src/librustc_middle/middle/stability.rs

   1 //! A pass that annotates every item and method with its stability level,
   2 //! propagating default levels lexically from parent to children ast nodes.
   3
   4 pub use self::StabilityLevel::*;
   5
   6 use crate::ty::{self, TyCtxt};
   7 use rustc_ast::CRATE_NODE_ID;
   8 use rustc_attr::{self as attr, ConstStability, Deprecation, Stability};
   9 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  10 use rustc_errors::{Applicability, DiagnosticBuilder};
  11 use rustc_feature::GateIssue;
  12 use rustc_hir as hir;
  13 use rustc_hir::def::DefKind;
  14 use rustc_hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX};
  15 use rustc_hir::{self, HirId};
  16 use rustc_session::lint::builtin::{DEPRECATED, DEPRECATED_IN_FUTURE, SOFT_UNSTABLE};
  17 use rustc_session::lint::{BuiltinLintDiagnostics, Lint, LintBuffer};
  18 use rustc_session::parse::feature_err_issue;
  19 use rustc_session::{DiagnosticMessageId, Session};
  20 use rustc_span::symbol::{sym, Symbol};
  21 use rustc_span::{MultiSpan, Span};
  22
  23 use std::num::NonZeroU32;
  24
  25 #[derive(PartialEq, Clone, Copy, Debug)]
  26 pub enum StabilityLevel {
  27     Unstable,
  28     Stable,
  29 }
  30
  31 impl StabilityLevel {
  32     pub fn from_attr_level(level: &attr::StabilityLevel) -> Self {
  33         if level.is_stable() { Stable } else { Unstable }
  34     }
  35 }
  36
  37 /// An entry in the `depr_map`.
  38 #[derive(Clone, HashStable)]
  39 pub struct DeprecationEntry {
  40     /// The metadata of the attribute associated with this entry.
  41     pub attr: Deprecation,
  42     /// The `DefId` where the attr was originally attached. `None` for non-local
  43     /// `DefId`'s.
  44     origin: Option<HirId>,
  45 }
  46
  47 impl DeprecationEntry {
  48     pub fn local(attr: Deprecation, id: HirId) -> DeprecationEntry {
  49         DeprecationEntry { attr, origin: Some(id) }
  50     }
  51
  52     pub fn external(attr: Deprecation) -> DeprecationEntry {
  53         DeprecationEntry { attr, origin: None }
  54     }
  55
  56     pub fn same_origin(&self, other: &DeprecationEntry) -> bool {
  57         match (self.origin, other.origin) {
  58             (Some(o1), Some(o2)) => o1 == o2,
  59             _ => false,
  60         }
  61     }
  62 }
  63
  64 /// A stability index, giving the stability level for items and methods.
  65 #[derive(HashStable)]
  66 pub struct Index<'tcx> {
  67     /// This is mostly a cache, except the stabilities of local items
  68     /// are filled by the annotator.
  69     pub stab_map: FxHashMap<HirId, &'tcx Stability>,
  70     pub const_stab_map: FxHashMap<HirId, &'tcx ConstStability>,
  71     pub depr_map: FxHashMap<HirId, DeprecationEntry>,
  72
  73     /// Maps for each crate whether it is part of the staged API.
  74     pub staged_api: FxHashMap<CrateNum, bool>,
  75
  76     /// Features enabled for this crate.
  77     pub active_features: FxHashSet<Symbol>,
  78 }
  79
  80 impl<'tcx> Index<'tcx> {
  81     pub fn local_stability(&self, id: HirId) -> Option<&'tcx Stability> {
  82         self.stab_map.get(&id).cloned()
  83     }
  84
  85     pub fn local_const_stability(&self, id: HirId) -> Option<&'tcx ConstStability> {
  86         self.const_stab_map.get(&id).cloned()
  87     }
  88
  89     pub fn local_deprecation_entry(&self, id: HirId) -> Option<DeprecationEntry> {
  90         self.depr_map.get(&id).cloned()
  91     }
  92 }
  93
  94 pub fn report_unstable(
  95     sess: &Session,
  96     feature: Symbol,
  97     reason: Option<Symbol>,
  98     issue: Option<NonZeroU32>,
  99     is_soft: bool,
 100     span: Span,
 101     soft_handler: impl FnOnce(&'static Lint, Span, &str),
 102 ) {
 103     let msg = match reason {
 104         Some(r) => format!("use of unstable library feature '{}': {}", feature, r),
 105         None => format!("use of unstable library feature '{}'", &feature),
 106     };
 107
 108     let msp: MultiSpan = span.into();
 109     let sm = &sess.parse_sess.source_map();
 110     let span_key = msp.primary_span().and_then(|sp: Span| {
 111         if !sp.is_dummy() {
 112             let file = sm.lookup_char_pos(sp.lo()).file;
 113             if file.is_imported() { None } else { Some(span) }
 114         } else {
 115             None
 116         }
 117     });
 118
 119     let error_id = (DiagnosticMessageId::StabilityId(issue), span_key, msg.clone());
 120     let fresh = sess.one_time_diagnostics.borrow_mut().insert(error_id);
 121     if fresh {
 122         if is_soft {
 123             soft_handler(SOFT_UNSTABLE, span, &msg)
 124         } else {
 125             feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg)
 126                 .emit();
 127         }
 128     }
 129 }
 130
 131 /// Checks whether an item marked with `deprecated(since="X")` is currently
 132 /// deprecated (i.e., whether X is not greater than the current rustc version).
 133 pub fn deprecation_in_effect(is_since_rustc_version: bool, since: Option<&str>) -> bool {
 134     let since = if let Some(since) = since {
 135         if is_since_rustc_version {
 136             since
 137         } else {
 138             // We assume that the deprecation is in effect if it's not a
 139             // rustc version.
 140             return true;
 141         }
 142     } else {
 143         // If since attribute is not set, then we're definitely in effect.
 144         return true;
 145     };
 146     fn parse_version(ver: &str) -> Vec<u32> {
 147         // We ignore non-integer components of the version (e.g., "nightly").
 148         ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
 149     }
 150
 151     if let Some(rustc) = option_env!("CFG_RELEASE") {
 152         let since: Vec<u32> = parse_version(&since);
 153         let rustc: Vec<u32> = parse_version(rustc);
 154         // We simply treat invalid `since` attributes as relating to a previous
 155         // Rust version, thus always displaying the warning.
 156         if since.len() != 3 {
 157             return true;
 158         }
 159         since <= rustc
 160     } else {
 161         // By default, a deprecation warning applies to
 162         // the current version of the compiler.
 163         true
 164     }
 165 }
 166
 167 pub fn deprecation_suggestion(
 168     diag: &mut DiagnosticBuilder<'_>,
 169     kind: &str,
 170     suggestion: Option<Symbol>,
 171     span: Span,
 172 ) {
 173     if let Some(suggestion) = suggestion {
 174         diag.span_suggestion(
 175             span,
 176             &format!("replace the use of the deprecated {}", kind),
 177             suggestion.to_string(),
 178             Applicability::MachineApplicable,
 179         );
 180     }
 181 }
 182
 183 pub fn deprecation_message(depr: &Deprecation, kind: &str, path: &str) -> (String, &'static Lint) {
 184     let (message, lint) = if deprecation_in_effect(
 185         depr.is_since_rustc_version,
 186         depr.since.map(Symbol::as_str).as_deref(),
 187     ) {
 188         (format!("use of deprecated {} `{}`", kind, path), DEPRECATED)
 189     } else {
 190         (
 191             format!(
 192                 "use of {} `{}` that will be deprecated in future version {}",
 193                 kind,
 194                 path,
 195                 depr.since.unwrap()
 196             ),
 197             DEPRECATED_IN_FUTURE,
 198         )
 199     };
 200     let message = match depr.note {
 201         Some(reason) => format!("{}: {}", message, reason),
 202         None => message,
 203     };
 204     (message, lint)
 205 }
 206
 207 pub fn early_report_deprecation(
 208     lint_buffer: &'a mut LintBuffer,
 209     message: &str,
 210     suggestion: Option<Symbol>,
 211     lint: &'static Lint,
 212     span: Span,
 213 ) {
 214     if span.in_derive_expansion() {
 215         return;
 216     }
 217
 218     let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span);
 219     lint_buffer.buffer_lint_with_diagnostic(lint, CRATE_NODE_ID, span, message, diag);
 220 }
 221
 222 fn late_report_deprecation(
 223     tcx: TyCtxt<'_>,
 224     message: &str,
 225     suggestion: Option<Symbol>,
 226     lint: &'static Lint,
 227     span: Span,
 228     hir_id: HirId,
 229     def_id: DefId,
 230 ) {
 231     if span.in_derive_expansion() {
 232         return;
 233     }
 234
 235     tcx.struct_span_lint_hir(lint, hir_id, span, |lint| {
 236         let mut diag = lint.build(message);
 237         if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
 238             let kind = tcx.def_kind(def_id).descr(def_id);
 239             deprecation_suggestion(&mut diag, kind, suggestion, span);
 240         }
 241         diag.emit()
 242     });
 243 }
 244
 245 /// Result of `TyCtxt::eval_stability`.
 246 pub enum EvalResult {
 247     /// We can use the item because it is stable or we provided the
 248     /// corresponding feature gate.
 249     Allow,
 250     /// We cannot use the item because it is unstable and we did not provide the
 251     /// corresponding feature gate.
 252     Deny { feature: Symbol, reason: Option<Symbol>, issue: Option<NonZeroU32>, is_soft: bool },
 253     /// The item does not have the `#[stable]` or `#[unstable]` marker assigned.
 254     Unmarked,
 255 }
 256
 257 // See issue #38412.
 258 fn skip_stability_check_due_to_privacy(tcx: TyCtxt<'_>, mut def_id: DefId) -> bool {
 259     // Check if `def_id` is a trait method.
 260     match tcx.def_kind(def_id) {
 261         DefKind::AssocFn | DefKind::AssocTy | DefKind::AssocConst => {
 262             if let ty::TraitContainer(trait_def_id) = tcx.associated_item(def_id).container {
 263                 // Trait methods do not declare visibility (even
 264                 // for visibility info in cstore). Use containing
 265                 // trait instead, so methods of `pub` traits are
 266                 // themselves considered `pub`.
 267                 def_id = trait_def_id;
 268             }
 269         }
 270         _ => {}
 271     }
 272
 273     let visibility = tcx.visibility(def_id);
 274
 275     match visibility {
 276         // Must check stability for `pub` items.
 277         ty::Visibility::Public => false,
 278
 279         // These are not visible outside crate; therefore
 280         // stability markers are irrelevant, if even present.
 281         ty::Visibility::Restricted(..) | ty::Visibility::Invisible => true,
 282     }
 283 }
 284
 285 impl<'tcx> TyCtxt<'tcx> {
 286     /// Evaluates the stability of an item.
 287     ///
 288     /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding
 289     /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
 290     /// unstable feature otherwise.
 291     ///
 292     /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been
 293     /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to
 294     /// `id`.
 295     pub fn eval_stability(self, def_id: DefId, id: Option<HirId>, span: Span) -> EvalResult {
 296         // Deprecated attributes apply in-crate and cross-crate.
 297         if let Some(id) = id {
 298             if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) {
 299                 let parent_def_id = self.hir().local_def_id(self.hir().get_parent_item(id));
 300                 let skip = self
 301                     .lookup_deprecation_entry(parent_def_id.to_def_id())
 302                     .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry));
 303
 304                 // #[deprecated] doesn't emit a notice if we're not on the
 305                 // topmost deprecation. For example, if a struct is deprecated,
 306                 // the use of a field won't be linted.
 307                 //
 308                 // #[rustc_deprecated] however wants to emit down the whole
 309                 // hierarchy.
 310                 if !skip || depr_entry.attr.is_since_rustc_version {
 311                     let path = &self.def_path_str(def_id);
 312                     let kind = self.def_kind(def_id).descr(def_id);
 313                     let (message, lint) = deprecation_message(&depr_entry.attr, kind, path);
 314                     late_report_deprecation(
 315                         self,
 316                         &message,
 317                         depr_entry.attr.suggestion,
 318                         lint,
 319                         span,
 320                         id,
 321                         def_id,
 322                     );
 323                 }
 324             };
 325         }
 326
 327         let is_staged_api =
 328             self.lookup_stability(DefId { index: CRATE_DEF_INDEX, ..def_id }).is_some();
 329         if !is_staged_api {
 330             return EvalResult::Allow;
 331         }
 332
 333         let stability = self.lookup_stability(def_id);
 334         debug!(
 335             "stability: \
 336                 inspecting def_id={:?} span={:?} of stability={:?}",
 337             def_id, span, stability
 338         );
 339
 340         // Only the cross-crate scenario matters when checking unstable APIs
 341         let cross_crate = !def_id.is_local();
 342         if !cross_crate {
 343             return EvalResult::Allow;
 344         }
 345
 346         // Issue #38412: private items lack stability markers.
 347         if skip_stability_check_due_to_privacy(self, def_id) {
 348             return EvalResult::Allow;
 349         }
 350
 351         match stability {
 352             Some(&Stability {
 353                 level: attr::Unstable { reason, issue, is_soft }, feature, ..
 354             }) => {
 355                 if span.allows_unstable(feature) {
 356                     debug!("stability: skipping span={:?} since it is internal", span);
 357                     return EvalResult::Allow;
 358                 }
 359                 if self.stability().active_features.contains(&feature) {
 360                     return EvalResult::Allow;
 361                 }
 362
 363                 // When we're compiling the compiler itself we may pull in
 364                 // crates from crates.io, but those crates may depend on other
 365                 // crates also pulled in from crates.io. We want to ideally be
 366                 // able to compile everything without requiring upstream
 367                 // modifications, so in the case that this looks like a
 368                 // `rustc_private` crate (e.g., a compiler crate) and we also have
 369                 // the `-Z force-unstable-if-unmarked` flag present (we're
 370                 // compiling a compiler crate), then let this missing feature
 371                 // annotation slide.
 372                 if feature == sym::rustc_private && issue == NonZeroU32::new(27812) {
 373                     if self.sess.opts.debugging_opts.force_unstable_if_unmarked {
 374                         return EvalResult::Allow;
 375                     }
 376                 }
 377
 378                 EvalResult::Deny { feature, reason, issue, is_soft }
 379             }
 380             Some(_) => {
 381                 // Stable APIs are always ok to call and deprecated APIs are
 382                 // handled by the lint emitting logic above.
 383                 EvalResult::Allow
 384             }
 385             None => EvalResult::Unmarked,
 386         }
 387     }
 388
 389     /// Checks if an item is stable or error out.
 390     ///
 391     /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not
 392     /// exist, emits an error.
 393     ///
 394     /// Additionally, this function will also check if the item is deprecated. If so, and `id` is
 395     /// not `None`, a deprecated lint attached to `id` will be emitted.
 396     pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) {
 397         let soft_handler = |lint, span, msg: &_| {
 398             self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, |lint| {
 399                 lint.build(msg).emit()
 400             })
 401         };
 402         match self.eval_stability(def_id, id, span) {
 403             EvalResult::Allow => {}
 404             EvalResult::Deny { feature, reason, issue, is_soft } => {
 405                 report_unstable(self.sess, feature, reason, issue, is_soft, span, soft_handler)
 406             }
 407             EvalResult::Unmarked => {
 408                 // The API could be uncallable for other reasons, for example when a private module
 409                 // was referenced.
 410                 self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
 411             }
 412         }
 413     }
 414
 415     pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> {
 416         self.lookup_deprecation_entry(id).map(|depr| depr.attr)
 417     }
 418 }