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};
26 Applicability, DecorateLint, LintDiagnosticBuilder, MultiSpan, SuggestionStyle,
29 use rustc_hir::def::Res;
30 use rustc_hir::def_id::{CrateNum, DefId};
31 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
32 use rustc_middle::middle::privacy::AccessLevels;
33 use rustc_middle::middle::stability;
34 use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout};
35 use rustc_middle::ty::print::with_no_trimmed_paths;
36 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, RegisteredTools, Ty, TyCtxt};
37 use rustc_session::lint::{BuiltinLintDiagnostics, LintExpectationId};
38 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
39 use rustc_session::Session;
40 use rustc_span::lev_distance::find_best_match_for_name;
41 use rustc_span::symbol::{sym, Ident, Symbol};
42 use rustc_span::{BytePos, Span, DUMMY_SP};
43 use rustc_target::abi;
50 /// Information about the registered lints.
52 /// This is basically the subset of `Context` that we can
53 /// build early in the compile pipeline.
54 pub struct LintStore {
56 lints: Vec<&'static Lint>,
58 /// Constructor functions for each variety of lint pass.
60 /// These should only be called once, but since we want to avoid locks or
61 /// interior mutability, we don't enforce this (and lints should, in theory,
62 /// be compatible with being constructed more than once, though not
63 /// necessarily in a sane manner. This is safe though.)
64 pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
65 pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
66 pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
67 /// This is unique in that we construct them per-module, so not once.
68 pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
70 /// Lints indexed by name.
71 by_name: FxHashMap<String, TargetLint>,
73 /// Map of registered lint groups to what lints they expand to.
74 lint_groups: FxHashMap<&'static str, LintGroup>,
77 /// The target of the `by_name` map, which accounts for renaming/deprecation.
80 /// A direct lint target
83 /// Temporary renaming, used for easing migration pain; see #16545
84 Renamed(String, LintId),
86 /// Lint with this name existed previously, but has been removed/deprecated.
87 /// The string argument is the reason for removal.
90 /// A lint name that should give no warnings and have no effect.
92 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
96 pub enum FindLintError {
103 /// Whether deprecation warnings should be suppressed for this alias.
108 lint_ids: Vec<LintId>,
110 depr: Option<LintAlias>,
114 pub enum CheckLintNameResult<'a> {
116 /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
117 NoLint(Option<Symbol>),
118 /// The lint refers to a tool that has not been registered.
120 /// The lint is either renamed or removed. This is the warning
121 /// message, and an optional new name (`None` if removed).
122 Warning(String, Option<String>),
123 /// The lint is from a tool. If the Option is None, then either
124 /// the lint does not exist in the tool or the code was not
125 /// compiled with the tool and therefore the lint was never
126 /// added to the `LintStore`. Otherwise the `LintId` will be
127 /// returned as if it where a rustc lint.
128 Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
132 pub fn new() -> LintStore {
135 pre_expansion_passes: vec![],
136 early_passes: vec![],
138 late_module_passes: vec![],
139 by_name: Default::default(),
140 lint_groups: Default::default(),
144 pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
148 pub fn get_lint_groups<'t>(
150 ) -> impl Iterator<Item = (&'static str, Vec<LintId>, bool)> + 't {
151 // This function is not used in a way which observes the order of lints.
152 #[allow(rustc::potential_query_instability)]
155 .filter(|(_, LintGroup { depr, .. })| {
156 // Don't display deprecated lint groups.
159 .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
160 (*k, lint_ids.clone(), *from_plugin)
164 pub fn register_early_pass(
166 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
168 self.early_passes.push(Box::new(pass));
171 /// This lint pass is softly deprecated. It misses expanded code and has caused a few
172 /// errors in the past. Currently, it is only used in Clippy. New implementations
173 /// should avoid using this interface, as it might be removed in the future.
175 /// * See [rust#69838](https://github.com/rust-lang/rust/pull/69838)
176 /// * See [rust-clippy#5518](https://github.com/rust-lang/rust-clippy/pull/5518)
177 pub fn register_pre_expansion_pass(
179 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
181 self.pre_expansion_passes.push(Box::new(pass));
184 pub fn register_late_pass(
186 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
188 self.late_passes.push(Box::new(pass));
191 pub fn register_late_mod_pass(
193 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
195 self.late_module_passes.push(Box::new(pass));
198 // Helper method for register_early/late_pass
199 pub fn register_lints(&mut self, lints: &[&'static Lint]) {
201 self.lints.push(lint);
203 let id = LintId::of(lint);
204 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
205 bug!("duplicate specification of lint {}", lint.name_lower())
208 if let Some(FutureIncompatibleInfo { reason, .. }) = lint.future_incompatible {
209 if let Some(edition) = reason.edition() {
211 .entry(edition.lint_name())
212 .or_insert(LintGroup {
214 from_plugin: lint.is_plugin,
220 // Lints belonging to the `future_incompatible` lint group are lints where a
221 // future version of rustc will cause existing code to stop compiling.
222 // Lints tied to an edition don't count because they are opt-in.
224 .entry("future_incompatible")
225 .or_insert(LintGroup {
227 from_plugin: lint.is_plugin,
237 pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
238 self.lint_groups.insert(
243 depr: Some(LintAlias { name: lint_name, silent: true }),
248 pub fn register_group(
252 deprecated_name: Option<&'static str>,
257 .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
259 if let Some(deprecated) = deprecated_name {
260 self.lint_groups.insert(
265 depr: Some(LintAlias { name, silent: false }),
271 bug!("duplicate specification of lint group {}", name);
275 /// This lint should give no warning and have no effect.
277 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
279 pub fn register_ignored(&mut self, name: &str) {
280 if self.by_name.insert(name.to_string(), Ignored).is_some() {
281 bug!("duplicate specification of lint {}", name);
285 /// This lint has been renamed; warn about using the new name and apply the lint.
287 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
288 let Some(&Id(target)) = self.by_name.get(new_name) else {
289 bug!("invalid lint renaming of {} to {}", old_name, new_name);
291 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
294 pub fn register_removed(&mut self, name: &str, reason: &str) {
295 self.by_name.insert(name.into(), Removed(reason.into()));
298 pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
299 match self.by_name.get(lint_name) {
300 Some(&Id(lint_id)) => Ok(vec![lint_id]),
301 Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
302 Some(&Removed(_)) => Err(FindLintError::Removed),
303 Some(&Ignored) => Ok(vec![]),
305 return match self.lint_groups.get(lint_name) {
306 Some(LintGroup { lint_ids, depr, .. }) => {
307 if let Some(LintAlias { name, .. }) = depr {
313 None => Err(FindLintError::Removed),
319 /// Checks the validity of lint names derived from the command line.
320 pub fn check_lint_name_cmdline(
325 registered_tools: &RegisteredTools,
327 let (tool_name, lint_name_only) = parse_lint_and_tool_name(lint_name);
328 if lint_name_only == crate::WARNINGS.name_lower() && matches!(level, Level::ForceWarn(_)) {
333 "`{}` lint group is not supported with ´--force-warn´",
334 crate::WARNINGS.name_lower()
339 let db = match self.check_lint_name(lint_name_only, tool_name, registered_tools) {
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));
350 Some(err.forget_guarantee())
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. \
361 CheckLintNameResult::NoTool => Some(
366 "unknown lint tool: `{}`",
373 if let Some(mut db) = db {
375 "requested on the command line with `{} {}`",
377 Level::Allow => "-A",
379 Level::ForceWarn(_) => "--force-warn",
381 Level::Forbid => "-F",
382 Level::Expect(_) => {
383 unreachable!("lints with the level of `expect` should not run this code");
393 /// True if this symbol represents a lint group name.
394 pub fn is_lint_group(&self, lint_name: Symbol) -> bool {
396 "is_lint_group(lint_name={:?}, lint_groups={:?})",
398 self.lint_groups.keys().collect::<Vec<_>>()
400 let lint_name_str = lint_name.as_str();
401 self.lint_groups.contains_key(lint_name_str) || {
402 let warnings_name_str = crate::WARNINGS.name_lower();
403 lint_name_str == warnings_name_str
407 /// Checks the name of a lint for its existence, and whether it was
408 /// renamed or removed. Generates a DiagnosticBuilder containing a
409 /// warning for renamed and removed lints. This is over both lint
410 /// names from attributes and those passed on the command line. Since
411 /// it emits non-fatal warnings and there are *two* lint passes that
412 /// inspect attributes, this is only run from the late pass to avoid
413 /// printing duplicate warnings.
414 pub fn check_lint_name(
417 tool_name: Option<Symbol>,
418 registered_tools: &RegisteredTools,
419 ) -> CheckLintNameResult<'_> {
420 if let Some(tool_name) = tool_name {
421 // FIXME: rustc and rustdoc are considered tools for lints, but not for attributes.
422 if tool_name != sym::rustc
423 && tool_name != sym::rustdoc
424 && !registered_tools.contains(&Ident::with_dummy_span(tool_name))
426 return CheckLintNameResult::NoTool;
430 let complete_name = if let Some(tool_name) = tool_name {
431 format!("{}::{}", tool_name, lint_name)
433 lint_name.to_string()
435 // If the lint was scoped with `tool::` check if the tool lint exists
436 if let Some(tool_name) = tool_name {
437 match self.by_name.get(&complete_name) {
438 None => match self.lint_groups.get(&*complete_name) {
439 // If the lint isn't registered, there are two possibilities:
441 // 1. The tool is currently running, so this lint really doesn't exist.
442 // FIXME: should this handle tools that never register a lint, like rustfmt?
443 tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
444 let tool_prefix = format!("{}::", tool_name);
445 return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
446 self.no_lint_suggestion(&complete_name)
448 // 2. The tool isn't currently running, so no lints will be registered.
449 // To avoid giving a false positive, ignore all unknown lints.
450 CheckLintNameResult::Tool(Err((None, String::new())))
453 Some(LintGroup { lint_ids, .. }) => {
454 return CheckLintNameResult::Tool(Ok(&lint_ids));
457 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
458 // If the lint was registered as removed or renamed by the lint tool, we don't need
459 // to treat tool_lints and rustc lints different and can use the code below.
463 match self.by_name.get(&complete_name) {
464 Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
465 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
466 Some(new_name.to_owned()),
468 Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
469 format!("lint `{}` has been removed: {}", complete_name, reason),
472 None => match self.lint_groups.get(&*complete_name) {
473 // If neither the lint, nor the lint group exists check if there is a `clippy::`
474 // variant of this lint
475 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
476 Some(LintGroup { lint_ids, depr, .. }) => {
477 // Check if the lint group name is deprecated
478 if let Some(LintAlias { name, silent }) = depr {
479 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
481 CheckLintNameResult::Ok(&lint_ids)
483 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
486 CheckLintNameResult::Ok(&lint_ids)
489 Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
490 Some(&Ignored) => CheckLintNameResult::Ok(&[]),
494 fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
495 let name_lower = lint_name.to_lowercase();
497 if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
498 // First check if the lint name is (partly) in upper case instead of lower case...
499 return CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)));
501 // ...if not, search for lints with a similar name
502 let groups = self.lint_groups.keys().copied().map(Symbol::intern);
503 let lints = self.lints.iter().map(|l| Symbol::intern(&l.name_lower()));
504 let names: Vec<Symbol> = groups.chain(lints).collect();
505 let suggestion = find_best_match_for_name(&names, Symbol::intern(&name_lower), None);
506 CheckLintNameResult::NoLint(suggestion)
509 fn check_tool_name_for_backwards_compat(
513 ) -> CheckLintNameResult<'_> {
514 let complete_name = format!("{}::{}", tool_name, lint_name);
515 match self.by_name.get(&complete_name) {
516 None => match self.lint_groups.get(&*complete_name) {
517 // Now we are sure, that this lint exists nowhere
518 None => self.no_lint_suggestion(lint_name),
519 Some(LintGroup { lint_ids, depr, .. }) => {
520 // Reaching this would be weird, but let's cover this case anyway
521 if let Some(LintAlias { name, silent }) = depr {
522 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
524 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
526 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
529 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
532 Some(&Id(ref id)) => {
533 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
536 tracing::debug!("got renamed lint {:?}", other);
537 CheckLintNameResult::NoLint(None)
543 /// Context for lint checking outside of type inference.
544 pub struct LateContext<'tcx> {
545 /// Type context we're checking in.
546 pub tcx: TyCtxt<'tcx>,
548 /// Current body, or `None` if outside a body.
549 pub enclosing_body: Option<hir::BodyId>,
551 /// Type-checking results for the current body. Access using the `typeck_results`
552 /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
553 // FIXME(eddyb) move all the code accessing internal fields like this,
554 // to this module, to avoid exposing it to lint logic.
555 pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
557 /// Parameter environment for the item we are in.
558 pub param_env: ty::ParamEnv<'tcx>,
560 /// Items accessible from the crate being checked.
561 pub access_levels: &'tcx AccessLevels,
563 /// The store of registered lints and the lint levels.
564 pub lint_store: &'tcx LintStore,
566 pub last_node_with_lint_attrs: hir::HirId,
568 /// Generic type parameters in scope for the item we are in.
569 pub generics: Option<&'tcx hir::Generics<'tcx>>,
571 /// We are only looking at one module
572 pub only_module: bool,
575 /// Context for lint checking of the AST, after expansion, before lowering to HIR.
576 pub struct EarlyContext<'a> {
577 pub builder: LintLevelsBuilder<'a>,
578 pub buffered: LintBuffer,
581 pub trait LintPassObject: Sized {}
583 impl LintPassObject for EarlyLintPassObject {}
585 impl LintPassObject for LateLintPassObject {}
587 pub trait LintContext: Sized {
588 type PassObject: LintPassObject;
590 fn sess(&self) -> &Session;
591 fn lints(&self) -> &LintStore;
593 fn lookup_with_diagnostics(
596 span: Option<impl Into<MultiSpan>>,
597 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
598 diagnostic: BuiltinLintDiagnostics,
600 self.lookup(lint, span, |lint| {
601 // We first generate a blank diagnostic.
602 let mut db = lint.build("");
604 // Now, set up surrounding context.
605 let sess = self.sess();
607 BuiltinLintDiagnostics::UnicodeTextFlow(span, content) => {
608 let spans: Vec<_> = content
610 .filter_map(|(i, c)| {
611 TEXT_FLOW_CONTROL_CHARS.contains(&c).then(|| {
612 let lo = span.lo() + BytePos(2 + i as u32);
613 (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32)))
617 let (an, s) = match spans.len() {
621 db.span_label(span, &format!(
622 "this comment contains {}invisible unicode text flow control codepoint{}",
626 for (c, span) in &spans {
627 db.span_label(*span, format!("{:?}", c));
630 "these kind of unicode codepoints change the way text flows on \
631 applications that support them, but can cause confusion because they \
632 change the order of characters on the screen",
634 if !spans.is_empty() {
635 db.multipart_suggestion_with_style(
636 "if their presence wasn't intentional, you can remove them",
637 spans.into_iter().map(|(_, span)| (span, "".to_string())).collect(),
638 Applicability::MachineApplicable,
639 SuggestionStyle::HideCodeAlways,
643 BuiltinLintDiagnostics::Normal => (),
644 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
645 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
647 // FIXME(Manishearth) ideally the emitting code
648 // can tell us whether or not this is global
650 if s.trim_start().starts_with("::") { "" } else { "::" };
652 (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
654 Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
656 db.span_suggestion(span, "use `crate`", sugg, app);
658 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
661 "names from parent modules are not accessible without an explicit import",
664 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
667 db.span_note(span_def, "the macro is defined here");
669 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
675 add_elided_lifetime_in_path_suggestion(
684 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
685 db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect);
687 BuiltinLintDiagnostics::UnusedImports(message, replaces, in_test_module) => {
688 if !replaces.is_empty() {
689 db.tool_only_multipart_suggestion(
692 Applicability::MachineApplicable,
696 if let Some(span) = in_test_module {
698 self.sess().source_map().guess_head_span(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,
859 BuiltinLintDiagnostics::NamedArgumentUsedPositionally(positional_arg, named_arg, name) => {
860 db.span_label(named_arg, "this named argument is only referred to by position in formatting string");
861 if let Some(positional_arg) = positional_arg {
862 let msg = format!("this formatting argument uses named argument `{}` by position", name);
863 db.span_label(positional_arg, msg);
864 db.span_suggestion_verbose(
866 "use the named argument by name to avoid ambiguity",
867 format!("{{{}}}", name),
868 Applicability::MaybeIncorrect,
873 // Rewrap `db`, and pass control to the user.
874 decorate(LintDiagnosticBuilder::new(db));
878 // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
879 // set the span in their `decorate` function (preferably using set_span).
880 fn lookup<S: Into<MultiSpan>>(
884 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
887 /// Emit a lint at `span` from a lint struct (some type that implements `DecorateLint`,
888 /// typically generated by `#[derive(LintDiagnostic)]`).
889 fn emit_spanned_lint<S: Into<MultiSpan>>(
893 decorator: impl for<'a> DecorateLint<'a, ()>,
895 self.lookup(lint, Some(span), |diag| decorator.decorate_lint(diag));
898 fn struct_span_lint<S: Into<MultiSpan>>(
902 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
904 self.lookup(lint, Some(span), decorate);
907 /// Emit a lint from a lint struct (some type that implements `DecorateLint`, typically
908 /// generated by `#[derive(LintDiagnostic)]`).
909 fn emit_lint(&self, lint: &'static Lint, decorator: impl for<'a> DecorateLint<'a, ()>) {
910 self.lookup(lint, None as Option<Span>, |diag| decorator.decorate_lint(diag));
913 /// Emit a lint at the appropriate level, with no associated span.
917 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
919 self.lookup(lint, None as Option<Span>, decorate);
922 /// This returns the lint level for the given lint at the current location.
923 fn get_lint_level(&self, lint: &'static Lint) -> Level;
925 /// This function can be used to manually fulfill an expectation. This can
926 /// be used for lints which contain several spans, and should be suppressed,
927 /// if either location was marked with an expectation.
929 /// Note that this function should only be called for [`LintExpectationId`]s
930 /// retrieved from the current lint pass. Buffered or manually created ids can
932 fn fulfill_expectation(&self, expectation: LintExpectationId) {
933 // We need to make sure that submitted expectation ids are correctly fulfilled suppressed
934 // and stored between compilation sessions. To not manually do these steps, we simply create
935 // a dummy diagnostic and emit is as usual, which will be suppressed and stored like a normal
936 // expected lint diagnostic.
939 "this is a dummy diagnostic, to submit and store an expectation",
946 impl<'a> EarlyContext<'a> {
949 warn_about_weird_lints: bool,
950 lint_store: &'a LintStore,
951 registered_tools: &'a RegisteredTools,
952 buffered: LintBuffer,
953 ) -> EarlyContext<'a> {
955 builder: LintLevelsBuilder::new(
957 warn_about_weird_lints,
966 impl LintContext for LateContext<'_> {
967 type PassObject = LateLintPassObject;
969 /// Gets the overall compiler `Session` object.
970 fn sess(&self) -> &Session {
974 fn lints(&self) -> &LintStore {
978 fn lookup<S: Into<MultiSpan>>(
982 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
984 let hir_id = self.last_node_with_lint_attrs;
987 Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
988 None => self.tcx.struct_lint_node(lint, hir_id, decorate),
992 fn get_lint_level(&self, lint: &'static Lint) -> Level {
993 self.tcx.lint_level_at_node(lint, self.last_node_with_lint_attrs).0
997 impl LintContext for EarlyContext<'_> {
998 type PassObject = EarlyLintPassObject;
1000 /// Gets the overall compiler `Session` object.
1001 fn sess(&self) -> &Session {
1002 &self.builder.sess()
1005 fn lints(&self) -> &LintStore {
1006 self.builder.lint_store()
1009 fn lookup<S: Into<MultiSpan>>(
1011 lint: &'static Lint,
1013 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>),
1015 self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
1018 fn get_lint_level(&self, lint: &'static Lint) -> Level {
1019 self.builder.lint_level(lint).0
1023 impl<'tcx> LateContext<'tcx> {
1024 /// Gets the type-checking results for the current body,
1025 /// or `None` if outside a body.
1026 pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
1027 self.cached_typeck_results.get().or_else(|| {
1028 self.enclosing_body.map(|body| {
1029 let typeck_results = self.tcx.typeck_body(body);
1030 self.cached_typeck_results.set(Some(typeck_results));
1036 /// Gets the type-checking results for the current body.
1037 /// As this will ICE if called outside bodies, only call when working with
1038 /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
1040 pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
1041 self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
1044 /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
1045 /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
1046 /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
1047 pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
1049 hir::QPath::Resolved(_, ref path) => path.res,
1050 hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
1051 .maybe_typeck_results()
1052 .filter(|typeck_results| typeck_results.hir_owner == id.owner)
1054 if self.tcx.has_typeck_results(id.owner.to_def_id()) {
1055 Some(self.tcx.typeck(id.owner))
1060 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
1061 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
1065 /// Check if a `DefId`'s path matches the given absolute type path usage.
1067 /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
1068 /// inherent `impl` blocks are matched with the name of the type.
1070 /// Instead of using this method, it is often preferable to instead use
1071 /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
1072 /// as paths get invalidated if the target definition moves.
1076 /// ```rust,ignore (no context or def id available)
1077 /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
1078 /// // The given `def_id` is that of an `Option` type
1082 /// Used by clippy, but should be replaced by diagnostic items eventually.
1083 pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
1084 let names = self.get_def_path(def_id);
1086 names.len() == path.len() && iter::zip(names, path).all(|(a, &b)| a == b)
1089 /// Gets the absolute path of `def_id` as a vector of `Symbol`.
1093 /// ```rust,ignore (no context or def id available)
1094 /// let def_path = cx.get_def_path(def_id);
1095 /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
1096 /// // The given `def_id` is that of an `Option` type
1099 pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
1100 pub struct AbsolutePathPrinter<'tcx> {
1101 pub tcx: TyCtxt<'tcx>,
1104 impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
1107 type Path = Vec<Symbol>;
1110 type DynExistential = ();
1113 fn tcx(&self) -> TyCtxt<'tcx> {
1117 fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
1121 fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
1125 fn print_dyn_existential(
1127 _predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
1128 ) -> Result<Self::DynExistential, Self::Error> {
1132 fn print_const(self, _ct: ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
1136 fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
1137 Ok(vec![self.tcx.crate_name(cnum)])
1143 trait_ref: Option<ty::TraitRef<'tcx>>,
1144 ) -> Result<Self::Path, Self::Error> {
1145 if trait_ref.is_none() {
1146 if let ty::Adt(def, substs) = self_ty.kind() {
1147 return self.print_def_path(def.did(), substs);
1151 // This shouldn't ever be needed, but just in case:
1152 with_no_trimmed_paths!({
1153 Ok(vec![match trait_ref {
1154 Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
1155 None => Symbol::intern(&format!("<{}>", self_ty)),
1160 fn path_append_impl(
1162 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1163 _disambiguated_data: &DisambiguatedDefPathData,
1165 trait_ref: Option<ty::TraitRef<'tcx>>,
1166 ) -> Result<Self::Path, Self::Error> {
1167 let mut path = print_prefix(self)?;
1169 // This shouldn't ever be needed, but just in case:
1170 path.push(match trait_ref {
1171 Some(trait_ref) => {
1172 with_no_trimmed_paths!(Symbol::intern(&format!(
1174 trait_ref.print_only_trait_path(),
1179 with_no_trimmed_paths!(Symbol::intern(&format!("<impl {}>", self_ty)))
1188 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1189 disambiguated_data: &DisambiguatedDefPathData,
1190 ) -> Result<Self::Path, Self::Error> {
1191 let mut path = print_prefix(self)?;
1193 // Skip `::{{extern}}` blocks and `::{{constructor}}` on tuple/unit structs.
1194 if let DefPathData::ForeignMod | DefPathData::Ctor = disambiguated_data.data {
1198 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
1202 fn path_generic_args(
1204 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1205 _args: &[GenericArg<'tcx>],
1206 ) -> Result<Self::Path, Self::Error> {
1211 AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
1215 impl<'tcx> abi::HasDataLayout for LateContext<'tcx> {
1217 fn data_layout(&self) -> &abi::TargetDataLayout {
1218 &self.tcx.data_layout
1222 impl<'tcx> ty::layout::HasTyCtxt<'tcx> for LateContext<'tcx> {
1224 fn tcx(&self) -> TyCtxt<'tcx> {
1229 impl<'tcx> ty::layout::HasParamEnv<'tcx> for LateContext<'tcx> {
1231 fn param_env(&self) -> ty::ParamEnv<'tcx> {
1236 impl<'tcx> LayoutOfHelpers<'tcx> for LateContext<'tcx> {
1237 type LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
1240 fn handle_layout_err(&self, err: LayoutError<'tcx>, _: Span, _: Ty<'tcx>) -> LayoutError<'tcx> {
1245 pub fn parse_lint_and_tool_name(lint_name: &str) -> (Option<Symbol>, &str) {
1246 match lint_name.split_once("::") {
1247 Some((tool_name, lint_name)) => {
1248 let tool_name = Symbol::intern(tool_name);
1250 (Some(tool_name), lint_name)
1252 None => (None, lint_name),