1 use crate::structured_errors::StructuredDiagnostic;
3 pluralize, Applicability, Diagnostic, DiagnosticBuilder, DiagnosticId, ErrorGuaranteed,
7 use rustc_middle::hir::map::fn_sig;
8 use rustc_middle::ty::{self as ty, AssocItems, AssocKind, TyCtxt};
9 use rustc_session::Session;
10 use rustc_span::def_id::DefId;
13 use GenericArgsInfo::*;
15 /// Handles the `wrong number of type / lifetime / ... arguments` family of error messages.
16 pub struct WrongNumberOfGenericArgs<'a, 'tcx> {
17 pub(crate) tcx: TyCtxt<'tcx>,
19 pub(crate) angle_brackets: AngleBrackets,
21 pub(crate) gen_args_info: GenericArgsInfo,
23 /// Offending path segment
24 pub(crate) path_segment: &'a hir::PathSegment<'a>,
26 /// Generic parameters as expected by type or trait
27 pub(crate) gen_params: &'a ty::Generics,
29 /// Index offset into parameters. Depends on whether `Self` is included and on
30 /// number of lifetime parameters in case we're processing missing or redundant
31 /// type or constant arguments.
32 pub(crate) params_offset: usize,
34 /// Generic arguments as provided by user
35 pub(crate) gen_args: &'a hir::GenericArgs<'a>,
37 /// DefId of the generic type
38 pub(crate) def_id: DefId,
41 // Provides information about the kind of arguments that were provided for
42 // the PathSegment, for which missing generic arguments were detected
44 pub(crate) enum AngleBrackets {
45 // No angle brackets were provided, but generic arguments exist in elided form
48 // No angle brackets were provided
51 // Angle brackets are available, but missing some generic arguments
55 // Information about the kind of arguments that are either missing or are unexpected
57 pub enum GenericArgsInfo {
59 num_missing_args: usize,
62 num_redundant_args: usize,
64 MissingTypesOrConsts {
65 num_missing_args: usize,
67 // type or const generic arguments can have default values
68 num_default_params: usize,
70 // lifetime arguments precede type and const parameters, this
71 // field gives the number of generic lifetime arguments to let
72 // us infer the position of type and const generic arguments
73 // in the angle brackets
78 num_redundant_args: usize,
80 // type or const generic arguments can have default values
81 num_default_params: usize,
83 // lifetime arguments precede type and const parameters, this
84 // field gives the number of generic lifetime arguments to let
85 // us infer the position of type and const generic arguments
86 // in the angle brackets
89 // if synthetic type arguments (e.g. `impl Trait`) are specified
94 impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
97 gen_args_info: GenericArgsInfo,
98 path_segment: &'a hir::PathSegment<'_>,
99 gen_params: &'a ty::Generics,
100 params_offset: usize,
101 gen_args: &'a hir::GenericArgs<'a>,
104 let angle_brackets = if gen_args.span_ext().is_none() {
105 if gen_args.is_empty() { AngleBrackets::Missing } else { AngleBrackets::Implied }
107 AngleBrackets::Available
122 fn missing_lifetimes(&self) -> bool {
123 match self.gen_args_info {
124 MissingLifetimes { .. } | ExcessLifetimes { .. } => true,
125 MissingTypesOrConsts { .. } | ExcessTypesOrConsts { .. } => false,
129 fn kind(&self) -> String {
130 if self.missing_lifetimes() { "lifetime".to_string() } else { "generic".to_string() }
133 fn num_provided_args(&self) -> usize {
134 if self.missing_lifetimes() {
135 self.num_provided_lifetime_args()
137 self.num_provided_type_or_const_args()
141 fn num_provided_lifetime_args(&self) -> usize {
142 match self.angle_brackets {
143 AngleBrackets::Missing => 0,
144 // Only lifetime arguments can be implied
145 AngleBrackets::Implied => self.gen_args.args.len(),
146 AngleBrackets::Available => self.gen_args.num_lifetime_params(),
150 fn num_provided_type_or_const_args(&self) -> usize {
151 match self.angle_brackets {
152 AngleBrackets::Missing => 0,
153 // Only lifetime arguments can be implied
154 AngleBrackets::Implied => 0,
155 AngleBrackets::Available => self.gen_args.num_generic_params(),
159 fn num_expected_lifetime_args(&self) -> usize {
160 let num_provided_args = self.num_provided_lifetime_args();
161 match self.gen_args_info {
162 MissingLifetimes { num_missing_args } => num_provided_args + num_missing_args,
163 ExcessLifetimes { num_redundant_args } => num_provided_args - num_redundant_args,
168 fn num_expected_type_or_const_args(&self) -> usize {
169 let num_provided_args = self.num_provided_type_or_const_args();
170 match self.gen_args_info {
171 MissingTypesOrConsts { num_missing_args, .. } => num_provided_args + num_missing_args,
172 ExcessTypesOrConsts { num_redundant_args, .. } => {
173 num_provided_args - num_redundant_args
179 // Gives the number of expected arguments taking into account default arguments
180 fn num_expected_type_or_const_args_including_defaults(&self) -> usize {
181 let provided_args = self.num_provided_type_or_const_args();
182 match self.gen_args_info {
183 MissingTypesOrConsts { num_missing_args, num_default_params, .. } => {
184 provided_args + num_missing_args - num_default_params
186 ExcessTypesOrConsts { num_redundant_args, num_default_params, .. } => {
187 provided_args - num_redundant_args - num_default_params
193 fn num_missing_lifetime_args(&self) -> usize {
194 let missing_args = self.num_expected_lifetime_args() - self.num_provided_lifetime_args();
195 assert!(missing_args > 0);
199 fn num_missing_type_or_const_args(&self) -> usize {
200 let missing_args = self.num_expected_type_or_const_args_including_defaults()
201 - self.num_provided_type_or_const_args();
202 assert!(missing_args > 0);
206 fn num_excess_lifetime_args(&self) -> usize {
207 match self.gen_args_info {
208 ExcessLifetimes { num_redundant_args } => num_redundant_args,
213 fn num_excess_type_or_const_args(&self) -> usize {
214 match self.gen_args_info {
215 ExcessTypesOrConsts { num_redundant_args, .. } => num_redundant_args,
220 fn too_many_args_provided(&self) -> bool {
221 match self.gen_args_info {
222 MissingLifetimes { .. } | MissingTypesOrConsts { .. } => false,
223 ExcessLifetimes { num_redundant_args }
224 | ExcessTypesOrConsts { num_redundant_args, .. } => {
225 assert!(num_redundant_args > 0);
231 fn not_enough_args_provided(&self) -> bool {
232 match self.gen_args_info {
233 MissingLifetimes { num_missing_args }
234 | MissingTypesOrConsts { num_missing_args, .. } => {
235 assert!(num_missing_args > 0);
238 ExcessLifetimes { .. } | ExcessTypesOrConsts { .. } => false,
242 // Helper method to get the index offset in angle brackets, at which type or const arguments
244 fn get_lifetime_args_offset(&self) -> usize {
245 match self.gen_args_info {
246 MissingLifetimes { .. } | ExcessLifetimes { .. } => 0,
247 MissingTypesOrConsts { args_offset, .. } | ExcessTypesOrConsts { args_offset, .. } => {
253 fn get_num_default_params(&self) -> usize {
254 match self.gen_args_info {
255 MissingTypesOrConsts { num_default_params, .. }
256 | ExcessTypesOrConsts { num_default_params, .. } => num_default_params,
261 fn is_synth_provided(&self) -> bool {
262 match self.gen_args_info {
263 ExcessTypesOrConsts { synth_provided, .. } => synth_provided,
268 // Helper function to choose a quantifier word for the number of expected arguments
269 // and to give a bound for the number of expected arguments
270 fn get_quantifier_and_bound(&self) -> (&'static str, usize) {
271 if self.get_num_default_params() == 0 {
272 match self.gen_args_info {
273 MissingLifetimes { .. } | ExcessLifetimes { .. } => {
274 ("", self.num_expected_lifetime_args())
276 MissingTypesOrConsts { .. } | ExcessTypesOrConsts { .. } => {
277 ("", self.num_expected_type_or_const_args())
281 match self.gen_args_info {
282 MissingLifetimes { .. } => ("at least ", self.num_expected_lifetime_args()),
283 MissingTypesOrConsts { .. } => {
284 ("at least ", self.num_expected_type_or_const_args_including_defaults())
286 ExcessLifetimes { .. } => ("at most ", self.num_expected_lifetime_args()),
287 ExcessTypesOrConsts { .. } => ("at most ", self.num_expected_type_or_const_args()),
292 // Creates lifetime name suggestions from the lifetime parameter names
293 fn get_lifetime_args_suggestions_from_param_names(
295 path_hir_id: Option<hir::HirId>,
296 num_params_to_take: usize,
298 debug!(?path_hir_id);
300 if let Some(path_hir_id) = path_hir_id {
301 let mut ret = Vec::new();
302 for (id, node) in self.tcx.hir().parent_iter(path_hir_id) {
304 let params = if let Some(generics) = node.generics() {
306 } else if let hir::Node::Ty(ty) = node
307 && let hir::TyKind::BareFn(bare_fn) = ty.kind
309 bare_fn.generic_params
313 ret.extend(params.iter().filter_map(|p| {
314 let hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Explicit }
316 else { return None };
317 let hir::ParamName::Plain(name) = p.name else { return None };
318 Some(name.to_string())
320 // Suggest `'static` when in const/static item-like.
321 if let hir::Node::Item(hir::Item {
322 kind: hir::ItemKind::Static { .. } | hir::ItemKind::Const { .. },
325 | hir::Node::TraitItem(hir::TraitItem {
326 kind: hir::TraitItemKind::Const { .. },
329 | hir::Node::ImplItem(hir::ImplItem {
330 kind: hir::ImplItemKind::Const { .. },
333 | hir::Node::ForeignItem(hir::ForeignItem {
334 kind: hir::ForeignItemKind::Static { .. },
337 | hir::Node::AnonConst(..) = node
340 std::iter::repeat("'static".to_owned())
341 .take(num_params_to_take.saturating_sub(ret.len())),
344 if ret.len() >= num_params_to_take {
345 return ret[..num_params_to_take].join(", ");
347 // We cannot refer to lifetimes defined in an outer function.
348 if let hir::Node::Item(_) = node {
354 // We could not gather enough lifetime parameters in the scope.
355 // We use the parameter names from the target type's definition instead.
359 .skip(self.params_offset + self.num_provided_lifetime_args())
360 .take(num_params_to_take)
361 .map(|param| param.name.to_string())
366 // Creates type or constant name suggestions from the provided parameter names
367 fn get_type_or_const_args_suggestions_from_param_names(
369 num_params_to_take: usize,
371 let fn_sig = self.tcx.hir().get_if_local(self.def_id).and_then(fn_sig);
372 let is_used_in_input = |def_id| {
373 fn_sig.map_or(false, |fn_sig| {
374 fn_sig.decl.inputs.iter().any(|ty| match ty.kind {
375 hir::TyKind::Path(hir::QPath::Resolved(
377 hir::Path { res: hir::def::Res::Def(_, id), .. },
386 .skip(self.params_offset + self.num_provided_type_or_const_args())
387 .take(num_params_to_take)
388 .map(|param| match param.kind {
389 // This is being inferred from the item's inputs, no need to set it.
390 ty::GenericParamDefKind::Type { .. } if is_used_in_input(param.def_id) => {
393 _ => param.name.to_string(),
399 fn get_unbound_associated_types(&self) -> Vec<String> {
400 if self.tcx.is_trait(self.def_id) {
401 let items: &AssocItems<'_> = self.tcx.associated_items(self.def_id);
403 .in_definition_order()
404 .filter(|item| item.kind == AssocKind::Type)
406 !self.gen_args.bindings.iter().any(|binding| binding.ident.name == item.name)
408 .map(|item| item.name.to_ident_string())
415 fn create_error_message(&self) -> String {
416 let def_path = self.tcx.def_path_str(self.def_id);
417 let def_kind = self.tcx.def_kind(self.def_id).descr(self.def_id);
418 let (quantifier, bound) = self.get_quantifier_and_bound();
419 let kind = self.kind();
420 let provided_lt_args = self.num_provided_lifetime_args();
421 let provided_type_or_const_args = self.num_provided_type_or_const_args();
423 let get_verb = |num_args| if num_args == 1 { "was" } else { "were" };
425 let (provided_args_str, verb) = match self.gen_args_info {
426 MissingLifetimes { .. } | ExcessLifetimes { .. } => (
427 format!("{} lifetime argument{}", provided_lt_args, pluralize!(provided_lt_args)),
428 get_verb(provided_lt_args),
430 MissingTypesOrConsts { .. } | ExcessTypesOrConsts { .. } => (
432 "{} generic argument{}",
433 provided_type_or_const_args,
434 pluralize!(provided_type_or_const_args)
436 get_verb(provided_type_or_const_args),
440 if self.gen_args.span_ext().is_some() {
442 "this {} takes {}{} {} argument{} but {} {} supplied",
448 provided_args_str.as_str(),
452 format!("missing generics for {} `{}`", def_kind, def_path)
456 fn start_diagnostics(&self) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
457 let span = self.path_segment.ident.span;
458 let msg = self.create_error_message();
460 self.tcx.sess.struct_span_err_with_code(span, &msg, self.code())
463 /// Builds the `expected 1 type argument / supplied 2 type arguments` message.
464 fn notify(&self, err: &mut Diagnostic) {
465 let (quantifier, bound) = self.get_quantifier_and_bound();
466 let provided_args = self.num_provided_args();
469 self.path_segment.ident.span,
471 "expected {}{} {} argument{}",
479 // When too many arguments were provided, we don't highlight each of them, because it
480 // would overlap with the suggestion to remove them:
483 // type Foo = Bar<usize, usize>;
484 // ----- ----- supplied 2 type arguments
485 // ^^^^^^^ remove this type argument
487 if self.too_many_args_provided() {
495 .skip(self.get_lifetime_args_offset())
499 for (i, arg) in args {
502 if i + 1 == provided_args {
504 "supplied {} {} argument{}",
507 pluralize!(provided_args)
516 fn suggest(&self, err: &mut Diagnostic) {
518 "suggest(self.provided {:?}, self.gen_args.span(): {:?})",
519 self.num_provided_args(),
520 self.gen_args.span(),
523 match self.angle_brackets {
524 AngleBrackets::Missing | AngleBrackets::Implied => self.suggest_adding_args(err),
525 AngleBrackets::Available => {
526 if self.not_enough_args_provided() {
527 self.suggest_adding_args(err);
528 } else if self.too_many_args_provided() {
529 self.suggest_removing_args_or_generics(err);
537 /// Suggests to add missing argument(s) when current invocation site already contains some
541 /// type Map = HashMap<String>;
543 fn suggest_adding_args(&self, err: &mut Diagnostic) {
544 if self.gen_args.parenthesized {
548 match self.gen_args_info {
549 MissingLifetimes { .. } => {
550 self.suggest_adding_lifetime_args(err);
552 MissingTypesOrConsts { .. } => {
553 self.suggest_adding_type_and_const_args(err);
559 fn suggest_adding_lifetime_args(&self, err: &mut Diagnostic) {
560 debug!("suggest_adding_lifetime_args(path_segment: {:?})", self.path_segment);
561 let num_missing_args = self.num_missing_lifetime_args();
562 let num_params_to_take = num_missing_args;
563 let msg = format!("add missing {} argument{}", self.kind(), pluralize!(num_missing_args));
565 let suggested_args = self.get_lifetime_args_suggestions_from_param_names(
566 self.path_segment.hir_id,
569 debug!("suggested_args: {:?}", &suggested_args);
571 match self.angle_brackets {
572 AngleBrackets::Missing => {
573 let span = self.path_segment.ident.span;
575 // insert a suggestion of the form "Y<'a, 'b>"
576 let ident = self.path_segment.ident.name.to_ident_string();
577 let sugg = format!("{}<{}>", ident, suggested_args);
578 debug!("sugg: {:?}", sugg);
580 err.span_suggestion_verbose(span, &msg, sugg, Applicability::HasPlaceholders);
583 AngleBrackets::Available => {
584 let (sugg_span, is_first) = if self.num_provided_lifetime_args() == 0 {
585 (self.gen_args.span().unwrap().shrink_to_lo(), true)
587 let last_lt = &self.gen_args.args[self.num_provided_lifetime_args() - 1];
588 (last_lt.span().shrink_to_hi(), false)
590 let has_non_lt_args = self.num_provided_type_or_const_args() != 0;
591 let has_bindings = !self.gen_args.bindings.is_empty();
593 let sugg_prefix = if is_first { "" } else { ", " };
595 if is_first && (has_non_lt_args || has_bindings) { ", " } else { "" };
597 let sugg = format!("{}{}{}", sugg_prefix, suggested_args, sugg_suffix);
598 debug!("sugg: {:?}", sugg);
600 err.span_suggestion_verbose(sugg_span, &msg, sugg, Applicability::HasPlaceholders);
602 AngleBrackets::Implied => {
603 // We never encounter missing lifetimes in situations in which lifetimes are elided
609 fn suggest_adding_type_and_const_args(&self, err: &mut Diagnostic) {
610 let num_missing_args = self.num_missing_type_or_const_args();
611 let msg = format!("add missing {} argument{}", self.kind(), pluralize!(num_missing_args));
614 self.get_type_or_const_args_suggestions_from_param_names(num_missing_args);
615 debug!("suggested_args: {:?}", suggested_args);
617 match self.angle_brackets {
618 AngleBrackets::Missing | AngleBrackets::Implied => {
619 let span = self.path_segment.ident.span;
621 // insert a suggestion of the form "Y<T, U>"
622 let ident = self.path_segment.ident.name.to_ident_string();
623 let sugg = format!("{}<{}>", ident, suggested_args);
624 debug!("sugg: {:?}", sugg);
626 err.span_suggestion_verbose(span, &msg, sugg, Applicability::HasPlaceholders);
628 AngleBrackets::Available => {
629 let gen_args_span = self.gen_args.span().unwrap();
631 self.get_lifetime_args_offset() + self.num_provided_type_or_const_args();
633 let (sugg_span, is_first) = if sugg_offset == 0 {
634 (gen_args_span.shrink_to_lo(), true)
636 let arg_span = self.gen_args.args[sugg_offset - 1].span();
637 // If we came here then inferred lifetime's spans can only point
638 // to either the opening bracket or to the space right after.
639 // Both of these spans have an `hi` lower than or equal to the span
640 // of the generics excluding the brackets.
641 // This allows us to check if `arg_span` is the artificial span of
642 // an inferred lifetime, in which case the generic we're suggesting to
643 // add will be the first visible, even if it isn't the actual first generic.
644 (arg_span.shrink_to_hi(), arg_span.hi() <= gen_args_span.lo())
647 let sugg_prefix = if is_first { "" } else { ", " };
649 if is_first && !self.gen_args.bindings.is_empty() { ", " } else { "" };
651 let sugg = format!("{}{}{}", sugg_prefix, suggested_args, sugg_suffix);
652 debug!("sugg: {:?}", sugg);
654 err.span_suggestion_verbose(sugg_span, &msg, sugg, Applicability::HasPlaceholders);
659 /// Suggests to remove redundant argument(s):
662 /// type Map = HashMap<String, String, String, String>;
664 fn suggest_removing_args_or_generics(&self, err: &mut Diagnostic) {
665 let num_provided_lt_args = self.num_provided_lifetime_args();
666 let num_provided_type_const_args = self.num_provided_type_or_const_args();
667 let unbound_types = self.get_unbound_associated_types();
668 let num_provided_args = num_provided_lt_args + num_provided_type_const_args;
669 assert!(num_provided_args > 0);
671 let num_redundant_lt_args = self.num_excess_lifetime_args();
672 let num_redundant_type_or_const_args = self.num_excess_type_or_const_args();
673 let num_redundant_args = num_redundant_lt_args + num_redundant_type_or_const_args;
675 let redundant_lifetime_args = num_redundant_lt_args > 0;
676 let redundant_type_or_const_args = num_redundant_type_or_const_args > 0;
678 let remove_entire_generics = num_redundant_args >= self.gen_args.args.len();
679 let provided_args_matches_unbound_traits =
680 unbound_types.len() == num_redundant_type_or_const_args;
682 let remove_lifetime_args = |err: &mut Diagnostic| {
683 let mut lt_arg_spans = Vec::new();
684 let mut found_redundant = false;
685 for arg in self.gen_args.args {
686 if let hir::GenericArg::Lifetime(_) = arg {
687 lt_arg_spans.push(arg.span());
688 if lt_arg_spans.len() > self.num_expected_lifetime_args() {
689 found_redundant = true;
691 } else if found_redundant {
692 // Argument which is redundant and separated like this `'c`
693 // is not included to avoid including `Bar` in span.
695 // type Foo<'a, T> = &'a T;
696 // let _: Foo<'a, 'b, Bar, 'c>;
702 let span_lo_redundant_lt_args = lt_arg_spans[self.num_expected_lifetime_args()];
703 let span_hi_redundant_lt_args = lt_arg_spans[lt_arg_spans.len() - 1];
705 let span_redundant_lt_args = span_lo_redundant_lt_args.to(span_hi_redundant_lt_args);
706 debug!("span_redundant_lt_args: {:?}", span_redundant_lt_args);
708 let num_redundant_lt_args = lt_arg_spans.len() - self.num_expected_lifetime_args();
709 let msg_lifetimes = format!(
710 "remove {these} lifetime argument{s}",
711 these = pluralize!("this", num_redundant_lt_args),
712 s = pluralize!(num_redundant_lt_args),
716 span_redundant_lt_args,
719 Applicability::MaybeIncorrect,
723 let remove_type_or_const_args = |err: &mut Diagnostic| {
724 let mut gen_arg_spans = Vec::new();
725 let mut found_redundant = false;
726 for arg in self.gen_args.args {
728 hir::GenericArg::Type(_)
729 | hir::GenericArg::Const(_)
730 | hir::GenericArg::Infer(_) => {
731 gen_arg_spans.push(arg.span());
732 if gen_arg_spans.len() > self.num_expected_type_or_const_args() {
733 found_redundant = true;
736 _ if found_redundant => break,
741 let span_lo_redundant_type_or_const_args =
742 gen_arg_spans[self.num_expected_type_or_const_args()];
743 let span_hi_redundant_type_or_const_args = gen_arg_spans[gen_arg_spans.len() - 1];
745 let span_redundant_type_or_const_args =
746 span_lo_redundant_type_or_const_args.to(span_hi_redundant_type_or_const_args);
747 debug!("span_redundant_type_or_const_args: {:?}", span_redundant_type_or_const_args);
749 let num_redundant_gen_args =
750 gen_arg_spans.len() - self.num_expected_type_or_const_args();
751 let msg_types_or_consts = format!(
752 "remove {these} generic argument{s}",
753 these = pluralize!("this", num_redundant_gen_args),
754 s = pluralize!(num_redundant_gen_args),
758 span_redundant_type_or_const_args,
759 &msg_types_or_consts,
761 Applicability::MaybeIncorrect,
765 // If there is a single unbound associated type and a single excess generic param
766 // suggest replacing the generic param with the associated type bound
767 if provided_args_matches_unbound_traits && !unbound_types.is_empty() {
768 let mut suggestions = vec![];
769 let unused_generics = &self.gen_args.args[self.num_expected_type_or_const_args()..];
770 for (potential, name) in iter::zip(unused_generics, &unbound_types) {
771 if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(potential.span()) {
772 suggestions.push((potential.span(), format!("{} = {}", name, snippet)));
776 if !suggestions.is_empty() {
777 err.multipart_suggestion(
779 "replace the generic bound{s} with the associated type{s}",
780 s = pluralize!(unbound_types.len())
783 Applicability::MaybeIncorrect,
786 } else if remove_entire_generics {
793 .with_lo(self.path_segment.ident.span.hi());
796 "remove these {}generics",
797 if self.gen_args.parenthesized { "parenthetical " } else { "" },
800 err.span_suggestion(span, &msg, String::new(), Applicability::MaybeIncorrect);
801 } else if redundant_lifetime_args && redundant_type_or_const_args {
802 remove_lifetime_args(err);
803 remove_type_or_const_args(err);
804 } else if redundant_lifetime_args {
805 remove_lifetime_args(err);
807 assert!(redundant_type_or_const_args);
808 remove_type_or_const_args(err);
812 /// Builds the `type defined here` message.
813 fn show_definition(&self, err: &mut Diagnostic) {
814 let mut spans: MultiSpan = if let Some(def_span) = self.tcx.def_ident_span(self.def_id) {
815 if self.tcx.sess.source_map().span_to_snippet(def_span).is_ok() {
825 let def_kind = self.tcx.def_kind(self.def_id).descr(self.def_id);
826 let (quantifier, bound) = self.get_quantifier_and_bound();
828 let params = if bound == 0 {
835 .skip(self.params_offset)
838 let span = self.tcx.def_span(param.def_id);
839 spans.push_span_label(span, String::new());
842 .map(|param| format!("`{}`", param.name))
846 format!(": {}", params)
850 "{} defined here, with {}{} {} parameter{}{}",
860 err.span_note(spans, &msg);
863 /// Add note if `impl Trait` is explicitly specified.
864 fn note_synth_provided(&self, err: &mut Diagnostic) {
865 if !self.is_synth_provided() {
869 err.note("`impl Trait` cannot be explicitly specified as a generic argument");
873 impl<'tcx> StructuredDiagnostic<'tcx> for WrongNumberOfGenericArgs<'_, 'tcx> {
874 fn session(&self) -> &Session {
878 fn code(&self) -> DiagnosticId {
879 rustc_errors::error_code!(E0107)
882 fn diagnostic_common(&self) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
883 let mut err = self.start_diagnostics();
885 self.notify(&mut err);
886 self.suggest(&mut err);
887 self.show_definition(&mut err);
888 self.note_synth_provided(&mut err);