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_ast::ast::{self, Expr, ExprKind, Ident, Item, ItemKind, NodeId, Path, Ty, TyKind};
9 use rustc_ast::util::lev_distance::find_best_match_for_name;
10 use rustc_data_structures::fx::FxHashSet;
11 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder};
13 use rustc_hir::def::Namespace::{self, *};
14 use rustc_hir::def::{self, CtorKind, DefKind};
15 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
16 use rustc_hir::PrimTy;
17 use rustc_session::config::nightly_options;
18 use rustc_span::hygiene::MacroKind;
19 use rustc_span::symbol::{kw, sym};
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(')'))
127 DefKind::Ctor(..) | DefKind::AssocFn | DefKind::Const | 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 "`Self` is only available in impls, traits, and type definitions".to_string(),
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 => "`self` value is a keyword and may not be bound to variables or shadowed"
191 _ => "`self` value is a keyword only available in methods with a `self` parameter"
194 if let Some(span) = &self.diagnostic_metadata.current_function {
195 err.span_label(*span, "this function doesn't have a `self` parameter");
197 return (err, Vec::new());
200 // Try to lookup name in more relaxed fashion for better error reporting.
201 let ident = path.last().unwrap().ident;
202 let candidates = self
204 .lookup_import_candidates(ident, ns, is_expected)
206 .filter(|ImportSuggestion { did, .. }| {
207 match (did, res.and_then(|res| res.opt_def_id())) {
208 (Some(suggestion_did), Some(actual_did)) => *suggestion_did != actual_did,
212 .collect::<Vec<_>>();
213 let crate_def_id = DefId::local(CRATE_DEF_INDEX);
214 if candidates.is_empty() && is_expected(Res::Def(DefKind::Enum, crate_def_id)) {
215 let enum_candidates = self.r.lookup_import_candidates(ident, ns, is_enum_variant);
216 let mut enum_candidates = enum_candidates
218 .map(|suggestion| import_candidate_to_enum_paths(&suggestion))
219 .collect::<Vec<_>>();
220 enum_candidates.sort();
222 if !enum_candidates.is_empty() {
223 // Contextualize for E0412 "cannot find type", but don't belabor the point
224 // (that it's a variant) for E0573 "expected type, found variant".
225 let preamble = if res.is_none() {
226 let others = match enum_candidates.len() {
228 2 => " and 1 other".to_owned(),
229 n => format!(" and {} others", n),
231 format!("there is an enum variant `{}`{}; ", enum_candidates[0].0, others)
235 let msg = format!("{}try using the variant's enum", preamble);
237 err.span_suggestions(
242 .map(|(_variant_path, enum_ty_path)| enum_ty_path)
243 // Variants re-exported in prelude doesn't mean `prelude::v1` is the
245 // FIXME: is there a more principled way to do this that
246 // would work for other re-exports?
247 .filter(|enum_ty_path| enum_ty_path != "std::prelude::v1")
248 // Also write `Option` rather than `std::prelude::v1::Option`.
249 .map(|enum_ty_path| {
250 // FIXME #56861: DRY-er prelude filtering.
251 enum_ty_path.trim_start_matches("std::prelude::v1::").to_owned()
253 Applicability::MachineApplicable,
257 if path.len() == 1 && self.self_type_is_available(span) {
258 if let Some(candidate) = self.lookup_assoc_candidate(ident, ns, is_expected) {
259 let self_is_available = self.self_value_is_available(path[0].ident.span, span);
261 AssocSuggestion::Field => {
262 if self_is_available {
265 "you might have meant to use the available field",
266 format!("self.{}", path_str),
267 Applicability::MachineApplicable,
270 err.span_label(span, "a field by this name exists in `Self`");
273 AssocSuggestion::MethodWithSelf if self_is_available => {
277 format!("self.{}", path_str),
278 Applicability::MachineApplicable,
281 AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
285 format!("Self::{}", path_str),
286 Applicability::MachineApplicable,
290 return (err, candidates);
293 // If the first argument in call is `self` suggest calling a method.
294 if let Some((call_span, args_span)) = self.call_has_self_arg(source) {
295 let mut args_snippet = String::new();
296 if let Some(args_span) = args_span {
297 if let Ok(snippet) = self.r.session.source_map().span_to_snippet(args_span) {
298 args_snippet = snippet;
304 &format!("try calling `{}` as a method", ident),
305 format!("self.{}({})", path_str, args_snippet),
306 Applicability::MachineApplicable,
308 return (err, candidates);
312 // Try Levenshtein algorithm.
313 let typo_sugg = self.lookup_typo_candidate(path, ns, is_expected, span);
314 let levenshtein_worked = self.r.add_typo_suggestion(&mut err, typo_sugg, ident_span);
316 // Try context-dependent help if relaxed lookup didn't work.
317 if let Some(res) = res {
318 if self.smart_resolve_context_dependent_help(
326 return (err, candidates);
331 if !levenshtein_worked {
332 err.span_label(base_span, fallback_label);
333 self.type_ascription_suggestion(&mut err, base_span);
334 match self.diagnostic_metadata.current_let_binding {
335 Some((pat_sp, Some(ty_sp), None)) if ty_sp.contains(base_span) && could_be_expr => {
336 err.span_suggestion_short(
337 pat_sp.between(ty_sp),
338 "use `=` if you meant to assign",
340 Applicability::MaybeIncorrect,
349 /// Check if the source is call expression and the first argument is `self`. If true,
350 /// return the span of whole call and the span for all arguments expect the first one (`self`).
351 fn call_has_self_arg(&self, source: PathSource<'_>) -> Option<(Span, Option<Span>)> {
352 let mut has_self_arg = None;
353 if let PathSource::Expr(parent) = source {
354 match &parent?.kind {
355 ExprKind::Call(_, args) if !args.is_empty() => {
356 let mut expr_kind = &args[0].kind;
359 ExprKind::Path(_, arg_name) if arg_name.segments.len() == 1 => {
360 if arg_name.segments[0].ident.name == kw::SelfLower {
361 let call_span = parent.unwrap().span;
362 let tail_args_span = if args.len() > 1 {
365 args.last().unwrap().span.hi(),
371 has_self_arg = Some((call_span, tail_args_span));
375 ExprKind::AddrOf(_, _, expr) => expr_kind = &expr.kind,
386 fn followed_by_brace(&self, span: Span) -> (bool, Option<Span>) {
387 // HACK(estebank): find a better way to figure out that this was a
388 // parser issue where a struct literal is being used on an expression
389 // where a brace being opened means a block is being started. Look
390 // ahead for the next text to see if `span` is followed by a `{`.
391 let sm = self.r.session.source_map();
394 sp = sm.next_point(sp);
395 match sm.span_to_snippet(sp) {
397 if snippet.chars().any(|c| !c.is_whitespace()) {
404 let followed_by_brace = match sm.span_to_snippet(sp) {
405 Ok(ref snippet) if snippet == "{" => true,
408 // In case this could be a struct literal that needs to be surrounded
409 // by parentheses, find the appropriate span.
411 let mut closing_brace = None;
413 sp = sm.next_point(sp);
414 match sm.span_to_snippet(sp) {
417 closing_brace = Some(span.to(sp));
424 // The bigger the span, the more likely we're incorrect --
425 // bound it to 100 chars long.
430 (followed_by_brace, closing_brace)
433 /// Provides context-dependent help for errors reported by the `smart_resolve_path_fragment`
435 /// Returns `true` if able to provide context-dependent help.
436 fn smart_resolve_context_dependent_help(
438 err: &mut DiagnosticBuilder<'a>,
440 source: PathSource<'_>,
443 fallback_label: &str,
445 let ns = source.namespace();
446 let is_expected = &|res| source.is_expected(res);
448 let path_sep = |err: &mut DiagnosticBuilder<'_>, expr: &Expr| match expr.kind {
449 ExprKind::Field(_, ident) => {
452 "use the path separator to refer to an item",
453 format!("{}::{}", path_str, ident),
454 Applicability::MaybeIncorrect,
458 ExprKind::MethodCall(ref segment, ..) => {
459 let span = expr.span.with_hi(segment.ident.span.hi());
462 "use the path separator to refer to an item",
463 format!("{}::{}", path_str, segment.ident),
464 Applicability::MaybeIncorrect,
471 let mut bad_struct_syntax_suggestion = |def_id: DefId| {
472 let (followed_by_brace, closing_brace) = self.followed_by_brace(span);
473 let mut suggested = false;
475 PathSource::Expr(Some(parent)) => {
476 suggested = path_sep(err, &parent);
478 PathSource::Expr(None) if followed_by_brace => {
479 if let Some(sp) = closing_brace {
480 err.multipart_suggestion(
481 "surround the struct literal with parentheses",
483 (sp.shrink_to_lo(), "(".to_string()),
484 (sp.shrink_to_hi(), ")".to_string()),
486 Applicability::MaybeIncorrect,
490 span, // Note the parentheses surrounding the suggestion below
492 "you might want to surround a struct literal with parentheses: \
493 `({} {{ /* fields */ }})`?",
503 if let Some(span) = self.r.definitions.opt_span(def_id) {
504 err.span_label(span, &format!("`{}` defined here", path_str));
506 err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?", path_str));
510 match (res, source) {
511 (Res::Def(DefKind::Macro(MacroKind::Bang), _), _) => {
512 err.span_suggestion_verbose(
514 "use `!` to invoke the macro",
516 Applicability::MaybeIncorrect,
518 if path_str == "try" && span.rust_2015() {
519 err.note("if you want the `try` keyword, you need to be in the 2018 edition");
522 (Res::Def(DefKind::TyAlias, def_id), PathSource::Trait(_)) => {
523 err.span_label(span, "type aliases cannot be used as traits");
524 if nightly_options::is_nightly_build() {
525 let msg = "you might have meant to use `#![feature(trait_alias)]` instead of a \
527 if let Some(span) = self.r.definitions.opt_span(def_id) {
528 err.span_help(span, msg);
534 (Res::Def(DefKind::Mod, _), PathSource::Expr(Some(parent))) => {
535 if !path_sep(err, &parent) {
539 (Res::Def(DefKind::Enum, def_id), PathSource::TupleStruct | PathSource::Expr(..)) => {
540 if let Some(variants) = self.collect_enum_variants(def_id) {
541 if !variants.is_empty() {
542 let msg = if variants.len() == 1 {
543 "try using the enum's variant"
545 "try using one of the enum's variants"
548 err.span_suggestions(
551 variants.iter().map(path_names_to_string),
552 Applicability::MaybeIncorrect,
556 err.note("did you mean to use one of the enum's variants?");
559 (Res::Def(DefKind::Struct, def_id), _) if ns == ValueNS => {
560 if let Some((ctor_def, ctor_vis)) = self.r.struct_constructors.get(&def_id).cloned()
562 let accessible_ctor =
563 self.r.is_accessible_from(ctor_vis, self.parent_scope.module);
564 if is_expected(ctor_def) && !accessible_ctor {
567 "constructor is not visible here due to private fields".to_string(),
571 bad_struct_syntax_suggestion(def_id);
576 DefKind::Union | DefKind::Variant | DefKind::Ctor(_, CtorKind::Fictive),
580 ) if ns == ValueNS => {
581 bad_struct_syntax_suggestion(def_id);
583 (Res::Def(DefKind::Ctor(_, CtorKind::Fn), def_id), _) if ns == ValueNS => {
584 if let Some(span) = self.r.definitions.opt_span(def_id) {
585 err.span_label(span, &format!("`{}` defined here", path_str));
587 err.span_label(span, format!("did you mean `{}( /* fields */ )`?", path_str));
589 (Res::SelfTy(..), _) if ns == ValueNS => {
590 err.span_label(span, fallback_label);
591 err.note("can't use `Self` as a constructor, you must use the implemented struct");
593 (Res::Def(DefKind::TyAlias | DefKind::AssocTy, _), _) if ns == ValueNS => {
594 err.note("can't use a type alias as a constructor");
601 fn lookup_assoc_candidate<FilterFn>(
606 ) -> Option<AssocSuggestion>
608 FilterFn: Fn(Res) -> bool,
610 fn extract_node_id(t: &Ty) -> Option<NodeId> {
612 TyKind::Path(None, _) => Some(t.id),
613 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
614 // This doesn't handle the remaining `Ty` variants as they are not
615 // that commonly the self_type, it might be interesting to provide
616 // support for those in future.
621 // Fields are generally expected in the same contexts as locals.
622 if filter_fn(Res::Local(ast::DUMMY_NODE_ID)) {
623 if let Some(node_id) =
624 self.diagnostic_metadata.current_self_type.as_ref().and_then(extract_node_id)
626 // Look for a field with the same name in the current self_type.
627 if let Some(resolution) = self.r.partial_res_map.get(&node_id) {
628 match resolution.base_res() {
629 Res::Def(DefKind::Struct | DefKind::Union, did)
630 if resolution.unresolved_segments() == 0 =>
632 if let Some(field_names) = self.r.field_names.get(&did) {
635 .any(|&field_name| ident.name == field_name.node)
637 return Some(AssocSuggestion::Field);
647 for assoc_type_ident in &self.diagnostic_metadata.current_trait_assoc_types {
648 if *assoc_type_ident == ident {
649 return Some(AssocSuggestion::AssocItem);
653 // Look for associated items in the current trait.
654 if let Some((module, _)) = self.current_trait_ref {
655 if let Ok(binding) = self.r.resolve_ident_in_module(
656 ModuleOrUniformRoot::Module(module),
663 let res = binding.res();
665 return Some(if self.r.has_self.contains(&res.def_id()) {
666 AssocSuggestion::MethodWithSelf
668 AssocSuggestion::AssocItem
677 fn lookup_typo_candidate(
681 filter_fn: &impl Fn(Res) -> bool,
683 ) -> Option<TypoSuggestion> {
684 let mut names = Vec::new();
686 // Search in lexical scope.
687 // Walk backwards up the ribs in scope and collect candidates.
688 for rib in self.ribs[ns].iter().rev() {
689 // Locals and type parameters
690 for (ident, &res) in &rib.bindings {
692 names.push(TypoSuggestion::from_res(ident.name, res));
696 if let RibKind::ModuleRibKind(module) = rib.kind {
697 // Items from this module
698 self.r.add_module_candidates(module, &mut names, &filter_fn);
700 if let ModuleKind::Block(..) = module.kind {
701 // We can see through blocks
703 // Items from the prelude
704 if !module.no_implicit_prelude {
705 let extern_prelude = self.r.extern_prelude.clone();
706 names.extend(extern_prelude.iter().flat_map(|(ident, _)| {
709 .maybe_process_path_extern(ident.name, ident.span)
710 .and_then(|crate_id| {
711 let crate_mod = Res::Def(
713 DefId { krate: crate_id, index: CRATE_DEF_INDEX },
716 if filter_fn(crate_mod) {
717 Some(TypoSuggestion::from_res(ident.name, crate_mod))
724 if let Some(prelude) = self.r.prelude {
725 self.r.add_module_candidates(prelude, &mut names, &filter_fn);
732 // Add primitive types to the mix
733 if filter_fn(Res::PrimTy(PrimTy::Bool)) {
735 self.r.primitive_type_table.primitive_types.iter().map(|(name, prim_ty)| {
736 TypoSuggestion::from_res(*name, Res::PrimTy(*prim_ty))
742 let mod_path = &path[..path.len() - 1];
743 if let PathResult::Module(module) =
744 self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No)
746 if let ModuleOrUniformRoot::Module(module) = module {
747 self.r.add_module_candidates(module, &mut names, &filter_fn);
752 let name = path[path.len() - 1].ident.name;
753 // Make sure error reporting is deterministic.
754 names.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
756 match find_best_match_for_name(
757 names.iter().map(|suggestion| &suggestion.candidate),
761 Some(found) if found != name => {
762 names.into_iter().find(|suggestion| suggestion.candidate == found)
768 /// Only used in a specific case of type ascription suggestions
769 fn get_colon_suggestion_span(&self, start: Span) -> Span {
770 let sm = self.r.session.source_map();
771 start.to(sm.next_point(start))
774 fn type_ascription_suggestion(&self, err: &mut DiagnosticBuilder<'_>, base_span: Span) {
775 let sm = self.r.session.source_map();
776 let base_snippet = sm.span_to_snippet(base_span);
777 if let Some(sp) = self.diagnostic_metadata.current_type_ascription.last() {
780 // Try to find the `:`; bail on first non-':' / non-whitespace.
781 sp = sm.next_point(sp);
782 if let Ok(snippet) = sm.span_to_snippet(sp.to(sm.next_point(sp))) {
783 let line_sp = sm.lookup_char_pos(sp.hi()).line;
784 let line_base_sp = sm.lookup_char_pos(base_span.lo()).line;
786 let mut show_label = true;
787 if line_sp != line_base_sp {
788 err.span_suggestion_short(
790 "did you mean to use `;` here instead?",
792 Applicability::MaybeIncorrect,
795 let colon_sp = self.get_colon_suggestion_span(sp);
797 self.get_colon_suggestion_span(colon_sp.shrink_to_hi());
799 .span_to_snippet(after_colon_sp)
805 "maybe you meant to write a path separator here",
807 Applicability::MaybeIncorrect,
811 if let Ok(base_snippet) = base_snippet {
812 let mut sp = after_colon_sp;
814 // Try to find an assignment
815 sp = sm.next_point(sp);
816 let snippet = sm.span_to_snippet(sp.to(sm.next_point(sp)));
818 Ok(ref x) if x.as_str() == "=" => {
821 "maybe you meant to write an assignment here",
822 format!("let {}", base_snippet),
823 Applicability::MaybeIncorrect,
828 Ok(ref x) if x.as_str() == "\n" => break,
838 "expecting a type here because of type ascription",
842 } else if !snippet.trim().is_empty() {
843 debug!("tried to find type ascription `:` token, couldn't find it");
853 fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> {
854 let mut result = None;
855 let mut seen_modules = FxHashSet::default();
856 let mut worklist = vec![(self.r.graph_root, Vec::new())];
858 while let Some((in_module, path_segments)) = worklist.pop() {
859 // abort if the module is already found
860 if result.is_some() {
864 in_module.for_each_child(self.r, |_, ident, _, name_binding| {
865 // abort if the module is already found or if name_binding is private external
866 if result.is_some() || !name_binding.vis.is_visible_locally() {
869 if let Some(module) = name_binding.module() {
871 let mut path_segments = path_segments.clone();
872 path_segments.push(ast::PathSegment::from_ident(ident));
873 let module_def_id = module.def_id().unwrap();
874 if module_def_id == def_id {
875 let path = Path { span: name_binding.span, segments: path_segments };
876 result = Some((module, ImportSuggestion { did: Some(def_id), path }));
878 // add the module to the lookup
879 if seen_modules.insert(module_def_id) {
880 worklist.push((module, path_segments));
890 fn collect_enum_variants(&mut self, def_id: DefId) -> Option<Vec<Path>> {
891 self.find_module(def_id).map(|(enum_module, enum_import_suggestion)| {
892 let mut variants = Vec::new();
893 enum_module.for_each_child(self.r, |_, ident, _, name_binding| {
894 if let Res::Def(DefKind::Variant, _) = name_binding.res() {
895 let mut segms = enum_import_suggestion.path.segments.clone();
896 segms.push(ast::PathSegment::from_ident(ident));
897 variants.push(Path { span: name_binding.span, segments: segms });
904 crate fn report_missing_type_error(
907 ) -> Option<(Span, &'static str, String, Applicability)> {
908 let ident = match path {
909 [segment] => segment.ident,
913 self.diagnostic_metadata.current_item,
914 self.diagnostic_metadata.currently_processing_generics,
916 (Some(Item { kind: ItemKind::Fn(..), ident, .. }), true) if ident.name == sym::main => {
917 // Ignore `fn main()` as we don't want to suggest `fn main<T>()`
919 (Some(Item { kind, .. }), true) => {
920 // Likely missing type parameter.
921 if let Some(generics) = kind.generics() {
922 let msg = "you might be missing a type parameter";
923 let (span, sugg) = if let [.., param] = &generics.params[..] {
924 let span = if let [.., bound] = ¶m.bounds[..] {
929 (span, format!(", {}", ident))
931 (generics.span, format!("<{}>", ident))
933 // Do not suggest if this is coming from macro expansion.
934 if !span.from_expansion() {
939 Applicability::MaybeIncorrect,
950 impl<'tcx> LifetimeContext<'_, 'tcx> {
951 crate fn report_missing_lifetime_specifiers(
955 ) -> DiagnosticBuilder<'tcx> {
960 "missing lifetime specifier{}",
965 crate fn emit_undeclared_lifetime_error(&self, lifetime_ref: &hir::Lifetime) {
966 let mut err = struct_span_err!(
970 "use of undeclared lifetime name `{}`",
973 err.span_label(lifetime_ref.span, "undeclared lifetime");
974 for missing in &self.missing_named_lifetime_spots {
976 MissingLifetimeSpot::Generics(generics) => {
977 let (span, sugg) = if let Some(param) =
978 generics.params.iter().find(|p| match p.kind {
979 hir::GenericParamKind::Type {
980 synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
985 (param.span.shrink_to_lo(), format!("{}, ", lifetime_ref))
987 (generics.span, format!("<{}>", lifetime_ref))
991 &format!("consider introducing lifetime `{}` here", lifetime_ref),
993 Applicability::MaybeIncorrect,
996 MissingLifetimeSpot::HigherRanked { span, span_type } => {
1000 "consider making the {} lifetime-generic with a new `{}` lifetime",
1004 span_type.suggestion(&lifetime_ref.to_string()),
1005 Applicability::MaybeIncorrect,
1008 "for more information on higher-ranked polymorphism, visit \
1009 https://doc.rust-lang.org/nomicon/hrtb.html",
1017 crate fn is_trait_ref_fn_scope(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) -> bool {
1018 if let def::Res::Def(_, did) = trait_ref.trait_ref.path.res {
1020 self.tcx.lang_items().fn_once_trait(),
1021 self.tcx.lang_items().fn_trait(),
1022 self.tcx.lang_items().fn_mut_trait(),
1024 .contains(&Some(did))
1026 let (span, span_type) = match &trait_ref.bound_generic_params {
1027 [] => (trait_ref.span.shrink_to_lo(), ForLifetimeSpanType::BoundEmpty),
1028 [.., bound] => (bound.span.shrink_to_hi(), ForLifetimeSpanType::BoundTail),
1030 self.missing_named_lifetime_spots
1031 .push(MissingLifetimeSpot::HigherRanked { span, span_type });
1038 crate fn add_missing_lifetime_specifiers_label(
1040 err: &mut DiagnosticBuilder<'_>,
1043 lifetime_names: &FxHashSet<ast::Ident>,
1044 params: &[ElisionFailureInfo],
1046 let snippet = self.tcx.sess.source_map().span_to_snippet(span).ok();
1051 "expected {} lifetime parameter{}",
1052 if count == 1 { "named".to_string() } else { count.to_string() },
1057 let suggest_existing = |err: &mut DiagnosticBuilder<'_>, sugg| {
1058 err.span_suggestion_verbose(
1060 &format!("consider using the `{}` lifetime", lifetime_names.iter().next().unwrap()),
1062 Applicability::MaybeIncorrect,
1065 let suggest_new = |err: &mut DiagnosticBuilder<'_>, sugg: &str| {
1066 for missing in self.missing_named_lifetime_spots.iter().rev() {
1067 let mut introduce_suggestion = vec![];
1070 introduce_suggestion.push(match missing {
1071 MissingLifetimeSpot::Generics(generics) => {
1072 msg = "consider introducing a named lifetime parameter".to_string();
1073 should_break = true;
1074 if let Some(param) = generics.params.iter().find(|p| match p.kind {
1075 hir::GenericParamKind::Type {
1076 synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
1081 (param.span.shrink_to_lo(), "'a, ".to_string())
1083 (generics.span, "<'a>".to_string())
1086 MissingLifetimeSpot::HigherRanked { span, span_type } => {
1088 "consider making the {} lifetime-generic with a new `'a` lifetime",
1091 should_break = false;
1093 "for more information on higher-ranked polymorphism, visit \
1094 https://doc.rust-lang.org/nomicon/hrtb.html",
1096 (*span, span_type.suggestion("'a"))
1099 for param in params {
1100 if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(param.span) {
1101 if snippet.starts_with('&') && !snippet.starts_with("&'") {
1102 introduce_suggestion
1103 .push((param.span, format!("&'a {}", &snippet[1..])));
1104 } else if snippet.starts_with("&'_ ") {
1105 introduce_suggestion
1106 .push((param.span, format!("&'a {}", &snippet[4..])));
1110 introduce_suggestion.push((span, sugg.to_string()));
1111 err.multipart_suggestion(&msg, introduce_suggestion, Applicability::MaybeIncorrect);
1118 match (lifetime_names.len(), lifetime_names.iter().next(), snippet.as_deref()) {
1119 (1, Some(name), Some("&")) => {
1120 suggest_existing(err, format!("&{} ", name));
1122 (1, Some(name), Some("'_")) => {
1123 suggest_existing(err, name.to_string());
1125 (1, Some(name), Some("")) => {
1126 suggest_existing(err, format!("{}, ", name).repeat(count));
1128 (1, Some(name), Some(snippet)) if !snippet.ends_with('>') => {
1134 std::iter::repeat(name.to_string())
1136 .collect::<Vec<_>>()
1141 (0, _, Some("&")) if count == 1 => {
1142 suggest_new(err, "&'a ");
1144 (0, _, Some("'_")) if count == 1 => {
1145 suggest_new(err, "'a");
1147 (0, _, Some(snippet)) if !snippet.ends_with('>') && count == 1 => {
1148 suggest_new(err, &format!("{}<'a>", snippet));
1150 (n, ..) if n > 1 => {
1151 let spans: Vec<Span> = lifetime_names.iter().map(|lt| lt.span).collect();
1152 err.span_note(spans, "these named lifetimes are available to use");
1153 if Some("") == snippet.as_deref() {
1154 // This happens when we have `Foo<T>` where we point at the space before `T`,
1155 // but this can be confusing so we give a suggestion with placeholders.
1156 err.span_suggestion_verbose(
1158 "consider using one of the available lifetimes here",
1159 "'lifetime, ".repeat(count),
1160 Applicability::HasPlaceholders,