1 use crate::diagnostics::{ImportSuggestion, TypoSuggestion};
2 use crate::late::lifetimes::{ElisionFailureInfo, LifetimeContext};
3 use crate::late::{LateResolutionVisitor, RibKind};
4 use crate::path_names_to_string;
5 use crate::{CrateLint, Module, ModuleKind, ModuleOrUniformRoot};
6 use crate::{PathResult, PathSource, Segment};
8 use rustc::session::config::nightly_options;
9 use rustc_data_structures::fx::FxHashSet;
10 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder};
12 use rustc_hir::def::Namespace::{self, *};
13 use rustc_hir::def::{self, CtorKind, DefKind};
14 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
15 use rustc_hir::PrimTy;
16 use rustc_span::hygiene::MacroKind;
17 use rustc_span::symbol::{kw, sym};
19 use syntax::ast::{self, Expr, ExprKind, Ident, Item, ItemKind, NodeId, Path, Ty, TyKind};
20 use syntax::util::lev_distance::find_best_match_for_name;
24 type Res = def::Res<ast::NodeId>;
26 /// A field or associated item from self type suggested in case of resolution failure.
27 enum AssocSuggestion {
33 crate enum MissingLifetimeSpot<'tcx> {
34 Generics(&'tcx hir::Generics<'tcx>),
35 HigherRanked { span: Span, span_type: ForLifetimeSpanType },
38 crate enum ForLifetimeSpanType {
45 impl ForLifetimeSpanType {
46 crate fn descr(&self) -> &'static str {
48 Self::BoundEmpty | Self::BoundTail => "bound",
49 Self::TypeEmpty | Self::TypeTail => "type",
53 crate fn suggestion(&self, sugg: &str) -> String {
55 Self::BoundEmpty | Self::TypeEmpty => format!("for<{}> ", sugg),
56 Self::BoundTail | Self::TypeTail => format!(", {}", sugg),
61 impl<'tcx> Into<MissingLifetimeSpot<'tcx>> for &'tcx hir::Generics<'tcx> {
62 fn into(self) -> MissingLifetimeSpot<'tcx> {
63 MissingLifetimeSpot::Generics(self)
67 fn is_self_type(path: &[Segment], namespace: Namespace) -> bool {
68 namespace == TypeNS && path.len() == 1 && path[0].ident.name == kw::SelfUpper
71 fn is_self_value(path: &[Segment], namespace: Namespace) -> bool {
72 namespace == ValueNS && path.len() == 1 && path[0].ident.name == kw::SelfLower
75 /// Gets the stringified path for an enum from an `ImportSuggestion` for an enum variant.
76 fn import_candidate_to_enum_paths(suggestion: &ImportSuggestion) -> (String, String) {
77 let variant_path = &suggestion.path;
78 let variant_path_string = path_names_to_string(variant_path);
80 let path_len = suggestion.path.segments.len();
81 let enum_path = ast::Path {
82 span: suggestion.path.span,
83 segments: suggestion.path.segments[0..path_len - 1].to_vec(),
85 let enum_path_string = path_names_to_string(&enum_path);
87 (variant_path_string, enum_path_string)
90 impl<'a> LateResolutionVisitor<'a, '_, '_> {
91 /// Handles error reporting for `smart_resolve_path_fragment` function.
92 /// Creates base error and amends it with one short label and possibly some longer helps/notes.
93 pub(crate) fn smart_resolve_report_errors(
97 source: PathSource<'_>,
99 ) -> (DiagnosticBuilder<'a>, Vec<ImportSuggestion>) {
100 let ident_span = path.last().map_or(span, |ident| ident.ident.span);
101 let ns = source.namespace();
102 let is_expected = &|res| source.is_expected(res);
103 let is_enum_variant = &|res| {
104 if let Res::Def(DefKind::Variant, _) = res { true } else { false }
107 // Make the base error.
108 let expected = source.descr_expected();
109 let path_str = Segment::names_to_string(path);
110 let item_str = path.last().unwrap().ident;
111 let (base_msg, fallback_label, base_span, could_be_expr) = if let Some(res) = res {
113 format!("expected {}, found {} `{}`", expected, res.descr(), path_str),
114 format!("not a {}", expected),
117 Res::Def(DefKind::Fn, _) => {
118 // Verify whether this is a fn call or an Fn used as a type.
122 .span_to_snippet(span)
123 .map(|snippet| snippet.ends_with(')'))
126 Res::Def(DefKind::Ctor(..), _)
127 | Res::Def(DefKind::Method, _)
128 | Res::Def(DefKind::Const, _)
129 | Res::Def(DefKind::AssocConst, _)
132 | Res::Local(_) => true,
137 let item_span = path.last().unwrap().ident.span;
138 let (mod_prefix, mod_str) = if path.len() == 1 {
139 (String::new(), "this scope".to_string())
140 } else if path.len() == 2 && path[0].ident.name == kw::PathRoot {
141 (String::new(), "the crate root".to_string())
143 let mod_path = &path[..path.len() - 1];
145 match self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No) {
146 PathResult::Module(ModuleOrUniformRoot::Module(module)) => module.res(),
149 .map_or(String::new(), |res| format!("{} ", res.descr()));
150 (mod_prefix, format!("`{}`", Segment::names_to_string(mod_path)))
153 format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
154 format!("not found in {}", mod_str),
160 let code = source.error_code(res.is_some());
161 let mut err = self.r.session.struct_span_err_with_code(base_span, &base_msg, code);
163 // Emit help message for fake-self from other languages (e.g., `this` in Javascript).
164 if ["this", "my"].contains(&&*item_str.as_str())
165 && self.self_value_is_available(path[0].ident.span, span)
171 Applicability::MaybeIncorrect,
175 // Emit special messages for unresolved `Self` and `self`.
176 if is_self_type(path, ns) {
177 err.code(rustc_errors::error_code!(E0411));
180 format!("`Self` is only available in impls, traits, and type definitions"),
182 return (err, Vec::new());
184 if is_self_value(path, ns) {
185 debug!("smart_resolve_path_fragment: E0424, source={:?}", source);
187 err.code(rustc_errors::error_code!(E0424));
188 err.span_label(span, match source {
189 PathSource::Pat => format!(
190 "`self` value is a keyword and may not be bound to variables or shadowed",
193 "`self` value is a keyword only available in methods with a `self` parameter",
196 if let Some(span) = &self.diagnostic_metadata.current_function {
197 err.span_label(*span, "this function doesn't have a `self` parameter");
199 return (err, Vec::new());
202 // Try to lookup name in more relaxed fashion for better error reporting.
203 let ident = path.last().unwrap().ident;
204 let candidates = self
206 .lookup_import_candidates(ident, ns, is_expected)
208 .filter(|ImportSuggestion { did, .. }| {
209 match (did, res.and_then(|res| res.opt_def_id())) {
210 (Some(suggestion_did), Some(actual_did)) => *suggestion_did != actual_did,
214 .collect::<Vec<_>>();
215 let crate_def_id = DefId::local(CRATE_DEF_INDEX);
216 if candidates.is_empty() && is_expected(Res::Def(DefKind::Enum, crate_def_id)) {
217 let enum_candidates = self.r.lookup_import_candidates(ident, ns, is_enum_variant);
218 let mut enum_candidates = enum_candidates
220 .map(|suggestion| import_candidate_to_enum_paths(&suggestion))
221 .collect::<Vec<_>>();
222 enum_candidates.sort();
224 if !enum_candidates.is_empty() {
225 // Contextualize for E0412 "cannot find type", but don't belabor the point
226 // (that it's a variant) for E0573 "expected type, found variant".
227 let preamble = if res.is_none() {
228 let others = match enum_candidates.len() {
230 2 => " and 1 other".to_owned(),
231 n => format!(" and {} others", n),
233 format!("there is an enum variant `{}`{}; ", enum_candidates[0].0, others)
237 let msg = format!("{}try using the variant's enum", preamble);
239 err.span_suggestions(
244 .map(|(_variant_path, enum_ty_path)| enum_ty_path)
245 // Variants re-exported in prelude doesn't mean `prelude::v1` is the
247 // FIXME: is there a more principled way to do this that
248 // would work for other re-exports?
249 .filter(|enum_ty_path| enum_ty_path != "std::prelude::v1")
250 // Also write `Option` rather than `std::prelude::v1::Option`.
251 .map(|enum_ty_path| {
252 // FIXME #56861: DRY-er prelude filtering.
253 enum_ty_path.trim_start_matches("std::prelude::v1::").to_owned()
255 Applicability::MachineApplicable,
259 if path.len() == 1 && self.self_type_is_available(span) {
260 if let Some(candidate) = self.lookup_assoc_candidate(ident, ns, is_expected) {
261 let self_is_available = self.self_value_is_available(path[0].ident.span, span);
263 AssocSuggestion::Field => {
264 if self_is_available {
267 "you might have meant to use the available field",
268 format!("self.{}", path_str),
269 Applicability::MachineApplicable,
272 err.span_label(span, "a field by this name exists in `Self`");
275 AssocSuggestion::MethodWithSelf if self_is_available => {
279 format!("self.{}", path_str),
280 Applicability::MachineApplicable,
283 AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
287 format!("Self::{}", path_str),
288 Applicability::MachineApplicable,
292 return (err, candidates);
295 // If the first argument in call is `self` suggest calling a method.
296 if let Some((call_span, args_span)) = self.call_has_self_arg(source) {
297 let mut args_snippet = String::new();
298 if let Some(args_span) = args_span {
299 if let Ok(snippet) = self.r.session.source_map().span_to_snippet(args_span) {
300 args_snippet = snippet;
306 &format!("try calling `{}` as a method", ident),
307 format!("self.{}({})", path_str, args_snippet),
308 Applicability::MachineApplicable,
310 return (err, candidates);
314 // Try Levenshtein algorithm.
315 let typo_sugg = self.lookup_typo_candidate(path, ns, is_expected, span);
316 let levenshtein_worked = self.r.add_typo_suggestion(&mut err, typo_sugg, ident_span);
318 // Try context-dependent help if relaxed lookup didn't work.
319 if let Some(res) = res {
320 if self.smart_resolve_context_dependent_help(
328 return (err, candidates);
333 if !levenshtein_worked {
334 err.span_label(base_span, fallback_label);
335 self.type_ascription_suggestion(&mut err, base_span);
336 match self.diagnostic_metadata.current_let_binding {
337 Some((pat_sp, Some(ty_sp), None)) if ty_sp.contains(base_span) && could_be_expr => {
338 err.span_suggestion_short(
339 pat_sp.between(ty_sp),
340 "use `=` if you meant to assign",
342 Applicability::MaybeIncorrect,
351 /// Check if the source is call expression and the first argument is `self`. If true,
352 /// return the span of whole call and the span for all arguments expect the first one (`self`).
353 fn call_has_self_arg(&self, source: PathSource<'_>) -> Option<(Span, Option<Span>)> {
354 let mut has_self_arg = None;
355 if let PathSource::Expr(parent) = source {
356 match &parent?.kind {
357 ExprKind::Call(_, args) if args.len() > 0 => {
358 let mut expr_kind = &args[0].kind;
361 ExprKind::Path(_, arg_name) if arg_name.segments.len() == 1 => {
362 if arg_name.segments[0].ident.name == kw::SelfLower {
363 let call_span = parent.unwrap().span;
364 let tail_args_span = if args.len() > 1 {
367 args.last().unwrap().span.hi(),
373 has_self_arg = Some((call_span, tail_args_span));
377 ExprKind::AddrOf(_, _, expr) => expr_kind = &expr.kind,
388 fn followed_by_brace(&self, span: Span) -> (bool, Option<(Span, String)>) {
389 // HACK(estebank): find a better way to figure out that this was a
390 // parser issue where a struct literal is being used on an expression
391 // where a brace being opened means a block is being started. Look
392 // ahead for the next text to see if `span` is followed by a `{`.
393 let sm = self.r.session.source_map();
396 sp = sm.next_point(sp);
397 match sm.span_to_snippet(sp) {
399 if snippet.chars().any(|c| !c.is_whitespace()) {
406 let followed_by_brace = match sm.span_to_snippet(sp) {
407 Ok(ref snippet) if snippet == "{" => true,
410 // In case this could be a struct literal that needs to be surrounded
411 // by parenthesis, find the appropriate span.
413 let mut closing_brace = None;
415 sp = sm.next_point(sp);
416 match sm.span_to_snippet(sp) {
419 let sp = span.to(sp);
420 if let Ok(snippet) = sm.span_to_snippet(sp) {
421 closing_brace = Some((sp, snippet));
429 // The bigger the span, the more likely we're incorrect --
430 // bound it to 100 chars long.
435 return (followed_by_brace, closing_brace);
438 /// Provides context-dependent help for errors reported by the `smart_resolve_path_fragment`
440 /// Returns `true` if able to provide context-dependent help.
441 fn smart_resolve_context_dependent_help(
443 err: &mut DiagnosticBuilder<'a>,
445 source: PathSource<'_>,
448 fallback_label: &str,
450 let ns = source.namespace();
451 let is_expected = &|res| source.is_expected(res);
453 let path_sep = |err: &mut DiagnosticBuilder<'_>, expr: &Expr| match expr.kind {
454 ExprKind::Field(_, ident) => {
457 "use the path separator to refer to an item",
458 format!("{}::{}", path_str, ident),
459 Applicability::MaybeIncorrect,
463 ExprKind::MethodCall(ref segment, ..) => {
464 let span = expr.span.with_hi(segment.ident.span.hi());
467 "use the path separator to refer to an item",
468 format!("{}::{}", path_str, segment.ident),
469 Applicability::MaybeIncorrect,
476 let mut bad_struct_syntax_suggestion = |def_id: DefId| {
477 let (followed_by_brace, closing_brace) = self.followed_by_brace(span);
478 let mut suggested = false;
480 PathSource::Expr(Some(parent)) => {
481 suggested = path_sep(err, &parent);
483 PathSource::Expr(None) if followed_by_brace => {
484 if let Some((sp, snippet)) = closing_brace {
487 "surround the struct literal with parenthesis",
488 format!("({})", snippet),
489 Applicability::MaybeIncorrect,
493 span, // Note the parenthesis surrounding the suggestion below
494 format!("did you mean `({} {{ /* fields */ }})`?", path_str),
502 if let Some(span) = self.r.definitions.opt_span(def_id) {
503 err.span_label(span, &format!("`{}` defined here", path_str));
505 err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?", path_str));
509 match (res, source) {
510 (Res::Def(DefKind::Macro(MacroKind::Bang), _), _) => {
513 "use `!` to invoke the macro",
514 format!("{}!", path_str),
515 Applicability::MaybeIncorrect,
517 if path_str == "try" && span.rust_2015() {
518 err.note("if you want the `try` keyword, you need to be in the 2018 edition");
521 (Res::Def(DefKind::TyAlias, _), PathSource::Trait(_)) => {
522 err.span_label(span, "type aliases cannot be used as traits");
523 if nightly_options::is_nightly_build() {
524 err.note("did you mean to use a trait alias?");
527 (Res::Def(DefKind::Mod, _), PathSource::Expr(Some(parent))) => {
528 if !path_sep(err, &parent) {
532 (Res::Def(DefKind::Enum, def_id), PathSource::TupleStruct)
533 | (Res::Def(DefKind::Enum, def_id), PathSource::Expr(..)) => {
534 if let Some(variants) = self.collect_enum_variants(def_id) {
535 if !variants.is_empty() {
536 let msg = if variants.len() == 1 {
537 "try using the enum's variant"
539 "try using one of the enum's variants"
542 err.span_suggestions(
545 variants.iter().map(path_names_to_string),
546 Applicability::MaybeIncorrect,
550 err.note("did you mean to use one of the enum's variants?");
553 (Res::Def(DefKind::Struct, def_id), _) if ns == ValueNS => {
554 if let Some((ctor_def, ctor_vis)) = self.r.struct_constructors.get(&def_id).cloned()
556 let accessible_ctor =
557 self.r.is_accessible_from(ctor_vis, self.parent_scope.module);
558 if is_expected(ctor_def) && !accessible_ctor {
561 format!("constructor is not visible here due to private fields"),
565 bad_struct_syntax_suggestion(def_id);
568 (Res::Def(DefKind::Union, def_id), _)
569 | (Res::Def(DefKind::Variant, def_id), _)
570 | (Res::Def(DefKind::Ctor(_, CtorKind::Fictive), def_id), _)
573 bad_struct_syntax_suggestion(def_id);
575 (Res::Def(DefKind::Ctor(_, CtorKind::Fn), def_id), _) if ns == ValueNS => {
576 if let Some(span) = self.r.definitions.opt_span(def_id) {
577 err.span_label(span, &format!("`{}` defined here", path_str));
579 err.span_label(span, format!("did you mean `{}( /* fields */ )`?", path_str));
581 (Res::SelfTy(..), _) if ns == ValueNS => {
582 err.span_label(span, fallback_label);
583 err.note("can't use `Self` as a constructor, you must use the implemented struct");
585 (Res::Def(DefKind::TyAlias, _), _) | (Res::Def(DefKind::AssocTy, _), _)
588 err.note("can't use a type alias as a constructor");
595 fn lookup_assoc_candidate<FilterFn>(
600 ) -> Option<AssocSuggestion>
602 FilterFn: Fn(Res) -> bool,
604 fn extract_node_id(t: &Ty) -> Option<NodeId> {
606 TyKind::Path(None, _) => Some(t.id),
607 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
608 // This doesn't handle the remaining `Ty` variants as they are not
609 // that commonly the self_type, it might be interesting to provide
610 // support for those in future.
615 // Fields are generally expected in the same contexts as locals.
616 if filter_fn(Res::Local(ast::DUMMY_NODE_ID)) {
617 if let Some(node_id) =
618 self.diagnostic_metadata.current_self_type.as_ref().and_then(extract_node_id)
620 // Look for a field with the same name in the current self_type.
621 if let Some(resolution) = self.r.partial_res_map.get(&node_id) {
622 match resolution.base_res() {
623 Res::Def(DefKind::Struct, did) | Res::Def(DefKind::Union, did)
624 if resolution.unresolved_segments() == 0 =>
626 if let Some(field_names) = self.r.field_names.get(&did) {
629 .any(|&field_name| ident.name == field_name.node)
631 return Some(AssocSuggestion::Field);
641 for assoc_type_ident in &self.diagnostic_metadata.current_trait_assoc_types {
642 if *assoc_type_ident == ident {
643 return Some(AssocSuggestion::AssocItem);
647 // Look for associated items in the current trait.
648 if let Some((module, _)) = self.current_trait_ref {
649 if let Ok(binding) = self.r.resolve_ident_in_module(
650 ModuleOrUniformRoot::Module(module),
657 let res = binding.res();
659 return Some(if self.r.has_self.contains(&res.def_id()) {
660 AssocSuggestion::MethodWithSelf
662 AssocSuggestion::AssocItem
671 fn lookup_typo_candidate(
675 filter_fn: &impl Fn(Res) -> bool,
677 ) -> Option<TypoSuggestion> {
678 let mut names = Vec::new();
680 // Search in lexical scope.
681 // Walk backwards up the ribs in scope and collect candidates.
682 for rib in self.ribs[ns].iter().rev() {
683 // Locals and type parameters
684 for (ident, &res) in &rib.bindings {
686 names.push(TypoSuggestion::from_res(ident.name, res));
690 if let RibKind::ModuleRibKind(module) = rib.kind {
691 // Items from this module
692 self.r.add_module_candidates(module, &mut names, &filter_fn);
694 if let ModuleKind::Block(..) = module.kind {
695 // We can see through blocks
697 // Items from the prelude
698 if !module.no_implicit_prelude {
699 let extern_prelude = self.r.extern_prelude.clone();
700 names.extend(extern_prelude.iter().flat_map(|(ident, _)| {
703 .maybe_process_path_extern(ident.name, ident.span)
704 .and_then(|crate_id| {
705 let crate_mod = Res::Def(
707 DefId { krate: crate_id, index: CRATE_DEF_INDEX },
710 if filter_fn(crate_mod) {
711 Some(TypoSuggestion::from_res(ident.name, crate_mod))
718 if let Some(prelude) = self.r.prelude {
719 self.r.add_module_candidates(prelude, &mut names, &filter_fn);
726 // Add primitive types to the mix
727 if filter_fn(Res::PrimTy(PrimTy::Bool)) {
729 self.r.primitive_type_table.primitive_types.iter().map(|(name, prim_ty)| {
730 TypoSuggestion::from_res(*name, Res::PrimTy(*prim_ty))
736 let mod_path = &path[..path.len() - 1];
737 if let PathResult::Module(module) =
738 self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No)
740 if let ModuleOrUniformRoot::Module(module) = module {
741 self.r.add_module_candidates(module, &mut names, &filter_fn);
746 let name = path[path.len() - 1].ident.name;
747 // Make sure error reporting is deterministic.
748 names.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
750 match find_best_match_for_name(
751 names.iter().map(|suggestion| &suggestion.candidate),
755 Some(found) if found != name => {
756 names.into_iter().find(|suggestion| suggestion.candidate == found)
762 /// Only used in a specific case of type ascription suggestions
763 fn get_colon_suggestion_span(&self, start: Span) -> Span {
764 let sm = self.r.session.source_map();
765 start.to(sm.next_point(start))
768 fn type_ascription_suggestion(&self, err: &mut DiagnosticBuilder<'_>, base_span: Span) {
769 let sm = self.r.session.source_map();
770 let base_snippet = sm.span_to_snippet(base_span);
771 if let Some(sp) = self.diagnostic_metadata.current_type_ascription.last() {
774 // Try to find the `:`; bail on first non-':' / non-whitespace.
775 sp = sm.next_point(sp);
776 if let Ok(snippet) = sm.span_to_snippet(sp.to(sm.next_point(sp))) {
777 let line_sp = sm.lookup_char_pos(sp.hi()).line;
778 let line_base_sp = sm.lookup_char_pos(base_span.lo()).line;
780 let mut show_label = true;
781 if line_sp != line_base_sp {
782 err.span_suggestion_short(
784 "did you mean to use `;` here instead?",
786 Applicability::MaybeIncorrect,
789 let colon_sp = self.get_colon_suggestion_span(sp);
791 self.get_colon_suggestion_span(colon_sp.shrink_to_hi());
793 .span_to_snippet(after_colon_sp)
799 "maybe you meant to write a path separator here",
801 Applicability::MaybeIncorrect,
805 if let Ok(base_snippet) = base_snippet {
806 let mut sp = after_colon_sp;
808 // Try to find an assignment
809 sp = sm.next_point(sp);
810 let snippet = sm.span_to_snippet(sp.to(sm.next_point(sp)));
812 Ok(ref x) if x.as_str() == "=" => {
815 "maybe you meant to write an assignment here",
816 format!("let {}", base_snippet),
817 Applicability::MaybeIncorrect,
822 Ok(ref x) if x.as_str() == "\n" => break,
832 "expecting a type here because of type ascription",
836 } else if !snippet.trim().is_empty() {
837 debug!("tried to find type ascription `:` token, couldn't find it");
847 fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> {
848 let mut result = None;
849 let mut seen_modules = FxHashSet::default();
850 let mut worklist = vec![(self.r.graph_root, Vec::new())];
852 while let Some((in_module, path_segments)) = worklist.pop() {
853 // abort if the module is already found
854 if result.is_some() {
858 in_module.for_each_child(self.r, |_, ident, _, name_binding| {
859 // abort if the module is already found or if name_binding is private external
860 if result.is_some() || !name_binding.vis.is_visible_locally() {
863 if let Some(module) = name_binding.module() {
865 let mut path_segments = path_segments.clone();
866 path_segments.push(ast::PathSegment::from_ident(ident));
867 let module_def_id = module.def_id().unwrap();
868 if module_def_id == def_id {
869 let path = Path { span: name_binding.span, segments: path_segments };
870 result = Some((module, ImportSuggestion { did: Some(def_id), path }));
872 // add the module to the lookup
873 if seen_modules.insert(module_def_id) {
874 worklist.push((module, path_segments));
884 fn collect_enum_variants(&mut self, def_id: DefId) -> Option<Vec<Path>> {
885 self.find_module(def_id).map(|(enum_module, enum_import_suggestion)| {
886 let mut variants = Vec::new();
887 enum_module.for_each_child(self.r, |_, ident, _, name_binding| {
888 if let Res::Def(DefKind::Variant, _) = name_binding.res() {
889 let mut segms = enum_import_suggestion.path.segments.clone();
890 segms.push(ast::PathSegment::from_ident(ident));
891 variants.push(Path { span: name_binding.span, segments: segms });
898 crate fn report_missing_type_error(
901 ) -> Option<(Span, &'static str, String, Applicability)> {
902 let ident = match path {
903 [segment] => segment.ident,
907 self.diagnostic_metadata.current_item,
908 self.diagnostic_metadata.currently_processing_generics,
910 (Some(Item { kind: ItemKind::Fn(..), ident, .. }), true) if ident.name == sym::main => {
911 // Ignore `fn main()` as we don't want to suggest `fn main<T>()`
913 (Some(Item { kind, .. }), true) => {
914 // Likely missing type parameter.
915 if let Some(generics) = kind.generics() {
916 let msg = "you might be missing a type parameter";
917 let (span, sugg) = if let [.., param] = &generics.params[..] {
918 let span = if let [.., bound] = ¶m.bounds[..] {
923 (span, format!(", {}", ident))
925 (generics.span, format!("<{}>", ident))
927 // Do not suggest if this is coming from macro expansion.
928 if !span.from_expansion() {
933 Applicability::MaybeIncorrect,
944 impl<'tcx> LifetimeContext<'_, 'tcx> {
945 crate fn report_missing_lifetime_specifiers(
949 ) -> DiagnosticBuilder<'tcx> {
954 "missing lifetime specifier{}",
959 crate fn emit_undeclared_lifetime_error(&self, lifetime_ref: &hir::Lifetime) {
960 let mut err = struct_span_err!(
964 "use of undeclared lifetime name `{}`",
967 err.span_label(lifetime_ref.span, "undeclared lifetime");
968 for missing in &self.missing_named_lifetime_spots {
970 MissingLifetimeSpot::Generics(generics) => {
971 let (span, sugg) = if let Some(param) = generics
974 .filter(|p| match p.kind {
975 hir::GenericParamKind::Type {
976 synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
983 (param.span.shrink_to_lo(), format!("{}, ", lifetime_ref))
985 (generics.span, format!("<{}>", lifetime_ref))
989 &format!("consider introducing lifetime `{}` here", lifetime_ref),
991 Applicability::MaybeIncorrect,
994 MissingLifetimeSpot::HigherRanked { span, span_type } => {
998 "consider making the {} lifetime-generic with a new `{}` lifetime",
1002 span_type.suggestion(&lifetime_ref.to_string()),
1003 Applicability::MaybeIncorrect,
1006 "for more information on higher-ranked polymorphism, visit \
1007 https://doc.rust-lang.org/nomicon/hrtb.html",
1015 crate fn is_trait_ref_fn_scope(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) -> bool {
1016 if let def::Res::Def(_, did) = trait_ref.trait_ref.path.res {
1018 self.tcx.lang_items().fn_once_trait(),
1019 self.tcx.lang_items().fn_trait(),
1020 self.tcx.lang_items().fn_mut_trait(),
1022 .contains(&Some(did))
1024 let (span, span_type) = match &trait_ref.bound_generic_params {
1025 [] => (trait_ref.span.shrink_to_lo(), ForLifetimeSpanType::BoundEmpty),
1026 [.., bound] => (bound.span.shrink_to_hi(), ForLifetimeSpanType::BoundTail),
1028 self.missing_named_lifetime_spots
1029 .push(MissingLifetimeSpot::HigherRanked { span, span_type });
1036 crate fn add_missing_lifetime_specifiers_label(
1038 err: &mut DiagnosticBuilder<'_>,
1041 lifetime_names: &FxHashSet<ast::Ident>,
1042 params: &[ElisionFailureInfo],
1045 err.span_label(span, format!("expected {} lifetime parameters", count));
1047 let snippet = self.tcx.sess.source_map().span_to_snippet(span).ok();
1048 let suggest_existing = |err: &mut DiagnosticBuilder<'_>, sugg| {
1049 err.span_suggestion(
1051 "consider using the named lifetime",
1053 Applicability::MaybeIncorrect,
1057 |err: &mut DiagnosticBuilder<'_>, sugg: &str| {
1058 err.span_label(span, "expected named lifetime parameter");
1060 for missing in self.missing_named_lifetime_spots.iter().rev() {
1061 let mut introduce_suggestion = vec![];
1064 introduce_suggestion.push(match missing {
1065 MissingLifetimeSpot::Generics(generics) => {
1066 msg = "consider introducing a named lifetime parameter".to_string();
1067 should_break = true;
1068 if let Some(param) = generics.params.iter().filter(|p| match p.kind {
1069 hir::GenericParamKind::Type {
1070 synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
1075 (param.span.shrink_to_lo(), "'a, ".to_string())
1077 (generics.span, "<'a>".to_string())
1080 MissingLifetimeSpot::HigherRanked { span, span_type } => {
1082 "consider making the {} lifetime-generic with a new `'a` lifetime",
1085 should_break = false;
1087 "for more information on higher-ranked polymorphism, visit \
1088 https://doc.rust-lang.org/nomicon/hrtb.html",
1090 (*span, span_type.suggestion("'a"))
1093 for param in params {
1094 if let Ok(snippet) =
1095 self.tcx.sess.source_map().span_to_snippet(param.span)
1097 if snippet.starts_with("&") && !snippet.starts_with("&'") {
1098 introduce_suggestion
1099 .push((param.span, format!("&'a {}", &snippet[1..])));
1100 } else if snippet.starts_with("&'_ ") {
1101 introduce_suggestion
1102 .push((param.span, format!("&'a {}", &snippet[4..])));
1106 introduce_suggestion.push((span, sugg.to_string()));
1107 err.multipart_suggestion(
1109 introduce_suggestion,
1110 Applicability::MaybeIncorrect,
1119 lifetime_names.len(),
1120 lifetime_names.iter().next(),
1121 snippet.as_ref().map(|s| s.as_str()),
1123 (1, Some(name), Some("&")) => {
1124 suggest_existing(err, format!("&{} ", name));
1126 (1, Some(name), Some("'_")) => {
1127 suggest_existing(err, name.to_string());
1129 (1, Some(name), Some(snippet)) if !snippet.ends_with(">") => {
1130 suggest_existing(err, format!("{}<{}>", snippet, name));
1132 (0, _, Some("&")) => {
1133 suggest_new(err, "&'a ");
1135 (0, _, Some("'_")) => {
1136 suggest_new(err, "'a");
1138 (0, _, Some(snippet)) if !snippet.ends_with(">") => {
1139 suggest_new(err, &format!("{}<'a>", snippet));
1142 err.span_label(span, "expected lifetime parameter");