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::{is_known_lint_tool, LintLevelsBuilder};
20 use crate::passes::{EarlyLintPassObject, LateLintPassObject};
21 use ast::util::unicode::TEXT_FLOW_CONTROL_CHARS;
23 use rustc_data_structures::fx::FxHashMap;
24 use rustc_data_structures::sync;
26 add_elided_lifetime_in_path_suggestion, struct_span_err, Applicability, 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::lint::LintDiagnosticBuilder;
33 use rustc_middle::middle::privacy::AccessLevels;
34 use rustc_middle::middle::stability;
35 use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout};
36 use rustc_middle::ty::print::with_no_trimmed_paths;
37 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
38 use rustc_serialize::json::Json;
39 use rustc_session::lint::{BuiltinLintDiagnostics, ExternDepSpec};
40 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
41 use rustc_session::Session;
42 use rustc_span::lev_distance::find_best_match_for_name;
43 use rustc_span::{symbol::Symbol, BytePos, MultiSpan, Span, DUMMY_SP};
44 use rustc_target::abi;
51 /// Information about the registered lints.
53 /// This is basically the subset of `Context` that we can
54 /// build early in the compile pipeline.
55 pub struct LintStore {
57 lints: Vec<&'static Lint>,
59 /// Constructor functions for each variety of lint pass.
61 /// These should only be called once, but since we want to avoid locks or
62 /// interior mutability, we don't enforce this (and lints should, in theory,
63 /// be compatible with being constructed more than once, though not
64 /// necessarily in a sane manner. This is safe though.)
65 pub pre_expansion_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
66 pub early_passes: Vec<Box<dyn Fn() -> EarlyLintPassObject + sync::Send + sync::Sync>>,
67 pub late_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
68 /// This is unique in that we construct them per-module, so not once.
69 pub late_module_passes: Vec<Box<dyn Fn() -> LateLintPassObject + sync::Send + sync::Sync>>,
71 /// Lints indexed by name.
72 by_name: FxHashMap<String, TargetLint>,
74 /// Map of registered lint groups to what lints they expand to.
75 lint_groups: FxHashMap<&'static str, LintGroup>,
78 /// The target of the `by_name` map, which accounts for renaming/deprecation.
81 /// A direct lint target
84 /// Temporary renaming, used for easing migration pain; see #16545
85 Renamed(String, LintId),
87 /// Lint with this name existed previously, but has been removed/deprecated.
88 /// The string argument is the reason for removal.
91 /// A lint name that should give no warnings and have no effect.
93 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
97 pub enum FindLintError {
104 /// Whether deprecation warnings should be suppressed for this alias.
109 lint_ids: Vec<LintId>,
111 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>(&'t self) -> Vec<(&'static str, Vec<LintId>, bool)> {
151 .filter(|(_, LintGroup { depr, .. })| {
152 // Don't display deprecated lint groups.
155 .map(|(k, LintGroup { lint_ids, from_plugin, .. })| {
156 (*k, lint_ids.clone(), *from_plugin)
161 pub fn register_early_pass(
163 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
165 self.early_passes.push(Box::new(pass));
169 pub fn register_pre_expansion_pass(
171 pass: impl Fn() -> EarlyLintPassObject + 'static + sync::Send + sync::Sync,
173 self.pre_expansion_passes.push(Box::new(pass));
176 pub fn register_late_pass(
178 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
180 self.late_passes.push(Box::new(pass));
183 pub fn register_late_mod_pass(
185 pass: impl Fn() -> LateLintPassObject + 'static + sync::Send + sync::Sync,
187 self.late_module_passes.push(Box::new(pass));
190 // Helper method for register_early/late_pass
191 pub fn register_lints(&mut self, lints: &[&'static Lint]) {
193 self.lints.push(lint);
195 let id = LintId::of(lint);
196 if self.by_name.insert(lint.name_lower(), Id(id)).is_some() {
197 bug!("duplicate specification of lint {}", lint.name_lower())
200 if let Some(FutureIncompatibleInfo { reason, .. }) = lint.future_incompatible {
201 if let Some(edition) = reason.edition() {
203 .entry(edition.lint_name())
204 .or_insert(LintGroup {
206 from_plugin: lint.is_plugin,
212 // Lints belonging to the `future_incompatible` lint group are lints where a
213 // future version of rustc will cause existing code to stop compiling.
214 // Lints tied to an edition don't count because they are opt-in.
216 .entry("future_incompatible")
217 .or_insert(LintGroup {
219 from_plugin: lint.is_plugin,
229 pub fn register_group_alias(&mut self, lint_name: &'static str, alias: &'static str) {
230 self.lint_groups.insert(
235 depr: Some(LintAlias { name: lint_name, silent: true }),
240 pub fn register_group(
244 deprecated_name: Option<&'static str>,
249 .insert(name, LintGroup { lint_ids: to, from_plugin, depr: None })
251 if let Some(deprecated) = deprecated_name {
252 self.lint_groups.insert(
257 depr: Some(LintAlias { name, silent: false }),
263 bug!("duplicate specification of lint group {}", name);
267 /// This lint should give no warning and have no effect.
269 /// This is used by rustc to avoid warning about old rustdoc lints before rustdoc registers them as tool lints.
271 pub fn register_ignored(&mut self, name: &str) {
272 if self.by_name.insert(name.to_string(), Ignored).is_some() {
273 bug!("duplicate specification of lint {}", name);
277 /// This lint has been renamed; warn about using the new name and apply the lint.
279 pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
280 let target = match self.by_name.get(new_name) {
281 Some(&Id(lint_id)) => lint_id,
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 crate_attrs: &[ast::Attribute],
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(sess, lint_name_only, tool_name, crate_attrs) {
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(
404 tool_name: Option<Symbol>,
405 crate_attrs: &[ast::Attribute],
406 ) -> CheckLintNameResult<'_> {
407 if let Some(tool_name) = tool_name {
408 if !is_known_lint_tool(tool_name, sess, crate_attrs) {
409 return CheckLintNameResult::NoTool;
413 let complete_name = if let Some(tool_name) = tool_name {
414 format!("{}::{}", tool_name, lint_name)
416 lint_name.to_string()
418 // If the lint was scoped with `tool::` check if the tool lint exists
419 if let Some(tool_name) = tool_name {
420 match self.by_name.get(&complete_name) {
421 None => match self.lint_groups.get(&*complete_name) {
422 // If the lint isn't registered, there are two possibilities:
424 // 1. The tool is currently running, so this lint really doesn't exist.
425 // FIXME: should this handle tools that never register a lint, like rustfmt?
426 tracing::debug!("lints={:?}", self.by_name.keys().collect::<Vec<_>>());
427 let tool_prefix = format!("{}::", tool_name);
428 return if self.by_name.keys().any(|lint| lint.starts_with(&tool_prefix)) {
429 self.no_lint_suggestion(&complete_name)
431 // 2. The tool isn't currently running, so no lints will be registered.
432 // To avoid giving a false positive, ignore all unknown lints.
433 CheckLintNameResult::Tool(Err((None, String::new())))
436 Some(LintGroup { lint_ids, .. }) => {
437 return CheckLintNameResult::Tool(Ok(&lint_ids));
440 Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
441 // If the lint was registered as removed or renamed by the lint tool, we don't need
442 // to treat tool_lints and rustc lints different and can use the code below.
446 match self.by_name.get(&complete_name) {
447 Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
448 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
449 Some(new_name.to_owned()),
451 Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
452 format!("lint `{}` has been removed: {}", complete_name, reason),
455 None => match self.lint_groups.get(&*complete_name) {
456 // If neither the lint, nor the lint group exists check if there is a `clippy::`
457 // variant of this lint
458 None => self.check_tool_name_for_backwards_compat(&complete_name, "clippy"),
459 Some(LintGroup { lint_ids, depr, .. }) => {
460 // Check if the lint group name is deprecated
461 if let Some(LintAlias { name, silent }) = depr {
462 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
464 CheckLintNameResult::Ok(&lint_ids)
466 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
469 CheckLintNameResult::Ok(&lint_ids)
472 Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
473 Some(&Ignored) => CheckLintNameResult::Ok(&[]),
477 fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
478 let name_lower = lint_name.to_lowercase();
480 if lint_name.chars().any(char::is_uppercase) && self.find_lints(&name_lower).is_ok() {
481 // First check if the lint name is (partly) in upper case instead of lower case...
482 return CheckLintNameResult::NoLint(Some(Symbol::intern(&name_lower)));
484 // ...if not, search for lints with a similar name
485 let groups = self.lint_groups.keys().copied().map(Symbol::intern);
486 let lints = self.lints.iter().map(|l| Symbol::intern(&l.name_lower()));
487 let names: Vec<Symbol> = groups.chain(lints).collect();
488 let suggestion = find_best_match_for_name(&names, Symbol::intern(&name_lower), None);
489 CheckLintNameResult::NoLint(suggestion)
492 fn check_tool_name_for_backwards_compat(
496 ) -> CheckLintNameResult<'_> {
497 let complete_name = format!("{}::{}", tool_name, lint_name);
498 match self.by_name.get(&complete_name) {
499 None => match self.lint_groups.get(&*complete_name) {
500 // Now we are sure, that this lint exists nowhere
501 None => self.no_lint_suggestion(lint_name),
502 Some(LintGroup { lint_ids, depr, .. }) => {
503 // Reaching this would be weird, but let's cover this case anyway
504 if let Some(LintAlias { name, silent }) = depr {
505 let LintGroup { lint_ids, .. } = self.lint_groups.get(name).unwrap();
507 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
509 CheckLintNameResult::Tool(Err((Some(&lint_ids), (*name).to_string())))
512 CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
515 Some(&Id(ref id)) => {
516 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
519 tracing::debug!("got renamed lint {:?}", other);
520 CheckLintNameResult::NoLint(None)
526 /// Context for lint checking after type checking.
527 pub struct LateContext<'tcx> {
528 /// Type context we're checking in.
529 pub tcx: TyCtxt<'tcx>,
531 /// Current body, or `None` if outside a body.
532 pub enclosing_body: Option<hir::BodyId>,
534 /// Type-checking results for the current body. Access using the `typeck_results`
535 /// and `maybe_typeck_results` methods, which handle querying the typeck results on demand.
536 // FIXME(eddyb) move all the code accessing internal fields like this,
537 // to this module, to avoid exposing it to lint logic.
538 pub(super) cached_typeck_results: Cell<Option<&'tcx ty::TypeckResults<'tcx>>>,
540 /// Parameter environment for the item we are in.
541 pub param_env: ty::ParamEnv<'tcx>,
543 /// Items accessible from the crate being checked.
544 pub access_levels: &'tcx AccessLevels,
546 /// The store of registered lints and the lint levels.
547 pub lint_store: &'tcx LintStore,
549 pub last_node_with_lint_attrs: hir::HirId,
551 /// Generic type parameters in scope for the item we are in.
552 pub generics: Option<&'tcx hir::Generics<'tcx>>,
554 /// We are only looking at one module
555 pub only_module: bool,
558 /// Context for lint checking of the AST, after expansion, before lowering to
560 pub struct EarlyContext<'a> {
561 /// Type context we're checking in.
562 pub sess: &'a Session,
564 /// The crate being checked.
565 pub krate: &'a ast::Crate,
567 pub builder: LintLevelsBuilder<'a>,
569 /// The store of registered lints and the lint levels.
570 pub lint_store: &'a LintStore,
572 pub buffered: LintBuffer,
575 pub trait LintPassObject: Sized {}
577 impl LintPassObject for EarlyLintPassObject {}
579 impl LintPassObject for LateLintPassObject {}
581 pub trait LintContext: Sized {
582 type PassObject: LintPassObject;
584 fn sess(&self) -> &Session;
585 fn lints(&self) -> &LintStore;
587 fn lookup_with_diagnostics(
590 span: Option<impl Into<MultiSpan>>,
591 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
592 diagnostic: BuiltinLintDiagnostics,
594 self.lookup(lint, span, |lint| {
595 // We first generate a blank diagnostic.
596 let mut db = lint.build("");
598 // Now, set up surrounding context.
599 let sess = self.sess();
601 BuiltinLintDiagnostics::UnicodeTextFlow(span, content) => {
602 let spans: Vec<_> = content
604 .filter_map(|(i, c)| {
605 TEXT_FLOW_CONTROL_CHARS.contains(&c).then(|| {
606 let lo = span.lo() + BytePos(2 + i as u32);
607 (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32)))
611 let (an, s) = match spans.len() {
615 db.span_label(span, &format!(
616 "this comment contains {}invisible unicode text flow control codepoint{}",
620 for (c, span) in &spans {
621 db.span_label(*span, format!("{:?}", c));
624 "these kind of unicode codepoints change the way text flows on \
625 applications that support them, but can cause confusion because they \
626 change the order of characters on the screen",
628 if !spans.is_empty() {
629 db.multipart_suggestion_with_style(
630 "if their presence wasn't intentional, you can remove them",
631 spans.into_iter().map(|(_, span)| (span, "".to_string())).collect(),
632 Applicability::MachineApplicable,
633 SuggestionStyle::HideCodeAlways,
637 BuiltinLintDiagnostics::Normal => (),
638 BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
639 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
640 Ok(s) if is_global => {
641 (format!("dyn ({})", s), Applicability::MachineApplicable)
643 Ok(s) => (format!("dyn {}", s), Applicability::MachineApplicable),
644 Err(_) => ("dyn <type>".to_string(), Applicability::HasPlaceholders),
646 db.span_suggestion(span, "use `dyn`", sugg, app);
648 BuiltinLintDiagnostics::AbsPathWithModule(span) => {
649 let (sugg, app) = match sess.source_map().span_to_snippet(span) {
651 // FIXME(Manishearth) ideally the emitting code
652 // can tell us whether or not this is global
654 if s.trim_start().starts_with("::") { "" } else { "::" };
656 (format!("crate{}{}", opt_colon, s), Applicability::MachineApplicable)
658 Err(_) => ("crate::<path>".to_string(), Applicability::HasPlaceholders),
660 db.span_suggestion(span, "use `crate`", sugg, app);
662 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(span) => {
665 "names from parent modules are not accessible without an explicit import",
668 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(
671 db.span_note(span_def, "the macro is defined here");
673 BuiltinLintDiagnostics::ElidedLifetimesInPaths(
680 add_elided_lifetime_in_path_suggestion(
690 BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
691 db.span_suggestion(span, ¬e, sugg, Applicability::MaybeIncorrect);
693 BuiltinLintDiagnostics::UnusedImports(message, replaces) => {
694 if !replaces.is_empty() {
695 db.tool_only_multipart_suggestion(
698 Applicability::MachineApplicable,
702 BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
703 for (span, is_imported) in spans {
704 let introduced = if is_imported { "imported" } else { "defined" };
707 format!("the item `{}` is already {} here", ident, introduced),
711 BuiltinLintDiagnostics::DeprecatedMacro(suggestion, span) => {
712 stability::deprecation_suggestion(&mut db, "macro", suggestion, span)
714 BuiltinLintDiagnostics::UnusedDocComment(span) => {
715 db.span_label(span, "rustdoc does not generate documentation for macro invocations");
716 db.help("to document an item produced by a macro, \
717 the macro must produce the documentation as part of its expansion");
719 BuiltinLintDiagnostics::PatternsInFnsWithoutBody(span, ident) => {
720 db.span_suggestion(span, "remove `mut` from the parameter", ident.to_string(), Applicability::MachineApplicable);
722 BuiltinLintDiagnostics::MissingAbi(span, default_abi) => {
723 db.span_label(span, "ABI should be specified here");
724 db.help(&format!("the default ABI is {}", default_abi.name()));
726 BuiltinLintDiagnostics::LegacyDeriveHelpers(span) => {
727 db.span_label(span, "the attribute is introduced here");
729 BuiltinLintDiagnostics::ExternDepSpec(krate, loc) => {
730 let json = match loc {
731 ExternDepSpec::Json(json) => {
732 db.help(&format!("remove unnecessary dependency `{}`", krate));
735 ExternDepSpec::Raw(raw) => {
736 db.help(&format!("remove unnecessary dependency `{}` at `{}`", krate, raw));
737 db.span_suggestion_with_style(
739 "raw extern location",
741 Applicability::Unspecified,
742 SuggestionStyle::CompletelyHidden,
747 db.tool_only_suggestion_with_metadata(
748 "json extern location",
749 Applicability::Unspecified,
753 BuiltinLintDiagnostics::ProcMacroBackCompat(note) => {
756 BuiltinLintDiagnostics::OrPatternsBackCompat(span,suggestion) => {
757 db.span_suggestion(span, "use pat_param to preserve semantics", suggestion, Applicability::MachineApplicable);
759 BuiltinLintDiagnostics::ReservedPrefix(span) => {
760 db.span_label(span, "unknown prefix");
761 db.span_suggestion_verbose(
763 "insert whitespace here to avoid this being parsed as a prefix in Rust 2021",
765 Applicability::MachineApplicable,
768 BuiltinLintDiagnostics::UnusedBuiltinAttribute {
775 &format!("the built-in attribute `{attr_name}` will be ignored, since it's applied to the macro invocation `{macro_name}`")
778 BuiltinLintDiagnostics::TrailingMacro(is_trailing, name) => {
780 db.note("macro invocations at the end of a block are treated as expressions");
781 db.note(&format!("to ignore the value produced by the macro, add a semicolon after the invocation of `{name}`"));
784 BuiltinLintDiagnostics::BreakWithLabelAndLoop(span) => {
785 db.multipart_suggestion(
786 "wrap this expression in parentheses",
787 vec![(span.shrink_to_lo(), "(".to_string()),
788 (span.shrink_to_hi(), ")".to_string())],
789 Applicability::MachineApplicable
792 BuiltinLintDiagnostics::NamedAsmLabel(help) => {
794 db.note("see the asm section of the unstable book <https://doc.rust-lang.org/nightly/unstable-book/library-features/asm.html#labels> for more information");
797 // Rewrap `db`, and pass control to the user.
798 decorate(LintDiagnosticBuilder::new(db));
802 // FIXME: These methods should not take an Into<MultiSpan> -- instead, callers should need to
803 // set the span in their `decorate` function (preferably using set_span).
804 fn lookup<S: Into<MultiSpan>>(
808 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
811 fn struct_span_lint<S: Into<MultiSpan>>(
815 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
817 self.lookup(lint, Some(span), decorate);
819 /// Emit a lint at the appropriate level, with no associated span.
820 fn lint(&self, lint: &'static Lint, decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>)) {
821 self.lookup(lint, None as Option<Span>, decorate);
825 impl<'a> EarlyContext<'a> {
828 lint_store: &'a LintStore,
829 krate: &'a ast::Crate,
830 crate_attrs: &'a [ast::Attribute],
831 buffered: LintBuffer,
832 warn_about_weird_lints: bool,
833 ) -> EarlyContext<'a> {
838 builder: LintLevelsBuilder::new(sess, warn_about_weird_lints, lint_store, crate_attrs),
844 impl LintContext for LateContext<'_> {
845 type PassObject = LateLintPassObject;
847 /// Gets the overall compiler `Session` object.
848 fn sess(&self) -> &Session {
852 fn lints(&self) -> &LintStore {
856 fn lookup<S: Into<MultiSpan>>(
860 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
862 let hir_id = self.last_node_with_lint_attrs;
865 Some(s) => self.tcx.struct_span_lint_hir(lint, hir_id, s, decorate),
866 None => self.tcx.struct_lint_node(lint, hir_id, decorate),
871 impl LintContext for EarlyContext<'_> {
872 type PassObject = EarlyLintPassObject;
874 /// Gets the overall compiler `Session` object.
875 fn sess(&self) -> &Session {
879 fn lints(&self) -> &LintStore {
883 fn lookup<S: Into<MultiSpan>>(
887 decorate: impl for<'a> FnOnce(LintDiagnosticBuilder<'a>),
889 self.builder.struct_lint(lint, span.map(|s| s.into()), decorate)
893 impl<'tcx> LateContext<'tcx> {
894 /// Gets the type-checking results for the current body,
895 /// or `None` if outside a body.
896 pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {
897 self.cached_typeck_results.get().or_else(|| {
898 self.enclosing_body.map(|body| {
899 let typeck_results = self.tcx.typeck_body(body);
900 self.cached_typeck_results.set(Some(typeck_results));
906 /// Gets the type-checking results for the current body.
907 /// As this will ICE if called outside bodies, only call when working with
908 /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
910 pub fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
911 self.maybe_typeck_results().expect("`LateContext::typeck_results` called outside of body")
914 /// Returns the final resolution of a `QPath`, or `Res::Err` if unavailable.
915 /// Unlike `.typeck_results().qpath_res(qpath, id)`, this can be used even outside
916 /// bodies (e.g. for paths in `hir::Ty`), without any risk of ICE-ing.
917 pub fn qpath_res(&self, qpath: &hir::QPath<'_>, id: hir::HirId) -> Res {
919 hir::QPath::Resolved(_, ref path) => path.res,
920 hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
921 .maybe_typeck_results()
922 .filter(|typeck_results| typeck_results.hir_owner == id.owner)
924 if self.tcx.has_typeck_results(id.owner.to_def_id()) {
925 Some(self.tcx.typeck(id.owner))
930 .and_then(|typeck_results| typeck_results.type_dependent_def(id))
931 .map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)),
935 /// Check if a `DefId`'s path matches the given absolute type path usage.
937 /// Anonymous scopes such as `extern` imports are matched with `kw::Empty`;
938 /// inherent `impl` blocks are matched with the name of the type.
940 /// Instead of using this method, it is often preferable to instead use
941 /// `rustc_diagnostic_item` or a `lang_item`. This is less prone to errors
942 /// as paths get invalidated if the target definition moves.
946 /// ```rust,ignore (no context or def id available)
947 /// if cx.match_def_path(def_id, &[sym::core, sym::option, sym::Option]) {
948 /// // The given `def_id` is that of an `Option` type
952 /// Used by clippy, but should be replaced by diagnostic items eventually.
953 pub fn match_def_path(&self, def_id: DefId, path: &[Symbol]) -> bool {
954 let names = self.get_def_path(def_id);
956 names.len() == path.len() && iter::zip(names, path).all(|(a, &b)| a == b)
959 /// Gets the absolute path of `def_id` as a vector of `Symbol`.
963 /// ```rust,ignore (no context or def id available)
964 /// let def_path = cx.get_def_path(def_id);
965 /// if let &[sym::core, sym::option, sym::Option] = &def_path[..] {
966 /// // The given `def_id` is that of an `Option` type
969 pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
970 pub struct AbsolutePathPrinter<'tcx> {
971 pub tcx: TyCtxt<'tcx>,
974 impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
977 type Path = Vec<Symbol>;
980 type DynExistential = ();
983 fn tcx(&self) -> TyCtxt<'tcx> {
987 fn print_region(self, _region: ty::Region<'_>) -> Result<Self::Region, Self::Error> {
991 fn print_type(self, _ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
995 fn print_dyn_existential(
997 _predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,
998 ) -> Result<Self::DynExistential, Self::Error> {
1002 fn print_const(self, _ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
1006 fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
1007 Ok(vec![self.tcx.crate_name(cnum)])
1013 trait_ref: Option<ty::TraitRef<'tcx>>,
1014 ) -> Result<Self::Path, Self::Error> {
1015 if trait_ref.is_none() {
1016 if let ty::Adt(def, substs) = self_ty.kind() {
1017 return self.print_def_path(def.did, substs);
1021 // This shouldn't ever be needed, but just in case:
1022 with_no_trimmed_paths(|| {
1023 Ok(vec![match trait_ref {
1024 Some(trait_ref) => Symbol::intern(&format!("{:?}", trait_ref)),
1025 None => Symbol::intern(&format!("<{}>", self_ty)),
1030 fn path_append_impl(
1032 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1033 _disambiguated_data: &DisambiguatedDefPathData,
1035 trait_ref: Option<ty::TraitRef<'tcx>>,
1036 ) -> Result<Self::Path, Self::Error> {
1037 let mut path = print_prefix(self)?;
1039 // This shouldn't ever be needed, but just in case:
1040 path.push(match trait_ref {
1041 Some(trait_ref) => with_no_trimmed_paths(|| {
1042 Symbol::intern(&format!(
1044 trait_ref.print_only_trait_path(),
1049 with_no_trimmed_paths(|| Symbol::intern(&format!("<impl {}>", self_ty)))
1058 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1059 disambiguated_data: &DisambiguatedDefPathData,
1060 ) -> Result<Self::Path, Self::Error> {
1061 let mut path = print_prefix(self)?;
1063 // Skip `::{{constructor}}` on tuple/unit structs.
1064 if let DefPathData::Ctor = disambiguated_data.data {
1068 path.push(Symbol::intern(&disambiguated_data.data.to_string()));
1072 fn path_generic_args(
1074 print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1075 _args: &[GenericArg<'tcx>],
1076 ) -> Result<Self::Path, Self::Error> {
1081 AbsolutePathPrinter { tcx: self.tcx }.print_def_path(def_id, &[]).unwrap()
1085 impl<'tcx> abi::HasDataLayout for LateContext<'tcx> {
1087 fn data_layout(&self) -> &abi::TargetDataLayout {
1088 &self.tcx.data_layout
1092 impl<'tcx> ty::layout::HasTyCtxt<'tcx> for LateContext<'tcx> {
1094 fn tcx(&self) -> TyCtxt<'tcx> {
1099 impl<'tcx> ty::layout::HasParamEnv<'tcx> for LateContext<'tcx> {
1101 fn param_env(&self) -> ty::ParamEnv<'tcx> {
1106 impl<'tcx> LayoutOfHelpers<'tcx> for LateContext<'tcx> {
1107 type LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>;
1110 fn handle_layout_err(&self, err: LayoutError<'tcx>, _: Span, _: Ty<'tcx>) -> LayoutError<'tcx> {
1115 pub fn parse_lint_and_tool_name(lint_name: &str) -> (Option<Symbol>, &str) {
1116 match lint_name.split_once("::") {
1117 Some((tool_name, lint_name)) => {
1118 let tool_name = Symbol::intern(tool_name);
1120 (Some(tool_name), lint_name)
1122 None => (None, lint_name),