1 use crate::diagnostics::{ImportSuggestion, LabelSuggestion, TypoSuggestion};
2 use crate::late::{AliasPossibility, LateResolutionVisitor, RibKind};
3 use crate::late::{LifetimeBinderKind, LifetimeRes, LifetimeRibKind, LifetimeUseSet};
4 use crate::path_names_to_string;
5 use crate::{Module, ModuleKind, ModuleOrUniformRoot};
6 use crate::{PathResult, PathSource, Segment};
8 use rustc_ast::visit::{FnCtxt, FnKind, LifetimeCtxt};
10 self as ast, AssocItemKind, Expr, ExprKind, GenericParam, GenericParamKind, Item, ItemKind,
11 MethodCall, NodeId, Path, Ty, TyKind, DUMMY_NODE_ID,
13 use rustc_ast_pretty::pprust::path_segment_to_string;
14 use rustc_data_structures::fx::FxHashSet;
16 pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
20 use rustc_hir::def::Namespace::{self, *};
21 use rustc_hir::def::{self, CtorKind, CtorOf, DefKind};
22 use rustc_hir::def_id::{DefId, CRATE_DEF_ID, LOCAL_CRATE};
23 use rustc_hir::PrimTy;
24 use rustc_middle::ty::DefIdTree;
25 use rustc_session::lint;
26 use rustc_session::parse::feature_err;
27 use rustc_session::Session;
28 use rustc_span::edition::Edition;
29 use rustc_span::hygiene::MacroKind;
30 use rustc_span::lev_distance::find_best_match_for_name;
31 use rustc_span::symbol::{kw, sym, Ident, Symbol};
32 use rustc_span::{BytePos, Span};
37 use thin_vec::ThinVec;
39 type Res = def::Res<ast::NodeId>;
41 /// A field or associated item from self type suggested in case of resolution failure.
42 enum AssocSuggestion {
44 MethodWithSelf { called: bool },
45 AssocFn { called: bool },
50 impl AssocSuggestion {
51 fn action(&self) -> &'static str {
53 AssocSuggestion::Field => "use the available field",
54 AssocSuggestion::MethodWithSelf { called: true } => {
55 "call the method with the fully-qualified path"
57 AssocSuggestion::MethodWithSelf { called: false } => {
58 "refer to the method with the fully-qualified path"
60 AssocSuggestion::AssocFn { called: true } => "call the associated function",
61 AssocSuggestion::AssocFn { called: false } => "refer to the associated function",
62 AssocSuggestion::AssocConst => "use the associated `const`",
63 AssocSuggestion::AssocType => "use the associated type",
68 fn is_self_type(path: &[Segment], namespace: Namespace) -> bool {
69 namespace == TypeNS && path.len() == 1 && path[0].ident.name == kw::SelfUpper
72 fn is_self_value(path: &[Segment], namespace: Namespace) -> bool {
73 namespace == ValueNS && path.len() == 1 && path[0].ident.name == kw::SelfLower
76 /// Gets the stringified path for an enum from an `ImportSuggestion` for an enum variant.
77 fn import_candidate_to_enum_paths(suggestion: &ImportSuggestion) -> (String, String) {
78 let variant_path = &suggestion.path;
79 let variant_path_string = path_names_to_string(variant_path);
81 let path_len = suggestion.path.segments.len();
82 let enum_path = ast::Path {
83 span: suggestion.path.span,
84 segments: suggestion.path.segments[0..path_len - 1].iter().cloned().collect(),
87 let enum_path_string = path_names_to_string(&enum_path);
89 (variant_path_string, enum_path_string)
92 /// Description of an elided lifetime.
93 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
94 pub(super) struct MissingLifetime {
95 /// Used to overwrite the resolution with the suggestion, to avoid cascasing errors.
97 /// Where to suggest adding the lifetime.
99 /// How the lifetime was introduced, to have the correct space and comma.
100 pub kind: MissingLifetimeKind,
101 /// Number of elided lifetimes, used for elision in path.
105 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
106 pub(super) enum MissingLifetimeKind {
107 /// An explicit `'_`.
109 /// An elided lifetime `&' ty`.
111 /// An elided lifetime in brackets with written brackets.
113 /// An elided lifetime with elided brackets.
117 /// Description of the lifetimes appearing in a function parameter.
118 /// This is used to provide a literal explanation to the elision failure.
119 #[derive(Clone, Debug)]
120 pub(super) struct ElisionFnParameter {
121 /// The index of the argument in the original definition.
123 /// The name of the argument if it's a simple ident.
124 pub ident: Option<Ident>,
125 /// The number of lifetimes in the parameter.
126 pub lifetime_count: usize,
127 /// The span of the parameter.
131 /// Description of lifetimes that appear as candidates for elision.
132 /// This is used to suggest introducing an explicit lifetime.
134 pub(super) enum LifetimeElisionCandidate {
135 /// This is not a real lifetime.
137 /// There is a named lifetime, we won't suggest anything.
139 Missing(MissingLifetime),
142 /// Only used for diagnostics.
146 fallback_label: String,
148 span_label: Option<(Span, &'static str)>,
150 suggestion: Option<(Span, &'static str, String)>,
155 Typo(TypoSuggestion),
156 Shadowed(Res, Option<Span>),
161 fn to_opt_suggestion(self) -> Option<TypoSuggestion> {
163 TypoCandidate::Typo(sugg) => Some(sugg),
164 TypoCandidate::Shadowed(_, _) | TypoCandidate::None => None,
169 impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
170 fn def_span(&self, def_id: DefId) -> Option<Span> {
172 LOCAL_CRATE => self.r.opt_span(def_id),
173 _ => Some(self.r.cstore().get_span_untracked(def_id, self.r.session)),
181 source: PathSource<'_>,
184 // Make the base error.
185 let mut expected = source.descr_expected();
186 let path_str = Segment::names_to_string(path);
187 let item_str = path.last().unwrap().ident;
188 if let Some(res) = res {
190 msg: format!("expected {}, found {} `{}`", expected, res.descr(), path_str),
191 fallback_label: format!("not a {expected}"),
193 span_label: match res {
194 Res::Def(kind, def_id) if kind == DefKind::TyParam => {
195 self.def_span(def_id).map(|span| (span, "found this type parameter"))
199 could_be_expr: match res {
200 Res::Def(DefKind::Fn, _) => {
201 // Verify whether this is a fn call or an Fn used as a type.
205 .span_to_snippet(span)
206 .map(|snippet| snippet.ends_with(')'))
210 DefKind::Ctor(..) | DefKind::AssocFn | DefKind::Const | DefKind::AssocConst,
215 | Res::Local(_) => true,
221 let item_span = path.last().unwrap().ident.span;
222 let (mod_prefix, mod_str, suggestion) = if path.len() == 1 {
223 debug!(?self.diagnostic_metadata.current_impl_items);
224 debug!(?self.diagnostic_metadata.current_function);
225 let suggestion = if self.current_trait_ref.is_none()
226 && let Some((fn_kind, _)) = self.diagnostic_metadata.current_function
227 && let Some(FnCtxt::Assoc(_)) = fn_kind.ctxt()
228 && let Some(items) = self.diagnostic_metadata.current_impl_items
229 && let Some(item) = items.iter().find(|i| {
230 if let AssocItemKind::Fn(..) | AssocItemKind::Const(..) = &i.kind
231 && i.ident.name == item_str.name
233 debug!(?item_str.name);
239 let self_sugg = match &item.kind {
240 AssocItemKind::Fn(fn_) if fn_.sig.decl.has_self() => "self.",
245 item_span.shrink_to_lo(),
247 AssocItemKind::Fn(..) => "consider using the associated function",
248 AssocItemKind::Const(..) => "consider using the associated constant",
249 _ => unreachable!("item kind was filtered above"),
251 self_sugg.to_string()
256 (String::new(), "this scope".to_string(), suggestion)
257 } else if path.len() == 2 && path[0].ident.name == kw::PathRoot {
258 if self.r.session.edition() > Edition::Edition2015 {
259 // In edition 2018 onwards, the `::foo` syntax may only pull from the extern prelude
260 // which overrides all other expectations of item type
262 (String::new(), "the list of imported crates".to_string(), None)
264 (String::new(), "the crate root".to_string(), None)
266 } else if path.len() == 2 && path[0].ident.name == kw::Crate {
267 (String::new(), "the crate root".to_string(), None)
269 let mod_path = &path[..path.len() - 1];
270 let mod_prefix = match self.resolve_path(mod_path, Some(TypeNS), None) {
271 PathResult::Module(ModuleOrUniformRoot::Module(module)) => module.res(),
274 .map_or_else(String::new, |res| format!("{} ", res.descr()));
275 (mod_prefix, format!("`{}`", Segment::names_to_string(mod_path)), None)
278 let (fallback_label, suggestion) = if path_str == "async"
279 && expected.starts_with("struct")
281 ("`async` blocks are only allowed in Rust 2018 or later".to_string(), suggestion)
283 // check if we are in situation of typo like `True` instead of `true`.
284 let override_suggestion =
285 if ["true", "false"].contains(&item_str.to_string().to_lowercase().as_str()) {
286 let item_typo = item_str.to_string().to_lowercase();
287 Some((item_span, "you may want to use a bool value instead", item_typo))
288 // FIXME(vincenzopalazzo): make the check smarter,
289 // and maybe expand with levenshtein distance checks
290 } else if item_str.as_str() == "printf" {
293 "you may have meant to use the `print` macro",
299 (format!("not found in {mod_str}"), override_suggestion)
303 msg: format!("cannot find {expected} `{item_str}` in {mod_prefix}{mod_str}"),
307 could_be_expr: false,
313 /// Handles error reporting for `smart_resolve_path_fragment` function.
314 /// Creates base error and amends it with one short label and possibly some longer helps/notes.
315 pub(crate) fn smart_resolve_report_errors(
319 source: PathSource<'_>,
321 ) -> (DiagnosticBuilder<'a, ErrorGuaranteed>, Vec<ImportSuggestion>) {
322 debug!(?res, ?source);
323 let base_error = self.make_base_error(path, span, source, res);
324 let code = source.error_code(res.is_some());
326 self.r.session.struct_span_err_with_code(base_error.span, &base_error.msg, code);
328 self.suggest_swapping_misplaced_self_ty_and_trait(&mut err, source, res, base_error.span);
330 if let Some((span, label)) = base_error.span_label {
331 err.span_label(span, label);
334 if let Some(ref sugg) = base_error.suggestion {
335 err.span_suggestion_verbose(sugg.0, sugg.1, &sugg.2, Applicability::MaybeIncorrect);
338 self.suggest_bare_struct_literal(&mut err);
340 if self.suggest_pattern_match_with_let(&mut err, source, span) {
342 err.span_label(base_error.span, &base_error.fallback_label);
343 return (err, Vec::new());
346 self.suggest_self_or_self_ref(&mut err, path, span);
347 self.detect_assoct_type_constraint_meant_as_path(&mut err, &base_error);
348 if self.suggest_self_ty(&mut err, source, path, span)
349 || self.suggest_self_value(&mut err, source, path, span)
351 return (err, Vec::new());
354 let (found, candidates) =
355 self.try_lookup_name_relaxed(&mut err, source, path, span, res, &base_error);
357 return (err, candidates);
360 if !self.type_ascription_suggestion(&mut err, base_error.span) {
362 self.suggest_trait_and_bounds(&mut err, source, res, span, &base_error);
364 // if we have suggested using pattern matching, then don't add needless suggestions
366 fallback |= self.suggest_typo(&mut err, source, path, span, &base_error);
370 err.span_label(base_error.span, &base_error.fallback_label);
373 self.err_code_special_cases(&mut err, source, path, span);
378 fn detect_assoct_type_constraint_meant_as_path(
380 err: &mut Diagnostic,
381 base_error: &BaseError,
383 let Some(ty) = self.diagnostic_metadata.current_type_path else { return; };
384 let TyKind::Path(_, path) = &ty.kind else { return; };
385 for segment in &path.segments {
386 let Some(params) = &segment.args else { continue; };
387 let ast::GenericArgs::AngleBracketed(ref params) = params.deref() else { continue; };
388 for param in ¶ms.args {
389 let ast::AngleBracketedArg::Constraint(constraint) = param else { continue; };
390 let ast::AssocConstraintKind::Bound { bounds } = &constraint.kind else {
393 for bound in bounds {
394 let ast::GenericBound::Trait(trait_ref, ast::TraitBoundModifier::None)
399 if base_error.span == trait_ref.span {
400 err.span_suggestion_verbose(
401 constraint.ident.span.between(trait_ref.span),
402 "you might have meant to write a path instead of an associated type bound",
404 Applicability::MachineApplicable,
412 fn suggest_self_or_self_ref(&mut self, err: &mut Diagnostic, path: &[Segment], span: Span) {
413 if !self.self_type_is_available() {
416 let Some(path_last_segment) = path.last() else { return };
417 let item_str = path_last_segment.ident;
418 // Emit help message for fake-self from other languages (e.g., `this` in Javascript).
419 if ["this", "my"].contains(&item_str.as_str()) {
420 err.span_suggestion_short(
422 "you might have meant to use `self` here instead",
424 Applicability::MaybeIncorrect,
426 if !self.self_value_is_available(path[0].ident.span) {
427 if let Some((FnKind::Fn(_, _, sig, ..), fn_span)) =
428 &self.diagnostic_metadata.current_function
430 let (span, sugg) = if let Some(param) = sig.decl.inputs.get(0) {
431 (param.span.shrink_to_lo(), "&self, ")
437 .span_through_char(*fn_span, '(')
442 err.span_suggestion_verbose(
444 "if you meant to use `self`, you are also missing a `self` receiver \
447 Applicability::MaybeIncorrect,
454 fn try_lookup_name_relaxed(
456 err: &mut Diagnostic,
457 source: PathSource<'_>,
461 base_error: &BaseError,
462 ) -> (bool, Vec<ImportSuggestion>) {
463 // Try to lookup name in more relaxed fashion for better error reporting.
464 let ident = path.last().unwrap().ident;
465 let is_expected = &|res| source.is_expected(res);
466 let ns = source.namespace();
467 let is_enum_variant = &|res| matches!(res, Res::Def(DefKind::Variant, _));
468 let path_str = Segment::names_to_string(path);
469 let ident_span = path.last().map_or(span, |ident| ident.ident.span);
470 let mut candidates = self
472 .lookup_import_candidates(ident, ns, &self.parent_scope, is_expected)
474 .filter(|ImportSuggestion { did, .. }| {
475 match (did, res.and_then(|res| res.opt_def_id())) {
476 (Some(suggestion_did), Some(actual_did)) => *suggestion_did != actual_did,
480 .collect::<Vec<_>>();
481 let crate_def_id = CRATE_DEF_ID.to_def_id();
482 // Try to filter out intrinsics candidates, as long as we have
483 // some other candidates to suggest.
484 let intrinsic_candidates: Vec<_> = candidates
485 .drain_filter(|sugg| {
486 let path = path_names_to_string(&sugg.path);
487 path.starts_with("core::intrinsics::") || path.starts_with("std::intrinsics::")
490 if candidates.is_empty() {
491 // Put them back if we have no more candidates to suggest...
492 candidates.extend(intrinsic_candidates);
494 if candidates.is_empty() && is_expected(Res::Def(DefKind::Enum, crate_def_id)) {
495 let mut enum_candidates: Vec<_> = self
497 .lookup_import_candidates(ident, ns, &self.parent_scope, is_enum_variant)
499 .map(|suggestion| import_candidate_to_enum_paths(&suggestion))
500 .filter(|(_, enum_ty_path)| !enum_ty_path.starts_with("std::prelude::"))
502 if !enum_candidates.is_empty() {
503 if let (PathSource::Type, Some(span)) =
504 (source, self.diagnostic_metadata.current_type_ascription.last())
510 .type_ascription_path_suggestions
514 // Already reported this issue on the lhs of the type ascription.
515 err.downgrade_to_delayed_bug();
516 return (true, candidates);
520 enum_candidates.sort();
522 // Contextualize for E0412 "cannot find type", but don't belabor the point
523 // (that it's a variant) for E0573 "expected type, found variant".
524 let preamble = if res.is_none() {
525 let others = match enum_candidates.len() {
527 2 => " and 1 other".to_owned(),
528 n => format!(" and {} others", n),
530 format!("there is an enum variant `{}`{}; ", enum_candidates[0].0, others)
534 let msg = format!("{}try using the variant's enum", preamble);
536 err.span_suggestions(
539 enum_candidates.into_iter().map(|(_variant_path, enum_ty_path)| enum_ty_path),
540 Applicability::MachineApplicable,
545 // Try Levenshtein algorithm.
547 self.lookup_typo_candidate(path, source.namespace(), is_expected).to_opt_suggestion();
548 if path.len() == 1 && self.self_type_is_available() {
549 if let Some(candidate) =
550 self.lookup_assoc_candidate(ident, ns, is_expected, source.is_call())
552 let self_is_available = self.self_value_is_available(path[0].ident.span);
554 AssocSuggestion::Field => {
555 if self_is_available {
558 "you might have meant to use the available field",
559 format!("self.{path_str}"),
560 Applicability::MachineApplicable,
563 err.span_label(span, "a field by this name exists in `Self`");
566 AssocSuggestion::MethodWithSelf { called } if self_is_available => {
567 let msg = if called {
568 "you might have meant to call the method"
570 "you might have meant to refer to the method"
575 format!("self.{path_str}"),
576 Applicability::MachineApplicable,
579 AssocSuggestion::MethodWithSelf { .. }
580 | AssocSuggestion::AssocFn { .. }
581 | AssocSuggestion::AssocConst
582 | AssocSuggestion::AssocType => {
585 &format!("you might have meant to {}", candidate.action()),
586 format!("Self::{path_str}"),
587 Applicability::MachineApplicable,
591 self.r.add_typo_suggestion(err, typo_sugg, ident_span);
592 return (true, candidates);
595 // If the first argument in call is `self` suggest calling a method.
596 if let Some((call_span, args_span)) = self.call_has_self_arg(source) {
597 let mut args_snippet = String::new();
598 if let Some(args_span) = args_span {
599 if let Ok(snippet) = self.r.session.source_map().span_to_snippet(args_span) {
600 args_snippet = snippet;
606 &format!("try calling `{ident}` as a method"),
607 format!("self.{path_str}({args_snippet})"),
608 Applicability::MachineApplicable,
610 return (true, candidates);
614 // Try context-dependent help if relaxed lookup didn't work.
615 if let Some(res) = res {
616 if self.smart_resolve_context_dependent_help(
622 &base_error.fallback_label,
624 // We do this to avoid losing a secondary span when we override the main error span.
625 self.r.add_typo_suggestion(err, typo_sugg, ident_span);
626 return (true, candidates);
630 // Try to find in last block rib
631 if let Some(rib) = &self.last_block_rib && let RibKind::NormalRibKind = rib.kind {
632 for (ident, &res) in &rib.bindings {
633 if let Res::Local(_) = res && path.len() == 1 &&
634 ident.span.eq_ctxt(path[0].ident.span) &&
635 ident.name == path[0].ident.name {
638 &format!("the binding `{}` is available in a different scope in the same function", path_str),
640 return (true, candidates);
645 return (false, candidates);
648 fn suggest_trait_and_bounds(
650 err: &mut Diagnostic,
651 source: PathSource<'_>,
654 base_error: &BaseError,
657 base_error.span.from_expansion() && base_error.span.desugaring_kind().is_none();
658 let mut fallback = false;
661 PathSource::Trait(AliasPossibility::Maybe),
662 Some(Res::Def(DefKind::Struct | DefKind::Enum | DefKind::Union, _)),
664 ) = (source, res, is_macro)
666 if let Some(bounds @ [_, .., _]) = self.diagnostic_metadata.current_trait_object {
668 let spans: Vec<Span> = bounds
670 .map(|bound| bound.span())
671 .filter(|&sp| sp != base_error.span)
674 let start_span = bounds[0].span();
675 // `end_span` is the end of the poly trait ref (Foo + 'baz + Bar><)
676 let end_span = bounds.last().unwrap().span();
677 // `last_bound_span` is the last bound of the poly trait ref (Foo + >'baz< + Bar)
678 let last_bound_span = spans.last().cloned().unwrap();
679 let mut multi_span: MultiSpan = spans.clone().into();
681 let msg = if sp == last_bound_span {
683 "...because of {these} bound{s}",
684 these = pluralize!("this", bounds.len() - 1),
685 s = pluralize!(bounds.len() - 1),
690 multi_span.push_span_label(sp, msg);
692 multi_span.push_span_label(base_error.span, "expected this type to be a trait...");
695 "`+` is used to constrain a \"trait object\" type with lifetimes or \
696 auto-traits; structs and enums can't be bound in that way",
698 if bounds.iter().all(|bound| match bound {
699 ast::GenericBound::Outlives(_) => true,
700 ast::GenericBound::Trait(tr, _) => tr.span == base_error.span,
702 let mut sugg = vec![];
703 if base_error.span != start_span {
704 sugg.push((start_span.until(base_error.span), String::new()));
706 if base_error.span != end_span {
707 sugg.push((base_error.span.shrink_to_hi().to(end_span), String::new()));
710 err.multipart_suggestion(
711 "if you meant to use a type and not a trait here, remove the bounds",
713 Applicability::MaybeIncorrect,
719 fallback |= self.restrict_assoc_type_in_where_clause(span, err);
725 err: &mut Diagnostic,
726 source: PathSource<'_>,
729 base_error: &BaseError,
731 let is_expected = &|res| source.is_expected(res);
732 let ident_span = path.last().map_or(span, |ident| ident.ident.span);
733 let typo_sugg = self.lookup_typo_candidate(path, source.namespace(), is_expected);
734 let is_in_same_file = &|sp1, sp2| {
735 let source_map = self.r.session.source_map();
736 let file1 = source_map.span_to_filename(sp1);
737 let file2 = source_map.span_to_filename(sp2);
740 // print 'you might have meant' if the candidate is (1) is a shadowed name with
741 // accessible definition and (2) either defined in the same crate as the typo
742 // (could be in a different file) or introduced in the same file as the typo
743 // (could belong to a different crate)
744 if let TypoCandidate::Shadowed(res, Some(sugg_span)) = typo_sugg
747 .map_or(false, |id| id.is_local() || is_in_same_file(span, sugg_span))
751 format!("you might have meant to refer to this {}", res.descr()),
755 let mut fallback = false;
756 let typo_sugg = typo_sugg.to_opt_suggestion();
757 if !self.r.add_typo_suggestion(err, typo_sugg, ident_span) {
759 match self.diagnostic_metadata.current_let_binding {
760 Some((pat_sp, Some(ty_sp), None))
761 if ty_sp.contains(base_error.span) && base_error.could_be_expr =>
763 err.span_suggestion_short(
764 pat_sp.between(ty_sp),
765 "use `=` if you meant to assign",
767 Applicability::MaybeIncorrect,
773 // If the trait has a single item (which wasn't matched by Levenshtein), suggest it
774 let suggestion = self.get_single_associated_item(&path, &source, is_expected);
775 if !self.r.add_typo_suggestion(err, suggestion, ident_span) {
776 fallback = !self.let_binding_suggestion(err, ident_span);
782 fn err_code_special_cases(
784 err: &mut Diagnostic,
785 source: PathSource<'_>,
789 if let Some(err_code) = &err.code {
790 if err_code == &rustc_errors::error_code!(E0425) {
791 for label_rib in &self.label_ribs {
792 for (label_ident, node_id) in &label_rib.bindings {
793 let ident = path.last().unwrap().ident;
794 if format!("'{}", ident) == label_ident.to_string() {
795 err.span_label(label_ident.span, "a label with a similar name exists");
796 if let PathSource::Expr(Some(Expr {
797 kind: ExprKind::Break(None, Some(_)),
803 "use the similarly named label",
805 Applicability::MaybeIncorrect,
807 // Do not lint against unused label when we suggest them.
808 self.diagnostic_metadata.unused_labels.remove(node_id);
813 } else if err_code == &rustc_errors::error_code!(E0412) {
814 if let Some(correct) = Self::likely_rust_type(path) {
817 "perhaps you intended to use this type",
819 Applicability::MaybeIncorrect,
826 /// Emit special messages for unresolved `Self` and `self`.
829 err: &mut Diagnostic,
830 source: PathSource<'_>,
834 if !is_self_type(path, source.namespace()) {
837 err.code(rustc_errors::error_code!(E0411));
838 err.span_label(span, "`Self` is only available in impls, traits, and type definitions");
839 if let Some(item_kind) = self.diagnostic_metadata.current_item {
840 if !item_kind.ident.span.is_dummy() {
842 item_kind.ident.span,
844 "`Self` not allowed in {} {}",
845 item_kind.kind.article(),
846 item_kind.kind.descr()
854 fn suggest_self_value(
856 err: &mut Diagnostic,
857 source: PathSource<'_>,
861 if !is_self_value(path, source.namespace()) {
865 debug!("smart_resolve_path_fragment: E0424, source={:?}", source);
866 err.code(rustc_errors::error_code!(E0424));
871 "`self` value is a keyword and may not be bound to variables or shadowed"
873 _ => "`self` value is a keyword only available in methods with a `self` parameter",
876 let is_assoc_fn = self.self_type_is_available();
877 if let Some((fn_kind, span)) = &self.diagnostic_metadata.current_function {
878 // The current function has a `self' parameter, but we were unable to resolve
879 // a reference to `self`. This can only happen if the `self` identifier we
880 // are resolving came from a different hygiene context.
881 if fn_kind.decl().inputs.get(0).map_or(false, |p| p.is_self()) {
882 err.span_label(*span, "this function has a `self` parameter, but a macro invocation can only access identifiers it receives from parameters");
884 let doesnt = if is_assoc_fn {
885 let (span, sugg) = fn_kind
889 .map(|p| (p.span.shrink_to_lo(), "&self, "))
891 // Try to look for the "(" after the function name, if possible.
892 // This avoids placing the suggestion into the visibility specifier.
895 .map_or(*span, |ident| span.with_lo(ident.span.hi()));
900 .span_through_char(span, '(')
905 err.span_suggestion_verbose(
907 "add a `self` receiver parameter to make the associated `fn` a method",
909 Applicability::MaybeIncorrect,
915 if let Some(ident) = fn_kind.ident() {
918 &format!("this function {} have a `self` parameter", doesnt),
922 } else if let Some(item_kind) = self.diagnostic_metadata.current_item {
924 item_kind.ident.span,
926 "`self` not allowed in {} {}",
927 item_kind.kind.article(),
928 item_kind.kind.descr()
935 fn suggest_swapping_misplaced_self_ty_and_trait(
937 err: &mut Diagnostic,
938 source: PathSource<'_>,
942 if let Some((trait_ref, self_ty)) =
943 self.diagnostic_metadata.currently_processing_impl_trait.clone()
944 && let TyKind::Path(_, self_ty_path) = &self_ty.kind
945 && let PathResult::Module(ModuleOrUniformRoot::Module(module)) =
946 self.resolve_path(&Segment::from_path(self_ty_path), Some(TypeNS), None)
947 && let ModuleKind::Def(DefKind::Trait, ..) = module.kind
948 && trait_ref.path.span == span
949 && let PathSource::Trait(_) = source
950 && let Some(Res::Def(DefKind::Struct | DefKind::Enum | DefKind::Union, _)) = res
951 && let Ok(self_ty_str) =
952 self.r.session.source_map().span_to_snippet(self_ty.span)
953 && let Ok(trait_ref_str) =
954 self.r.session.source_map().span_to_snippet(trait_ref.path.span)
956 err.multipart_suggestion(
957 "`impl` items mention the trait being implemented first and the type it is being implemented for second",
958 vec![(trait_ref.path.span, self_ty_str), (self_ty.span, trait_ref_str)],
959 Applicability::MaybeIncorrect,
964 fn suggest_bare_struct_literal(&mut self, err: &mut Diagnostic) {
965 if let Some(span) = self.diagnostic_metadata.current_block_could_be_bare_struct_literal {
966 err.multipart_suggestion(
967 "you might have meant to write a `struct` literal",
969 (span.shrink_to_lo(), "{ SomeStruct ".to_string()),
970 (span.shrink_to_hi(), "}".to_string()),
972 Applicability::HasPlaceholders,
977 fn suggest_pattern_match_with_let(
979 err: &mut Diagnostic,
980 source: PathSource<'_>,
983 if let PathSource::Expr(_) = source &&
986 kind: ExprKind::Assign(lhs, _, _),
988 }) = self.diagnostic_metadata.in_if_condition {
989 // Icky heuristic so we don't suggest:
990 // `if (i + 2) = 2` => `if let (i + 2) = 2` (approximately pattern)
991 // `if 2 = i` => `if let 2 = i` (lhs needs to contain error span)
992 if lhs.is_approximately_pattern() && lhs.span.contains(span) {
993 err.span_suggestion_verbose(
994 expr_span.shrink_to_lo(),
995 "you might have meant to use pattern matching",
997 Applicability::MaybeIncorrect,
1005 fn get_single_associated_item(
1008 source: &PathSource<'_>,
1009 filter_fn: &impl Fn(Res) -> bool,
1010 ) -> Option<TypoSuggestion> {
1011 if let crate::PathSource::TraitItem(_) = source {
1012 let mod_path = &path[..path.len() - 1];
1013 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) =
1014 self.resolve_path(mod_path, None, None)
1016 let resolutions = self.r.resolutions(module).borrow();
1017 let targets: Vec<_> =
1020 .filter_map(|(key, resolution)| {
1021 resolution.borrow().binding.map(|binding| binding.res()).and_then(
1022 |res| if filter_fn(res) { Some((key, res)) } else { None },
1026 if targets.len() == 1 {
1027 let target = targets[0];
1028 return Some(TypoSuggestion::single_item_from_ident(target.0.ident, target.1));
1035 /// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
1036 fn restrict_assoc_type_in_where_clause(&mut self, span: Span, err: &mut Diagnostic) -> bool {
1037 // Detect that we are actually in a `where` predicate.
1038 let (bounded_ty, bounds, where_span) =
1039 if let Some(ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
1041 bound_generic_params,
1044 })) = self.diagnostic_metadata.current_where_predicate
1046 if !bound_generic_params.is_empty() {
1049 (bounded_ty, bounds, span)
1054 // Confirm that the target is an associated type.
1055 let (ty, position, path) = if let ast::TyKind::Path(Some(qself), path) = &bounded_ty.kind {
1056 // use this to verify that ident is a type param.
1057 let Some(partial_res) = self.r.partial_res_map.get(&bounded_ty.id) else {
1061 partial_res.full_res(),
1062 Some(hir::def::Res::Def(hir::def::DefKind::AssocTy, _))
1066 (&qself.ty, qself.position, path)
1071 let peeled_ty = ty.peel_refs();
1072 if let ast::TyKind::Path(None, type_param_path) = &peeled_ty.kind {
1073 // Confirm that the `SelfTy` is a type parameter.
1074 let Some(partial_res) = self.r.partial_res_map.get(&peeled_ty.id) else {
1078 partial_res.full_res(),
1079 Some(hir::def::Res::Def(hir::def::DefKind::TyParam, _))
1084 [ast::PathSegment { ident: constrain_ident, args: None, .. }],
1085 [ast::GenericBound::Trait(poly_trait_ref, ast::TraitBoundModifier::None)],
1086 ) = (&type_param_path.segments[..], &bounds[..])
1088 if let [ast::PathSegment { ident, args: None, .. }] =
1089 &poly_trait_ref.trait_ref.path.segments[..]
1091 if ident.span == span {
1092 err.span_suggestion_verbose(
1094 &format!("constrain the associated type to `{}`", ident),
1100 .span_to_snippet(ty.span) // Account for `<&'a T as Foo>::Bar`.
1101 .unwrap_or_else(|_| constrain_ident.to_string()),
1102 path.segments[..position]
1104 .map(|segment| path_segment_to_string(segment))
1105 .collect::<Vec<_>>()
1107 path.segments[position..]
1109 .map(|segment| path_segment_to_string(segment))
1110 .collect::<Vec<_>>()
1114 Applicability::MaybeIncorrect,
1124 /// Check if the source is call expression and the first argument is `self`. If true,
1125 /// return the span of whole call and the span for all arguments expect the first one (`self`).
1126 fn call_has_self_arg(&self, source: PathSource<'_>) -> Option<(Span, Option<Span>)> {
1127 let mut has_self_arg = None;
1128 if let PathSource::Expr(Some(parent)) = source {
1129 match &parent.kind {
1130 ExprKind::Call(_, args) if !args.is_empty() => {
1131 let mut expr_kind = &args[0].kind;
1134 ExprKind::Path(_, arg_name) if arg_name.segments.len() == 1 => {
1135 if arg_name.segments[0].ident.name == kw::SelfLower {
1136 let call_span = parent.span;
1137 let tail_args_span = if args.len() > 1 {
1140 args.last().unwrap().span.hi(),
1147 has_self_arg = Some((call_span, tail_args_span));
1151 ExprKind::AddrOf(_, _, expr) => expr_kind = &expr.kind,
1162 fn followed_by_brace(&self, span: Span) -> (bool, Option<Span>) {
1163 // HACK(estebank): find a better way to figure out that this was a
1164 // parser issue where a struct literal is being used on an expression
1165 // where a brace being opened means a block is being started. Look
1166 // ahead for the next text to see if `span` is followed by a `{`.
1167 let sm = self.r.session.source_map();
1168 let sp = sm.span_look_ahead(span, None, Some(50));
1169 let followed_by_brace = matches!(sm.span_to_snippet(sp), Ok(ref snippet) if snippet == "{");
1170 // In case this could be a struct literal that needs to be surrounded
1171 // by parentheses, find the appropriate span.
1172 let closing_span = sm.span_look_ahead(span, Some("}"), Some(50));
1173 let closing_brace: Option<Span> = sm
1174 .span_to_snippet(closing_span)
1175 .map_or(None, |s| if s == "}" { Some(span.to(closing_span)) } else { None });
1176 (followed_by_brace, closing_brace)
1179 /// Provides context-dependent help for errors reported by the `smart_resolve_path_fragment`
1181 /// Returns `true` if able to provide context-dependent help.
1182 fn smart_resolve_context_dependent_help(
1184 err: &mut Diagnostic,
1186 source: PathSource<'_>,
1189 fallback_label: &str,
1191 let ns = source.namespace();
1192 let is_expected = &|res| source.is_expected(res);
1194 let path_sep = |err: &mut Diagnostic, expr: &Expr, kind: DefKind| {
1195 const MESSAGE: &str = "use the path separator to refer to an item";
1197 let (lhs_span, rhs_span) = match &expr.kind {
1198 ExprKind::Field(base, ident) => (base.span, ident.span),
1199 ExprKind::MethodCall(box MethodCall { receiver, span, .. }) => {
1200 (receiver.span, *span)
1205 if lhs_span.eq_ctxt(rhs_span) {
1206 err.span_suggestion(
1207 lhs_span.between(rhs_span),
1210 Applicability::MaybeIncorrect,
1213 } else if kind == DefKind::Struct
1214 && let Some(lhs_source_span) = lhs_span.find_ancestor_inside(expr.span)
1215 && let Ok(snippet) = self.r.session.source_map().span_to_snippet(lhs_source_span)
1217 // The LHS is a type that originates from a macro call.
1218 // We have to add angle brackets around it.
1220 err.span_suggestion_verbose(
1221 lhs_source_span.until(rhs_span),
1223 format!("<{snippet}>::"),
1224 Applicability::MaybeIncorrect,
1228 // Either we were unable to obtain the source span / the snippet or
1229 // the LHS originates from a macro call and it is not a type and thus
1230 // there is no way to replace `.` with `::` and still somehow suggest
1237 let find_span = |source: &PathSource<'_>, err: &mut Diagnostic| {
1239 PathSource::Expr(Some(Expr { span, kind: ExprKind::Call(_, _), .. }))
1240 | PathSource::TupleStruct(span, _) => {
1241 // We want the main underline to cover the suggested code as well for
1243 err.set_span(*span);
1250 let mut bad_struct_syntax_suggestion = |def_id: DefId| {
1251 let (followed_by_brace, closing_brace) = self.followed_by_brace(span);
1254 PathSource::Expr(Some(
1255 parent @ Expr { kind: ExprKind::Field(..) | ExprKind::MethodCall(..), .. },
1256 )) if path_sep(err, &parent, DefKind::Struct) => {}
1262 | ExprKind::Binary(..)
1263 | ExprKind::Unary(..)
1265 | ExprKind::While(..)
1266 | ExprKind::ForLoop(..)
1267 | ExprKind::Match(..),
1270 ) if followed_by_brace => {
1271 if let Some(sp) = closing_brace {
1272 err.span_label(span, fallback_label);
1273 err.multipart_suggestion(
1274 "surround the struct literal with parentheses",
1276 (sp.shrink_to_lo(), "(".to_string()),
1277 (sp.shrink_to_hi(), ")".to_string()),
1279 Applicability::MaybeIncorrect,
1283 span, // Note the parentheses surrounding the suggestion below
1285 "you might want to surround a struct literal with parentheses: \
1286 `({} {{ /* fields */ }})`?",
1292 PathSource::Expr(_) | PathSource::TupleStruct(..) | PathSource::Pat => {
1293 let span = find_span(&source, err);
1294 if let Some(span) = self.def_span(def_id) {
1295 err.span_label(span, &format!("`{}` defined here", path_str));
1297 let (tail, descr, applicability) = match source {
1298 PathSource::Pat | PathSource::TupleStruct(..) => {
1299 ("", "pattern", Applicability::MachineApplicable)
1301 _ => (": val", "literal", Applicability::HasPlaceholders),
1303 let (fields, applicability) = match self.r.field_names.get(&def_id) {
1307 .map(|f| format!("{}{}", f.node, tail))
1308 .collect::<Vec<String>>()
1312 None => ("/* fields */".to_string(), Applicability::HasPlaceholders),
1314 let pad = match self.r.field_names.get(&def_id) {
1315 Some(fields) if fields.is_empty() => "",
1318 err.span_suggestion(
1320 &format!("use struct {} syntax instead", descr),
1321 format!("{path_str} {{{pad}{fields}{pad}}}"),
1326 err.span_label(span, fallback_label);
1331 match (res, source) {
1333 Res::Def(DefKind::Macro(MacroKind::Bang), _),
1334 PathSource::Expr(Some(Expr {
1335 kind: ExprKind::Index(..) | ExprKind::Call(..), ..
1337 | PathSource::Struct,
1339 err.span_label(span, fallback_label);
1340 err.span_suggestion_verbose(
1341 span.shrink_to_hi(),
1342 "use `!` to invoke the macro",
1344 Applicability::MaybeIncorrect,
1346 if path_str == "try" && span.rust_2015() {
1347 err.note("if you want the `try` keyword, you need Rust 2018 or later");
1350 (Res::Def(DefKind::Macro(MacroKind::Bang), _), _) => {
1351 err.span_label(span, fallback_label);
1353 (Res::Def(DefKind::TyAlias, def_id), PathSource::Trait(_)) => {
1354 err.span_label(span, "type aliases cannot be used as traits");
1355 if self.r.session.is_nightly_build() {
1356 let msg = "you might have meant to use `#![feature(trait_alias)]` instead of a \
1358 if let Some(span) = self.def_span(def_id) {
1359 if let Ok(snip) = self.r.session.source_map().span_to_snippet(span) {
1360 // The span contains a type alias so we should be able to
1361 // replace `type` with `trait`.
1362 let snip = snip.replacen("type", "trait", 1);
1363 err.span_suggestion(span, msg, snip, Applicability::MaybeIncorrect);
1365 err.span_help(span, msg);
1373 Res::Def(kind @ (DefKind::Mod | DefKind::Trait), _),
1374 PathSource::Expr(Some(parent)),
1376 if !path_sep(err, &parent, kind) {
1381 Res::Def(DefKind::Enum, def_id),
1382 PathSource::TupleStruct(..) | PathSource::Expr(..),
1385 .diagnostic_metadata
1386 .current_type_ascription
1392 .type_ascription_path_suggestions
1398 err.downgrade_to_delayed_bug();
1399 // We already suggested changing `:` into `::` during parsing.
1403 self.suggest_using_enum_variant(err, source, def_id, span);
1405 (Res::Def(DefKind::Struct, def_id), source) if ns == ValueNS => {
1406 let (ctor_def, ctor_vis, fields) =
1407 if let Some(struct_ctor) = self.r.struct_constructors.get(&def_id).cloned() {
1408 if let PathSource::Expr(Some(parent)) = source {
1409 if let ExprKind::Field(..) | ExprKind::MethodCall(..) = parent.kind {
1410 bad_struct_syntax_suggestion(def_id);
1416 bad_struct_syntax_suggestion(def_id);
1420 let is_accessible = self.r.is_accessible_from(ctor_vis, self.parent_scope.module);
1421 if !is_expected(ctor_def) || is_accessible {
1425 let field_spans = match source {
1426 // e.g. `if let Enum::TupleVariant(field1, field2) = _`
1427 PathSource::TupleStruct(_, pattern_spans) => {
1428 err.set_primary_message(
1429 "cannot match against a tuple struct which contains private fields",
1432 // Use spans of the tuple struct pattern.
1433 Some(Vec::from(pattern_spans))
1435 // e.g. `let _ = Enum::TupleVariant(field1, field2);`
1436 _ if source.is_call() => {
1437 err.set_primary_message(
1438 "cannot initialize a tuple struct which contains private fields",
1441 // Use spans of the tuple struct definition.
1445 .map(|fields| fields.iter().map(|f| f.span).collect::<Vec<_>>())
1450 if let Some(spans) =
1451 field_spans.filter(|spans| spans.len() > 0 && fields.len() == spans.len())
1453 let non_visible_spans: Vec<Span> = iter::zip(&fields, &spans)
1454 .filter(|(vis, _)| {
1455 !self.r.is_accessible_from(**vis, self.parent_scope.module)
1457 .map(|(_, span)| *span)
1460 if non_visible_spans.len() > 0 {
1461 if let Some(fields) = self.r.field_visibility_spans.get(&def_id) {
1462 err.multipart_suggestion_verbose(
1464 "consider making the field{} publicly accessible",
1465 pluralize!(fields.len())
1467 fields.iter().map(|span| (*span, "pub ".to_string())).collect(),
1468 Applicability::MaybeIncorrect,
1472 let mut m: MultiSpan = non_visible_spans.clone().into();
1475 .for_each(|s| m.push_span_label(s, "private field"));
1476 err.span_note(m, "constructor is not visible here due to private fields");
1482 err.span_label(span, "constructor is not visible here due to private fields");
1484 (Res::Def(DefKind::Union | DefKind::Variant, def_id), _) if ns == ValueNS => {
1485 bad_struct_syntax_suggestion(def_id);
1487 (Res::Def(DefKind::Ctor(_, CtorKind::Const), def_id), _) if ns == ValueNS => {
1489 PathSource::Expr(_) | PathSource::TupleStruct(..) | PathSource::Pat => {
1490 let span = find_span(&source, err);
1491 if let Some(span) = self.def_span(def_id) {
1492 err.span_label(span, &format!("`{}` defined here", path_str));
1494 err.span_suggestion(
1496 "use this syntax instead",
1498 Applicability::MaybeIncorrect,
1504 (Res::Def(DefKind::Ctor(_, CtorKind::Fn), ctor_def_id), _) if ns == ValueNS => {
1505 let def_id = self.r.parent(ctor_def_id);
1506 if let Some(span) = self.def_span(def_id) {
1507 err.span_label(span, &format!("`{}` defined here", path_str));
1509 let fields = self.r.field_names.get(&def_id).map_or_else(
1510 || "/* fields */".to_string(),
1511 |fields| vec!["_"; fields.len()].join(", "),
1513 err.span_suggestion(
1515 "use the tuple variant pattern syntax instead",
1516 format!("{}({})", path_str, fields),
1517 Applicability::HasPlaceholders,
1520 (Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }, _) if ns == ValueNS => {
1521 err.span_label(span, fallback_label);
1522 err.note("can't use `Self` as a constructor, you must use the implemented struct");
1524 (Res::Def(DefKind::TyAlias | DefKind::AssocTy, _), _) if ns == ValueNS => {
1525 err.note("can't use a type alias as a constructor");
1532 /// Given the target `ident` and `kind`, search for the similarly named associated item
1533 /// in `self.current_trait_ref`.
1534 pub(crate) fn find_similarly_named_assoc_item(
1537 kind: &AssocItemKind,
1538 ) -> Option<Symbol> {
1539 let (module, _) = self.current_trait_ref.as_ref()?;
1540 if ident == kw::Underscore {
1541 // We do nothing for `_`.
1545 let resolutions = self.r.resolutions(module);
1546 let targets = resolutions
1549 .filter_map(|(key, res)| res.borrow().binding.map(|binding| (key, binding.res())))
1550 .filter(|(_, res)| match (kind, res) {
1551 (AssocItemKind::Const(..), Res::Def(DefKind::AssocConst, _)) => true,
1552 (AssocItemKind::Fn(_), Res::Def(DefKind::AssocFn, _)) => true,
1553 (AssocItemKind::Type(..), Res::Def(DefKind::AssocTy, _)) => true,
1556 .map(|(key, _)| key.ident.name)
1557 .collect::<Vec<_>>();
1559 find_best_match_for_name(&targets, ident, None)
1562 fn lookup_assoc_candidate<FilterFn>(
1566 filter_fn: FilterFn,
1568 ) -> Option<AssocSuggestion>
1570 FilterFn: Fn(Res) -> bool,
1572 fn extract_node_id(t: &Ty) -> Option<NodeId> {
1574 TyKind::Path(None, _) => Some(t.id),
1575 TyKind::Ref(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
1576 // This doesn't handle the remaining `Ty` variants as they are not
1577 // that commonly the self_type, it might be interesting to provide
1578 // support for those in future.
1582 // Fields are generally expected in the same contexts as locals.
1583 if filter_fn(Res::Local(ast::DUMMY_NODE_ID)) {
1584 if let Some(node_id) =
1585 self.diagnostic_metadata.current_self_type.as_ref().and_then(extract_node_id)
1587 // Look for a field with the same name in the current self_type.
1588 if let Some(resolution) = self.r.partial_res_map.get(&node_id) {
1589 if let Some(Res::Def(DefKind::Struct | DefKind::Union, did)) =
1590 resolution.full_res()
1592 if let Some(field_names) = self.r.field_names.get(&did) {
1593 if field_names.iter().any(|&field_name| ident.name == field_name.node) {
1594 return Some(AssocSuggestion::Field);
1602 if let Some(items) = self.diagnostic_metadata.current_trait_assoc_items {
1603 for assoc_item in items {
1604 if assoc_item.ident == ident {
1605 return Some(match &assoc_item.kind {
1606 ast::AssocItemKind::Const(..) => AssocSuggestion::AssocConst,
1607 ast::AssocItemKind::Fn(box ast::Fn { sig, .. }) if sig.decl.has_self() => {
1608 AssocSuggestion::MethodWithSelf { called }
1610 ast::AssocItemKind::Fn(..) => AssocSuggestion::AssocFn { called },
1611 ast::AssocItemKind::Type(..) => AssocSuggestion::AssocType,
1612 ast::AssocItemKind::MacCall(_) => continue,
1618 // Look for associated items in the current trait.
1619 if let Some((module, _)) = self.current_trait_ref {
1620 if let Ok(binding) = self.r.maybe_resolve_ident_in_module(
1621 ModuleOrUniformRoot::Module(module),
1626 let res = binding.res();
1628 if self.r.has_self.contains(&res.def_id()) {
1629 return Some(AssocSuggestion::MethodWithSelf { called });
1632 Res::Def(DefKind::AssocFn, _) => {
1633 return Some(AssocSuggestion::AssocFn { called });
1635 Res::Def(DefKind::AssocConst, _) => {
1636 return Some(AssocSuggestion::AssocConst);
1638 Res::Def(DefKind::AssocTy, _) => {
1639 return Some(AssocSuggestion::AssocType);
1651 fn lookup_typo_candidate(
1655 filter_fn: &impl Fn(Res) -> bool,
1656 ) -> TypoCandidate {
1657 let mut names = Vec::new();
1658 if path.len() == 1 {
1659 let mut ctxt = path.last().unwrap().ident.span.ctxt();
1661 // Search in lexical scope.
1662 // Walk backwards up the ribs in scope and collect candidates.
1663 for rib in self.ribs[ns].iter().rev() {
1664 let rib_ctxt = if rib.kind.contains_params() {
1665 ctxt.normalize_to_macros_2_0()
1667 ctxt.normalize_to_macro_rules()
1670 // Locals and type parameters
1671 for (ident, &res) in &rib.bindings {
1672 if filter_fn(res) && ident.span.ctxt() == rib_ctxt {
1673 names.push(TypoSuggestion::typo_from_ident(*ident, res));
1677 if let RibKind::MacroDefinition(def) = rib.kind && def == self.r.macro_def(ctxt) {
1678 // If an invocation of this macro created `ident`, give up on `ident`
1679 // and switch to `ident`'s source from the macro definition.
1685 if let RibKind::ModuleRibKind(module) = rib.kind {
1686 // Items from this module
1687 self.r.add_module_candidates(module, &mut names, &filter_fn, Some(ctxt));
1689 if let ModuleKind::Block = module.kind {
1690 // We can see through blocks
1692 // Items from the prelude
1693 if !module.no_implicit_prelude {
1694 let extern_prelude = self.r.extern_prelude.clone();
1695 names.extend(extern_prelude.iter().flat_map(|(ident, _)| {
1698 .maybe_process_path_extern(ident.name)
1699 .and_then(|crate_id| {
1701 Res::Def(DefKind::Mod, crate_id.as_def_id());
1703 if filter_fn(crate_mod) {
1704 Some(TypoSuggestion::typo_from_ident(*ident, crate_mod))
1711 if let Some(prelude) = self.r.prelude {
1712 self.r.add_module_candidates(prelude, &mut names, &filter_fn, None);
1719 // Add primitive types to the mix
1720 if filter_fn(Res::PrimTy(PrimTy::Bool)) {
1721 names.extend(PrimTy::ALL.iter().map(|prim_ty| {
1722 TypoSuggestion::typo_from_name(prim_ty.name(), Res::PrimTy(*prim_ty))
1726 // Search in module.
1727 let mod_path = &path[..path.len() - 1];
1728 if let PathResult::Module(ModuleOrUniformRoot::Module(module)) =
1729 self.resolve_path(mod_path, Some(TypeNS), None)
1731 self.r.add_module_candidates(module, &mut names, &filter_fn, None);
1735 let name = path[path.len() - 1].ident.name;
1736 // Make sure error reporting is deterministic.
1737 names.sort_by(|a, b| a.candidate.as_str().partial_cmp(b.candidate.as_str()).unwrap());
1739 match find_best_match_for_name(
1740 &names.iter().map(|suggestion| suggestion.candidate).collect::<Vec<Symbol>>(),
1745 let Some(sugg) = names.into_iter().find(|suggestion| suggestion.candidate == found) else {
1746 return TypoCandidate::None;
1749 TypoCandidate::Shadowed(sugg.res, sugg.span)
1751 TypoCandidate::Typo(sugg)
1754 _ => TypoCandidate::None,
1758 // Returns the name of the Rust type approximately corresponding to
1759 // a type name in another programming language.
1760 fn likely_rust_type(path: &[Segment]) -> Option<Symbol> {
1761 let name = path[path.len() - 1].ident.as_str();
1762 // Common Java types
1764 "byte" => sym::u8, // In Java, bytes are signed, but in practice one almost always wants unsigned bytes.
1765 "short" => sym::i16,
1766 "Bool" => sym::bool,
1767 "Boolean" => sym::bool,
1768 "boolean" => sym::bool,
1771 "float" => sym::f32,
1772 "double" => sym::f64,
1777 /// Only used in a specific case of type ascription suggestions
1778 fn get_colon_suggestion_span(&self, start: Span) -> Span {
1779 let sm = self.r.session.source_map();
1780 start.to(sm.next_point(start))
1783 fn type_ascription_suggestion(&self, err: &mut Diagnostic, base_span: Span) -> bool {
1784 let sm = self.r.session.source_map();
1785 let base_snippet = sm.span_to_snippet(base_span);
1786 if let Some(&sp) = self.diagnostic_metadata.current_type_ascription.last() {
1787 if let Ok(snippet) = sm.span_to_snippet(sp) {
1788 let len = snippet.trim_end().len() as u32;
1789 if snippet.trim() == ":" {
1791 sp.with_lo(sp.lo() + BytePos(len - 1)).with_hi(sp.lo() + BytePos(len));
1792 let mut show_label = true;
1793 if sm.is_multiline(sp) {
1794 err.span_suggestion_short(
1796 "maybe you meant to write `;` here",
1798 Applicability::MaybeIncorrect,
1801 let after_colon_sp =
1802 self.get_colon_suggestion_span(colon_sp.shrink_to_hi());
1803 if snippet.len() == 1 {
1805 err.span_suggestion(
1807 "maybe you meant to write a path separator here",
1809 Applicability::MaybeIncorrect,
1816 .type_ascription_path_suggestions
1820 err.downgrade_to_delayed_bug();
1823 if let Ok(base_snippet) = base_snippet {
1824 // Try to find an assignment
1825 let eq_span = sm.span_look_ahead(after_colon_sp, Some("="), Some(50));
1826 if let Ok(ref snippet) = sm.span_to_snippet(eq_span) && snippet == "=" {
1827 err.span_suggestion(
1829 "maybe you meant to write an assignment here",
1830 format!("let {}", base_snippet),
1831 Applicability::MaybeIncorrect,
1840 "expecting a type here because of type ascription",
1850 // try to give a suggestion for this pattern: `name = blah`, which is common in other languages
1851 // suggest `let name = blah` to introduce a new binding
1852 fn let_binding_suggestion(&mut self, err: &mut Diagnostic, ident_span: Span) -> bool {
1853 if let Some(Expr { kind: ExprKind::Assign(lhs, .. ), .. }) = self.diagnostic_metadata.in_assignment &&
1854 let ast::ExprKind::Path(None, _) = lhs.kind {
1855 if !ident_span.from_expansion() {
1856 err.span_suggestion_verbose(
1857 ident_span.shrink_to_lo(),
1858 "you might have meant to introduce a new binding",
1860 Applicability::MaybeIncorrect,
1868 fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> {
1869 let mut result = None;
1870 let mut seen_modules = FxHashSet::default();
1871 let mut worklist = vec![(self.r.graph_root, ThinVec::new())];
1873 while let Some((in_module, path_segments)) = worklist.pop() {
1874 // abort if the module is already found
1875 if result.is_some() {
1879 in_module.for_each_child(self.r, |_, ident, _, name_binding| {
1880 // abort if the module is already found or if name_binding is private external
1881 if result.is_some() || !name_binding.vis.is_visible_locally() {
1884 if let Some(module) = name_binding.module() {
1886 let mut path_segments = path_segments.clone();
1887 path_segments.push(ast::PathSegment::from_ident(ident));
1888 let module_def_id = module.def_id();
1889 if module_def_id == def_id {
1891 Path { span: name_binding.span, segments: path_segments, tokens: None };
1903 // add the module to the lookup
1904 if seen_modules.insert(module_def_id) {
1905 worklist.push((module, path_segments));
1915 fn collect_enum_ctors(&mut self, def_id: DefId) -> Option<Vec<(Path, DefId, CtorKind)>> {
1916 self.find_module(def_id).map(|(enum_module, enum_import_suggestion)| {
1917 let mut variants = Vec::new();
1918 enum_module.for_each_child(self.r, |_, ident, _, name_binding| {
1919 if let Res::Def(DefKind::Ctor(CtorOf::Variant, kind), def_id) = name_binding.res() {
1920 let mut segms = enum_import_suggestion.path.segments.clone();
1921 segms.push(ast::PathSegment::from_ident(ident));
1922 let path = Path { span: name_binding.span, segments: segms, tokens: None };
1923 variants.push((path, def_id, kind));
1930 /// Adds a suggestion for using an enum's variant when an enum is used instead.
1931 fn suggest_using_enum_variant(
1933 err: &mut Diagnostic,
1934 source: PathSource<'_>,
1938 let Some(variants) = self.collect_enum_ctors(def_id) else {
1939 err.note("you might have meant to use one of the enum's variants");
1943 let suggest_only_tuple_variants =
1944 matches!(source, PathSource::TupleStruct(..)) || source.is_call();
1945 if suggest_only_tuple_variants {
1946 // Suggest only tuple variants regardless of whether they have fields and do not
1947 // suggest path with added parentheses.
1948 let suggestable_variants = variants
1950 .filter(|(.., kind)| *kind == CtorKind::Fn)
1951 .map(|(variant, ..)| path_names_to_string(variant))
1952 .collect::<Vec<_>>();
1954 let non_suggestable_variant_count = variants.len() - suggestable_variants.len();
1956 let source_msg = if source.is_call() {
1958 } else if matches!(source, PathSource::TupleStruct(..)) {
1964 if !suggestable_variants.is_empty() {
1965 let msg = if non_suggestable_variant_count == 0 && suggestable_variants.len() == 1 {
1966 format!("try {} the enum's variant", source_msg)
1968 format!("try {} one of the enum's variants", source_msg)
1971 err.span_suggestions(
1974 suggestable_variants,
1975 Applicability::MaybeIncorrect,
1979 // If the enum has no tuple variants..
1980 if non_suggestable_variant_count == variants.len() {
1981 err.help(&format!("the enum has no tuple variants {}", source_msg));
1984 // If there are also non-tuple variants..
1985 if non_suggestable_variant_count == 1 {
1987 "you might have meant {} the enum's non-tuple variant",
1990 } else if non_suggestable_variant_count >= 1 {
1992 "you might have meant {} one of the enum's non-tuple variants",
1997 let needs_placeholder = |ctor_def_id: DefId, kind: CtorKind| {
1998 let def_id = self.r.parent(ctor_def_id);
1999 let has_no_fields = self.r.field_names.get(&def_id).map_or(false, |f| f.is_empty());
2001 CtorKind::Const => false,
2002 CtorKind::Fn if has_no_fields => false,
2007 let suggestable_variants = variants
2009 .filter(|(_, def_id, kind)| !needs_placeholder(*def_id, *kind))
2010 .map(|(variant, _, kind)| (path_names_to_string(variant), kind))
2011 .map(|(variant, kind)| match kind {
2012 CtorKind::Const => variant,
2013 CtorKind::Fn => format!("({}())", variant),
2015 .collect::<Vec<_>>();
2016 let no_suggestable_variant = suggestable_variants.is_empty();
2018 if !no_suggestable_variant {
2019 let msg = if suggestable_variants.len() == 1 {
2020 "you might have meant to use the following enum variant"
2022 "you might have meant to use one of the following enum variants"
2025 err.span_suggestions(
2028 suggestable_variants,
2029 Applicability::MaybeIncorrect,
2033 let suggestable_variants_with_placeholders = variants
2035 .filter(|(_, def_id, kind)| needs_placeholder(*def_id, *kind))
2036 .map(|(variant, _, kind)| (path_names_to_string(variant), kind))
2037 .filter_map(|(variant, kind)| match kind {
2038 CtorKind::Fn => Some(format!("({}(/* fields */))", variant)),
2041 .collect::<Vec<_>>();
2043 if !suggestable_variants_with_placeholders.is_empty() {
2045 match (no_suggestable_variant, suggestable_variants_with_placeholders.len()) {
2046 (true, 1) => "the following enum variant is available",
2047 (true, _) => "the following enum variants are available",
2048 (false, 1) => "alternatively, the following enum variant is available",
2050 "alternatively, the following enum variants are also available"
2054 err.span_suggestions(
2057 suggestable_variants_with_placeholders,
2058 Applicability::HasPlaceholders,
2063 if def_id.is_local() {
2064 if let Some(span) = self.def_span(def_id) {
2065 err.span_note(span, "the enum is defined here");
2070 pub(crate) fn report_missing_type_error(
2073 ) -> Option<(Span, &'static str, String, Applicability)> {
2074 let (ident, span) = match path {
2076 if !segment.has_generic_args
2077 && segment.ident.name != kw::SelfUpper
2078 && segment.ident.name != kw::Dyn =>
2080 (segment.ident.to_string(), segment.ident.span)
2084 let mut iter = ident.chars().map(|c| c.is_uppercase());
2085 let single_uppercase_char =
2086 matches!(iter.next(), Some(true)) && matches!(iter.next(), None);
2087 if !self.diagnostic_metadata.currently_processing_generics && !single_uppercase_char {
2090 match (self.diagnostic_metadata.current_item, single_uppercase_char, self.diagnostic_metadata.currently_processing_generics) {
2091 (Some(Item { kind: ItemKind::Fn(..), ident, .. }), _, _) if ident.name == sym::main => {
2092 // Ignore `fn main()` as we don't want to suggest `fn main<T>()`
2097 kind @ ItemKind::Fn(..)
2098 | kind @ ItemKind::Enum(..)
2099 | kind @ ItemKind::Struct(..)
2100 | kind @ ItemKind::Union(..),
2105 // Without the 2nd `true`, we'd suggest `impl <T>` for `impl T` when a type `T` isn't found
2106 | (Some(Item { kind: kind @ ItemKind::Impl(..), .. }), true, true)
2107 | (Some(Item { kind, .. }), false, _) => {
2108 // Likely missing type parameter.
2109 if let Some(generics) = kind.generics() {
2110 if span.overlaps(generics.span) {
2111 // Avoid the following:
2112 // error[E0405]: cannot find trait `A` in this scope
2113 // --> $DIR/typo-suggestion-named-underscore.rs:CC:LL
2115 // L | fn foo<T: A>(x: T) {} // Shouldn't suggest underscore
2116 // | ^- help: you might be missing a type parameter: `, A`
2118 // | not found in this scope
2121 let msg = "you might be missing a type parameter";
2122 let (span, sugg) = if let [.., param] = &generics.params[..] {
2123 let span = if let [.., bound] = ¶m.bounds[..] {
2125 } else if let GenericParam {
2126 kind: GenericParamKind::Const { ty, kw_span: _, default }, ..
2128 default.as_ref().map(|def| def.value.span).unwrap_or(ty.span)
2132 (span, format!(", {}", ident))
2134 (generics.span, format!("<{}>", ident))
2136 // Do not suggest if this is coming from macro expansion.
2137 if span.can_be_used_for_suggestions() {
2139 span.shrink_to_hi(),
2142 Applicability::MaybeIncorrect,
2152 /// Given the target `label`, search the `rib_index`th label rib for similarly named labels,
2153 /// optionally returning the closest match and whether it is reachable.
2154 pub(crate) fn suggestion_for_label_in_rib(
2158 ) -> Option<LabelSuggestion> {
2159 // Are ribs from this `rib_index` within scope?
2160 let within_scope = self.is_label_valid_from_rib(rib_index);
2162 let rib = &self.label_ribs[rib_index];
2166 .filter(|(id, _)| id.span.eq_ctxt(label.span))
2167 .map(|(id, _)| id.name)
2168 .collect::<Vec<Symbol>>();
2170 find_best_match_for_name(&names, label.name, None).map(|symbol| {
2171 // Upon finding a similar name, get the ident that it was from - the span
2172 // contained within helps make a useful diagnostic. In addition, determine
2173 // whether this candidate is within scope.
2174 let (ident, _) = rib.bindings.iter().find(|(ident, _)| ident.name == symbol).unwrap();
2175 (*ident, within_scope)
2179 pub(crate) fn maybe_report_lifetime_uses(
2181 generics_span: Span,
2182 params: &[ast::GenericParam],
2184 for (param_index, param) in params.iter().enumerate() {
2185 let GenericParamKind::Lifetime = param.kind else { continue };
2187 let def_id = self.r.local_def_id(param.id);
2189 let use_set = self.lifetime_uses.remove(&def_id);
2191 "Use set for {:?}({:?} at {:?}) is {:?}",
2192 def_id, param.ident, param.ident.span, use_set
2195 let deletion_span = || {
2196 if params.len() == 1 {
2197 // if sole lifetime, remove the entire `<>` brackets
2199 } else if param_index == 0 {
2200 // if removing within `<>` brackets, we also want to
2201 // delete a leading or trailing comma as appropriate
2203 param.span().find_ancestor_inside(generics_span),
2204 params[param_index + 1].span().find_ancestor_inside(generics_span),
2206 (Some(param_span), Some(next_param_span)) => {
2207 Some(param_span.to(next_param_span.shrink_to_lo()))
2212 // if removing within `<>` brackets, we also want to
2213 // delete a leading or trailing comma as appropriate
2215 param.span().find_ancestor_inside(generics_span),
2216 params[param_index - 1].span().find_ancestor_inside(generics_span),
2218 (Some(param_span), Some(prev_param_span)) => {
2219 Some(prev_param_span.shrink_to_hi().to(param_span))
2226 Some(LifetimeUseSet::Many) => {}
2227 Some(LifetimeUseSet::One { use_span, use_ctxt }) => {
2228 debug!(?param.ident, ?param.ident.span, ?use_span);
2230 let elidable = matches!(use_ctxt, LifetimeCtxt::Ref);
2232 let deletion_span = deletion_span();
2233 self.r.lint_buffer.buffer_lint_with_diagnostic(
2234 lint::builtin::SINGLE_USE_LIFETIMES,
2237 &format!("lifetime parameter `{}` only used once", param.ident),
2238 lint::BuiltinLintDiagnostics::SingleUseLifetime {
2239 param_span: param.ident.span,
2240 use_span: Some((use_span, elidable)),
2246 debug!(?param.ident, ?param.ident.span);
2248 let deletion_span = deletion_span();
2249 self.r.lint_buffer.buffer_lint_with_diagnostic(
2250 lint::builtin::UNUSED_LIFETIMES,
2253 &format!("lifetime parameter `{}` never used", param.ident),
2254 lint::BuiltinLintDiagnostics::SingleUseLifetime {
2255 param_span: param.ident.span,
2265 pub(crate) fn emit_undeclared_lifetime_error(
2267 lifetime_ref: &ast::Lifetime,
2268 outer_lifetime_ref: Option<Ident>,
2270 debug_assert_ne!(lifetime_ref.ident.name, kw::UnderscoreLifetime);
2271 let mut err = if let Some(outer) = outer_lifetime_ref {
2272 let mut err = struct_span_err!(
2274 lifetime_ref.ident.span,
2276 "can't use generic parameters from outer item",
2278 err.span_label(lifetime_ref.ident.span, "use of generic parameter from outer item");
2279 err.span_label(outer.span, "lifetime parameter from outer item");
2282 let mut err = struct_span_err!(
2284 lifetime_ref.ident.span,
2286 "use of undeclared lifetime name `{}`",
2289 err.span_label(lifetime_ref.ident.span, "undeclared lifetime");
2292 self.suggest_introducing_lifetime(
2294 Some(lifetime_ref.ident.name.as_str()),
2295 |err, _, span, message, suggestion| {
2296 err.span_suggestion(span, message, suggestion, Applicability::MaybeIncorrect);
2303 fn suggest_introducing_lifetime(
2305 err: &mut Diagnostic,
2307 suggest: impl Fn(&mut Diagnostic, bool, Span, &str, String) -> bool,
2309 let mut suggest_note = true;
2310 for rib in self.lifetime_ribs.iter().rev() {
2311 let mut should_continue = true;
2313 LifetimeRibKind::Generics { binder: _, span, kind } => {
2314 if !span.can_be_used_for_suggestions() && suggest_note && let Some(name) = name {
2315 suggest_note = false; // Avoid displaying the same help multiple times.
2319 "lifetime `{}` is missing in item created through this procedural macro",
2326 let higher_ranked = matches!(
2328 LifetimeBinderKind::BareFnType
2329 | LifetimeBinderKind::PolyTrait
2330 | LifetimeBinderKind::WhereBound
2332 let (span, sugg) = if span.is_empty() {
2335 if higher_ranked { "for" } else { "" },
2336 name.unwrap_or("'a"),
2337 if higher_ranked { " " } else { "" },
2342 self.r.session.source_map().span_through_char(span, '<').shrink_to_hi();
2343 let sugg = format!("{}, ", name.unwrap_or("'a"));
2347 let message = format!(
2348 "consider making the {} lifetime-generic with a new `{}` lifetime",
2350 name.unwrap_or("'a"),
2352 should_continue = suggest(err, true, span, &message, sugg);
2354 "for more information on higher-ranked polymorphism, visit \
2355 https://doc.rust-lang.org/nomicon/hrtb.html",
2357 } else if let Some(name) = name {
2358 let message = format!("consider introducing lifetime `{}` here", name);
2359 should_continue = suggest(err, false, span, &message, sugg);
2361 let message = "consider introducing a named lifetime parameter";
2362 should_continue = suggest(err, false, span, &message, sugg);
2365 LifetimeRibKind::Item => break,
2368 if !should_continue {
2374 pub(crate) fn emit_non_static_lt_in_const_generic_error(&self, lifetime_ref: &ast::Lifetime) {
2377 lifetime_ref.ident.span,
2379 "use of non-static lifetime `{}` in const generic",
2383 "for more information, see issue #74052 \
2384 <https://github.com/rust-lang/rust/issues/74052>",
2389 /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`.
2390 /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by
2391 /// `body_id` is an anonymous constant and `lifetime_ref` is non-static.
2392 pub(crate) fn maybe_emit_forbidden_non_static_lifetime_error(
2394 lifetime_ref: &ast::Lifetime,
2396 let feature_active = self.r.session.features_untracked().generic_const_exprs;
2397 if !feature_active {
2399 &self.r.session.parse_sess,
2400 sym::generic_const_exprs,
2401 lifetime_ref.ident.span,
2402 "a non-static lifetime is not allowed in a `const`",
2408 pub(crate) fn report_missing_lifetime_specifiers(
2410 lifetime_refs: Vec<MissingLifetime>,
2411 function_param_lifetimes: Option<(Vec<MissingLifetime>, Vec<ElisionFnParameter>)>,
2412 ) -> ErrorGuaranteed {
2413 let num_lifetimes: usize = lifetime_refs.iter().map(|lt| lt.count).sum();
2414 let spans: Vec<_> = lifetime_refs.iter().map(|lt| lt.span).collect();
2416 let mut err = struct_span_err!(
2420 "missing lifetime specifier{}",
2421 pluralize!(num_lifetimes)
2423 self.add_missing_lifetime_specifiers_label(
2426 function_param_lifetimes,
2431 fn add_missing_lifetime_specifiers_label(
2433 err: &mut Diagnostic,
2434 lifetime_refs: Vec<MissingLifetime>,
2435 function_param_lifetimes: Option<(Vec<MissingLifetime>, Vec<ElisionFnParameter>)>,
2437 for < in &lifetime_refs {
2441 "expected {} lifetime parameter{}",
2442 if lt.count == 1 { "named".to_string() } else { lt.count.to_string() },
2443 pluralize!(lt.count),
2448 let mut in_scope_lifetimes: Vec<_> = self
2452 .take_while(|rib| !matches!(rib.kind, LifetimeRibKind::Item))
2453 .flat_map(|rib| rib.bindings.iter())
2454 .map(|(&ident, &res)| (ident, res))
2455 .filter(|(ident, _)| ident.name != kw::UnderscoreLifetime)
2457 debug!(?in_scope_lifetimes);
2459 debug!(?function_param_lifetimes);
2460 if let Some((param_lifetimes, params)) = &function_param_lifetimes {
2461 let elided_len = param_lifetimes.len();
2462 let num_params = params.len();
2464 let mut m = String::new();
2466 for (i, info) in params.iter().enumerate() {
2467 let ElisionFnParameter { ident, index, lifetime_count, span } = *info;
2468 debug_assert_ne!(lifetime_count, 0);
2470 err.span_label(span, "");
2473 if i + 1 < num_params {
2475 } else if num_params == 2 {
2478 m.push_str(", or ");
2482 let help_name = if let Some(ident) = ident {
2483 format!("`{}`", ident)
2485 format!("argument {}", index + 1)
2488 if lifetime_count == 1 {
2489 m.push_str(&help_name[..])
2491 m.push_str(&format!("one of {}'s {} lifetimes", help_name, lifetime_count)[..])
2495 if num_params == 0 {
2497 "this function's return type contains a borrowed value, \
2498 but there is no value for it to be borrowed from",
2500 if in_scope_lifetimes.is_empty() {
2501 in_scope_lifetimes = vec![(
2502 Ident::with_dummy_span(kw::StaticLifetime),
2503 (DUMMY_NODE_ID, LifetimeRes::Static),
2506 } else if elided_len == 0 {
2508 "this function's return type contains a borrowed value with \
2509 an elided lifetime, but the lifetime cannot be derived from \
2512 if in_scope_lifetimes.is_empty() {
2513 in_scope_lifetimes = vec![(
2514 Ident::with_dummy_span(kw::StaticLifetime),
2515 (DUMMY_NODE_ID, LifetimeRes::Static),
2518 } else if num_params == 1 {
2520 "this function's return type contains a borrowed value, \
2521 but the signature does not say which {} it is borrowed from",
2526 "this function's return type contains a borrowed value, \
2527 but the signature does not say whether it is borrowed from {}",
2533 let existing_name = match &in_scope_lifetimes[..] {
2534 [] => Symbol::intern("'a"),
2535 [(existing, _)] => existing.name,
2536 _ => Symbol::intern("'lifetime"),
2539 let mut spans_suggs: Vec<_> = Vec::new();
2540 let build_sugg = |lt: MissingLifetime| match lt.kind {
2541 MissingLifetimeKind::Underscore => {
2542 debug_assert_eq!(lt.count, 1);
2543 (lt.span, existing_name.to_string())
2545 MissingLifetimeKind::Ampersand => {
2546 debug_assert_eq!(lt.count, 1);
2547 (lt.span.shrink_to_hi(), format!("{} ", existing_name))
2549 MissingLifetimeKind::Comma => {
2550 let sugg: String = std::iter::repeat([existing_name.as_str(), ", "])
2554 (lt.span.shrink_to_hi(), sugg)
2556 MissingLifetimeKind::Brackets => {
2557 let sugg: String = std::iter::once("<")
2559 std::iter::repeat(existing_name.as_str()).take(lt.count).intersperse(", "),
2563 (lt.span.shrink_to_hi(), sugg)
2566 for < in &lifetime_refs {
2567 spans_suggs.push(build_sugg(lt));
2569 debug!(?spans_suggs);
2570 match in_scope_lifetimes.len() {
2572 if let Some((param_lifetimes, _)) = function_param_lifetimes {
2573 for lt in param_lifetimes {
2574 spans_suggs.push(build_sugg(lt))
2577 self.suggest_introducing_lifetime(
2580 |err, higher_ranked, span, message, intro_sugg| {
2581 err.multipart_suggestion_verbose(
2583 std::iter::once((span, intro_sugg))
2584 .chain(spans_suggs.iter().cloned())
2586 Applicability::MaybeIncorrect,
2593 err.multipart_suggestion_verbose(
2594 &format!("consider using the `{}` lifetime", existing_name),
2596 Applicability::MaybeIncorrect,
2599 // Record as using the suggested resolution.
2600 let (_, (_, res)) = in_scope_lifetimes[0];
2601 for < in &lifetime_refs {
2602 self.r.lifetimes_res_map.insert(lt.id, res);
2606 let lifetime_spans: Vec<_> =
2607 in_scope_lifetimes.iter().map(|(ident, _)| ident.span).collect();
2608 err.span_note(lifetime_spans, "these named lifetimes are available to use");
2610 if spans_suggs.len() > 0 {
2611 // This happens when we have `Foo<T>` where we point at the space before `T`,
2612 // but this can be confusing so we give a suggestion with placeholders.
2613 err.multipart_suggestion_verbose(
2614 "consider using one of the available lifetimes here",
2616 Applicability::HasPlaceholders,
2624 /// Report lifetime/lifetime shadowing as an error.
2625 pub fn signal_lifetime_shadowing(sess: &Session, orig: Ident, shadower: Ident) {
2626 let mut err = struct_span_err!(
2630 "lifetime name `{}` shadows a lifetime name that is already in scope",
2633 err.span_label(orig.span, "first declared here");
2634 err.span_label(shadower.span, format!("lifetime `{}` already in scope", orig.name));
2638 /// Shadowing involving a label is only a warning for historical reasons.
2639 //FIXME: make this a proper lint.
2640 pub fn signal_label_shadowing(sess: &Session, orig: Span, shadower: Ident) {
2641 let name = shadower.name;
2642 let shadower = shadower.span;
2643 let mut err = sess.struct_span_warn(
2645 &format!("label name `{}` shadows a label name that is already in scope", name),
2647 err.span_label(orig, "first declared here");
2648 err.span_label(shadower, format!("label `{}` already in scope", name));