::Allow;
423 // Only the cross-crate scenario matters when checking unstable APIs
424 let cross_crate = !def_id.is_local();
426 return EvalResult::Allow;
429 let stability = self.lookup_stability(def_id);
432 inspecting def_id={:?} span={:?} of stability={:?}",
433 def_id, span, stability
436 // Issue #38412: private items lack stability markers.
437 if skip_stability_check_due_to_privacy(self, def_id) {
438 return EvalResult::Allow;
443 level: attr::Unstable { reason, issue, is_soft, implied_by },
447 if span.allows_unstable(feature) {
448 debug!("stability: skipping span={:?} since it is internal", span);
449 return EvalResult::Allow;
451 if self.features().active(feature) {
452 return EvalResult::Allow;
455 // If this item was previously part of a now-stabilized feature which is still
456 // active (i.e. the user hasn't removed the attribute for the stabilized feature
457 // yet) then allow use of this item.
458 if let Some(implied_by) = implied_by && self.features().active(implied_by) {
459 return EvalResult::Allow;
462 // When we're compiling the compiler itself we may pull in
463 // crates from crates.io, but those crates may depend on other
464 // crates also pulled in from crates.io. We want to ideally be
465 // able to compile everything without requiring upstream
466 // modifications, so in the case that this looks like a
467 // `rustc_private` crate (e.g., a compiler crate) and we also have
468 // the `-Z force-unstable-if-unmarked` flag present (we're
469 // compiling a compiler crate), then let this missing feature
471 if feature == sym::rustc_private && issue == NonZeroU32::new(27812) {
472 if self.sess.opts.unstable_opts.force_unstable_if_unmarked {
473 return EvalResult::Allow;
477 if matches!(allow_unstable, AllowUnstable::Yes) {
478 return EvalResult::Allow;
481 let suggestion = suggestion_for_allocator_api(self, def_id, span, feature);
484 reason: reason.to_opt_reason(),
491 // Stable APIs are always ok to call and deprecated APIs are
492 // handled by the lint emitting logic above.
495 None => EvalResult::Unmarked,
499 /// Evaluates the default-impl stability of an item.
501 /// Returns `EvalResult::Allow` if the item's default implementation is stable, or unstable but the corresponding
502 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
503 /// unstable feature otherwise.
504 pub fn eval_default_body_stability(self, def_id: DefId, span: Span) -> EvalResult {
505 let is_staged_api = self.lookup_stability(def_id.krate.as_def_id()).is_some();
507 return EvalResult::Allow;
510 // Only the cross-crate scenario matters when checking unstable APIs
511 let cross_crate = !def_id.is_local();
513 return EvalResult::Allow;
516 let stability = self.lookup_default_body_stability(def_id);
518 "body stability: inspecting def_id={def_id:?} span={span:?} of stability={stability:?}"
521 // Issue #38412: private items lack stability markers.
522 if skip_stability_check_due_to_privacy(self, def_id) {
523 return EvalResult::Allow;
527 Some(DefaultBodyStability {
528 level: attr::Unstable { reason, issue, is_soft, .. },
531 if span.allows_unstable(feature) {
532 debug!("body stability: skipping span={:?} since it is internal", span);
533 return EvalResult::Allow;
535 if self.features().active(feature) {
536 return EvalResult::Allow;
541 reason: reason.to_opt_reason(),
548 // Stable APIs are always ok to call
551 None => EvalResult::Unmarked,
555 /// Checks if an item is stable or error out.
557 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
558 /// exist, emits an error.
560 /// This function will also check if the item is deprecated.
561 /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted.
563 /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature.
564 pub fn check_stability(
569 method_span: Option<Span>,
571 self.check_stability_allow_unstable(def_id, id, span, method_span, AllowUnstable::No)
574 /// Checks if an item is stable or error out.
576 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
577 /// exist, emits an error.
579 /// This function will also check if the item is deprecated.
580 /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted.
582 /// Pass `AllowUnstable::Yes` to `allow_unstable` to force an unstable item to be allowed. Deprecation warnings will be emitted normally.
584 /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature.
585 pub fn check_stability_allow_unstable(
590 method_span: Option<Span>,
591 allow_unstable: AllowUnstable,
593 self.check_optional_stability(
600 // The API could be uncallable for other reasons, for example when a private module
602 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
607 /// Like `check_stability`, except that we permit items to have custom behaviour for
608 /// missing stability attributes (not necessarily just emit a `bug!`). This is necessary
609 /// for default generic parameters, which only have stability attributes if they were
610 /// added after the type on which they're defined.
612 /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature.
613 pub fn check_optional_stability(
618 method_span: Option<Span>,
619 allow_unstable: AllowUnstable,
620 unmarked: impl FnOnce(Span, DefId),
622 let soft_handler = |lint, span, msg: &_| {
623 self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, msg, |lint| lint)
626 self.eval_stability_allow_unstable(def_id, id, span, method_span, allow_unstable);
627 let is_allowed = matches!(eval_result, EvalResult::Allow);
629 EvalResult::Allow => {}
630 EvalResult::Deny { feature, reason, issue, suggestion, is_soft } => report_unstable(
640 EvalResult::Unmarked => unmarked(span, def_id),
646 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
647 self.lookup_deprecation_entry(id).map(|depr| depr.attr)