1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649
//! 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, TyCtxt};
use rustc_ast::NodeId;
use rustc_attr::{self as attr, ConstStability, DefaultBodyStability, 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 default_body_stab_map: FxHashMap<LocalDefId, DefaultBodyStability>,
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_default_body_stability(&self, def_id: LocalDefId) -> Option<DefaultBodyStability> {
self.default_body_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, String),
) {
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, 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 {kind} `{path}` that will be deprecated in a future Rust version")
} 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(
lint_buffer: &mut LintBuffer,
message: String,
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: String,
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, message, |diag| {
if let hir::Node::Expr(_) = tcx.hir().get(hir_id) {
let kind = tcx.def_descr(def_id);
deprecation_suggestion(diag, kind, suggestion, method_span);
}
diag
});
}
/// 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(..) => 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())
.is_some_and(|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_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;
}
// Only the cross-crate scenario matters when checking unstable APIs
let cross_crate = !def_id.is_local();
if !cross_crate {
return EvalResult::Allow;
}
let stability = self.lookup_stability(def_id);
debug!(
"stability: \
inspecting def_id={:?} span={:?} of stability={:?}",
def_id, span, stability
);
// 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,
}
}
/// Evaluates the default-impl stability of an item.
///
/// Returns `EvalResult::Allow` if the item's default implementation is stable, or unstable but the corresponding
/// `#![feature]` has been provided. Returns `EvalResult::Deny` which describes the offending
/// unstable feature otherwise.
pub fn eval_default_body_stability(self, def_id: DefId, span: Span) -> EvalResult {
let is_staged_api = self.lookup_stability(def_id.krate.as_def_id()).is_some();
if !is_staged_api {
return EvalResult::Allow;
}
// Only the cross-crate scenario matters when checking unstable APIs
let cross_crate = !def_id.is_local();
if !cross_crate {
return EvalResult::Allow;
}
let stability = self.lookup_default_body_stability(def_id);
debug!(
"body stability: inspecting def_id={def_id:?} span={span:?} of stability={stability:?}"
);
// Issue #38412: private items lack stability markers.
if skip_stability_check_due_to_privacy(self, def_id) {
return EvalResult::Allow;
}
match stability {
Some(DefaultBodyStability {
level: attr::Unstable { reason, issue, is_soft, .. },
feature,
}) => {
if span.allows_unstable(feature) {
debug!("body stability: skipping span={:?} since it is internal", span);
return EvalResult::Allow;
}
if self.features().active(feature) {
return EvalResult::Allow;
}
EvalResult::Deny {
feature,
reason: reason.to_opt_reason(),
issue,
suggestion: None,
is_soft,
}
}
Some(_) => {
// Stable APIs are always ok to call
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: String| {
self.struct_span_lint_hir(lint, id.unwrap_or(hir::CRATE_HIR_ID), span, msg, |lint| lint)
};
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)
}
}