1 //! Implementation of lint checking.
3 //! The lint checking is mostly consolidated into one pass which runs
4 //! after all other analyses. Throughout compilation, lint warnings
5 //! can be added via the `add_lint` method on the Session structure. This
6 //! requires a span and an ID of the node that the lint is being added to. The
7 //! lint isn't actually emitted at that time because it is unknown what the
8 //! actual lint level at that location is.
10 //! To actually emit lint warnings/errors, a separate pass is used.
11 //! A context keeps track of the current state of all lint levels.
12 //! Upon entering a node of the ast which can modify the lint settings, the
13 //! previous lint state is pushed onto a stack and the ast is then recursed
14 //! upon. As the ast is traversed, this keeps track of the current lint level
15 //! for all lint attributes.
17 use self::TargetLint::*;
19 use crate::levels::LintLevelsBuilder;
20 use crate::passes::{EarlyLintPassObject, LateLintPassObject};
22 use rustc_data_structures::fx::FxHashMap;
23 use rustc_data_structures::sync;
24 use rustc_errors::{add_elided_lifetime_in_path_suggestion, struct_span_err, Applicability};
26 use rustc_hir::def::Res;
27 use rustc_hir::def_id::{CrateNum, DefId};
28 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
29 use rustc_middle::lint::LintDiagnosticBuilder;
30 use rustc_middle::middle::privacy::AccessLevels;
31 use rustc_middle::middle::stability;
32 use rustc_middle::ty::layout::{LayoutError, TyAndLayout};
33 use rustc_middle::ty::print::with_no_trimmed_paths;
34 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
35 use rustc_session::lint::BuiltinLintDiagnostics;
36 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
37 use rustc_session::Session;
38 use rustc_session::SessionLintStore;
39 use rustc_span::lev_distance::find_best_match_for_name;
40 use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
41 use rustc_target::abi::LayoutOf;
47 /// Information about the registered lints.
49 /// This is basically the subset of `Context` that we can
50 /// build early in the compile pipeline.
51 pub struct LintStore {
53 lints: Vec<&'static Lint>,
55 /// Constructor functions for each variety of lint pass.
57 /// These should only be called once, but since we want to avoid locks or
58 /// interior mutability, we don't enforce this (and lints should, in theory,
59 /// be compatible with being constructed more than once, though not
60 /// necessarily in a sane manner. This is safe though.)
61 pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
62 pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
63 pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
64 /// This is unique in that we construct them per-module, so not once.
65 pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
67 /// Lints indexed by name.
68 by_name: FxHashMap<String, TargetLint>,
70 /// Map of registered lint groups to what lints they expand to.
71 lint_groups: FxHashMap<&'static str, LintGroup>,
74 impl SessionLintStore for LintStore {
75 fn name_to_lint(&self, lint_name: &str) -> LintId {
77 .find_lints(lint_name)
78 .unwrap_or_else(|_| panic!("Failed to find lint with name `{}`", lint_name));
80 if let &[lint] = lints.as_slice() {
83 panic!("Found mutliple lints with name `{}`: {:?}", lint_name, lints);
88 /// The target of the `by_name` map, which accounts for renaming/deprecation.
90 /// A direct lint target
93 /// Temporary renaming, used for easing migration pain; see #16545
94 Renamed(String, LintId),
96 /// Lint with this name existed previously, but has been removed/deprecated.
97 /// The string argument is the reason for removal.
101 pub enum FindLintError {
108 /// Whether deprecation warnings should be suppressed for this alias.
113 lint_ids: Vec<LintId>,
115 depr: Option<LintAlias>,
118 pub enum CheckLintNameResult<'a> {
120 /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
121 NoLint(Option<Symbol>),
122 /// The lint is either renamed or removed. This is the warning
123 /// message, and an optional new name (`None` if removed).
124 Warning(String, Option<String>),
125 /// The lint is from a tool. If the Option is None, then either
126 /// the lint does not exist in the tool or the code was not
127 /// compiled with the tool and therefore the lint was never
128 /// added to the `LintStore`. Otherwise the `LintId` will be
129 /// returned as if it where a rustc lint.
130 Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
134 pub fn new() -> LintStore {
137 pre_expansion_passes: vec![],
138 early_passes: vec![],
140 late_module_passes: vec![],
141 by_name: Default::default(),
142 lint_groups: Default::default(),
146 pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
150 pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
153 .filter(|(_, LintGroup { depr, .. })| {
154 // Don't display deprecated lint groups.
157 .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
158 (*k, lint_ids.clone(), *from_plugin)
163 pub fn register_early_pass(
165 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
167 self.early_passes.push(Box::new(pass));
170 pub fn register_pre_expansion_pass(
172 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
174 self.pre_expansion_passes.push(Box::new(pass));
177 pub fn register_late_pass(
179 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
181 self.late_passes.push(Box::new(pass));
184 pub fn register_late_mod_pass(
186 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
188 self.late_module_passes.push(Box::new(pass));
191 // Helper method for register_early/late_pass
192 pub fn register_lints(&mut self, lints: &[&'static Lint]) {
194 self.lints.push(lint);
196 let id = LintId::of(lint);
197 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
198 bug!("duplicate specification of lint {}", lint.name_lower())
201 if let Some(FutureIncompatibleInfo { edition, .. }) = lint.future_incompatible {
202 if let Some(edition) = edition {
204 .entry(edition.lint_name())
205 .or_insert(LintGroup {
207 from_plugin: lint.is_plugin,
215 .entry("future_incompatible")
216 .or_insert(LintGroup {
218 from_plugin: lint.is_plugin,
227 pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
228 self.lint_groups.insert(
233 depr: Some(LintAlias { name: lint_name, silent: true }),
238 pub fn register_group(
242 deprecated_name: Option<&'static str>,
247 .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
249 if let Some(deprecated) = deprecated_name {
250 self.lint_groups.insert(
255 depr: Some(LintAlias { name, silent: false }),
261 bug!("duplicate specification of lint group {}", name);
266 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
267 let target = match self.by_name.get(new_name) {
268 Some(&Id(lint_id)) => lint_id,
269 _ => bug!("invalid lint renaming of {} to {}", old_name, new_name),
271 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
274 pub fn register_removed(&mut self, name: &str, reason: &str) {
275 self.by_name.insert(name.into(), Removed(reason.into()));
278 pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
279 match self.by_name.get(lint_name) {
280 Some(&Id(lint_id)) => Ok(vec![lint_id]),
281 Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
282 Some(&Removed(_)) => Err(FindLintError::Removed),
284 return match self.lint_groups.get(lint_name) {
285 Some(LintGroup { lint_ids, depr, .. }) => {
286 if let Some(LintAlias { name, .. }) = depr {
292 None => Err(FindLintError::Removed),
298 /// Checks the validity of lint names derived from the command line
299 pub fn check_lint_name_cmdline(&self, sess: &Session, lint_name: &str, level: Level) {
300 let db = match self.check_lint_name(lint_name, None) {
301 CheckLintNameResult::Ok(_) => None,
302 CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
303 CheckLintNameResult::NoLint(suggestion) => {
305 struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
307 if let Some(suggestion) = suggestion {
308 err.help(&format!("did you mean: `{}`", suggestion));
313 CheckLintNameResult::Tool(result) => match result {
314 Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
315 "lint name `{}` is deprecated \
316 and does not have an effect anymore. \
324 if let Some(mut db) = db {
326 "requested on the command line with `{} {}`",
328 Level::Allow => "-A",
331 Level::Forbid => "-F",
340 /// True if this symbol represents a lint group name.
341 pub fn is_lint_group(&self, lint_name: Symbol) -> bool {
343 "is_lint_group(lint_name={:?}, lint_groups={:?})",
345 self.lint_groups.keys().collect::<Vec<_>>()
347 let lint_name_str = &*lint_name.as_str();
348 self.lint_groups.contains_key(&lint_name_str) || {
349 let warnings_name_str = crate::WARNINGS.name_lower();
350 lint_name_str == &*warnings_name_str
354 /// Checks the name of a lint for its existence, and whether it was
355 /// renamed or removed. Generates a DiagnosticBuilder containing a
356 /// warning for renamed and removed lints. This is over both lint
357 /// names from attributes and those passed on the command line. Since
358 /// it emits non-fatal warnings and there are *two* lint passes that
359 /// inspect attributes, this is only run from the late pass to avoid
360 /// printing duplicate warnings.
361 pub fn check_lint_name(
364 tool_name: Option<Symbol>,
365 ) -> CheckLintNameResult<'_> {
366 let complete_name = if let Some(tool_name) = tool_name {
367 format!("{}::{}", tool_name, lint_name)
369 lint_name.to_string()
371 // If the lint was scoped with `tool::` check if the tool lint exists
372 if let Some(tool_name) = tool_name {
373 match self.by_name.get(&complete_name) {
374 None => match self.lint_groups.get(&*complete_name) {
375 // If the lint isn't registered, there are two possibilities:
377 // 1. The tool is currently running, so this lint really doesn't exist.
378 // FIXME: should this handle tools that never register a lint, like rustfmt?
379 tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
380 let tool_prefix = format!("{}::", tool_name);
381 return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
382 self.no_lint_suggestion(&complete_name)
384 // 2. The tool isn't currently running, so no lints will be registered.
385 // To avoid giving a false positive, ignore all unknown lints.
386 CheckLintNameResult::Tool(Err((None, String::new())))
389 Some(LintGroup { lint_ids, .. }) => {
390 return CheckLintNameResult::Tool(Ok(&lint_ids));
393 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
394 // If the lint was registered as removed or renamed by the lint tool, we don't need
395 // to treat tool_lints and rustc lints different and can use the code below.
399 match self.by_name.get(&complete_name) {
400 Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
401 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
402 Some(new_name.to_owned()),
404 Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
405 format!("lint `{}` has been removed: {}", complete_name, reason),
408 None => match self.lint_groups.get(&*complete_name) {
409 // If neither the lint, nor the lint group exists check if there is a `clippy::`
410 // variant of this lint
411 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
412 Some(LintGroup { lint_ids, depr, .. }) => {
413 // Check if the lint group name is deprecated
414 if let Some(LintAlias { name, silent }) = depr {
415 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
417 CheckLintNameResult::Ok(&lint_ids)
419 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
422 CheckLintNameResult::Ok(&lint_ids)
425 Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
429 fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
430 let name_lower = lint_name.to_lowercase();
432 self.get_lints().iter().map(|l| Symbol::intern(&l.name_lower())).collect::<Vec<_>>();
434 if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
435 // First check if the lint name is (partly) in upper case instead of lower case...
436 CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)))
438 // ...if not, search for lints with a similar name
439 let suggestion = find_best_match_for_name(&symbols, Symbol::intern(&name_lower), None);
440 CheckLintNameResult::NoLint(suggestion)
444 fn check_tool_name_for_backwards_compat(
448 ) -> CheckLintNameResult<'_> {
449 let complete_name = format!("{}::{}", tool_name, lint_name);
450 match self.by_name.get(&complete_name) {
451 None => match self.lint_groups.get(&*complete_name) {
452 // Now we are sure, that this lint exists nowhere
453 None => self.no_lint_suggestion(lint_name),
454 Some(LintGroup { lint_ids, depr, .. }) => {
455 // Reaching this would be weird, but let's cover this case anyway
456 if let Some(LintAlias { name, silent }) = depr {
457 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
459 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
461 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
464 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
467 Some(&Id(ref id)) => {
468 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
470 _ => CheckLintNameResult::NoLint(None),
475 /// Context for lint checking after type checking.
476 pub struct LateContext<'tcx> {
477 /// Type context we're checking in.
478 pub tcx: TyCtxt<'tcx>,
480 /// Current body, or `None` if outside a body.
481 pub enclosing_body: Option<hir::BodyId>,
483 /// Type-checking results for the current body. Access using the `typeck_results`
484 /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
485 // FIXME(eddyb) move all the code accessing internal fields like this,
486 // to this module, to avoid exposing it to lint logic.
487 pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
489 /// Parameter environment for the item we are in.
490 pub param_env: ty::ParamEnv<'tcx>,
492 /// Items accessible from the crate being checked.
493 pub access_levels: &'tcx AccessLevels,
495 /// The store of registered lints and the lint levels.
496 pub lint_store: &'tcx LintStore,
498 pub last_node_with_lint_attrs: hir::HirId,
500 /// Generic type parameters in scope for the item we are in.
501 pub generics: Option<&'tcx hir::Generics<'tcx>>,
503 /// We are only looking at one module
504 pub only_module: bool,
507 /// Context for lint checking of the AST, after expansion, before lowering to
509 pub struct EarlyContext<'a> {
510 /// Type context we're checking in.
511 pub sess: &'a Session,
513 /// The crate being checked.
514 pub krate: &'a ast::Crate,
516 pub builder: LintLevelsBuilder<'a>,
518 /// The store of registered lints and the lint levels.
519 pub lint_store: &'a LintStore,
521 pub buffered: LintBuffer,
524 pub trait LintPassObject: Sized {}
526 impl LintPassObject for EarlyLintPassObject {}
528 impl LintPassObject for LateLintPassObject {}
530 pub trait LintContext: Sized {
531 type PassObject: LintPassObject;
533 fn sess(&self) -> &Session;
534 fn lints(&self) -> &LintStore;
536 fn lookup_with_diagnostics(
539 span: Option<impl Into<MultiSpan>>,
540 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
541 diagnostic: BuiltinLintDiagnostics,
543 self.lookup(lint, span, |lint| {
544 // We first generate a blank diagnostic.
545 let mut db = lint.build("");
547 // Now, set up surrounding context.
548 let sess = self.sess();
550 BuiltinLintDiagnostics::Normal => (),
551 BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
552 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
553 Ok(s) if is_global => {
554 (format!("dyn ({})", s), Applicability::MachineApplicable)
556 Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
557 Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders),
559 db.span_suggestion(span, "use `dyn`", sugg, app);
561 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
562 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
564 // FIXME(Manishearth) ideally the emitting code
565 // can tell us whether or not this is global
567 if s.trim_start().starts_with("::") { "" } else { "::" };
569 (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
571 Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
573 db.span_suggestion(span, "use `crate`", sugg, app);
575 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
578 "names from parent modules are not accessible without an explicit import",
581 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
584 db.span_note(span_def, "the macro is defined here");
586 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
593 add_elided_lifetime_in_path_suggestion(
603 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
604 db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect);
606 BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
607 if !replaces.is_empty() {
608 db.tool_only_multipart_suggestion(
611 Applicability::MachineApplicable,
615 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
616 for (span, is_imported) in spans {
617 let introduced = if is_imported { "imported" } else { "defined" };
620 format!("the item `{}` is already {} here", ident, introduced),
624 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
625 stability::deprecation_suggestion(&mut db, "macro", suggestion, span)
627 BuiltinLintDiagnostics::UnusedDocComment(span) => {
628 db.span_label(span, "rustdoc does not generate documentation for macro invocations");
629 db.help("to document an item produced by a macro, \
630 the macro must produce the documentation as part of its expansion");
632 BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => {
633 db.span_suggestion(span, "remove `mut` from the parameter", ident.to_string(), Applicability::MachineApplicable);
635 BuiltinLintDiagnostics::MissingAbi(span, default_abi) => {
636 db.span_label(span, "ABI should be specified here");
637 db.help(&format!("the default ABI is {}", default_abi.name()));
640 // Rewrap `db`, and pass control to the user.
641 decorate(LintDiagnosticBuilder::new(db));
645 // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
646 // set the span in their `decorate` function (preferably using set_span).
647 fn lookup<S: Into<MultiSpan>>(
651 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
654 fn struct_span_lint<S: Into<MultiSpan>>(
658 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
660 self.lookup(lint, Some(span), decorate);
662 /// Emit a lint at the appropriate level, with no associated span.
663 fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
664 self.lookup(lint, None as Option<Span>, decorate);
668 impl<'a> EarlyContext<'a> {
671 lint_store: &'a LintStore,
672 krate: &'a ast::Crate,
673 buffered: LintBuffer,
674 warn_about_weird_lints: bool,
675 ) -> EarlyContext<'a> {
680 builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store),
686 impl LintContext for LateContext<'_> {
687 type PassObject = LateLintPassObject;
689 /// Gets the overall compiler `Session` object.
690 fn sess(&self) -> &Session {
694 fn lints(&self) -> &LintStore {
698 fn lookup<S: Into<MultiSpan>>(
702 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
704 let hir_id = self.last_node_with_lint_attrs;
707 Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
708 None => self.tcx.struct_lint_node(lint, hir_id, decorate),
713 impl LintContext for EarlyContext<'_> {
714 type PassObject = EarlyLintPassObject;
716 /// Gets the overall compiler `Session` object.
717 fn sess(&self) -> &Session {
721 fn lints(&self) -> &LintStore {
725 fn lookup<S: Into<MultiSpan>>(
729 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
731 self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
735 impl<'tcx> LateContext<'tcx> {
736 /// Gets the type-checking results for the current body,
737 /// or `None` if outside a body.
738 pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
739 self.cached_typeck_results.get().or_else(|| {
740 self.enclosing_body.map(|body| {
741 let typeck_results = self.tcx.typeck_body(body);
742 self.cached_typeck_results.set(Some(typeck_results));
748 /// Gets the type-checking results for the current body.
749 /// As this will ICE if called outside bodies, only call when working with
750 /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
752 pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
753 self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
756 /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
757 /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
758 /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
759 pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
761 hir::QPath::Resolved(_, ref path) => path.res,
762 hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
763 .maybe_typeck_results()
764 .filter(|typeck_results| typeck_results.hir_owner == id.owner)
766 if self.tcx.has_typeck_results(id.owner.to_def_id()) {
767 Some(self.tcx.typeck(id.owner))
772 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
773 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
777 /// Check if a `DefId`'s path matches the given absolute type path usage.
779 /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
780 /// inherent `impl` blocks are matched with the name of the type.
782 /// Instead of using this method, it is often preferable to instead use
783 /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
784 /// as paths get invalidated if the target definition moves.
788 /// ```rust,ignore (no context or def id available)
789 /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
790 /// // The given `def_id` is that of an `Option` type
793 pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
794 let names = self.get_def_path(def_id);
796 names.len() == path.len() && names.into_iter().zip(path.iter()).all(|(a, &b)| a == b)
799 /// Gets the absolute path of `def_id` as a vector of `Symbol`.
803 /// ```rust,ignore (no context or def id available)
804 /// let def_path = cx.get_def_path(def_id);
805 /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
806 /// // The given `def_id` is that of an `Option` type
809 pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
810 pub struct AbsolutePathPrinter<'tcx> {
811 pub tcx: TyCtxt<'tcx>,
814 impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
817 type Path = Vec<Symbol>;
820 type DynExistential = ();
823 fn tcx(&self) -> TyCtxt<'tcx> {
827 fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
831 fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
835 fn print_dyn_existential(
837 _predicates: &'tcx ty::List<ty::Binder<ty::ExistentialPredicate<'tcx>>>,
838 ) -> Result<Self::DynExistential, Self::Error> {
842 fn print_const(self, _ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
846 fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
847 Ok(vec![self.tcx.original_crate_name(cnum)])
853 trait_ref: Option<ty::TraitRef<'tcx>>,
854 ) -> Result<Self::Path, Self::Error> {
855 if trait_ref.is_none() {
856 if let ty::Adt(def, substs) = self_ty.kind() {
857 return self.print_def_path(def.did, substs);
861 // This shouldn't ever be needed, but just in case:
862 with_no_trimmed_paths(|| {
863 Ok(vec![match trait_ref {
864 Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
865 None => Symbol::intern(&format!("<{}>", self_ty)),
872 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
873 _disambiguated_data: &DisambiguatedDefPathData,
875 trait_ref: Option<ty::TraitRef<'tcx>>,
876 ) -> Result<Self::Path, Self::Error> {
877 let mut path = print_prefix(self)?;
879 // This shouldn't ever be needed, but just in case:
880 path.push(match trait_ref {
881 Some(trait_ref) => with_no_trimmed_paths(|| {
882 Symbol::intern(&format!(
884 trait_ref.print_only_trait_path(),
889 with_no_trimmed_paths(|| Symbol::intern(&format!("<impl {}>", self_ty)))
898 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
899 disambiguated_data: &DisambiguatedDefPathData,
900 ) -> Result<Self::Path, Self::Error> {
901 let mut path = print_prefix(self)?;
903 // Skip `::{{constructor}}` on tuple/unit structs.
904 if let DefPathData::Ctor = disambiguated_data.data {
908 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
912 fn path_generic_args(
914 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
915 _args: &[GenericArg<'tcx>],
916 ) -> Result<Self::Path, Self::Error> {
921 AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
925 impl<'tcx> LayoutOf for LateContext<'tcx> {
927 type TyAndLayout = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
929 fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout {
930 self.tcx.layout_of(self.param_env.and(ty))