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};
21 use rustc_ast::util::unicode::TEXT_FLOW_CONTROL_CHARS;
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};
25 use rustc_errors::{Applicability, MultiSpan, SuggestionStyle};
27 use rustc_hir::def::Res;
28 use rustc_hir::def_id::{CrateNum, DefId};
29 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
30 use rustc_middle::lint::LintDiagnosticBuilder;
31 use rustc_middle::middle::privacy::AccessLevels;
32 use rustc_middle::middle::stability;
33 use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout};
34 use rustc_middle::ty::print::with_no_trimmed_paths;
35 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, RegisteredTools, Ty, TyCtxt};
36 use rustc_session::lint::BuiltinLintDiagnostics;
37 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
38 use rustc_session::Session;
39 use rustc_span::lev_distance::find_best_match_for_name;
40 use rustc_span::symbol::{sym, Ident, Symbol};
41 use rustc_span::{BytePos, Span, DUMMY_SP};
42 use rustc_target::abi;
49 /// Information about the registered lints.
51 /// This is basically the subset of `Context` that we can
52 /// build early in the compile pipeline.
53 pub struct LintStore {
55 lints: Vec<&'static Lint>,
57 /// Constructor functions for each variety of lint pass.
59 /// These should only be called once, but since we want to avoid locks or
60 /// interior mutability, we don't enforce this (and lints should, in theory,
61 /// be compatible with being constructed more than once, though not
62 /// necessarily in a sane manner. This is safe though.)
63 pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
64 pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
65 pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
66 /// This is unique in that we construct them per-module, so not once.
67 pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
69 /// Lints indexed by name.
70 by_name: FxHashMap<String, TargetLint>,
72 /// Map of registered lint groups to what lints they expand to.
73 lint_groups: FxHashMap<&'static str, LintGroup>,
76 /// The target of the `by_name` map, which accounts for renaming/deprecation.
79 /// A direct lint target
82 /// Temporary renaming, used for easing migration pain; see #16545
83 Renamed(String, LintId),
85 /// Lint with this name existed previously, but has been removed/deprecated.
86 /// The string argument is the reason for removal.
89 /// A lint name that should give no warnings and have no effect.
91 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
95 pub enum FindLintError {
102 /// Whether deprecation warnings should be suppressed for this alias.
107 lint_ids: Vec<LintId>,
109 depr: Option<LintAlias>,
113 pub enum CheckLintNameResult<'a> {
115 /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
116 NoLint(Option<Symbol>),
117 /// The lint refers to a tool that has not been registered.
119 /// The lint is either renamed or removed. This is the warning
120 /// message, and an optional new name (`None` if removed).
121 Warning(String, Option<String>),
122 /// The lint is from a tool. If the Option is None, then either
123 /// the lint does not exist in the tool or the code was not
124 /// compiled with the tool and therefore the lint was never
125 /// added to the `LintStore`. Otherwise the `LintId` will be
126 /// returned as if it where a rustc lint.
127 Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
131 pub fn new() -> LintStore {
134 pre_expansion_passes: vec![],
135 early_passes: vec![],
137 late_module_passes: vec![],
138 by_name: Default::default(),
139 lint_groups: Default::default(),
143 pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
147 pub fn get_lint_groups<'t>(
149 ) -> impl Iterator<Item = (&'static str, Vec<LintId>, bool)> + 't {
150 // This function is not used in a way which observes the order of lints.
151 #[allow(rustc::potential_query_instability)]
154 .filter(|(_, LintGroup { depr, .. })| {
155 // Don't display deprecated lint groups.
158 .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
159 (*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 /// This lint pass is softly deprecated. It misses expanded code and has caused a few
171 /// errors in the past. Currently, it is only used in Clippy. New implementations
172 /// should avoid using this interface, as it might be removed in the future.
174 /// * See [rust#69838](https://github.com/rust-lang/rust/pull/69838)
175 /// * See [rust-clippy#5518](https://github.com/rust-lang/rust-clippy/pull/5518)
176 pub fn register_pre_expansion_pass(
178 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
180 self.pre_expansion_passes.push(Box::new(pass));
183 pub fn register_late_pass(
185 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
187 self.late_passes.push(Box::new(pass));
190 pub fn register_late_mod_pass(
192 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
194 self.late_module_passes.push(Box::new(pass));
197 // Helper method for register_early/late_pass
198 pub fn register_lints(&mut self, lints: &[&'static Lint]) {
200 self.lints.push(lint);
202 let id = LintId::of(lint);
203 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
204 bug!("duplicate specification of lint {}", lint.name_lower())
207 if let Some(FutureIncompatibleInfo { reason, .. }) = lint.future_incompatible {
208 if let Some(edition) = reason.edition() {
210 .entry(edition.lint_name())
211 .or_insert(LintGroup {
213 from_plugin: lint.is_plugin,
219 // Lints belonging to the `future_incompatible` lint group are lints where a
220 // future version of rustc will cause existing code to stop compiling.
221 // Lints tied to an edition don't count because they are opt-in.
223 .entry("future_incompatible")
224 .or_insert(LintGroup {
226 from_plugin: lint.is_plugin,
236 pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
237 self.lint_groups.insert(
242 depr: Some(LintAlias { name: lint_name, silent: true }),
247 pub fn register_group(
251 deprecated_name: Option<&'static str>,
256 .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
258 if let Some(deprecated) = deprecated_name {
259 self.lint_groups.insert(
264 depr: Some(LintAlias { name, silent: false }),
270 bug!("duplicate specification of lint group {}", name);
274 /// This lint should give no warning and have no effect.
276 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
278 pub fn register_ignored(&mut self, name: &str) {
279 if self.by_name.insert(name.to_string(), Ignored).is_some() {
280 bug!("duplicate specification of lint {}", name);
284 /// This lint has been renamed; warn about using the new name and apply the lint.
286 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
287 let Some(&Id(target)) = self.by_name.get(new_name) else {
288 bug!("invalid lint renaming of {} to {}", old_name, new_name);
290 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
293 pub fn register_removed(&mut self, name: &str, reason: &str) {
294 self.by_name.insert(name.into(), Removed(reason.into()));
297 pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
298 match self.by_name.get(lint_name) {
299 Some(&Id(lint_id)) => Ok(vec![lint_id]),
300 Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
301 Some(&Removed(_)) => Err(FindLintError::Removed),
302 Some(&Ignored) => Ok(vec![]),
304 return match self.lint_groups.get(lint_name) {
305 Some(LintGroup { lint_ids, depr, .. }) => {
306 if let Some(LintAlias { name, .. }) = depr {
312 None => Err(FindLintError::Removed),
318 /// Checks the validity of lint names derived from the command line.
319 pub fn check_lint_name_cmdline(
324 registered_tools: &RegisteredTools,
326 let (tool_name, lint_name_only) = parse_lint_and_tool_name(lint_name);
327 if lint_name_only == crate::WARNINGS.name_lower() && level == Level::ForceWarn {
332 "`{}` lint group is not supported with ´--force-warn´",
333 crate::WARNINGS.name_lower()
338 let db = match self.check_lint_name(lint_name_only, tool_name, registered_tools) {
339 CheckLintNameResult::Ok(_) => None,
340 CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
341 CheckLintNameResult::NoLint(suggestion) => {
343 struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
345 if let Some(suggestion) = suggestion {
346 err.help(&format!("did you mean: `{}`", suggestion));
349 Some(err.forget_guarantee())
351 CheckLintNameResult::Tool(result) => match result {
352 Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
353 "lint name `{}` is deprecated \
354 and does not have an effect anymore. \
360 CheckLintNameResult::NoTool => Some(
365 "unknown lint tool: `{}`",
372 if let Some(mut db) = db {
374 "requested on the command line with `{} {}`",
376 Level::Allow => "-A",
378 Level::ForceWarn => "--force-warn",
380 Level::Forbid => "-F",
381 Level::Expect(_) => {
382 unreachable!("lints with the level of `expect` should not run this code");
392 /// True if this symbol represents a lint group name.
393 pub fn is_lint_group(&self, lint_name: Symbol) -> bool {
395 "is_lint_group(lint_name={:?}, lint_groups={:?})",
397 self.lint_groups.keys().collect::<Vec<_>>()
399 let lint_name_str = lint_name.as_str();
400 self.lint_groups.contains_key(lint_name_str) || {
401 let warnings_name_str = crate::WARNINGS.name_lower();
402 lint_name_str == warnings_name_str
406 /// Checks the name of a lint for its existence, and whether it was
407 /// renamed or removed. Generates a DiagnosticBuilder containing a
408 /// warning for renamed and removed lints. This is over both lint
409 /// names from attributes and those passed on the command line. Since
410 /// it emits non-fatal warnings and there are *two* lint passes that
411 /// inspect attributes, this is only run from the late pass to avoid
412 /// printing duplicate warnings.
413 pub fn check_lint_name(
416 tool_name: Option<Symbol>,
417 registered_tools: &RegisteredTools,
418 ) -> CheckLintNameResult<'_> {
419 if let Some(tool_name) = tool_name {
420 // FIXME: rustc and rustdoc are considered tools for lints, but not for attributes.
421 if tool_name != sym::rustc
422 && tool_name != sym::rustdoc
423 && !registered_tools.contains(&Ident::with_dummy_span(tool_name))
425 return CheckLintNameResult::NoTool;
429 let complete_name = if let Some(tool_name) = tool_name {
430 format!("{}::{}", tool_name, lint_name)
432 lint_name.to_string()
434 // If the lint was scoped with `tool::` check if the tool lint exists
435 if let Some(tool_name) = tool_name {
436 match self.by_name.get(&complete_name) {
437 None => match self.lint_groups.get(&*complete_name) {
438 // If the lint isn't registered, there are two possibilities:
440 // 1. The tool is currently running, so this lint really doesn't exist.
441 // FIXME: should this handle tools that never register a lint, like rustfmt?
442 tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
443 let tool_prefix = format!("{}::", tool_name);
444 return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
445 self.no_lint_suggestion(&complete_name)
447 // 2. The tool isn't currently running, so no lints will be registered.
448 // To avoid giving a false positive, ignore all unknown lints.
449 CheckLintNameResult::Tool(Err((None, String::new())))
452 Some(LintGroup { lint_ids, .. }) => {
453 return CheckLintNameResult::Tool(Ok(&lint_ids));
456 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
457 // If the lint was registered as removed or renamed by the lint tool, we don't need
458 // to treat tool_lints and rustc lints different and can use the code below.
462 match self.by_name.get(&complete_name) {
463 Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
464 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
465 Some(new_name.to_owned()),
467 Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
468 format!("lint `{}` has been removed: {}", complete_name, reason),
471 None => match self.lint_groups.get(&*complete_name) {
472 // If neither the lint, nor the lint group exists check if there is a `clippy::`
473 // variant of this lint
474 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
475 Some(LintGroup { lint_ids, depr, .. }) => {
476 // Check if the lint group name is deprecated
477 if let Some(LintAlias { name, silent }) = depr {
478 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
480 CheckLintNameResult::Ok(&lint_ids)
482 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
485 CheckLintNameResult::Ok(&lint_ids)
488 Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
489 Some(&Ignored) => CheckLintNameResult::Ok(&[]),
493 fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
494 let name_lower = lint_name.to_lowercase();
496 if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
497 // First check if the lint name is (partly) in upper case instead of lower case...
498 return CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)));
500 // ...if not, search for lints with a similar name
501 let groups = self.lint_groups.keys().copied().map(Symbol::intern);
502 let lints = self.lints.iter().map(|l| Symbol::intern(&l.name_lower()));
503 let names: Vec<Symbol> = groups.chain(lints).collect();
504 let suggestion = find_best_match_for_name(&names, Symbol::intern(&name_lower), None);
505 CheckLintNameResult::NoLint(suggestion)
508 fn check_tool_name_for_backwards_compat(
512 ) -> CheckLintNameResult<'_> {
513 let complete_name = format!("{}::{}", tool_name, lint_name);
514 match self.by_name.get(&complete_name) {
515 None => match self.lint_groups.get(&*complete_name) {
516 // Now we are sure, that this lint exists nowhere
517 None => self.no_lint_suggestion(lint_name),
518 Some(LintGroup { lint_ids, depr, .. }) => {
519 // Reaching this would be weird, but let's cover this case anyway
520 if let Some(LintAlias { name, silent }) = depr {
521 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
523 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
525 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
528 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
531 Some(&Id(ref id)) => {
532 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
535 tracing::debug!("got renamed lint {:?}", other);
536 CheckLintNameResult::NoLint(None)
542 /// Context for lint checking outside of type inference.
543 pub struct LateContext<'tcx> {
544 /// Type context we're checking in.
545 pub tcx: TyCtxt<'tcx>,
547 /// Current body, or `None` if outside a body.
548 pub enclosing_body: Option<hir::BodyId>,
550 /// Type-checking results for the current body. Access using the `typeck_results`
551 /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
552 // FIXME(eddyb) move all the code accessing internal fields like this,
553 // to this module, to avoid exposing it to lint logic.
554 pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
556 /// Parameter environment for the item we are in.
557 pub param_env: ty::ParamEnv<'tcx>,
559 /// Items accessible from the crate being checked.
560 pub access_levels: &'tcx AccessLevels,
562 /// The store of registered lints and the lint levels.
563 pub lint_store: &'tcx LintStore,
565 pub last_node_with_lint_attrs: hir::HirId,
567 /// Generic type parameters in scope for the item we are in.
568 pub generics: Option<&'tcx hir::Generics<'tcx>>,
570 /// We are only looking at one module
571 pub only_module: bool,
574 /// Context for lint checking of the AST, after expansion, before lowering to HIR.
575 pub struct EarlyContext<'a> {
576 pub builder: LintLevelsBuilder<'a>,
577 pub buffered: LintBuffer,
580 pub trait LintPassObject: Sized {}
582 impl LintPassObject for EarlyLintPassObject {}
584 impl LintPassObject for LateLintPassObject {}
586 pub trait LintContext: Sized {
587 type PassObject: LintPassObject;
589 fn sess(&self) -> &Session;
590 fn lints(&self) -> &LintStore;
592 fn lookup_with_diagnostics(
595 span: Option<impl Into<MultiSpan>>,
596 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
597 diagnostic: BuiltinLintDiagnostics,
599 self.lookup(lint, span, |lint| {
600 // We first generate a blank diagnostic.
601 let mut db = lint.build("");
603 // Now, set up surrounding context.
604 let sess = self.sess();
606 BuiltinLintDiagnostics::UnicodeTextFlow(span, content) => {
607 let spans: Vec<_> = content
609 .filter_map(|(i, c)| {
610 TEXT_FLOW_CONTROL_CHARS.contains(&c).then(|| {
611 let lo = span.lo() + BytePos(2 + i as u32);
612 (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32)))
616 let (an, s) = match spans.len() {
620 db.span_label(span, &format!(
621 "this comment contains {}invisible unicode text flow control codepoint{}",
625 for (c, span) in &spans {
626 db.span_label(*span, format!("{:?}", c));
629 "these kind of unicode codepoints change the way text flows on \
630 applications that support them, but can cause confusion because they \
631 change the order of characters on the screen",
633 if !spans.is_empty() {
634 db.multipart_suggestion_with_style(
635 "if their presence wasn't intentional, you can remove them",
636 spans.into_iter().map(|(_, span)| (span, "".to_string())).collect(),
637 Applicability::MachineApplicable,
638 SuggestionStyle::HideCodeAlways,
642 BuiltinLintDiagnostics::Normal => (),
643 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
644 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
646 // FIXME(Manishearth) ideally the emitting code
647 // can tell us whether or not this is global
649 if s.trim_start().starts_with("::") { "" } else { "::" };
651 (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
653 Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
655 db.span_suggestion(span, "use `crate`", sugg, app);
657 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
660 "names from parent modules are not accessible without an explicit import",
663 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
666 db.span_note(span_def, "the macro is defined here");
668 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
674 add_elided_lifetime_in_path_suggestion(
683 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
684 db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect);
686 BuiltinLintDiagnostics::UnusedImports(message, replaces, in_test_module) => {
687 if !replaces.is_empty() {
688 db.tool_only_multipart_suggestion(
691 Applicability::MachineApplicable,
695 if let Some(span) = in_test_module {
696 let def_span = self.sess().source_map().guess_head_span(span);
698 span.shrink_to_lo().to(def_span),
699 "consider adding a `#[cfg(test)]` to the containing module",
703 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
704 for (span, is_imported) in spans {
705 let introduced = if is_imported { "imported" } else { "defined" };
708 format!("the item `{}` is already {} here", ident, introduced),
712 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
713 stability::deprecation_suggestion(&mut db, "macro", suggestion, span)
715 BuiltinLintDiagnostics::UnusedDocComment(span) => {
716 db.span_label(span, "rustdoc does not generate documentation for macro invocations");
717 db.help("to document an item produced by a macro, \
718 the macro must produce the documentation as part of its expansion");
720 BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => {
721 db.span_suggestion(span, "remove `mut` from the parameter", ident, Applicability::MachineApplicable);
723 BuiltinLintDiagnostics::MissingAbi(span, default_abi) => {
724 db.span_label(span, "ABI should be specified here");
725 db.help(&format!("the default ABI is {}", default_abi.name()));
727 BuiltinLintDiagnostics::LegacyDeriveHelpers(span) => {
728 db.span_label(span, "the attribute is introduced here");
730 BuiltinLintDiagnostics::ProcMacroBackCompat(note) => {
733 BuiltinLintDiagnostics::OrPatternsBackCompat(span,suggestion) => {
734 db.span_suggestion(span, "use pat_param to preserve semantics", suggestion, Applicability::MachineApplicable);
736 BuiltinLintDiagnostics::ReservedPrefix(span) => {
737 db.span_label(span, "unknown prefix");
738 db.span_suggestion_verbose(
740 "insert whitespace here to avoid this being parsed as a prefix in Rust 2021",
742 Applicability::MachineApplicable,
745 BuiltinLintDiagnostics::UnusedBuiltinAttribute {
752 &format!("the built-in attribute `{attr_name}` will be ignored, since it's applied to the macro invocation `{macro_name}`")
755 BuiltinLintDiagnostics::TrailingMacro(is_trailing, name) => {
757 db.note("macro invocations at the end of a block are treated as expressions");
758 db.note(&format!("to ignore the value produced by the macro, add a semicolon after the invocation of `{name}`"));
761 BuiltinLintDiagnostics::BreakWithLabelAndLoop(span) => {
762 db.multipart_suggestion(
763 "wrap this expression in parentheses",
764 vec![(span.shrink_to_lo(), "(".to_string()),
765 (span.shrink_to_hi(), ")".to_string())],
766 Applicability::MachineApplicable
769 BuiltinLintDiagnostics::NamedAsmLabel(help) => {
771 db.note("see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information");
773 BuiltinLintDiagnostics::UnexpectedCfg((name, name_span), None) => {
774 let Some(names_valid) = &sess.parse_sess.check_config.names_valid else {
775 bug!("it shouldn't be possible to have a diagnostic on a name if name checking is not enabled");
777 let possibilities: Vec<Symbol> = names_valid.iter().map(|s| *s).collect();
779 // Suggest the most probable if we found one
780 if let Some(best_match) = find_best_match_for_name(&possibilities, name, None) {
781 db.span_suggestion(name_span, "did you mean", best_match, Applicability::MaybeIncorrect);
784 BuiltinLintDiagnostics::UnexpectedCfg((name, name_span), Some((value, value_span))) => {
785 let Some(values) = &sess.parse_sess.check_config.values_valid.get(&name) else {
786 bug!("it shouldn't be possible to have a diagnostic on a value whose name is not in values");
788 let possibilities: Vec<Symbol> = values.iter().map(|&s| s).collect();
790 // Show the full list if all possible values for a given name, but don't do it
791 // for names as the possibilities could be very long
792 if !possibilities.is_empty() {
794 let mut possibilities = possibilities.iter().map(Symbol::as_str).collect::<Vec<_>>();
795 possibilities.sort();
797 let possibilities = possibilities.join(", ");
798 db.note(&format!("expected values for `{name}` are: {possibilities}"));
801 // Suggest the most probable if we found one
802 if let Some(best_match) = find_best_match_for_name(&possibilities, value, None) {
803 db.span_suggestion(value_span, "did you mean", format!("\"{best_match}\""), Applicability::MaybeIncorrect);
806 db.note(&format!("no expected value for `{name}`"));
807 if name != sym::feature {
808 db.span_suggestion(name_span.shrink_to_hi().to(value_span), "remove the value", "", Applicability::MaybeIncorrect);
812 BuiltinLintDiagnostics::DeprecatedWhereclauseLocation(new_span, suggestion) => {
813 db.multipart_suggestion(
814 "move it to the end of the type declaration",
815 vec![(db.span.primary_span().unwrap(), "".to_string()), (new_span, suggestion)],
816 Applicability::MachineApplicable,
819 "see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information",
822 BuiltinLintDiagnostics::SingleUseLifetime {
824 use_span: Some((use_span, elide)),
827 debug!(?param_span, ?use_span, ?deletion_span);
828 db.span_label(param_span, "this lifetime...");
829 db.span_label(use_span, "...is used only here");
830 let msg = "elide the single-use lifetime";
831 let (use_span, replace_lt) = if elide {
832 let use_span = sess.source_map().span_extend_while(
835 ).unwrap_or(use_span);
836 (use_span, String::new())
838 (use_span, "'_".to_owned())
840 db.multipart_suggestion(
842 vec![(deletion_span, String::new()), (use_span, replace_lt)],
843 Applicability::MachineApplicable,
846 BuiltinLintDiagnostics::SingleUseLifetime {
851 debug!(?deletion_span);
854 "elide the unused lifetime",
856 Applicability::MachineApplicable,
860 // Rewrap `db`, and pass control to the user.
861 decorate(LintDiagnosticBuilder::new(db));
865 // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
866 // set the span in their `decorate` function (preferably using set_span).
867 fn lookup<S: Into<MultiSpan>>(
871 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
874 fn struct_span_lint<S: Into<MultiSpan>>(
878 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
880 self.lookup(lint, Some(span), decorate);
882 /// Emit a lint at the appropriate level, with no associated span.
886 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
888 self.lookup(lint, None as Option<Span>, decorate);
892 impl<'a> EarlyContext<'a> {
895 warn_about_weird_lints: bool,
896 lint_store: &'a LintStore,
897 registered_tools: &'a RegisteredTools,
898 buffered: LintBuffer,
899 ) -> EarlyContext<'a> {
901 builder: LintLevelsBuilder::new(
903 warn_about_weird_lints,
912 impl LintContext for LateContext<'_> {
913 type PassObject = LateLintPassObject;
915 /// Gets the overall compiler `Session` object.
916 fn sess(&self) -> &Session {
920 fn lints(&self) -> &LintStore {
924 fn lookup<S: Into<MultiSpan>>(
928 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
930 let hir_id = self.last_node_with_lint_attrs;
933 Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
934 None => self.tcx.struct_lint_node(lint, hir_id, decorate),
939 impl LintContext for EarlyContext<'_> {
940 type PassObject = EarlyLintPassObject;
942 /// Gets the overall compiler `Session` object.
943 fn sess(&self) -> &Session {
947 fn lints(&self) -> &LintStore {
948 self.builder.lint_store()
951 fn lookup<S: Into<MultiSpan>>(
955 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
957 self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
961 impl<'tcx> LateContext<'tcx> {
962 /// Gets the type-checking results for the current body,
963 /// or `None` if outside a body.
964 pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
965 self.cached_typeck_results.get().or_else(|| {
966 self.enclosing_body.map(|body| {
967 let typeck_results = self.tcx.typeck_body(body);
968 self.cached_typeck_results.set(Some(typeck_results));
974 /// Gets the type-checking results for the current body.
975 /// As this will ICE if called outside bodies, only call when working with
976 /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
978 pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
979 self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
982 /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
983 /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
984 /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
985 pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
987 hir::QPath::Resolved(_, ref path) => path.res,
988 hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
989 .maybe_typeck_results()
990 .filter(|typeck_results| typeck_results.hir_owner == id.owner)
992 if self.tcx.has_typeck_results(id.owner.to_def_id()) {
993 Some(self.tcx.typeck(id.owner))
998 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
999 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
1003 /// Check if a `DefId`'s path matches the given absolute type path usage.
1005 /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
1006 /// inherent `impl` blocks are matched with the name of the type.
1008 /// Instead of using this method, it is often preferable to instead use
1009 /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
1010 /// as paths get invalidated if the target definition moves.
1014 /// ```rust,ignore (no context or def id available)
1015 /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
1016 /// // The given `def_id` is that of an `Option` type
1020 /// Used by clippy, but should be replaced by diagnostic items eventually.
1021 pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
1022 let names = self.get_def_path(def_id);
1024 names.len() == path.len() && iter::zip(names, path).all(|(a, &b)| a == b)
1027 /// Gets the absolute path of `def_id` as a vector of `Symbol`.
1031 /// ```rust,ignore (no context or def id available)
1032 /// let def_path = cx.get_def_path(def_id);
1033 /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
1034 /// // The given `def_id` is that of an `Option` type
1037 pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
1038 pub struct AbsolutePathPrinter<'tcx> {
1039 pub tcx: TyCtxt<'tcx>,
1042 impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
1045 type Path = Vec<Symbol>;
1048 type DynExistential = ();
1051 fn tcx(&self) -> TyCtxt<'tcx> {
1055 fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
1059 fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
1063 fn print_dyn_existential(
1065 _predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
1066 ) -> Result<Self::DynExistential, Self::Error> {
1070 fn print_const(self, _ct: ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
1074 fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
1075 Ok(vec![self.tcx.crate_name(cnum)])
1081 trait_ref: Option<ty::TraitRef<'tcx>>,
1082 ) -> Result<Self::Path, Self::Error> {
1083 if trait_ref.is_none() {
1084 if let ty::Adt(def, substs) = self_ty.kind() {
1085 return self.print_def_path(def.did(), substs);
1089 // This shouldn't ever be needed, but just in case:
1090 with_no_trimmed_paths!({
1091 Ok(vec![match trait_ref {
1092 Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
1093 None => Symbol::intern(&format!("<{}>", self_ty)),
1098 fn path_append_impl(
1100 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1101 _disambiguated_data: &DisambiguatedDefPathData,
1103 trait_ref: Option<ty::TraitRef<'tcx>>,
1104 ) -> Result<Self::Path, Self::Error> {
1105 let mut path = print_prefix(self)?;
1107 // This shouldn't ever be needed, but just in case:
1108 path.push(match trait_ref {
1109 Some(trait_ref) => {
1110 with_no_trimmed_paths!(Symbol::intern(&format!(
1112 trait_ref.print_only_trait_path(),
1117 with_no_trimmed_paths!(Symbol::intern(&format!("<impl {}>", self_ty)))
1126 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1127 disambiguated_data: &DisambiguatedDefPathData,
1128 ) -> Result<Self::Path, Self::Error> {
1129 let mut path = print_prefix(self)?;
1131 // Skip `::{{extern}}` blocks and `::{{constructor}}` on tuple/unit structs.
1132 if let DefPathData::ForeignMod | DefPathData::Ctor = disambiguated_data.data {
1136 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
1140 fn path_generic_args(
1142 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1143 _args: &[GenericArg<'tcx>],
1144 ) -> Result<Self::Path, Self::Error> {
1149 AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
1153 impl<'tcx> abi::HasDataLayout for LateContext<'tcx> {
1155 fn data_layout(&self) -> &abi::TargetDataLayout {
1156 &self.tcx.data_layout
1160 impl<'tcx> ty::layout::HasTyCtxt<'tcx> for LateContext<'tcx> {
1162 fn tcx(&self) -> TyCtxt<'tcx> {
1167 impl<'tcx> ty::layout::HasParamEnv<'tcx> for LateContext<'tcx> {
1169 fn param_env(&self) -> ty::ParamEnv<'tcx> {
1174 impl<'tcx> LayoutOfHelpers<'tcx> for LateContext<'tcx> {
1175 type LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
1178 fn handle_layout_err(&self, err: LayoutError<'tcx>, _: Span, _: Ty<'tcx>) -> LayoutError<'tcx> {
1183 pub fn parse_lint_and_tool_name(lint_name: &str) -> (Option<Symbol>, &str) {
1184 match lint_name.split_once("::") {
1185 Some((tool_name, lint_name)) => {
1186 let tool_name = Symbol::intern(tool_name);
1188 (Some(tool_name), lint_name)
1190 None => (None, lint_name),