diff options
Diffstat (limited to 'compiler/rustc_middle/src/middle/stability.rs')
| -rw-r--r-- | compiler/rustc_middle/src/middle/stability.rs | 591 |
1 files changed, 591 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/middle/stability.rs b/compiler/rustc_middle/src/middle/stability.rs new file mode 100644 index 000000000..414912dd0 --- /dev/null +++ b/compiler/rustc_middle/src/middle/stability.rs @@ -0,0 +1,591 @@ +//! A pass that annotates every item and method with its stability level, +//! propagating default levels lexically from parent to children ast nodes. + +pub use self::StabilityLevel::*; + +use crate::ty::{self, DefIdTree, TyCtxt}; +use rustc_ast::NodeId; +use rustc_attr::{self as attr, ConstStability, Deprecation, Stability}; +use rustc_data_structures::fx::FxHashMap; +use rustc_errors::{Applicability, Diagnostic}; +use rustc_feature::GateIssue; +use rustc_hir::def::DefKind; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_hir::{self as hir, HirId}; +use rustc_middle::ty::print::with_no_trimmed_paths; +use rustc_session::lint::builtin::{DEPRECATED, DEPRECATED_IN_FUTURE, SOFT_UNSTABLE}; +use rustc_session::lint::{BuiltinLintDiagnostics, Level, Lint, LintBuffer}; +use rustc_session::parse::feature_err_issue; +use rustc_session::Session; +use rustc_span::symbol::{sym, Symbol}; +use rustc_span::Span; +use std::num::NonZeroU32; + +#[derive(PartialEq, Clone, Copy, Debug)] +pub enum StabilityLevel { + Unstable, + Stable, +} + +/// An entry in the `depr_map`. +#[derive(Copy, Clone, HashStable, Debug, Encodable, Decodable)] +pub struct DeprecationEntry { + /// The metadata of the attribute associated with this entry. + pub attr: Deprecation, + /// The `DefId` where the attr was originally attached. `None` for non-local + /// `DefId`'s. + origin: Option<LocalDefId>, +} + +impl DeprecationEntry { + pub fn local(attr: Deprecation, def_id: LocalDefId) -> DeprecationEntry { + DeprecationEntry { attr, origin: Some(def_id) } + } + + pub fn external(attr: Deprecation) -> DeprecationEntry { + DeprecationEntry { attr, origin: None } + } + + pub fn same_origin(&self, other: &DeprecationEntry) -> bool { + match (self.origin, other.origin) { + (Some(o1), Some(o2)) => o1 == o2, + _ => false, + } + } +} + +/// A stability index, giving the stability level for items and methods. +#[derive(HashStable, Debug)] +pub struct Index { + /// This is mostly a cache, except the stabilities of local items + /// are filled by the annotator. + pub stab_map: FxHashMap<LocalDefId, Stability>, + pub const_stab_map: FxHashMap<LocalDefId, ConstStability>, + pub depr_map: FxHashMap<LocalDefId, DeprecationEntry>, + /// Mapping from feature name to feature name based on the `implied_by` field of `#[unstable]` + /// attributes. If a `#[unstable(feature = "implier", implied_by = "impliee")]` attribute + /// exists, then this map will have a `impliee -> implier` entry. + /// + /// This mapping is necessary unless both the `#[stable]` and `#[unstable]` attributes should + /// specify their implications (both `implies` and `implied_by`). If only one of the two + /// attributes do (as in the current implementation, `implied_by` in `#[unstable]`), then this + /// mapping is necessary for diagnostics. When a "unnecessary feature attribute" error is + /// reported, only the `#[stable]` attribute information is available, so the map is necessary + /// to know that the feature implies another feature. If it were reversed, and the `#[stable]` + /// attribute had an `implies` meta item, then a map would be necessary when avoiding a "use of + /// unstable feature" error for a feature that was implied. + pub implications: FxHashMap<Symbol, Symbol>, +} + +impl Index { + pub fn local_stability(&self, def_id: LocalDefId) -> Option<Stability> { + self.stab_map.get(&def_id).copied() + } + + pub fn local_const_stability(&self, def_id: LocalDefId) -> Option<ConstStability> { + self.const_stab_map.get(&def_id).copied() + } + + pub fn local_deprecation_entry(&self, def_id: LocalDefId) -> Option<DeprecationEntry> { + self.depr_map.get(&def_id).cloned() + } +} + +pub fn report_unstable( + sess: &Session, + feature: Symbol, + reason: Option<Symbol>, + issue: Option<NonZeroU32>, + suggestion: Option<(Span, String, String, Applicability)>, + is_soft: bool, + span: Span, + soft_handler: impl FnOnce(&'static Lint, Span, &str), +) { + let msg = match reason { + Some(r) => format!("use of unstable library feature '{}': {}", feature, r), + None => format!("use of unstable library feature '{}'", &feature), + }; + + if is_soft { + soft_handler(SOFT_UNSTABLE, span, &msg) + } else { + let mut err = + feature_err_issue(&sess.parse_sess, feature, span, GateIssue::Library(issue), &msg); + if let Some((inner_types, ref msg, sugg, applicability)) = suggestion { + err.span_suggestion(inner_types, msg, sugg, applicability); + } + err.emit(); + } +} + +/// Checks whether an item marked with `deprecated(since="X")` is currently +/// deprecated (i.e., whether X is not greater than the current rustc version). +pub fn deprecation_in_effect(depr: &Deprecation) -> bool { + let is_since_rustc_version = depr.is_since_rustc_version; + let since = depr.since.as_ref().map(Symbol::as_str); + + fn parse_version(ver: &str) -> Vec<u32> { + // We ignore non-integer components of the version (e.g., "nightly"). + ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect() + } + + if !is_since_rustc_version { + // The `since` field doesn't have semantic purpose without `#![staged_api]`. + return true; + } + + if let Some(since) = since { + if since == "TBD" { + return false; + } + + if let Some(rustc) = option_env!("CFG_RELEASE") { + let since: Vec<u32> = parse_version(&since); + let rustc: Vec<u32> = parse_version(rustc); + // We simply treat invalid `since` attributes as relating to a previous + // Rust version, thus always displaying the warning. + if since.len() != 3 { + return true; + } + return since <= rustc; + } + }; + + // Assume deprecation is in effect if "since" field is missing + // or if we can't determine the current Rust version. + true +} + +pub fn deprecation_suggestion( + diag: &mut Diagnostic, + kind: &str, + suggestion: Option<Symbol>, + span: Span, +) { + if let Some(suggestion) = suggestion { + diag.span_suggestion_verbose( + span, + &format!("replace the use of the deprecated {}", kind), + suggestion, + Applicability::MachineApplicable, + ); + } +} + +fn deprecation_lint(is_in_effect: bool) -> &'static Lint { + if is_in_effect { DEPRECATED } else { DEPRECATED_IN_FUTURE } +} + +fn deprecation_message( + is_in_effect: bool, + since: Option<Symbol>, + note: Option<Symbol>, + kind: &str, + path: &str, +) -> String { + let message = if is_in_effect { + format!("use of deprecated {} `{}`", kind, path) + } else { + let since = since.as_ref().map(Symbol::as_str); + + if since == Some("TBD") { + format!("use of {} `{}` that will be deprecated in a future Rust version", kind, path) + } else { + format!( + "use of {} `{}` that will be deprecated in future version {}", + kind, + path, + since.unwrap() + ) + } + }; + + match note { + Some(reason) => format!("{}: {}", message, reason), + None => message, + } +} + +pub fn deprecation_message_and_lint( + depr: &Deprecation, + kind: &str, + path: &str, +) -> (String, &'static Lint) { + let is_in_effect = deprecation_in_effect(depr); + ( + deprecation_message(is_in_effect, depr.since, depr.note, kind, path), + deprecation_lint(is_in_effect), + ) +} + +pub fn early_report_deprecation<'a>( + lint_buffer: &'a mut LintBuffer, + message: &str, + suggestion: Option<Symbol>, + lint: &'static Lint, + span: Span, + node_id: NodeId, +) { + if span.in_derive_expansion() { + return; + } + + let diag = BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span); + lint_buffer.buffer_lint_with_diagnostic(lint, node_id, span, message, diag); +} + +fn late_report_deprecation( + tcx: TyCtxt<'_>, + message: &str, + suggestion: Option<Symbol>, + lint: &'static Lint, + span: Span, + method_span: Option<Span>, + hir_id: HirId, + def_id: DefId, +) { + if span.in_derive_expansion() { + return; + } + let method_span = method_span.unwrap_or(span); + tcx.struct_span_lint_hir(lint, hir_id, method_span, |lint| { + let mut diag = lint.build(message); + if let hir::Node::Expr(_) = tcx.hir().get(hir_id) { + let kind = tcx.def_kind(def_id).descr(def_id); + deprecation_suggestion(&mut diag, kind, suggestion, method_span); + } + diag.emit(); + }); +} + +/// Result of `TyCtxt::eval_stability`. +pub enum EvalResult { + /// We can use the item because it is stable or we provided the + /// corresponding feature gate. + Allow, + /// We cannot use the item because it is unstable and we did not provide the + /// corresponding feature gate. + Deny { + feature: Symbol, + reason: Option<Symbol>, + issue: Option<NonZeroU32>, + suggestion: Option<(Span, String, String, Applicability)>, + is_soft: bool, + }, + /// The item does not have the `#[stable]` or `#[unstable]` marker assigned. + Unmarked, +} + +// See issue #38412. +fn skip_stability_check_due_to_privacy(tcx: TyCtxt<'_>, def_id: DefId) -> bool { + if tcx.def_kind(def_id) == DefKind::TyParam { + // Have no visibility, considered public for the purpose of this check. + return false; + } + match tcx.visibility(def_id) { + // Must check stability for `pub` items. + ty::Visibility::Public => false, + + // These are not visible outside crate; therefore + // stability markers are irrelevant, if even present. + ty::Visibility::Restricted(..) | ty::Visibility::Invisible => true, + } +} + +// See issue #83250. +fn suggestion_for_allocator_api( + tcx: TyCtxt<'_>, + def_id: DefId, + span: Span, + feature: Symbol, +) -> Option<(Span, String, String, Applicability)> { + if feature == sym::allocator_api { + if let Some(trait_) = tcx.opt_parent(def_id) { + if tcx.is_diagnostic_item(sym::Vec, trait_) { + let sm = tcx.sess.parse_sess.source_map(); + let inner_types = sm.span_extend_to_prev_char(span, '<', true); + if let Ok(snippet) = sm.span_to_snippet(inner_types) { + return Some(( + inner_types, + "consider wrapping the inner types in tuple".to_string(), + format!("({})", snippet), + Applicability::MaybeIncorrect, + )); + } + } + } + } + None +} + +/// An override option for eval_stability. +pub enum AllowUnstable { + /// Don't emit an unstable error for the item + Yes, + /// Handle the item normally + No, +} + +impl<'tcx> TyCtxt<'tcx> { + /// Evaluates the stability of an item. + /// + /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding + /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending + /// unstable feature otherwise. + /// + /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been + /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to + /// `id`. + pub fn eval_stability( + self, + def_id: DefId, + id: Option<HirId>, + span: Span, + method_span: Option<Span>, + ) -> EvalResult { + self.eval_stability_allow_unstable(def_id, id, span, method_span, AllowUnstable::No) + } + + /// Evaluates the stability of an item. + /// + /// Returns `EvalResult::Allow` if the item is stable, or unstable but the corresponding + /// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending + /// unstable feature otherwise. + /// + /// If `id` is `Some(_)`, this function will also check if the item at `def_id` has been + /// deprecated. If the item is indeed deprecated, we will emit a deprecation lint attached to + /// `id`. + /// + /// Pass `AllowUnstable::Yes` to `allow_unstable` to force an unstable item to be allowed. Deprecation warnings will be emitted normally. + pub fn eval_stability_allow_unstable( + self, + def_id: DefId, + id: Option<HirId>, + span: Span, + method_span: Option<Span>, + allow_unstable: AllowUnstable, + ) -> EvalResult { + // Deprecated attributes apply in-crate and cross-crate. + if let Some(id) = id { + if let Some(depr_entry) = self.lookup_deprecation_entry(def_id) { + let parent_def_id = self.hir().get_parent_item(id); + let skip = self + .lookup_deprecation_entry(parent_def_id.to_def_id()) + .map_or(false, |parent_depr| parent_depr.same_origin(&depr_entry)); + + // #[deprecated] doesn't emit a notice if we're not on the + // topmost deprecation. For example, if a struct is deprecated, + // the use of a field won't be linted. + // + // With #![staged_api], we want to emit down the whole + // hierarchy. + let depr_attr = &depr_entry.attr; + if !skip || depr_attr.is_since_rustc_version { + // Calculating message for lint involves calling `self.def_path_str`. + // Which by default to calculate visible path will invoke expensive `visible_parent_map` query. + // So we skip message calculation altogether, if lint is allowed. + let is_in_effect = deprecation_in_effect(depr_attr); + let lint = deprecation_lint(is_in_effect); + if self.lint_level_at_node(lint, id).0 != Level::Allow { + let def_path = with_no_trimmed_paths!(self.def_path_str(def_id)); + let def_kind = self.def_kind(def_id).descr(def_id); + + late_report_deprecation( + self, + &deprecation_message( + is_in_effect, + depr_attr.since, + depr_attr.note, + def_kind, + &def_path, + ), + depr_attr.suggestion, + lint, + span, + method_span, + id, + def_id, + ); + } + } + }; + } + + let is_staged_api = self.lookup_stability(def_id.krate.as_def_id()).is_some(); + if !is_staged_api { + return EvalResult::Allow; + } + + let stability = self.lookup_stability(def_id); + debug!( + "stability: \ + inspecting def_id={:?} span={:?} of stability={:?}", + def_id, span, stability + ); + + // Only the cross-crate scenario matters when checking unstable APIs + let cross_crate = !def_id.is_local(); + if !cross_crate { + return EvalResult::Allow; + } + + // Issue #38412: private items lack stability markers. + if skip_stability_check_due_to_privacy(self, def_id) { + return EvalResult::Allow; + } + + match stability { + Some(Stability { + level: attr::Unstable { reason, issue, is_soft, implied_by }, + feature, + .. + }) => { + if span.allows_unstable(feature) { + debug!("stability: skipping span={:?} since it is internal", span); + return EvalResult::Allow; + } + if self.features().active(feature) { + return EvalResult::Allow; + } + + // If this item was previously part of a now-stabilized feature which is still + // active (i.e. the user hasn't removed the attribute for the stabilized feature + // yet) then allow use of this item. + if let Some(implied_by) = implied_by && self.features().active(implied_by) { + return EvalResult::Allow; + } + + // When we're compiling the compiler itself we may pull in + // crates from crates.io, but those crates may depend on other + // crates also pulled in from crates.io. We want to ideally be + // able to compile everything without requiring upstream + // modifications, so in the case that this looks like a + // `rustc_private` crate (e.g., a compiler crate) and we also have + // the `-Z force-unstable-if-unmarked` flag present (we're + // compiling a compiler crate), then let this missing feature + // annotation slide. + if feature == sym::rustc_private && issue == NonZeroU32::new(27812) { + if self.sess.opts.unstable_opts.force_unstable_if_unmarked { + return EvalResult::Allow; + } + } + + if matches!(allow_unstable, AllowUnstable::Yes) { + return EvalResult::Allow; + } + + let suggestion = suggestion_for_allocator_api(self, def_id, span, feature); + EvalResult::Deny { + feature, + reason: reason.to_opt_reason(), + issue, + suggestion, + is_soft, + } + } + Some(_) => { + // Stable APIs are always ok to call and deprecated APIs are + // handled by the lint emitting logic above. + EvalResult::Allow + } + None => EvalResult::Unmarked, + } + } + + /// Checks if an item is stable or error out. + /// + /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not + /// exist, emits an error. + /// + /// This function will also check if the item is deprecated. + /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted. + /// + /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature. + pub fn check_stability( + self, + def_id: DefId, + id: Option<HirId>, + span: Span, + method_span: Option<Span>, + ) -> bool { + self.check_stability_allow_unstable(def_id, id, span, method_span, AllowUnstable::No) + } + + /// Checks if an item is stable or error out. + /// + /// If the item defined by `def_id` is unstable and the corresponding `#![feature]` does not + /// exist, emits an error. + /// + /// This function will also check if the item is deprecated. + /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted. + /// + /// Pass `AllowUnstable::Yes` to `allow_unstable` to force an unstable item to be allowed. Deprecation warnings will be emitted normally. + /// + /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature. + pub fn check_stability_allow_unstable( + self, + def_id: DefId, + id: Option<HirId>, + span: Span, + method_span: Option<Span>, + allow_unstable: AllowUnstable, + ) -> bool { + self.check_optional_stability( + def_id, + id, + span, + method_span, + allow_unstable, + |span, def_id| { + // The API could be uncallable for other reasons, for example when a private module + // was referenced. + self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id)); + }, + ) + } + + /// Like `check_stability`, except that we permit items to have custom behaviour for + /// missing stability attributes (not necessarily just emit a `bug!`). This is necessary + /// for default generic parameters, which only have stability attributes if they were + /// added after the type on which they're defined. + /// + /// Returns `true` if item is allowed aka, stable or unstable under an enabled feature. + pub fn check_optional_stability( + self, + def_id: DefId, + id: Option<HirId>, + span: Span, + method_span: Option<Span>, + allow_unstable: AllowUnstable, + unmarked: impl FnOnce(Span, DefId), + ) -> bool { + let soft_handler = |lint, span, msg: &_| { + self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, |lint| { + lint.build(msg).emit(); + }) + }; + let eval_result = + self.eval_stability_allow_unstable(def_id, id, span, method_span, allow_unstable); + let is_allowed = matches!(eval_result, EvalResult::Allow); + match eval_result { + EvalResult::Allow => {} + EvalResult::Deny { feature, reason, issue, suggestion, is_soft } => report_unstable( + self.sess, + feature, + reason, + issue, + suggestion, + is_soft, + span, + soft_handler, + ), + EvalResult::Unmarked => unmarked(span, def_id), + } + + is_allowed + } + + pub fn lookup_deprecation(self, id: DefId) -> Option<Deprecation> { + self.lookup_deprecation_entry(id).map(|depr| depr.attr) + } +} |