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;
25 add_elided_lifetime_in_path_suggestion, struct_span_err, Applicability, SuggestionStyle,
28 use rustc_hir::def::Res;
29 use rustc_hir::def_id::{CrateNum, DefId};
30 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
31 use rustc_middle::lint::LintDiagnosticBuilder;
32 use rustc_middle::middle::privacy::AccessLevels;
33 use rustc_middle::middle::stability;
34 use rustc_middle::ty::layout::{LayoutError, TyAndLayout};
35 use rustc_middle::ty::print::with_no_trimmed_paths;
36 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
37 use rustc_serialize::json::Json;
38 use rustc_session::lint::{BuiltinLintDiagnostics, ExternDepSpec};
39 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
40 use rustc_session::Session;
41 use rustc_session::SessionLintStore;
42 use rustc_span::lev_distance::find_best_match_for_name;
43 use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
44 use rustc_target::abi::LayoutOf;
51 /// Information about the registered lints.
53 /// This is basically the subset of `Context` that we can
54 /// build early in the compile pipeline.
55 pub struct LintStore {
57 lints: Vec<&'static Lint>,
59 /// Constructor functions for each variety of lint pass.
61 /// These should only be called once, but since we want to avoid locks or
62 /// interior mutability, we don't enforce this (and lints should, in theory,
63 /// be compatible with being constructed more than once, though not
64 /// necessarily in a sane manner. This is safe though.)
65 pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
66 pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
67 pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
68 /// This is unique in that we construct them per-module, so not once.
69 pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
71 /// Lints indexed by name.
72 by_name: FxHashMap<String, TargetLint>,
74 /// Map of registered lint groups to what lints they expand to.
75 lint_groups: FxHashMap<&'static str, LintGroup>,
78 impl SessionLintStore for LintStore {
79 fn name_to_lint(&self, lint_name: &str) -> LintId {
81 .find_lints(lint_name)
82 .unwrap_or_else(|_| panic!("Failed to find lint with name `{}`", lint_name));
84 if let &[lint] = lints.as_slice() {
87 panic!("Found mutliple lints with name `{}`: {:?}", lint_name, lints);
92 /// The target of the `by_name` map, which accounts for renaming/deprecation.
95 /// A direct lint target
98 /// Temporary renaming, used for easing migration pain; see #16545
99 Renamed(String, LintId),
101 /// Lint with this name existed previously, but has been removed/deprecated.
102 /// The string argument is the reason for removal.
105 /// A lint name that should give no warnings and have no effect.
107 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
111 pub enum FindLintError {
118 /// Whether deprecation warnings should be suppressed for this alias.
123 lint_ids: Vec<LintId>,
125 depr: Option<LintAlias>,
128 pub enum CheckLintNameResult<'a> {
130 /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
131 NoLint(Option<Symbol>),
132 /// The lint is either renamed or removed. This is the warning
133 /// message, and an optional new name (`None` if removed).
134 Warning(String, Option<String>),
135 /// The lint is from a tool. If the Option is None, then either
136 /// the lint does not exist in the tool or the code was not
137 /// compiled with the tool and therefore the lint was never
138 /// added to the `LintStore`. Otherwise the `LintId` will be
139 /// returned as if it where a rustc lint.
140 Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
144 pub fn new() -> LintStore {
147 pre_expansion_passes: vec![],
148 early_passes: vec![],
150 late_module_passes: vec![],
151 by_name: Default::default(),
152 lint_groups: Default::default(),
156 pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
160 pub fn get_lint_groups<'t>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
163 .filter(|(_, LintGroup { depr, .. })| {
164 // Don't display deprecated lint groups.
167 .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
168 (*k, lint_ids.clone(), *from_plugin)
173 pub fn register_early_pass(
175 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
177 self.early_passes.push(Box::new(pass));
181 pub fn register_pre_expansion_pass(
183 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
185 self.pre_expansion_passes.push(Box::new(pass));
188 pub fn register_late_pass(
190 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
192 self.late_passes.push(Box::new(pass));
195 pub fn register_late_mod_pass(
197 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
199 self.late_module_passes.push(Box::new(pass));
202 // Helper method for register_early/late_pass
203 pub fn register_lints(&mut self, lints: &[&'static Lint]) {
205 self.lints.push(lint);
207 let id = LintId::of(lint);
208 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
209 bug!("duplicate specification of lint {}", lint.name_lower())
212 if let Some(FutureIncompatibleInfo { edition, .. }) = lint.future_incompatible {
213 if let Some(edition) = edition {
215 .entry(edition.lint_name())
216 .or_insert(LintGroup {
218 from_plugin: lint.is_plugin,
226 .entry("future_incompatible")
227 .or_insert(LintGroup {
229 from_plugin: lint.is_plugin,
238 pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
239 self.lint_groups.insert(
244 depr: Some(LintAlias { name: lint_name, silent: true }),
249 pub fn register_group(
253 deprecated_name: Option<&'static str>,
258 .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
260 if let Some(deprecated) = deprecated_name {
261 self.lint_groups.insert(
266 depr: Some(LintAlias { name, silent: false }),
272 bug!("duplicate specification of lint group {}", name);
276 /// This lint should be available with either the old or the new name.
278 /// Using the old name will not give a warning.
279 /// You must register a lint with the new name before calling this function.
281 pub fn register_alias(&mut self, old_name: &str, new_name: &str) {
282 let target = match self.by_name.get(new_name) {
283 Some(&Id(lint_id)) => lint_id,
284 _ => bug!("cannot add alias {} for lint {} that does not exist", old_name, new_name),
286 match self.by_name.insert(old_name.to_string(), Id(target)) {
287 None | Some(Ignored) => {}
288 Some(x) => bug!("duplicate specification of lint {} (was {:?})", old_name, x),
292 /// This lint should give no warning and have no effect.
294 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
296 pub fn register_ignored(&mut self, name: &str) {
297 if self.by_name.insert(name.to_string(), Ignored).is_some() {
298 bug!("duplicate specification of lint {}", name);
302 /// This lint has been renamed; warn about using the new name and apply the lint.
304 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
305 let target = match self.by_name.get(new_name) {
306 Some(&Id(lint_id)) => lint_id,
307 _ => bug!("invalid lint renaming of {} to {}", old_name, new_name),
309 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
312 pub fn register_removed(&mut self, name: &str, reason: &str) {
313 self.by_name.insert(name.into(), Removed(reason.into()));
316 pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
317 match self.by_name.get(lint_name) {
318 Some(&Id(lint_id)) => Ok(vec![lint_id]),
319 Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
320 Some(&Removed(_)) => Err(FindLintError::Removed),
321 Some(&Ignored) => Ok(vec![]),
323 return match self.lint_groups.get(lint_name) {
324 Some(LintGroup { lint_ids, depr, .. }) => {
325 if let Some(LintAlias { name, .. }) = depr {
331 None => Err(FindLintError::Removed),
337 /// Checks the validity of lint names derived from the command line
338 pub fn check_lint_name_cmdline(&self, sess: &Session, lint_name: &str, level: Level) {
339 let db = match self.check_lint_name(lint_name, None) {
340 CheckLintNameResult::Ok(_) => None,
341 CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
342 CheckLintNameResult::NoLint(suggestion) => {
344 struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
346 if let Some(suggestion) = suggestion {
347 err.help(&format!("did you mean: `{}`", suggestion));
352 CheckLintNameResult::Tool(result) => match result {
353 Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
354 "lint name `{}` is deprecated \
355 and does not have an effect anymore. \
363 if let Some(mut db) = db {
365 "requested on the command line with `{} {}`",
367 Level::Allow => "-A",
370 Level::Forbid => "-F",
379 /// True if this symbol represents a lint group name.
380 pub fn is_lint_group(&self, lint_name: Symbol) -> bool {
382 "is_lint_group(lint_name={:?}, lint_groups={:?})",
384 self.lint_groups.keys().collect::<Vec<_>>()
386 let lint_name_str = &*lint_name.as_str();
387 self.lint_groups.contains_key(&lint_name_str) || {
388 let warnings_name_str = crate::WARNINGS.name_lower();
389 lint_name_str == &*warnings_name_str
393 /// Checks the name of a lint for its existence, and whether it was
394 /// renamed or removed. Generates a DiagnosticBuilder containing a
395 /// warning for renamed and removed lints. This is over both lint
396 /// names from attributes and those passed on the command line. Since
397 /// it emits non-fatal warnings and there are *two* lint passes that
398 /// inspect attributes, this is only run from the late pass to avoid
399 /// printing duplicate warnings.
400 pub fn check_lint_name(
403 tool_name: Option<Symbol>,
404 ) -> CheckLintNameResult<'_> {
405 let complete_name = if let Some(tool_name) = tool_name {
406 format!("{}::{}", tool_name, lint_name)
408 lint_name.to_string()
410 // If the lint was scoped with `tool::` check if the tool lint exists
411 if let Some(tool_name) = tool_name {
412 match self.by_name.get(&complete_name) {
413 None => match self.lint_groups.get(&*complete_name) {
414 // If the lint isn't registered, there are two possibilities:
416 // 1. The tool is currently running, so this lint really doesn't exist.
417 // FIXME: should this handle tools that never register a lint, like rustfmt?
418 tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
419 let tool_prefix = format!("{}::", tool_name);
420 return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
421 self.no_lint_suggestion(&complete_name)
423 // 2. The tool isn't currently running, so no lints will be registered.
424 // To avoid giving a false positive, ignore all unknown lints.
425 CheckLintNameResult::Tool(Err((None, String::new())))
428 Some(LintGroup { lint_ids, .. }) => {
429 return CheckLintNameResult::Tool(Ok(&lint_ids));
432 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
433 // If the lint was registered as removed or renamed by the lint tool, we don't need
434 // to treat tool_lints and rustc lints different and can use the code below.
438 match self.by_name.get(&complete_name) {
439 Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
440 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
441 Some(new_name.to_owned()),
443 Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
444 format!("lint `{}` has been removed: {}", complete_name, reason),
447 None => match self.lint_groups.get(&*complete_name) {
448 // If neither the lint, nor the lint group exists check if there is a `clippy::`
449 // variant of this lint
450 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
451 Some(LintGroup { lint_ids, depr, .. }) => {
452 // Check if the lint group name is deprecated
453 if let Some(LintAlias { name, silent }) = depr {
454 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
456 CheckLintNameResult::Ok(&lint_ids)
458 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
461 CheckLintNameResult::Ok(&lint_ids)
464 Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
465 Some(&Ignored) => CheckLintNameResult::Ok(&[]),
469 fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
470 let name_lower = lint_name.to_lowercase();
472 self.get_lints().iter().map(|l| Symbol::intern(&l.name_lower())).collect::<Vec<_>>();
474 if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
475 // First check if the lint name is (partly) in upper case instead of lower case...
476 CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)))
478 // ...if not, search for lints with a similar name
479 let suggestion = find_best_match_for_name(&symbols, Symbol::intern(&name_lower), None);
480 CheckLintNameResult::NoLint(suggestion)
484 fn check_tool_name_for_backwards_compat(
488 ) -> CheckLintNameResult<'_> {
489 let complete_name = format!("{}::{}", tool_name, lint_name);
490 match self.by_name.get(&complete_name) {
491 None => match self.lint_groups.get(&*complete_name) {
492 // Now we are sure, that this lint exists nowhere
493 None => self.no_lint_suggestion(lint_name),
494 Some(LintGroup { lint_ids, depr, .. }) => {
495 // Reaching this would be weird, but let's cover this case anyway
496 if let Some(LintAlias { name, silent }) = depr {
497 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
499 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
501 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
504 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
507 Some(&Id(ref id)) => {
508 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
511 tracing::debug!("got renamed lint {:?}", other);
512 CheckLintNameResult::NoLint(None)
518 /// Context for lint checking after type checking.
519 pub struct LateContext<'tcx> {
520 /// Type context we're checking in.
521 pub tcx: TyCtxt<'tcx>,
523 /// Current body, or `None` if outside a body.
524 pub enclosing_body: Option<hir::BodyId>,
526 /// Type-checking results for the current body. Access using the `typeck_results`
527 /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
528 // FIXME(eddyb) move all the code accessing internal fields like this,
529 // to this module, to avoid exposing it to lint logic.
530 pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
532 /// Parameter environment for the item we are in.
533 pub param_env: ty::ParamEnv<'tcx>,
535 /// Items accessible from the crate being checked.
536 pub access_levels: &'tcx AccessLevels,
538 /// The store of registered lints and the lint levels.
539 pub lint_store: &'tcx LintStore,
541 pub last_node_with_lint_attrs: hir::HirId,
543 /// Generic type parameters in scope for the item we are in.
544 pub generics: Option<&'tcx hir::Generics<'tcx>>,
546 /// We are only looking at one module
547 pub only_module: bool,
550 /// Context for lint checking of the AST, after expansion, before lowering to
552 pub struct EarlyContext<'a> {
553 /// Type context we're checking in.
554 pub sess: &'a Session,
556 /// The crate being checked.
557 pub krate: &'a ast::Crate,
559 pub builder: LintLevelsBuilder<'a>,
561 /// The store of registered lints and the lint levels.
562 pub lint_store: &'a LintStore,
564 pub buffered: LintBuffer,
567 pub trait LintPassObject: Sized {}
569 impl LintPassObject for EarlyLintPassObject {}
571 impl LintPassObject for LateLintPassObject {}
573 pub trait LintContext: Sized {
574 type PassObject: LintPassObject;
576 fn sess(&self) -> &Session;
577 fn lints(&self) -> &LintStore;
579 fn lookup_with_diagnostics(
582 span: Option<impl Into<MultiSpan>>,
583 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
584 diagnostic: BuiltinLintDiagnostics,
586 self.lookup(lint, span, |lint| {
587 // We first generate a blank diagnostic.
588 let mut db = lint.build("");
590 // Now, set up surrounding context.
591 let sess = self.sess();
593 BuiltinLintDiagnostics::Normal => (),
594 BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
595 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
596 Ok(s) if is_global => {
597 (format!("dyn ({})", s), Applicability::MachineApplicable)
599 Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
600 Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders),
602 db.span_suggestion(span, "use `dyn`", sugg, app);
604 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
605 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
607 // FIXME(Manishearth) ideally the emitting code
608 // can tell us whether or not this is global
610 if s.trim_start().starts_with("::") { "" } else { "::" };
612 (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
614 Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
616 db.span_suggestion(span, "use `crate`", sugg, app);
618 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
621 "names from parent modules are not accessible without an explicit import",
624 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
627 db.span_note(span_def, "the macro is defined here");
629 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
636 add_elided_lifetime_in_path_suggestion(
646 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
647 db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect);
649 BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
650 if !replaces.is_empty() {
651 db.tool_only_multipart_suggestion(
654 Applicability::MachineApplicable,
658 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
659 for (span, is_imported) in spans {
660 let introduced = if is_imported { "imported" } else { "defined" };
663 format!("the item `{}` is already {} here", ident, introduced),
667 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
668 stability::deprecation_suggestion(&mut db, "macro", suggestion, span)
670 BuiltinLintDiagnostics::UnusedDocComment(span) => {
671 db.span_label(span, "rustdoc does not generate documentation for macro invocations");
672 db.help("to document an item produced by a macro, \
673 the macro must produce the documentation as part of its expansion");
675 BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => {
676 db.span_suggestion(span, "remove `mut` from the parameter", ident.to_string(), Applicability::MachineApplicable);
678 BuiltinLintDiagnostics::MissingAbi(span, default_abi) => {
679 db.span_label(span, "ABI should be specified here");
680 db.help(&format!("the default ABI is {}", default_abi.name()));
682 BuiltinLintDiagnostics::LegacyDeriveHelpers(span) => {
683 db.span_label(span, "the attribute is introduced here");
685 BuiltinLintDiagnostics::ExternDepSpec(krate, loc) => {
686 let json = match loc {
687 ExternDepSpec::Json(json) => {
688 db.help(&format!("remove unnecessary dependency `{}`", krate));
691 ExternDepSpec::Raw(raw) => {
692 db.help(&format!("remove unnecessary dependency `{}` at `{}`", krate, raw));
693 db.span_suggestion_with_style(
695 "raw extern location",
697 Applicability::Unspecified,
698 SuggestionStyle::CompletelyHidden,
703 db.tool_only_suggestion_with_metadata(
704 "json extern location",
705 Applicability::Unspecified,
709 BuiltinLintDiagnostics::ProcMacroBackCompat(note) => {
712 BuiltinLintDiagnostics::OrPatternsBackCompat(span,suggestion) => {
713 db.span_suggestion(span, "use pat2015 to preserve semantics", suggestion, Applicability::MachineApplicable);
716 // Rewrap `db`, and pass control to the user.
717 decorate(LintDiagnosticBuilder::new(db));
721 // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
722 // set the span in their `decorate` function (preferably using set_span).
723 fn lookup<S: Into<MultiSpan>>(
727 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
730 fn struct_span_lint<S: Into<MultiSpan>>(
734 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
736 self.lookup(lint, Some(span), decorate);
738 /// Emit a lint at the appropriate level, with no associated span.
739 fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
740 self.lookup(lint, None as Option<Span>, decorate);
744 impl<'a> EarlyContext<'a> {
747 lint_store: &'a LintStore,
748 krate: &'a ast::Crate,
749 buffered: LintBuffer,
750 warn_about_weird_lints: bool,
751 ) -> EarlyContext<'a> {
756 builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store, &krate.attrs),
762 impl LintContext for LateContext<'_> {
763 type PassObject = LateLintPassObject;
765 /// Gets the overall compiler `Session` object.
766 fn sess(&self) -> &Session {
770 fn lints(&self) -> &LintStore {
774 fn lookup<S: Into<MultiSpan>>(
778 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
780 let hir_id = self.last_node_with_lint_attrs;
783 Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
784 None => self.tcx.struct_lint_node(lint, hir_id, decorate),
789 impl LintContext for EarlyContext<'_> {
790 type PassObject = EarlyLintPassObject;
792 /// Gets the overall compiler `Session` object.
793 fn sess(&self) -> &Session {
797 fn lints(&self) -> &LintStore {
801 fn lookup<S: Into<MultiSpan>>(
805 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
807 self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
811 impl<'tcx> LateContext<'tcx> {
812 /// Gets the type-checking results for the current body,
813 /// or `None` if outside a body.
814 pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
815 self.cached_typeck_results.get().or_else(|| {
816 self.enclosing_body.map(|body| {
817 let typeck_results = self.tcx.typeck_body(body);
818 self.cached_typeck_results.set(Some(typeck_results));
824 /// Gets the type-checking results for the current body.
825 /// As this will ICE if called outside bodies, only call when working with
826 /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
828 pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
829 self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
832 /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
833 /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
834 /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
835 pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
837 hir::QPath::Resolved(_, ref path) => path.res,
838 hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
839 .maybe_typeck_results()
840 .filter(|typeck_results| typeck_results.hir_owner == id.owner)
842 if self.tcx.has_typeck_results(id.owner.to_def_id()) {
843 Some(self.tcx.typeck(id.owner))
848 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
849 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
853 /// Check if a `DefId`'s path matches the given absolute type path usage.
855 /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
856 /// inherent `impl` blocks are matched with the name of the type.
858 /// Instead of using this method, it is often preferable to instead use
859 /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
860 /// as paths get invalidated if the target definition moves.
864 /// ```rust,ignore (no context or def id available)
865 /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
866 /// // The given `def_id` is that of an `Option` type
870 /// Used by clippy, but should be replaced by diagnostic items eventually.
871 pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
872 let names = self.get_def_path(def_id);
874 names.len() == path.len() && iter::zip(names, path).all(|(a, &b)| a == b)
877 /// Gets the absolute path of `def_id` as a vector of `Symbol`.
881 /// ```rust,ignore (no context or def id available)
882 /// let def_path = cx.get_def_path(def_id);
883 /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
884 /// // The given `def_id` is that of an `Option` type
887 pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
888 pub struct AbsolutePathPrinter<'tcx> {
889 pub tcx: TyCtxt<'tcx>,
892 impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
895 type Path = Vec<Symbol>;
898 type DynExistential = ();
901 fn tcx(&self) -> TyCtxt<'tcx> {
905 fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
909 fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
913 fn print_dyn_existential(
915 _predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
916 ) -> Result<Self::DynExistential, Self::Error> {
920 fn print_const(self, _ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
924 fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
925 Ok(vec![self.tcx.original_crate_name(cnum)])
931 trait_ref: Option<ty::TraitRef<'tcx>>,
932 ) -> Result<Self::Path, Self::Error> {
933 if trait_ref.is_none() {
934 if let ty::Adt(def, substs) = self_ty.kind() {
935 return self.print_def_path(def.did, substs);
939 // This shouldn't ever be needed, but just in case:
940 with_no_trimmed_paths(|| {
941 Ok(vec![match trait_ref {
942 Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
943 None => Symbol::intern(&format!("<{}>", self_ty)),
950 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
951 _disambiguated_data: &DisambiguatedDefPathData,
953 trait_ref: Option<ty::TraitRef<'tcx>>,
954 ) -> Result<Self::Path, Self::Error> {
955 let mut path = print_prefix(self)?;
957 // This shouldn't ever be needed, but just in case:
958 path.push(match trait_ref {
959 Some(trait_ref) => with_no_trimmed_paths(|| {
960 Symbol::intern(&format!(
962 trait_ref.print_only_trait_path(),
967 with_no_trimmed_paths(|| Symbol::intern(&format!("<impl {}>", self_ty)))
976 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
977 disambiguated_data: &DisambiguatedDefPathData,
978 ) -> Result<Self::Path, Self::Error> {
979 let mut path = print_prefix(self)?;
981 // Skip `::{{constructor}}` on tuple/unit structs.
982 if let DefPathData::Ctor = disambiguated_data.data {
986 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
990 fn path_generic_args(
992 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
993 _args: &[GenericArg<'tcx>],
994 ) -> Result<Self::Path, Self::Error> {
999 AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
1003 impl<'tcx> LayoutOf for LateContext<'tcx> {
1005 type TyAndLayout = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
1007 fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout {
1008 self.tcx.layout_of(self.param_env.and(ty))