/
suggest.rs
1636 lines (1548 loc) · 75 KB
/
suggest.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
//! Give useful errors and suggestions to users when an item can't be
//! found or is otherwise invalid.
use crate::check::FnCtxt;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Namespace, Res};
use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
use rustc_hir::intravisit;
use rustc_hir::lang_items::LangItem;
use rustc_hir::{ExprKind, Node, QPath};
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_middle::ty::fast_reject::simplify_type;
use rustc_middle::ty::print::with_crate_prefix;
use rustc_middle::ty::{
self, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness,
};
use rustc_span::lev_distance;
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::{source_map, FileName, Span};
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
use rustc_trait_selection::traits::Obligation;
use std::cmp::Ordering;
use std::iter;
use super::probe::Mode;
use super::{CandidateSource, MethodError, NoMatchData};
impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
fn is_fn_ty(&self, ty: Ty<'tcx>, span: Span) -> bool {
let tcx = self.tcx;
match ty.kind() {
// Not all of these (e.g., unsafe fns) implement `FnOnce`,
// so we look for these beforehand.
ty::Closure(..) | ty::FnDef(..) | ty::FnPtr(_) => true,
// If it's not a simple function, look for things which implement `FnOnce`.
_ => {
let fn_once = match tcx.lang_items().require(LangItem::FnOnce) {
Ok(fn_once) => fn_once,
Err(..) => return false,
};
self.autoderef(span, ty).any(|(ty, _)| {
self.probe(|_| {
let fn_once_substs = tcx.mk_substs_trait(
ty,
&[self
.next_ty_var(TypeVariableOrigin {
kind: TypeVariableOriginKind::MiscVariable,
span,
})
.into()],
);
let trait_ref = ty::TraitRef::new(fn_once, fn_once_substs);
let poly_trait_ref = trait_ref.to_poly_trait_ref();
let obligation = Obligation::misc(
span,
self.body_id,
self.param_env,
poly_trait_ref.without_const().to_predicate(tcx),
);
self.predicate_may_hold(&obligation)
})
})
}
}
}
pub fn report_method_error(
&self,
span: Span,
rcvr_ty: Ty<'tcx>,
item_name: Ident,
source: SelfSource<'tcx>,
error: MethodError<'tcx>,
args: Option<&'tcx [hir::Expr<'tcx>]>,
) -> Option<DiagnosticBuilder<'_>> {
let orig_span = span;
let mut span = span;
// Avoid suggestions when we don't know what's going on.
if rcvr_ty.references_error() {
return None;
}
let report_candidates = |span: Span,
err: &mut DiagnosticBuilder<'_>,
mut sources: Vec<CandidateSource>,
sugg_span: Span| {
sources.sort();
sources.dedup();
// Dynamic limit to avoid hiding just one candidate, which is silly.
let limit = if sources.len() == 5 { 5 } else { 4 };
for (idx, source) in sources.iter().take(limit).enumerate() {
match *source {
CandidateSource::ImplSource(impl_did) => {
// Provide the best span we can. Use the item, if local to crate, else
// the impl, if local to crate (item may be defaulted), else nothing.
let item = match self
.associated_item(impl_did, item_name, Namespace::ValueNS)
.or_else(|| {
let impl_trait_ref = self.tcx.impl_trait_ref(impl_did)?;
self.associated_item(
impl_trait_ref.def_id,
item_name,
Namespace::ValueNS,
)
}) {
Some(item) => item,
None => continue,
};
let note_span = self
.tcx
.hir()
.span_if_local(item.def_id)
.or_else(|| self.tcx.hir().span_if_local(impl_did));
let impl_ty = self.tcx.at(span).type_of(impl_did);
let insertion = match self.tcx.impl_trait_ref(impl_did) {
None => String::new(),
Some(trait_ref) => format!(
" of the trait `{}`",
self.tcx.def_path_str(trait_ref.def_id)
),
};
let (note_str, idx) = if sources.len() > 1 {
(
format!(
"candidate #{} is defined in an impl{} for the type `{}`",
idx + 1,
insertion,
impl_ty,
),
Some(idx + 1),
)
} else {
(
format!(
"the candidate is defined in an impl{} for the type `{}`",
insertion, impl_ty,
),
None,
)
};
if let Some(note_span) = note_span {
// We have a span pointing to the method. Show note with snippet.
err.span_note(
self.tcx.sess.source_map().guess_head_span(note_span),
¬e_str,
);
} else {
err.note(¬e_str);
}
if let Some(trait_ref) = self.tcx.impl_trait_ref(impl_did) {
let path = self.tcx.def_path_str(trait_ref.def_id);
let ty = match item.kind {
ty::AssocKind::Const | ty::AssocKind::Type => rcvr_ty,
ty::AssocKind::Fn => self
.tcx
.fn_sig(item.def_id)
.inputs()
.skip_binder()
.get(0)
.filter(|ty| ty.is_region_ptr() && !rcvr_ty.is_region_ptr())
.copied()
.unwrap_or(rcvr_ty),
};
print_disambiguation_help(
item_name,
args,
err,
path,
ty,
item.kind,
item.def_id,
sugg_span,
idx,
self.tcx.sess.source_map(),
);
}
}
CandidateSource::TraitSource(trait_did) => {
let item =
match self.associated_item(trait_did, item_name, Namespace::ValueNS) {
Some(item) => item,
None => continue,
};
let item_span = self
.tcx
.sess
.source_map()
.guess_head_span(self.tcx.def_span(item.def_id));
let idx = if sources.len() > 1 {
let msg = &format!(
"candidate #{} is defined in the trait `{}`",
idx + 1,
self.tcx.def_path_str(trait_did)
);
err.span_note(item_span, msg);
Some(idx + 1)
} else {
let msg = &format!(
"the candidate is defined in the trait `{}`",
self.tcx.def_path_str(trait_did)
);
err.span_note(item_span, msg);
None
};
let path = self.tcx.def_path_str(trait_did);
print_disambiguation_help(
item_name,
args,
err,
path,
rcvr_ty,
item.kind,
item.def_id,
sugg_span,
idx,
self.tcx.sess.source_map(),
);
}
}
}
if sources.len() > limit {
err.note(&format!("and {} others", sources.len() - limit));
}
};
let sugg_span = if let SelfSource::MethodCall(expr) = source {
// Given `foo.bar(baz)`, `expr` is `bar`, but we want to point to the whole thing.
self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id)).span
} else {
span
};
match error {
MethodError::NoMatch(NoMatchData {
static_candidates: static_sources,
unsatisfied_predicates,
out_of_scope_traits,
lev_candidate,
mode,
}) => {
let tcx = self.tcx;
let actual = self.resolve_vars_if_possible(rcvr_ty);
let ty_str = self.ty_to_string(actual);
let is_method = mode == Mode::MethodCall;
let item_kind = if is_method {
"method"
} else if actual.is_enum() {
"variant or associated item"
} else {
match (item_name.as_str().chars().next(), actual.is_fresh_ty()) {
(Some(name), false) if name.is_lowercase() => "function or associated item",
(Some(_), false) => "associated item",
(Some(_), true) | (None, false) => "variant or associated item",
(None, true) => "variant",
}
};
let mut err = if !actual.references_error() {
// Suggest clamping down the type if the method that is being attempted to
// be used exists at all, and the type is an ambiguous numeric type
// ({integer}/{float}).
let mut candidates = all_traits(self.tcx).into_iter().filter_map(|info| {
self.associated_item(info.def_id, item_name, Namespace::ValueNS)
});
// There are methods that are defined on the primitive types and won't be
// found when exploring `all_traits`, but we also need them to be acurate on
// our suggestions (#47759).
let fund_assoc = |opt_def_id: Option<DefId>| {
opt_def_id
.and_then(|id| self.associated_item(id, item_name, Namespace::ValueNS))
.is_some()
};
let lang_items = tcx.lang_items();
let found_candidate = candidates.next().is_some()
|| fund_assoc(lang_items.i8_impl())
|| fund_assoc(lang_items.i16_impl())
|| fund_assoc(lang_items.i32_impl())
|| fund_assoc(lang_items.i64_impl())
|| fund_assoc(lang_items.i128_impl())
|| fund_assoc(lang_items.u8_impl())
|| fund_assoc(lang_items.u16_impl())
|| fund_assoc(lang_items.u32_impl())
|| fund_assoc(lang_items.u64_impl())
|| fund_assoc(lang_items.u128_impl())
|| fund_assoc(lang_items.f32_impl())
|| fund_assoc(lang_items.f32_runtime_impl())
|| fund_assoc(lang_items.f64_impl())
|| fund_assoc(lang_items.f64_runtime_impl());
if let (true, false, SelfSource::MethodCall(expr), true) = (
actual.is_numeric(),
actual.has_concrete_skeleton(),
source,
found_candidate,
) {
let mut err = struct_span_err!(
tcx.sess,
span,
E0689,
"can't call {} `{}` on ambiguous numeric type `{}`",
item_kind,
item_name,
ty_str
);
let concrete_type = if actual.is_integral() { "i32" } else { "f32" };
match expr.kind {
ExprKind::Lit(ref lit) => {
// numeric literal
let snippet = tcx
.sess
.source_map()
.span_to_snippet(lit.span)
.unwrap_or_else(|_| "<numeric literal>".to_owned());
err.span_suggestion(
lit.span,
&format!(
"you must specify a concrete type for this numeric value, \
like `{}`",
concrete_type
),
format!("{}_{}", snippet, concrete_type),
Applicability::MaybeIncorrect,
);
}
ExprKind::Path(ref qpath) => {
// local binding
if let QPath::Resolved(_, path) = qpath {
if let hir::def::Res::Local(hir_id) = path.res {
let span = tcx.hir().span(hir_id);
let snippet = tcx.sess.source_map().span_to_snippet(span);
let filename = tcx.sess.source_map().span_to_filename(span);
let parent_node = self
.tcx
.hir()
.get(self.tcx.hir().get_parent_node(hir_id));
let msg = format!(
"you must specify a type for this binding, like `{}`",
concrete_type,
);
match (filename, parent_node, snippet) {
(
FileName::Real(_),
Node::Local(hir::Local {
source: hir::LocalSource::Normal,
ty,
..
}),
Ok(ref snippet),
) => {
err.span_suggestion(
// account for `let x: _ = 42;`
// ^^^^
span.to(ty
.as_ref()
.map(|ty| ty.span)
.unwrap_or(span)),
&msg,
format!("{}: {}", snippet, concrete_type),
Applicability::MaybeIncorrect,
);
}
_ => {
err.span_label(span, msg);
}
}
}
}
}
_ => {}
}
err.emit();
return None;
} else {
span = item_name.span;
let mut err = struct_span_err!(
tcx.sess,
span,
E0599,
"no {} named `{}` found for {} `{}` in the current scope",
item_kind,
item_name,
actual.prefix_string(self.tcx),
ty_str,
);
if let Mode::MethodCall = mode {
if let SelfSource::MethodCall(call) = source {
self.suggest_await_before_method(
&mut err, item_name, actual, call, span,
);
}
}
if let Some(span) =
tcx.sess.confused_type_with_std_module.borrow().get(&span)
{
if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(*span) {
err.span_suggestion(
*span,
"you are looking for the module in `std`, \
not the primitive type",
format!("std::{}", snippet),
Applicability::MachineApplicable,
);
}
}
if let ty::RawPtr(_) = &actual.kind() {
err.note(
"try using `<*const T>::as_ref()` to get a reference to the \
type behind the pointer: https://doc.rust-lang.org/std/\
primitive.pointer.html#method.as_ref",
);
err.note(
"using `<*const T>::as_ref()` on a pointer \
which is unaligned or points to invalid \
or uninitialized memory is undefined behavior",
);
}
err
}
} else {
tcx.sess.diagnostic().struct_dummy()
};
if let Some(def) = actual.ty_adt_def() {
if let Some(full_sp) = tcx.hir().span_if_local(def.did) {
let def_sp = tcx.sess.source_map().guess_head_span(full_sp);
err.span_label(
def_sp,
format!(
"{} `{}` not found {}",
item_kind,
item_name,
if def.is_enum() && !is_method { "here" } else { "for this" }
),
);
}
}
let mut label_span_not_found = || {
if unsatisfied_predicates.is_empty() {
err.span_label(span, format!("{item_kind} not found in `{ty_str}`"));
} else {
err.span_label(span, format!("{item_kind} cannot be called on `{ty_str}` due to unsatisfied trait bounds"));
}
self.tcx.sess.trait_methods_not_found.borrow_mut().insert(orig_span);
};
// If the method name is the name of a field with a function or closure type,
// give a helping note that it has to be called as `(x.f)(...)`.
if let SelfSource::MethodCall(expr) = source {
let field_receiver =
self.autoderef(span, rcvr_ty).find_map(|(ty, _)| match ty.kind() {
ty::Adt(def, substs) if !def.is_enum() => {
let variant = &def.non_enum_variant();
self.tcx.find_field_index(item_name, variant).map(|index| {
let field = &variant.fields[index];
let field_ty = field.ty(tcx, substs);
(field, field_ty)
})
}
_ => None,
});
if let Some((field, field_ty)) = field_receiver {
let scope = self.tcx.parent_module(self.body_id).to_def_id();
let is_accessible = field.vis.is_accessible_from(scope, self.tcx);
if is_accessible {
if self.is_fn_ty(&field_ty, span) {
let expr_span = expr.span.to(item_name.span);
err.multipart_suggestion(
&format!(
"to call the function stored in `{}`, \
surround the field access with parentheses",
item_name,
),
vec![
(expr_span.shrink_to_lo(), '('.to_string()),
(expr_span.shrink_to_hi(), ')'.to_string()),
],
Applicability::MachineApplicable,
);
} else {
let call_expr = self
.tcx
.hir()
.expect_expr(self.tcx.hir().get_parent_node(expr.hir_id));
if let Some(span) = call_expr.span.trim_start(item_name.span) {
err.span_suggestion(
span,
"remove the arguments",
String::new(),
Applicability::MaybeIncorrect,
);
}
}
}
let field_kind = if is_accessible { "field" } else { "private field" };
err.span_label(item_name.span, format!("{}, not a method", field_kind));
} else if lev_candidate.is_none() && static_sources.is_empty() {
label_span_not_found();
}
} else {
label_span_not_found();
}
if self.is_fn_ty(&rcvr_ty, span) {
fn report_function<T: std::fmt::Display>(
err: &mut DiagnosticBuilder<'_>,
name: T,
) {
err.note(
&format!("`{}` is a function, perhaps you wish to call it", name,),
);
}
if let SelfSource::MethodCall(expr) = source {
if let Ok(expr_string) = tcx.sess.source_map().span_to_snippet(expr.span) {
report_function(&mut err, expr_string);
} else if let ExprKind::Path(QPath::Resolved(_, ref path)) = expr.kind {
if let Some(segment) = path.segments.last() {
report_function(&mut err, segment.ident);
}
}
}
}
if !static_sources.is_empty() {
err.note(
"found the following associated functions; to be used as methods, \
functions must have a `self` parameter",
);
err.span_label(span, "this is an associated function, not a method");
}
if static_sources.len() == 1 {
let ty_str = if let Some(CandidateSource::ImplSource(impl_did)) =
static_sources.get(0)
{
// When the "method" is resolved through dereferencing, we really want the
// original type that has the associated function for accurate suggestions.
// (#61411)
let ty = tcx.at(span).type_of(*impl_did);
match (&ty.peel_refs().kind(), &actual.peel_refs().kind()) {
(ty::Adt(def, _), ty::Adt(def_actual, _)) if def == def_actual => {
// Use `actual` as it will have more `substs` filled in.
self.ty_to_value_string(actual.peel_refs())
}
_ => self.ty_to_value_string(ty.peel_refs()),
}
} else {
self.ty_to_value_string(actual.peel_refs())
};
if let SelfSource::MethodCall(expr) = source {
err.span_suggestion(
expr.span.to(span),
"use associated function syntax instead",
format!("{}::{}", ty_str, item_name),
Applicability::MachineApplicable,
);
} else {
err.help(&format!("try with `{}::{}`", ty_str, item_name,));
}
report_candidates(span, &mut err, static_sources, sugg_span);
} else if static_sources.len() > 1 {
report_candidates(span, &mut err, static_sources, sugg_span);
}
let mut restrict_type_params = false;
let mut unsatisfied_bounds = false;
if !unsatisfied_predicates.is_empty() {
let def_span = |def_id| {
self.tcx.sess.source_map().guess_head_span(self.tcx.def_span(def_id))
};
let mut type_params = FxHashMap::default();
let mut bound_spans = vec![];
let mut collect_type_param_suggestions =
|self_ty: Ty<'tcx>, parent_pred: &ty::Predicate<'tcx>, obligation: &str| {
// We don't care about regions here, so it's fine to skip the binder here.
if let (ty::Param(_), ty::PredicateKind::Trait(p, _)) =
(self_ty.kind(), parent_pred.kind().skip_binder())
{
if let ty::Adt(def, _) = p.trait_ref.self_ty().kind() {
let node = def.did.as_local().map(|def_id| {
self.tcx
.hir()
.get(self.tcx.hir().local_def_id_to_hir_id(def_id))
});
if let Some(hir::Node::Item(hir::Item { kind, .. })) = node {
if let Some(g) = kind.generics() {
let key = match g.where_clause.predicates {
[.., pred] => (pred.span().shrink_to_hi(), false),
[] => (
g.where_clause
.span_for_predicates_or_empty_place(),
true,
),
};
type_params
.entry(key)
.or_insert_with(FxHashSet::default)
.insert(obligation.to_owned());
}
}
}
}
};
let mut bound_span_label = |self_ty: Ty<'_>, obligation: &str, quiet: &str| {
let msg = format!(
"doesn't satisfy `{}`",
if obligation.len() > 50 { quiet } else { obligation }
);
match &self_ty.kind() {
// Point at the type that couldn't satisfy the bound.
ty::Adt(def, _) => bound_spans.push((def_span(def.did), msg)),
// Point at the trait object that couldn't satisfy the bound.
ty::Dynamic(preds, _) => {
for pred in preds.iter() {
match pred.skip_binder() {
ty::ExistentialPredicate::Trait(tr) => {
bound_spans.push((def_span(tr.def_id), msg.clone()))
}
ty::ExistentialPredicate::Projection(_)
| ty::ExistentialPredicate::AutoTrait(_) => {}
}
}
}
// Point at the closure that couldn't satisfy the bound.
ty::Closure(def_id, _) => bound_spans
.push((def_span(*def_id), format!("doesn't satisfy `{}`", quiet))),
_ => {}
}
};
let mut format_pred = |pred: ty::Predicate<'tcx>| {
let bound_predicate = pred.kind();
match bound_predicate.skip_binder() {
ty::PredicateKind::Projection(pred) => {
let pred = bound_predicate.rebind(pred);
// `<Foo as Iterator>::Item = String`.
let projection_ty = pred.skip_binder().projection_ty;
let substs_with_infer_self = tcx.mk_substs(
iter::once(tcx.mk_ty_var(ty::TyVid { index: 0 }).into())
.chain(projection_ty.substs.iter().skip(1)),
);
let quiet_projection_ty = ty::ProjectionTy {
substs: substs_with_infer_self,
item_def_id: projection_ty.item_def_id,
};
let ty = pred.skip_binder().ty;
let obligation = format!("{} = {}", projection_ty, ty);
let quiet = format!("{} = {}", quiet_projection_ty, ty);
bound_span_label(projection_ty.self_ty(), &obligation, &quiet);
Some((obligation, projection_ty.self_ty()))
}
ty::PredicateKind::Trait(poly_trait_ref, _) => {
let p = poly_trait_ref.trait_ref;
let self_ty = p.self_ty();
let path = p.print_only_trait_path();
let obligation = format!("{}: {}", self_ty, path);
let quiet = format!("_: {}", path);
bound_span_label(self_ty, &obligation, &quiet);
Some((obligation, self_ty))
}
_ => None,
}
};
let mut bound_list = unsatisfied_predicates
.iter()
.filter_map(|(pred, parent_pred)| {
format_pred(*pred).map(|(p, self_ty)| match parent_pred {
None => format!("`{}`", &p),
Some(parent_pred) => match format_pred(*parent_pred) {
None => format!("`{}`", &p),
Some((parent_p, _)) => {
collect_type_param_suggestions(self_ty, parent_pred, &p);
format!("`{}`\nwhich is required by `{}`", p, parent_p)
}
},
})
})
.enumerate()
.collect::<Vec<(usize, String)>>();
for ((span, empty_where), obligations) in type_params.into_iter() {
restrict_type_params = true;
// #74886: Sort here so that the output is always the same.
let mut obligations = obligations.into_iter().collect::<Vec<_>>();
obligations.sort();
err.span_suggestion_verbose(
span,
&format!(
"consider restricting the type parameter{s} to satisfy the \
trait bound{s}",
s = pluralize!(obligations.len())
),
format!(
"{} {}",
if empty_where { " where" } else { "," },
obligations.join(", ")
),
Applicability::MaybeIncorrect,
);
}
bound_list.sort_by(|(_, a), (_, b)| a.cmp(&b)); // Sort alphabetically.
bound_list.dedup_by(|(_, a), (_, b)| a == b); // #35677
bound_list.sort_by_key(|(pos, _)| *pos); // Keep the original predicate order.
bound_spans.sort();
bound_spans.dedup();
for (span, msg) in bound_spans.into_iter() {
err.span_label(span, &msg);
}
if !bound_list.is_empty() {
let bound_list = bound_list
.into_iter()
.map(|(_, path)| path)
.collect::<Vec<_>>()
.join("\n");
let actual_prefix = actual.prefix_string(self.tcx);
err.set_primary_message(&format!(
"the {item_kind} `{item_name}` exists for {actual_prefix} `{ty_str}`, but its trait bounds were not satisfied"
));
err.note(&format!(
"the following trait bounds were not satisfied:\n{bound_list}"
));
unsatisfied_bounds = true;
}
}
if actual.is_numeric() && actual.is_fresh() || restrict_type_params {
} else {
self.suggest_traits_to_import(
&mut err,
span,
rcvr_ty,
item_name,
source,
out_of_scope_traits,
&unsatisfied_predicates,
unsatisfied_bounds,
);
}
// Don't emit a suggestion if we found an actual method
// that had unsatisfied trait bounds
if unsatisfied_predicates.is_empty() && actual.is_enum() {
let adt_def = actual.ty_adt_def().expect("enum is not an ADT");
if let Some(suggestion) = lev_distance::find_best_match_for_name(
&adt_def.variants.iter().map(|s| s.ident.name).collect::<Vec<_>>(),
item_name.name,
None,
) {
err.span_suggestion(
span,
"there is a variant with a similar name",
suggestion.to_string(),
Applicability::MaybeIncorrect,
);
}
}
let mut fallback_span = true;
let msg = "remove this method call";
if item_name.name == sym::as_str && actual.peel_refs().is_str() {
if let SelfSource::MethodCall(expr) = source {
let call_expr =
self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id));
if let Some(span) = call_expr.span.trim_start(expr.span) {
err.span_suggestion(
span,
msg,
String::new(),
Applicability::MachineApplicable,
);
fallback_span = false;
}
}
if fallback_span {
err.span_label(span, msg);
}
} else if let Some(lev_candidate) = lev_candidate {
// Don't emit a suggestion if we found an actual method
// that had unsatisfied trait bounds
if unsatisfied_predicates.is_empty() {
let def_kind = lev_candidate.kind.as_def_kind();
err.span_suggestion(
span,
&format!(
"there is {} {} with a similar name",
def_kind.article(),
def_kind.descr(lev_candidate.def_id),
),
lev_candidate.ident.to_string(),
Applicability::MaybeIncorrect,
);
}
}
return Some(err);
}
MethodError::Ambiguity(sources) => {
let mut err = struct_span_err!(
self.sess(),
item_name.span,
E0034,
"multiple applicable items in scope"
);
err.span_label(item_name.span, format!("multiple `{}` found", item_name));
report_candidates(span, &mut err, sources, sugg_span);
err.emit();
}
MethodError::PrivateMatch(kind, def_id, out_of_scope_traits) => {
let kind = kind.descr(def_id);
let mut err = struct_span_err!(
self.tcx.sess,
item_name.span,
E0624,
"{} `{}` is private",
kind,
item_name
);
err.span_label(item_name.span, &format!("private {}", kind));
self.suggest_valid_traits(&mut err, out_of_scope_traits);
err.emit();
}
MethodError::IllegalSizedBound(candidates, needs_mut, bound_span) => {
let msg = format!("the `{}` method cannot be invoked on a trait object", item_name);
let mut err = self.sess().struct_span_err(span, &msg);
err.span_label(bound_span, "this has a `Sized` requirement");
if !candidates.is_empty() {
let help = format!(
"{an}other candidate{s} {were} found in the following trait{s}, perhaps \
add a `use` for {one_of_them}:",
an = if candidates.len() == 1 { "an" } else { "" },
s = pluralize!(candidates.len()),
were = if candidates.len() == 1 { "was" } else { "were" },
one_of_them = if candidates.len() == 1 { "it" } else { "one_of_them" },
);
self.suggest_use_candidates(&mut err, help, candidates);
}
if let ty::Ref(region, t_type, mutability) = rcvr_ty.kind() {
if needs_mut {
let trait_type = self.tcx.mk_ref(
region,
ty::TypeAndMut { ty: t_type, mutbl: mutability.invert() },
);
err.note(&format!("you need `{}` instead of `{}`", trait_type, rcvr_ty));
}
}
err.emit();
}
MethodError::BadReturnType => bug!("no return type expectations but got BadReturnType"),
}
None
}
/// Print out the type for use in value namespace.
fn ty_to_value_string(&self, ty: Ty<'tcx>) -> String {
match ty.kind() {
ty::Adt(def, substs) => format!("{}", ty::Instance::new(def.did, substs)),
_ => self.ty_to_string(ty),
}
}
fn suggest_await_before_method(
&self,
err: &mut DiagnosticBuilder<'_>,
item_name: Ident,
ty: Ty<'tcx>,
call: &hir::Expr<'_>,
span: Span,
) {
let output_ty = match self.infcx.get_impl_future_output_ty(ty) {
Some(output_ty) => self.resolve_vars_if_possible(output_ty),
_ => return,
};
let method_exists = self.method_exists(item_name, output_ty, call.hir_id, true);
debug!("suggest_await_before_method: is_method_exist={}", method_exists);
if method_exists {
err.span_suggestion_verbose(
span.shrink_to_lo(),
"consider `await`ing on the `Future` and calling the method on its `Output`",
"await.".to_string(),
Applicability::MaybeIncorrect,
);
}
}
fn suggest_use_candidates(
&self,
err: &mut DiagnosticBuilder<'_>,
mut msg: String,
candidates: Vec<DefId>,
) {
let module_did = self.tcx.parent_module(self.body_id);
let module_id = self.tcx.hir().local_def_id_to_hir_id(module_did);
let krate = self.tcx.hir().krate();
let (span, found_use) = UsePlacementFinder::check(self.tcx, krate, module_id);
if let Some(span) = span {
let path_strings = candidates.iter().map(|did| {
// Produce an additional newline to separate the new use statement
// from the directly following item.
let additional_newline = if found_use { "" } else { "\n" };
format!(
"use {};\n{}",
with_crate_prefix(|| self.tcx.def_path_str(*did)),
additional_newline
)
});
err.span_suggestions(span, &msg, path_strings, Applicability::MaybeIncorrect);
} else {
let limit = if candidates.len() == 5 { 5 } else { 4 };
for (i, trait_did) in candidates.iter().take(limit).enumerate() {
if candidates.len() > 1 {
msg.push_str(&format!(
"\ncandidate #{}: `use {};`",
i + 1,
with_crate_prefix(|| self.tcx.def_path_str(*trait_did))
));
} else {
msg.push_str(&format!(
"\n`use {};`",
with_crate_prefix(|| self.tcx.def_path_str(*trait_did))
));
}
}
if candidates.len() > limit {
msg.push_str(&format!("\nand {} others", candidates.len() - limit));
}
err.note(&msg[..]);
}
}
fn suggest_valid_traits(
&self,
err: &mut DiagnosticBuilder<'_>,
valid_out_of_scope_traits: Vec<DefId>,
) -> bool {
if !valid_out_of_scope_traits.is_empty() {
let mut candidates = valid_out_of_scope_traits;
candidates.sort();
candidates.dedup();
err.help("items from traits can only be used if the trait is in scope");
let msg = format!(
"the following {traits_are} implemented but not in scope; \
perhaps add a `use` for {one_of_them}:",
traits_are = if candidates.len() == 1 { "trait is" } else { "traits are" },
one_of_them = if candidates.len() == 1 { "it" } else { "one of them" },
);
self.suggest_use_candidates(err, msg, candidates);
true
} else {
false
}
}
fn suggest_traits_to_import(
&self,
err: &mut DiagnosticBuilder<'_>,
span: Span,
rcvr_ty: Ty<'tcx>,
item_name: Ident,
source: SelfSource<'tcx>,
valid_out_of_scope_traits: Vec<DefId>,
unsatisfied_predicates: &[(ty::Predicate<'tcx>, Option<ty::Predicate<'tcx>>)],
unsatisfied_bounds: bool,
) {
let mut alt_rcvr_sugg = false;
if let (SelfSource::MethodCall(rcvr), false) = (source, unsatisfied_bounds) {
debug!(?span, ?item_name, ?rcvr_ty, ?rcvr);
let skippable = [
self.tcx.lang_items().clone_trait(),
self.tcx.lang_items().deref_trait(),
self.tcx.lang_items().deref_mut_trait(),
self.tcx.lang_items().drop_trait(),
];