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>,
68 pub fn local_stability(&self, def_id: LocalDefId) -> Option<Stability> {
69 self.stab_map.get(&def_id).copied()
72 pub fn local_const_stability(&self, def_id: LocalDefId) -> Option<ConstStability> {
73 self.const_stab_map.get(&def_id).copied()
76 pub fn local_deprecation_entry(&self, def_id: LocalDefId) -> Option<DeprecationEntry> {
77 self.depr_map.get(&def_id).cloned()
81 pub fn report_unstable(
84 reason: Option<Symbol>,
85 issue: Option<NonZeroU32>,
86 suggestion: Option<(Span, String, String, Applicability)>,
89 soft_handler: impl FnOnce(&'static Lint, Span, &str),
91 let msg = match reason {
92 Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
93 None => format!("use of unstable library feature '{}'", &feature),
97 soft_handler(SOFT_UNSTABLE, span, &msg)
100 feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg);
101 if let Some((inner_types, ref msg, sugg, applicability)) = suggestion {
102 err.span_suggestion(inner_types, msg, sugg, applicability);
108 /// Checks whether an item marked with `deprecated(since="X")` is currently
109 /// deprecated (i.e., whether X is not greater than the current rustc version).
110 pub fn deprecation_in_effect(depr: &Deprecation) -> bool {
111 let is_since_rustc_version = depr.is_since_rustc_version;
112 let since = depr.since.as_ref().map(Symbol::as_str);
114 fn parse_version(ver: &str) -> Vec<u32> {
115 // We ignore non-integer components of the version (e.g., "nightly").
116 ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
119 if !is_since_rustc_version {
120 // The `since` field doesn't have semantic purpose without `#![staged_api]`.
124 if let Some(since) = since {
129 if let Some(rustc) = option_env!("CFG_RELEASE") {
130 let since: Vec<u32> = parse_version(&since);
131 let rustc: Vec<u32> = parse_version(rustc);
132 // We simply treat invalid `since` attributes as relating to a previous
133 // Rust version, thus always displaying the warning.
134 if since.len() != 3 {
137 return since <= rustc;
141 // Assume deprecation is in effect if "since" field is missing
142 // or if we can't determine the current Rust version.
146 pub fn deprecation_suggestion(
147 diag: &mut Diagnostic,
149 suggestion: Option<Symbol>,
152 if let Some(suggestion) = suggestion {
153 diag.span_suggestion_verbose(
155 &format!("replace the use of the deprecated {}", kind),
157 Applicability::MachineApplicable,
162 fn deprecation_lint(is_in_effect: bool) -> &'static Lint {
163 if is_in_effect { DEPRECATED } else { DEPRECATED_IN_FUTURE }
166 fn deprecation_message(
168 since: Option<Symbol>,
169 note: Option<Symbol>,
173 let message = if is_in_effect {
174 format!("use of deprecated {} `{}`", kind, path)
176 let since = since.as_ref().map(Symbol::as_str);
178 if since == Some("TBD") {
179 format!("use of {} `{}` that will be deprecated in a future Rust version", kind, path)
182 "use of {} `{}` that will be deprecated in future version {}",
191 Some(reason) => format!("{}: {}", message, reason),
196 pub fn deprecation_message_and_lint(
200 ) -> (String, &'static Lint) {
201 let is_in_effect = deprecation_in_effect(depr);
203 deprecation_message(is_in_effect, depr.since, depr.note, kind, path),
204 deprecation_lint(is_in_effect),
208 pub fn early_report_deprecation<'a>(
209 lint_buffer: &'a mut LintBuffer,
211 suggestion: Option<Symbol>,
216 if span.in_derive_expansion() {
220 let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span);
221 lint_buffer.buffer_lint_with_diagnostic(lint, node_id, span, message, diag);
224 fn late_report_deprecation(
227 suggestion: Option<Symbol>,
230 method_span: Option<Span>,
234 if span.in_derive_expansion() {
237 let method_span = method_span.unwrap_or(span);
238 tcx.struct_span_lint_hir(lint, hir_id, method_span, |lint| {
239 let mut diag = lint.build(message);
240 if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
241 let kind = tcx.def_kind(def_id).descr(def_id);
242 deprecation_suggestion(&mut diag, kind, suggestion, method_span);
248 /// Result of `TyCtxt::eval_stability`.
249 pub enum EvalResult {
250 /// We can use the item because it is stable or we provided the
251 /// corresponding feature gate.
253 /// We cannot use the item because it is unstable and we did not provide the
254 /// corresponding feature gate.
257 reason: Option<Symbol>,
258 issue: Option<NonZeroU32>,
259 suggestion: Option<(Span, String, String, Applicability)>,
262 /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
267 fn skip_stability_check_due_to_privacy(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
268 if tcx.def_kind(def_id) == DefKind::TyParam {
269 // Have no visibility, considered public for the purpose of this check.
272 match tcx.visibility(def_id) {
273 // Must check stability for `pub` items.
274 ty::Visibility::Public => false,
276 // These are not visible outside crate; therefore
277 // stability markers are irrelevant, if even present.
278 ty::Visibility::Restricted(..) | ty::Visibility::Invisible => true,
283 fn suggestion_for_allocator_api(
288 ) -> Option<(Span, String, String, Applicability)> {
289 if feature == sym::allocator_api {
290 if let Some(trait_) = tcx.opt_parent(def_id) {
291 if tcx.is_diagnostic_item(sym::Vec, trait_) {
292 let sm = tcx.sess.parse_sess.source_map();
293 let inner_types = sm.span_extend_to_prev_char(span, '<', true);
294 if let Ok(snippet) = sm.span_to_snippet(inner_types) {
297 "consider wrapping the inner types in tuple".to_string(),
298 format!("({})", snippet),
299 Applicability::MaybeIncorrect,
308 /// An override option for eval_stability.
309 pub enum AllowUnstable {
310 /// Don't emit an unstable error for the item
312 /// Handle the item normally
316 impl<'tcx> TyCtxt<'tcx> {
317 /// Evaluates the stability of an item.
319 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
320 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
321 /// unstable feature otherwise.
323 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
324 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
326 pub fn eval_stability(
331 method_span: Option<Span>,
333 self.eval_stability_allow_unstable(def_id, id, span, method_span, AllowUnstable::No)
336 /// Evaluates the stability of an item.
338 /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
339 /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
340 /// unstable feature otherwise.
342 /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
343 /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
346 /// Pass `AllowUnstable::Yes` to `allow_unstable` to force an unstable item to be allowed. Deprecation warnings will be emitted normally.
347 pub fn eval_stability_allow_unstable(
352 method_span: Option<Span>,
353 allow_unstable: AllowUnstable,
355 // Deprecated attributes apply in-crate and cross-crate.
356 if let Some(id) = id {
357 if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
358 let parent_def_id = self.hir().get_parent_item(id);
360 .lookup_deprecation_entry(parent_def_id.to_def_id())
361 .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
363 // #[deprecated] doesn't emit a notice if we're not on the
364 // topmost deprecation. For example, if a struct is deprecated,
365 // the use of a field won't be linted.
367 // With #![staged_api], we want to emit down the whole
369 let depr_attr = &depr_entry.attr;
370 if !skip || depr_attr.is_since_rustc_version {
371 // Calculating message for lint involves calling `self.def_path_str`.
372 // Which by default to calculate visible path will invoke expensive `visible_parent_map` query.
373 // So we skip message calculation altogether, if lint is allowed.
374 let is_in_effect = deprecation_in_effect(depr_attr);
375 let lint = deprecation_lint(is_in_effect);
376 if self.lint_level_at_node(lint, id).0 != Level::Allow {
377 let def_path = with_no_trimmed_paths!(self.def_path_str(def_id));
378 let def_kind = self.def_kind(def_id).descr(def_id);
380 late_report_deprecation(
382 &deprecation_message(
389 depr_attr.suggestion,
401 let is_staged_api = self.lookup_stability(def_id.krate.as_def_id()).is_some();
403 return EvalResult::Allow;
406 let stability = self.lookup_stability(def_id);
409 inspecting def_id={:?} span={:?} of stability={:?}",
410 def_id, span, stability
413 // Only the cross-crate scenario matters when checking unstable APIs
414 let cross_crate = !def_id.is_local();
416 return EvalResult::Allow;
419 // Issue #38412: private items lack stability markers.
420 if skip_stability_check_due_to_privacy(self, def_id) {
421 return EvalResult::Allow;
426 level: attr::Unstable { reason, issue, is_soft }, feature, ..
428 if span.allows_unstable(feature) {
429 debug!("stability: skipping span={:?} since it is internal", span);
430 return EvalResult::Allow;
432 if self.features().active(feature) {
433 return EvalResult::Allow;
436 // When we're compiling the compiler itself we may pull in
437 // crates from crates.io, but those crates may depend on other
438 // crates also pulled in from crates.io. We want to ideally be
439 // able to compile everything without requiring upstream
440 // modifications, so in the case that this looks like a
441 // `rustc_private` crate (e.g., a compiler crate) and we also have
442 // the `-Z force-unstable-if-unmarked` flag present (we're
443 // compiling a compiler crate), then let this missing feature
445 if feature == sym::rustc_private && issue == NonZeroU32::new(27812) {
446 if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
447 return EvalResult::Allow;
451 if matches!(allow_unstable, AllowUnstable::Yes) {
452 return EvalResult::Allow;
455 let suggestion = suggestion_for_allocator_api(self, def_id, span, feature);
456 EvalResult::Deny { feature, reason, issue, suggestion, is_soft }
459 // Stable APIs are always ok to call and deprecated APIs are
460 // handled by the lint emitting logic above.
463 None => EvalResult::Unmarked,
467 /// Checks if an item is stable or error out.
469 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
470 /// exist, emits an error.
472 /// This function will also check if the item is deprecated.
473 /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted.
474 pub fn check_stability(
479 method_span: Option<Span>,
481 self.check_stability_allow_unstable(def_id, id, span, method_span, AllowUnstable::No)
484 /// Checks if an item is stable or error out.
486 /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
487 /// exist, emits an error.
489 /// This function will also check if the item is deprecated.
490 /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted.
492 /// Pass `AllowUnstable::Yes` to `allow_unstable` to force an unstable item to be allowed. Deprecation warnings will be emitted normally.
493 pub fn check_stability_allow_unstable(
498 method_span: Option<Span>,
499 allow_unstable: AllowUnstable,
501 self.check_optional_stability(
508 // The API could be uncallable for other reasons, for example when a private module
510 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
515 /// Like `check_stability`, except that we permit items to have custom behaviour for
516 /// missing stability attributes (not necessarily just emit a `bug!`). This is necessary
517 /// for default generic parameters, which only have stability attributes if they were
518 /// added after the type on which they're defined.
519 pub fn check_optional_stability(
524 method_span: Option<Span>,
525 allow_unstable: AllowUnstable,
526 unmarked: impl FnOnce(Span, DefId),
528 let soft_handler = |lint, span, msg: &_| {
529 self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, |lint| {
530 lint.build(msg).emit();
533 match self.eval_stability_allow_unstable(def_id, id, span, method_span, allow_unstable) {
534 EvalResult::Allow => {}
535 EvalResult::Deny { feature, reason, issue, suggestion, is_soft } => report_unstable(
545 EvalResult::Unmarked => unmarked(span, def_id),
549 pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
550 self.lookup_deprecation_entry(id).map(|depr| depr.attr)