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, 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 depr_map: FxHashMap<LocalDefId, DeprecationEntry>,
65 /// Mapping from feature name to feature name based on the `implied_by` field of `#[unstable]`
66 /// attributes. If a `#[unstable(feature = "implier", implied_by = "impliee")]` attribute
67 /// exists, then this map will have a `impliee -> implier` entry.
69 /// This mapping is necessary unless both the `#[stable]` and `#[unstable]` attributes should
70 /// specify their implications (both `implies` and `implied_by`). If only one of the two
71 /// attributes do (as in the current implementation, `implied_by` in `#[unstable]`), then this
72 /// mapping is necessary for diagnostics. When a "unnecessary feature attribute" error is
73 /// reported, only the `#[stable]` attribute information is available, so the map is necessary
74 /// to know that the feature implies another feature. If it were reversed, and the `#[stable]`
75 /// attribute had an `implies` meta item, then a map would be necessary when avoiding a "use of
76 /// unstable feature" error for a feature that was implied.
77 pub implications: FxHashMap<Symbol, Symbol>,
81 pub fn local_stability(&self, def_id: LocalDefId) -> Option<Stability> {
82 self.stab_map.get(&def_id).copied()
85 pub fn local_const_stability(&self, def_id: LocalDefId) -> Option<ConstStability> {
86 self.const_stab_map.get(&def_id).copied()
89 pub fn local_deprecation_entry(&self, def_id: LocalDefId) -> Option<DeprecationEntry> {
90 self.depr_map.get(&def_id).cloned()
94 pub fn report_unstable(
97 reason: Option<Symbol>,
98 issue: Option<NonZeroU32>,
99 suggestion: Option<(Span, String, String, Applicability)>,
102 soft_handler: impl FnOnce(&'static Lint, Span, &str),
104 let msg = match reason {
105 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
106 None => format!("use of unstable library feature '{}'", &feature),
110 soft_handler(SOFT_UNSTABLE, span, &msg)
113 feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg);
114 if let Some((inner_types, ref msg, sugg, applicability)) = suggestion {
115 err.span_suggestion(inner_types, msg, sugg, applicability);
121 /// Checks whether an item marked with `deprecated(since="X")` is currently
122 /// deprecated (i.e., whether X is not greater than the current rustc version).
123 pub fn deprecation_in_effect(depr: &Deprecation) -> bool {
124 let is_since_rustc_version = depr.is_since_rustc_version;
125 let since = depr.since.as_ref().map(Symbol::as_str);
127 fn parse_version(ver: &str) -> Vec<u32> {
128 // We ignore non-integer components of the version (e.g., "nightly").
129 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
132 if !is_since_rustc_version {
133 // The `since` field doesn't have semantic purpose without `#![staged_api]`.
137 if let Some(since) = since {
142 if let Some(rustc) = option_env!("CFG_RELEASE") {
143 let since: Vec<u32> = parse_version(&since);
144 let rustc: Vec<u32> = parse_version(rustc);
145 // We simply treat invalid `since` attributes as relating to a previous
146 // Rust version, thus always displaying the warning.
147 if since.len() != 3 {
150 return since <= rustc;
154 // Assume deprecation is in effect if "since" field is missing
155 // or if we can't determine the current Rust version.
159 pub fn deprecation_suggestion(
160 diag: &mut Diagnostic,
162 suggestion: Option<Symbol>,
165 if let Some(suggestion) = suggestion {
166 diag.span_suggestion_verbose(
168 &format!("replace the use of the deprecated {}", kind),
170 Applicability::MachineApplicable,
175 fn deprecation_lint(is_in_effect: bool) -> &'static Lint {
176 if is_in_effect { DEPRECATED } else { DEPRECATED_IN_FUTURE }
179 fn deprecation_message(
181 since: Option<Symbol>,
182 note: Option<Symbol>,
186 let message = if is_in_effect {
187 format!("use of deprecated {} `{}`", kind, path)
189 let since = since.as_ref().map(Symbol::as_str);
191 if since == Some("TBD") {
192 format!("use of {} `{}` that will be deprecated in a future Rust version", kind, path)
195 "use of {} `{}` that will be deprecated in future version {}",
204 Some(reason) => format!("{}: {}", message, reason),
209 pub fn deprecation_message_and_lint(
213 ) -> (String, &'static Lint) {
214 let is_in_effect = deprecation_in_effect(depr);
216 deprecation_message(is_in_effect, depr.since, depr.note, kind, path),
217 deprecation_lint(is_in_effect),
221 pub fn early_report_deprecation<'a>(
222 lint_buffer: &'a mut LintBuffer,
224 suggestion: Option<Symbol>,
229 if span.in_derive_expansion() {
233 let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span);
234 lint_buffer.buffer_lint_with_diagnostic(lint, node_id, span, message, diag);
237 fn late_report_deprecation(
240 suggestion: Option<Symbol>,
243 method_span: Option<Span>,
247 if span.in_derive_expansion() {
250 let method_span = method_span.unwrap_or(span);
251 tcx.struct_span_lint_hir(lint, hir_id, method_span, |lint| {
252 let mut diag = lint.build(message);
253 if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
254 let kind = tcx.def_kind(def_id).descr(def_id);
255 deprecation_suggestion(&mut diag, kind, suggestion, method_span);
261 /// Result of `TyCtxt::eval_stability`.
262 pub enum EvalResult {
263 /// We can use the item because it is stable or we provided the
264 /// corresponding feature gate.
266 /// We cannot use the item because it is unstable and we did not provide the
267 /// corresponding feature gate.
270 reason: Option<Symbol>,
271 issue: Option<NonZeroU32>,
272 suggestion: Option<(Span, String, String, Applicability)>,
275 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
280 fn skip_stability_check_due_to_privacy(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
281 if tcx.def_kind(def_id) == DefKind::TyParam {
282 // Have no visibility, considered public for the purpose of this check.
285 match tcx.visibility(def_id) {
286 // Must check stability for `pub` items.
287 ty::Visibility::Public => false,
289 // These are not visible outside crate; therefore
290 // stability markers are irrelevant, if even present.
291 ty::Visibility::Restricted(..) | ty::Visibility::Invisible => true,
296 fn suggestion_for_allocator_api(
301 ) -> Option<(Span, String, String, Applicability)> {
302 if feature == sym::allocator_api {
303 if let Some(trait_) = tcx.opt_parent(def_id) {
304 if tcx.is_diagnostic_item(sym::Vec, trait_) {
305 let sm = tcx.sess.parse_sess.source_map();
306 let inner_types = sm.span_extend_to_prev_char(span, '<', true);
307 if let Ok(snippet) = sm.span_to_snippet(inner_types) {
310 "consider wrapping the inner types in tuple".to_string(),
311 format!("({})", snippet),
312 Applicability::MaybeIncorrect,
321 /// An override option for eval_stability.
322 pub enum AllowUnstable {
323 /// Don't emit an unstable error for the item
325 /// Handle the item normally
329 impl<'tcx> TyCtxt<'tcx> {
330 /// Evaluates the stability of an item.
332 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
333 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
334 /// unstable feature otherwise.
336 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
337 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
339 pub fn eval_stability(
344 method_span: Option<Span>,
346 self.eval_stability_allow_unstable(def_id, id, span, method_span, AllowUnstable::No)
349 /// Evaluates the stability of an item.
351 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
352 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
353 /// unstable feature otherwise.
355 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
356 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
359 /// Pass `AllowUnstable::Yes` to `allow_unstable` to force an unstable item to be allowed. Deprecation warnings will be emitted normally.
360 pub fn eval_stability_allow_unstable(
365 method_span: Option<Span>,
366 allow_unstable: AllowUnstable,
368 // Deprecated attributes apply in-crate and cross-crate.
369 if let Some(id) = id {
370 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
371 let parent_def_id = self.hir().get_parent_item(id);
373 .lookup_deprecation_entry(parent_def_id.to_def_id())
374 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
376 // #[deprecated] doesn't emit a notice if we're not on the
377 // topmost deprecation. For example, if a struct is deprecated,
378 // the use of a field won't be linted.
380 // With #![staged_api], we want to emit down the whole
382 let depr_attr = &depr_entry.attr;
383 if !skip || depr_attr.is_since_rustc_version {
384 // Calculating message for lint involves calling `self.def_path_str`.
385 // Which by default to calculate visible path will invoke expensive `visible_parent_map` query.
386 // So we skip message calculation altogether, if lint is allowed.
387 let is_in_effect = deprecation_in_effect(depr_attr);
388 let lint = deprecation_lint(is_in_effect);
389 if self.lint_level_at_node(lint, id).0 != Level::Allow {
390 let def_path = with_no_trimmed_paths!(self.def_path_str(def_id));
391 let def_kind = self.def_kind(def_id).descr(def_id);
393 late_report_deprecation(
395 &deprecation_message(
402 depr_attr.suggestion,
414 let is_staged_api = self.lookup_stability(def_id.krate.as_def_id()).is_some();
416 return EvalResult::Allow;
419 let stability = self.lookup_stability(def_id);
422 inspecting def_id={:?} span={:?} of stability={:?}",
423 def_id, span, stability
426 // Only the cross-crate scenario matters when checking unstable APIs
427 let cross_crate = !def_id.is_local();
429 return EvalResult::Allow;
432 // Issue #38412: private items lack stability markers.
433 if skip_stability_check_due_to_privacy(self, def_id) {
434 return EvalResult::Allow;
439 level: attr::Unstable { reason, issue, is_soft, implied_by },
443 if span.allows_unstable(feature) {
444 debug!("stability: skipping span={:?} since it is internal", span);
445 return EvalResult::Allow;
447 if self.features().active(feature) {
448 return EvalResult::Allow;
451 // If this item was previously part of a now-stabilized feature which is still
452 // active (i.e. the user hasn't removed the attribute for the stabilized feature
453 // yet) then allow use of this item.
454 if let Some(implied_by) = implied_by && self.features().active(implied_by) {
455 return EvalResult::Allow;
458 // When we're compiling the compiler itself we may pull in
459 // crates from crates.io, but those crates may depend on other
460 // crates also pulled in from crates.io. We want to ideally be
461 // able to compile everything without requiring upstream
462 // modifications, so in the case that this looks like a
463 // `rustc_private` crate (e.g., a compiler crate) and we also have
464 // the `-Z force-unstable-if-unmarked` flag present (we're
465 // compiling a compiler crate), then let this missing feature
467 if feature == sym::rustc_private && issue == NonZeroU32::new(27812) {
468 if self.sess.opts.unstable_opts.force_unstable_if_unmarked {
469 return EvalResult::Allow;
473 if matches!(allow_unstable, AllowUnstable::Yes) {
474 return EvalResult::Allow;
477 let suggestion = suggestion_for_allocator_api(self, def_id, span, feature);
480 reason: reason.to_opt_reason(),
487 // Stable APIs are always ok to call and deprecated APIs are
488 // handled by the lint emitting logic above.
491 None => EvalResult::Unmarked,
495 /// Checks if an item is stable or error out.
497 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
498 /// exist, emits an error.
500 /// This function will also check if the item is deprecated.
501 /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted.
503 /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature.
504 pub fn check_stability(
509 method_span: Option<Span>,
511 self.check_stability_allow_unstable(def_id, id, span, method_span, AllowUnstable::No)
514 /// Checks if an item is stable or error out.
516 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
517 /// exist, emits an error.
519 /// This function will also check if the item is deprecated.
520 /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted.
522 /// Pass `AllowUnstable::Yes` to `allow_unstable` to force an unstable item to be allowed. Deprecation warnings will be emitted normally.
524 /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature.
525 pub fn check_stability_allow_unstable(
530 method_span: Option<Span>,
531 allow_unstable: AllowUnstable,
533 self.check_optional_stability(
540 // The API could be uncallable for other reasons, for example when a private module
542 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
547 /// Like `check_stability`, except that we permit items to have custom behaviour for
548 /// missing stability attributes (not necessarily just emit a `bug!`). This is necessary
549 /// for default generic parameters, which only have stability attributes if they were
550 /// added after the type on which they're defined.
552 /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature.
553 pub fn check_optional_stability(
558 method_span: Option<Span>,
559 allow_unstable: AllowUnstable,
560 unmarked: impl FnOnce(Span, DefId),
562 let soft_handler = |lint, span, msg: &_| {
563 self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, |lint| {
564 lint.build(msg).emit();
568 self.eval_stability_allow_unstable(def_id, id, span, method_span, allow_unstable);
569 let is_allowed = matches!(eval_result, EvalResult::Allow);
571 EvalResult::Allow => {}
572 EvalResult::Deny { feature, reason, issue, suggestion, is_soft } => report_unstable(
582 EvalResult::Unmarked => unmarked(span, def_id),
588 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
589 self.lookup_deprecation_entry(id).map(|depr| depr.attr)