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::{struct_span_err, Applicability, SuggestionStyle};
26 use rustc_hir::def::Res;
27 use rustc_hir::def_id::{CrateNum, DefId};
28 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
29 use rustc_middle::lint::LintDiagnosticBuilder;
30 use rustc_middle::middle::privacy::AccessLevels;
31 use rustc_middle::middle::stability;
32 use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout};
33 use rustc_middle::ty::print::with_no_trimmed_paths;
34 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, RegisteredTools, Ty, TyCtxt};
35 use rustc_serialize::json::Json;
36 use rustc_session::lint::{BuiltinLintDiagnostics, ExternDepSpec};
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, MultiSpan, 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>,
112 pub enum CheckLintNameResult<'a> {
114 /// Lint doesn't exist. Potentially contains a suggestion for a correct lint name.
115 NoLint(Option<Symbol>),
116 /// The lint refers to a tool that has not been registered.
118 /// The lint is either renamed or removed. This is the warning
119 /// message, and an optional new name (`None` if removed).
120 Warning(String, Option<String>),
121 /// The lint is from a tool. If the Option is None, then either
122 /// the lint does not exist in the tool or the code was not
123 /// compiled with the tool and therefore the lint was never
124 /// added to the `LintStore`. Otherwise the `LintId` will be
125 /// returned as if it where a rustc lint.
126 Tool(Result<&'a [LintId], (Option<&'a [LintId]>, String)>),
130 pub fn new() -> LintStore {
133 pre_expansion_passes: vec![],
134 early_passes: vec![],
136 late_module_passes: vec![],
137 by_name: Default::default(),
138 lint_groups: Default::default(),
142 pub fn get_lints<'t>(&'t self) -> &'t [&'static Lint] {
146 pub fn get_lint_groups<'t>(
148 ) -> impl Iterator<Item = (&'static str, Vec<LintId>, bool)> + 't {
149 // This function is not used in a way which observes the order of lints.
150 #[cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]
153 .filter(|(_, LintGroup { depr, .. })| {
154 // Don't display deprecated lint groups.
157 .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
158 (*k, lint_ids.clone(), *from_plugin)
162 pub fn register_early_pass(
164 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
166 self.early_passes.push(Box::new(pass));
170 pub fn register_pre_expansion_pass(
172 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
174 self.pre_expansion_passes.push(Box::new(pass));
177 pub fn register_late_pass(
179 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
181 self.late_passes.push(Box::new(pass));
184 pub fn register_late_mod_pass(
186 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
188 self.late_module_passes.push(Box::new(pass));
191 // Helper method for register_early/late_pass
192 pub fn register_lints(&mut self, lints: &[&'static Lint]) {
194 self.lints.push(lint);
196 let id = LintId::of(lint);
197 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
198 bug!("duplicate specification of lint {}", lint.name_lower())
201 if let Some(FutureIncompatibleInfo { reason, .. }) = lint.future_incompatible {
202 if let Some(edition) = reason.edition() {
204 .entry(edition.lint_name())
205 .or_insert(LintGroup {
207 from_plugin: lint.is_plugin,
213 // Lints belonging to the `future_incompatible` lint group are lints where a
214 // future version of rustc will cause existing code to stop compiling.
215 // Lints tied to an edition don't count because they are opt-in.
217 .entry("future_incompatible")
218 .or_insert(LintGroup {
220 from_plugin: lint.is_plugin,
230 pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
231 self.lint_groups.insert(
236 depr: Some(LintAlias { name: lint_name, silent: true }),
241 pub fn register_group(
245 deprecated_name: Option<&'static str>,
250 .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
252 if let Some(deprecated) = deprecated_name {
253 self.lint_groups.insert(
258 depr: Some(LintAlias { name, silent: false }),
264 bug!("duplicate specification of lint group {}", name);
268 /// This lint should give no warning and have no effect.
270 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
272 pub fn register_ignored(&mut self, name: &str) {
273 if self.by_name.insert(name.to_string(), Ignored).is_some() {
274 bug!("duplicate specification of lint {}", name);
278 /// This lint has been renamed; warn about using the new name and apply the lint.
280 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
281 let Some(&Id(target)) = self.by_name.get(new_name) else {
282 bug!("invalid lint renaming of {} to {}", old_name, new_name);
284 self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
287 pub fn register_removed(&mut self, name: &str, reason: &str) {
288 self.by_name.insert(name.into(), Removed(reason.into()));
291 pub fn find_lints(&self, mut lint_name: &str) -> Result<Vec<LintId>, FindLintError> {
292 match self.by_name.get(lint_name) {
293 Some(&Id(lint_id)) => Ok(vec![lint_id]),
294 Some(&Renamed(_, lint_id)) => Ok(vec![lint_id]),
295 Some(&Removed(_)) => Err(FindLintError::Removed),
296 Some(&Ignored) => Ok(vec![]),
298 return match self.lint_groups.get(lint_name) {
299 Some(LintGroup { lint_ids, depr, .. }) => {
300 if let Some(LintAlias { name, .. }) = depr {
306 None => Err(FindLintError::Removed),
312 /// Checks the validity of lint names derived from the command line.
313 pub fn check_lint_name_cmdline(
318 registered_tools: &RegisteredTools,
320 let (tool_name, lint_name_only) = parse_lint_and_tool_name(lint_name);
321 if lint_name_only == crate::WARNINGS.name_lower() && level == Level::ForceWarn {
322 return struct_span_err!(
326 "`{}` lint group is not supported with ´--force-warn´",
327 crate::WARNINGS.name_lower()
331 let db = match self.check_lint_name(lint_name_only, tool_name, registered_tools) {
332 CheckLintNameResult::Ok(_) => None,
333 CheckLintNameResult::Warning(ref msg, _) => Some(sess.struct_warn(msg)),
334 CheckLintNameResult::NoLint(suggestion) => {
336 struct_span_err!(sess, DUMMY_SP, E0602, "unknown lint: `{}`", lint_name);
338 if let Some(suggestion) = suggestion {
339 err.help(&format!("did you mean: `{}`", suggestion));
344 CheckLintNameResult::Tool(result) => match result {
345 Err((Some(_), new_name)) => Some(sess.struct_warn(&format!(
346 "lint name `{}` is deprecated \
347 and does not have an effect anymore. \
353 CheckLintNameResult::NoTool => Some(struct_span_err!(
357 "unknown lint tool: `{}`",
362 if let Some(mut db) = db {
364 "requested on the command line with `{} {}`",
366 Level::Allow => "-A",
368 Level::ForceWarn => "--force-warn",
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 registered_tools: &RegisteredTools,
405 ) -> CheckLintNameResult<'_> {
406 if let Some(tool_name) = tool_name {
407 // FIXME: rustc and rustdoc are considered tools for lints, but not for attributes.
408 if tool_name != sym::rustc
409 && tool_name != sym::rustdoc
410 && !registered_tools.contains(&Ident::with_dummy_span(tool_name))
412 return CheckLintNameResult::NoTool;
416 let complete_name = if let Some(tool_name) = tool_name {
417 format!("{}::{}", tool_name, lint_name)
419 lint_name.to_string()
421 // If the lint was scoped with `tool::` check if the tool lint exists
422 if let Some(tool_name) = tool_name {
423 match self.by_name.get(&complete_name) {
424 None => match self.lint_groups.get(&*complete_name) {
425 // If the lint isn't registered, there are two possibilities:
427 // 1. The tool is currently running, so this lint really doesn't exist.
428 // FIXME: should this handle tools that never register a lint, like rustfmt?
429 tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
430 let tool_prefix = format!("{}::", tool_name);
431 return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
432 self.no_lint_suggestion(&complete_name)
434 // 2. The tool isn't currently running, so no lints will be registered.
435 // To avoid giving a false positive, ignore all unknown lints.
436 CheckLintNameResult::Tool(Err((None, String::new())))
439 Some(LintGroup { lint_ids, .. }) => {
440 return CheckLintNameResult::Tool(Ok(&lint_ids));
443 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
444 // If the lint was registered as removed or renamed by the lint tool, we don't need
445 // to treat tool_lints and rustc lints different and can use the code below.
449 match self.by_name.get(&complete_name) {
450 Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
451 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
452 Some(new_name.to_owned()),
454 Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
455 format!("lint `{}` has been removed: {}", complete_name, reason),
458 None => match self.lint_groups.get(&*complete_name) {
459 // If neither the lint, nor the lint group exists check if there is a `clippy::`
460 // variant of this lint
461 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
462 Some(LintGroup { lint_ids, depr, .. }) => {
463 // Check if the lint group name is deprecated
464 if let Some(LintAlias { name, silent }) = depr {
465 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
467 CheckLintNameResult::Ok(&lint_ids)
469 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
472 CheckLintNameResult::Ok(&lint_ids)
475 Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
476 Some(&Ignored) => CheckLintNameResult::Ok(&[]),
480 fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
481 let name_lower = lint_name.to_lowercase();
483 if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
484 // First check if the lint name is (partly) in upper case instead of lower case...
485 return CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)));
487 // ...if not, search for lints with a similar name
488 let groups = self.lint_groups.keys().copied().map(Symbol::intern);
489 let lints = self.lints.iter().map(|l| Symbol::intern(&l.name_lower()));
490 let names: Vec<Symbol> = groups.chain(lints).collect();
491 let suggestion = find_best_match_for_name(&names, Symbol::intern(&name_lower), None);
492 CheckLintNameResult::NoLint(suggestion)
495 fn check_tool_name_for_backwards_compat(
499 ) -> CheckLintNameResult<'_> {
500 let complete_name = format!("{}::{}", tool_name, lint_name);
501 match self.by_name.get(&complete_name) {
502 None => match self.lint_groups.get(&*complete_name) {
503 // Now we are sure, that this lint exists nowhere
504 None => self.no_lint_suggestion(lint_name),
505 Some(LintGroup { lint_ids, depr, .. }) => {
506 // Reaching this would be weird, but let's cover this case anyway
507 if let Some(LintAlias { name, silent }) = depr {
508 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
510 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
512 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
515 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
518 Some(&Id(ref id)) => {
519 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
522 tracing::debug!("got renamed lint {:?}", other);
523 CheckLintNameResult::NoLint(None)
529 /// Context for lint checking outside of type inference.
530 pub struct LateContext<'tcx> {
531 /// Type context we're checking in.
532 pub tcx: TyCtxt<'tcx>,
534 /// Current body, or `None` if outside a body.
535 pub enclosing_body: Option<hir::BodyId>,
537 /// Type-checking results for the current body. Access using the `typeck_results`
538 /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
539 // FIXME(eddyb) move all the code accessing internal fields like this,
540 // to this module, to avoid exposing it to lint logic.
541 pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
543 /// Parameter environment for the item we are in.
544 pub param_env: ty::ParamEnv<'tcx>,
546 /// Items accessible from the crate being checked.
547 pub access_levels: &'tcx AccessLevels,
549 /// The store of registered lints and the lint levels.
550 pub lint_store: &'tcx LintStore,
552 pub last_node_with_lint_attrs: hir::HirId,
554 /// Generic type parameters in scope for the item we are in.
555 pub generics: Option<&'tcx hir::Generics<'tcx>>,
557 /// We are only looking at one module
558 pub only_module: bool,
561 /// Context for lint checking of the AST, after expansion, before lowering to HIR.
562 pub struct EarlyContext<'a> {
563 pub builder: LintLevelsBuilder<'a>,
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::UnicodeTextFlow(span, content) => {
594 let spans: Vec<_> = content
596 .filter_map(|(i, c)| {
597 TEXT_FLOW_CONTROL_CHARS.contains(&c).then(|| {
598 let lo = span.lo() + BytePos(2 + i as u32);
599 (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32)))
603 let (an, s) = match spans.len() {
607 db.span_label(span, &format!(
608 "this comment contains {}invisible unicode text flow control codepoint{}",
612 for (c, span) in &spans {
613 db.span_label(*span, format!("{:?}", c));
616 "these kind of unicode codepoints change the way text flows on \
617 applications that support them, but can cause confusion because they \
618 change the order of characters on the screen",
620 if !spans.is_empty() {
621 db.multipart_suggestion_with_style(
622 "if their presence wasn't intentional, you can remove them",
623 spans.into_iter().map(|(_, span)| (span, "".to_string())).collect(),
624 Applicability::MachineApplicable,
625 SuggestionStyle::HideCodeAlways,
629 BuiltinLintDiagnostics::Normal => (),
630 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
631 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
633 // FIXME(Manishearth) ideally the emitting code
634 // can tell us whether or not this is global
636 if s.trim_start().starts_with("::") { "" } else { "::" };
638 (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
640 Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
642 db.span_suggestion(span, "use `crate`", sugg, app);
644 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
647 "names from parent modules are not accessible without an explicit import",
650 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
653 db.span_note(span_def, "the macro is defined here");
655 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
656 db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect);
658 BuiltinLintDiagnostics::UnusedImports(message, replaces, in_test_module) => {
659 if !replaces.is_empty() {
660 db.tool_only_multipart_suggestion(
663 Applicability::MachineApplicable,
667 if let Some(span) = in_test_module {
668 let def_span = self.sess().source_map().guess_head_span(span);
670 span.shrink_to_lo().to(def_span),
671 "consider adding a `#[cfg(test)]` to the containing module",
675 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
676 for (span, is_imported) in spans {
677 let introduced = if is_imported { "imported" } else { "defined" };
680 format!("the item `{}` is already {} here", ident, introduced),
684 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
685 stability::deprecation_suggestion(&mut db, "macro", suggestion, span)
687 BuiltinLintDiagnostics::UnusedDocComment(span) => {
688 db.span_label(span, "rustdoc does not generate documentation for macro invocations");
689 db.help("to document an item produced by a macro, \
690 the macro must produce the documentation as part of its expansion");
692 BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => {
693 db.span_suggestion(span, "remove `mut` from the parameter", ident.to_string(), Applicability::MachineApplicable);
695 BuiltinLintDiagnostics::MissingAbi(span, default_abi) => {
696 db.span_label(span, "ABI should be specified here");
697 db.help(&format!("the default ABI is {}", default_abi.name()));
699 BuiltinLintDiagnostics::LegacyDeriveHelpers(span) => {
700 db.span_label(span, "the attribute is introduced here");
702 BuiltinLintDiagnostics::ExternDepSpec(krate, loc) => {
703 let json = match loc {
704 ExternDepSpec::Json(json) => {
705 db.help(&format!("remove unnecessary dependency `{}`", krate));
708 ExternDepSpec::Raw(raw) => {
709 db.help(&format!("remove unnecessary dependency `{}` at `{}`", krate, raw));
710 db.span_suggestion_with_style(
712 "raw extern location",
714 Applicability::Unspecified,
715 SuggestionStyle::CompletelyHidden,
720 db.tool_only_suggestion_with_metadata(
721 "json extern location",
722 Applicability::Unspecified,
726 BuiltinLintDiagnostics::ProcMacroBackCompat(note) => {
729 BuiltinLintDiagnostics::OrPatternsBackCompat(span,suggestion) => {
730 db.span_suggestion(span, "use pat_param to preserve semantics", suggestion, Applicability::MachineApplicable);
732 BuiltinLintDiagnostics::ReservedPrefix(span) => {
733 db.span_label(span, "unknown prefix");
734 db.span_suggestion_verbose(
736 "insert whitespace here to avoid this being parsed as a prefix in Rust 2021",
738 Applicability::MachineApplicable,
741 BuiltinLintDiagnostics::UnusedBuiltinAttribute {
748 &format!("the built-in attribute `{attr_name}` will be ignored, since it's applied to the macro invocation `{macro_name}`")
751 BuiltinLintDiagnostics::TrailingMacro(is_trailing, name) => {
753 db.note("macro invocations at the end of a block are treated as expressions");
754 db.note(&format!("to ignore the value produced by the macro, add a semicolon after the invocation of `{name}`"));
757 BuiltinLintDiagnostics::BreakWithLabelAndLoop(span) => {
758 db.multipart_suggestion(
759 "wrap this expression in parentheses",
760 vec![(span.shrink_to_lo(), "(".to_string()),
761 (span.shrink_to_hi(), ")".to_string())],
762 Applicability::MachineApplicable
765 BuiltinLintDiagnostics::NamedAsmLabel(help) => {
767 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");
770 // Rewrap `db`, and pass control to the user.
771 decorate(LintDiagnosticBuilder::new(db));
775 // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
776 // set the span in their `decorate` function (preferably using set_span).
777 fn lookup<S: Into<MultiSpan>>(
781 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
784 fn struct_span_lint<S: Into<MultiSpan>>(
788 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
790 self.lookup(lint, Some(span), decorate);
792 /// Emit a lint at the appropriate level, with no associated span.
793 fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
794 self.lookup(lint, None as Option<Span>, decorate);
798 impl<'a> EarlyContext<'a> {
801 warn_about_weird_lints: bool,
802 lint_store: &'a LintStore,
803 registered_tools: &'a RegisteredTools,
804 buffered: LintBuffer,
805 ) -> EarlyContext<'a> {
807 builder: LintLevelsBuilder::new(
809 warn_about_weird_lints,
818 impl LintContext for LateContext<'_> {
819 type PassObject = LateLintPassObject;
821 /// Gets the overall compiler `Session` object.
822 fn sess(&self) -> &Session {
826 fn lints(&self) -> &LintStore {
830 fn lookup<S: Into<MultiSpan>>(
834 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
836 let hir_id = self.last_node_with_lint_attrs;
839 Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
840 None => self.tcx.struct_lint_node(lint, hir_id, decorate),
845 impl LintContext for EarlyContext<'_> {
846 type PassObject = EarlyLintPassObject;
848 /// Gets the overall compiler `Session` object.
849 fn sess(&self) -> &Session {
853 fn lints(&self) -> &LintStore {
854 self.builder.lint_store()
857 fn lookup<S: Into<MultiSpan>>(
861 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
863 self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
867 impl<'tcx> LateContext<'tcx> {
868 /// Gets the type-checking results for the current body,
869 /// or `None` if outside a body.
870 pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
871 self.cached_typeck_results.get().or_else(|| {
872 self.enclosing_body.map(|body| {
873 let typeck_results = self.tcx.typeck_body(body);
874 self.cached_typeck_results.set(Some(typeck_results));
880 /// Gets the type-checking results for the current body.
881 /// As this will ICE if called outside bodies, only call when working with
882 /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
884 pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
885 self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
888 /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
889 /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
890 /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
891 pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
893 hir::QPath::Resolved(_, ref path) => path.res,
894 hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
895 .maybe_typeck_results()
896 .filter(|typeck_results| typeck_results.hir_owner == id.owner)
898 if self.tcx.has_typeck_results(id.owner.to_def_id()) {
899 Some(self.tcx.typeck(id.owner))
904 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
905 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
909 /// Check if a `DefId`'s path matches the given absolute type path usage.
911 /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
912 /// inherent `impl` blocks are matched with the name of the type.
914 /// Instead of using this method, it is often preferable to instead use
915 /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
916 /// as paths get invalidated if the target definition moves.
920 /// ```rust,ignore (no context or def id available)
921 /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
922 /// // The given `def_id` is that of an `Option` type
926 /// Used by clippy, but should be replaced by diagnostic items eventually.
927 pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
928 let names = self.get_def_path(def_id);
930 names.len() == path.len() && iter::zip(names, path).all(|(a, &b)| a == b)
933 /// Gets the absolute path of `def_id` as a vector of `Symbol`.
937 /// ```rust,ignore (no context or def id available)
938 /// let def_path = cx.get_def_path(def_id);
939 /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
940 /// // The given `def_id` is that of an `Option` type
943 pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
944 pub struct AbsolutePathPrinter<'tcx> {
945 pub tcx: TyCtxt<'tcx>,
948 impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
951 type Path = Vec<Symbol>;
954 type DynExistential = ();
957 fn tcx(&self) -> TyCtxt<'tcx> {
961 fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
965 fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
969 fn print_dyn_existential(
971 _predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
972 ) -> Result<Self::DynExistential, Self::Error> {
976 fn print_const(self, _ct: ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
980 fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
981 Ok(vec![self.tcx.crate_name(cnum)])
987 trait_ref: Option<ty::TraitRef<'tcx>>,
988 ) -> Result<Self::Path, Self::Error> {
989 if trait_ref.is_none() {
990 if let ty::Adt(def, substs) = self_ty.kind() {
991 return self.print_def_path(def.did, substs);
995 // This shouldn't ever be needed, but just in case:
996 with_no_trimmed_paths!({
997 Ok(vec![match trait_ref {
998 Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
999 None => Symbol::intern(&format!("<{}>", self_ty)),
1004 fn path_append_impl(
1006 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1007 _disambiguated_data: &DisambiguatedDefPathData,
1009 trait_ref: Option<ty::TraitRef<'tcx>>,
1010 ) -> Result<Self::Path, Self::Error> {
1011 let mut path = print_prefix(self)?;
1013 // This shouldn't ever be needed, but just in case:
1014 path.push(match trait_ref {
1015 Some(trait_ref) => {
1016 with_no_trimmed_paths!(Symbol::intern(&format!(
1018 trait_ref.print_only_trait_path(),
1023 with_no_trimmed_paths!(Symbol::intern(&format!("<impl {}>", self_ty)))
1032 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1033 disambiguated_data: &DisambiguatedDefPathData,
1034 ) -> Result<Self::Path, Self::Error> {
1035 let mut path = print_prefix(self)?;
1037 // Skip `::{{extern}}` blocks and `::{{constructor}}` on tuple/unit structs.
1038 if let DefPathData::ForeignMod | DefPathData::Ctor = disambiguated_data.data {
1042 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
1046 fn path_generic_args(
1048 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1049 _args: &[GenericArg<'tcx>],
1050 ) -> Result<Self::Path, Self::Error> {
1055 AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
1059 impl<'tcx> abi::HasDataLayout for LateContext<'tcx> {
1061 fn data_layout(&self) -> &abi::TargetDataLayout {
1062 &self.tcx.data_layout
1066 impl<'tcx> ty::layout::HasTyCtxt<'tcx> for LateContext<'tcx> {
1068 fn tcx(&self) -> TyCtxt<'tcx> {
1073 impl<'tcx> ty::layout::HasParamEnv<'tcx> for LateContext<'tcx> {
1075 fn param_env(&self) -> ty::ParamEnv<'tcx> {
1080 impl<'tcx> LayoutOfHelpers<'tcx> for LateContext<'tcx> {
1081 type LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
1084 fn handle_layout_err(&self, err: LayoutError<'tcx>, _: Span, _: Ty<'tcx>) -> LayoutError<'tcx> {
1089 pub fn parse_lint_and_tool_name(lint_name: &str) -> (Option<Symbol>, &str) {
1090 match lint_name.split_once("::") {
1091 Some((tool_name, lint_name)) => {
1092 let tool_name = Symbol::intern(tool_name);
1094 (Some(tool_name), lint_name)
1096 None => (None, lint_name),