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meithecattemeithecatte
committedMar 26, 2025··
ExprUseVisitor: properly report discriminant reads
This solves the "can't find the upvar" ICEs that resulted from `maybe_read_scrutinee` being unfit for purpose.
1 parent 908504e commit ce47a4c

9 files changed

+371
-49
lines changed
 

‎compiler/rustc_hir_typeck/src/expr_use_visitor.rs

Lines changed: 90 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -941,6 +941,19 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
941941
}
942942

943943
/// The core driver for walking a pattern
944+
///
945+
/// This should mirror how pattern-matching gets lowered to MIR, as
946+
/// otherwise lowering will ICE when trying to resolve the upvars.
947+
///
948+
/// However, it is okay to approximate it here by doing *more* accesses than
949+
/// the actual MIR builder will, which is useful when some checks are too
950+
/// cumbersome to perform here. For example, if after typeck it becomes
951+
/// clear that only one variant of an enum is inhabited, and therefore a
952+
/// read of the discriminant is not necessary, `walk_pat` will have
953+
/// over-approximated the necessary upvar capture granularity.
954+
///
955+
/// Do note that discrepancies like these do still create obscure corners
956+
/// in the semantics of the language, and should be avoided if possible.
944957
#[instrument(skip(self), level = "debug")]
945958
fn walk_pat(
946959
&self,
@@ -950,6 +963,11 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
950963
) -> Result<(), Cx::Error> {
951964
let tcx = self.cx.tcx();
952965
self.cat_pattern(discr_place.clone(), pat, &mut |place, pat| {
966+
debug!("walk_pat: pat.kind={:?}", pat.kind);
967+
let read_discriminant = || {
968+
self.delegate.borrow_mut().borrow(place, discr_place.hir_id, BorrowKind::Immutable);
969+
};
970+
953971
match pat.kind {
954972
PatKind::Binding(_, canonical_id, ..) => {
955973
debug!("walk_pat: binding place={:?} pat={:?}", place, pat);
@@ -972,11 +990,7 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
972990
// binding when lowering pattern guards to ensure that the guard does not
973991
// modify the scrutinee.
974992
if has_guard {
975-
self.delegate.borrow_mut().borrow(
976-
place,
977-
discr_place.hir_id,
978-
BorrowKind::Immutable,
979-
);
993+
read_discriminant();
980994
}
981995

982996
// It is also a borrow or copy/move of the value being matched.
@@ -1008,13 +1022,70 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
10081022
PatKind::Never => {
10091023
// A `!` pattern always counts as an immutable read of the discriminant,
10101024
// even in an irrefutable pattern.
1011-
self.delegate.borrow_mut().borrow(
1012-
place,
1013-
discr_place.hir_id,
1014-
BorrowKind::Immutable,
1015-
);
1025+
read_discriminant();
1026+
}
1027+
PatKind::Expr(PatExpr { kind: PatExprKind::Path(qpath), hir_id, span }) => {
1028+
// A `Path` pattern is just a name like `Foo`. This is either a
1029+
// named constant or else it refers to an ADT variant
1030+
1031+
let res = self.cx.typeck_results().qpath_res(qpath, *hir_id);
1032+
match res {
1033+
Res::Def(DefKind::Const, _) | Res::Def(DefKind::AssocConst, _) => {
1034+
// Named constants have to be equated with the value
1035+
// being matched, so that's a read of the value being matched.
1036+
//
1037+
// FIXME: Does the MIR code skip this read when matching on a ZST?
1038+
// If so, we can also skip it here.
1039+
read_discriminant();
1040+
}
1041+
_ => {
1042+
// Otherwise, this is a struct/enum variant, and so it's
1043+
// only a read if we need to read the discriminant.
1044+
if self.is_multivariant_adt(place.place.ty(), *span) {
1045+
read_discriminant();
1046+
}
1047+
}
1048+
}
1049+
}
1050+
PatKind::Expr(_) | PatKind::Range(..) => {
1051+
// When matching against a literal or range, we need to
1052+
// borrow the place to compare it against the pattern.
1053+
//
1054+
// FIXME: What if the type being matched only has one
1055+
// possible value?
1056+
// FIXME: What if the range is the full range of the type
1057+
// and doesn't actually require a discriminant read?
1058+
read_discriminant();
1059+
}
1060+
PatKind::Struct(..) | PatKind::TupleStruct(..) => {
1061+
if self.is_multivariant_adt(place.place.ty(), pat.span) {
1062+
read_discriminant();
1063+
}
1064+
}
1065+
PatKind::Slice(lhs, wild, rhs) => {
1066+
// We don't need to test the length if the pattern is `[..]`
1067+
if matches!((lhs, wild, rhs), (&[], Some(_), &[]))
1068+
// Arrays have a statically known size, so
1069+
// there is no need to read their length
1070+
|| place.place.ty().peel_refs().is_array()
1071+
{
1072+
// No read necessary
1073+
} else {
1074+
read_discriminant();
1075+
}
1076+
}
1077+
PatKind::Or(_)
1078+
| PatKind::Box(_)
1079+
| PatKind::Ref(..)
1080+
| PatKind::Guard(..)
1081+
| PatKind::Tuple(..)
1082+
| PatKind::Wild
1083+
| PatKind::Err(_) => {
1084+
// If the PatKind is Or, Box, Ref, Guard, or Tuple, the relevant accesses
1085+
// are made later as these patterns contains subpatterns.
1086+
// If the PatKind is Wild or Err, they are made when processing the other patterns
1087+
// being examined
10161088
}
1017-
_ => {}
10181089
}
10191090

10201091
Ok(())
@@ -1849,6 +1920,14 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
18491920
Ok(())
18501921
}
18511922

1923+
/// Checks whether a type has multiple variants, and therefore, whether a
1924+
/// read of the discriminant might be necessary. Note that the actual MIR
1925+
/// builder code does a more specific check, filtering out variants that
1926+
/// happen to be uninhabited.
1927+
///
1928+
/// Here, we cannot perform such an accurate checks, because querying
1929+
/// whether a type is inhabited requires that it has been fully inferred,
1930+
/// which cannot be guaranteed at this point.
18521931
fn is_multivariant_adt(&self, ty: Ty<'tcx>, span: Span) -> bool {
18531932
if let ty::Adt(def, _) = self.cx.try_structurally_resolve_type(span, ty).kind() {
18541933
// Note that if a non-exhaustive SingleVariant is defined in another crate, we need

‎tests/ui/closures/2229_closure_analysis/capture-enums.rs

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -22,13 +22,15 @@ fn multi_variant_enum() {
2222
//~| Min Capture analysis includes:
2323
if let Info::Point(_, _, str) = point {
2424
//~^ NOTE: Capturing point[] -> Immutable
25+
//~| NOTE: Capturing point[] -> Immutable
2526
//~| NOTE: Capturing point[(2, 0)] -> ByValue
2627
//~| NOTE: Min Capture point[] -> ByValue
2728
println!("{}", str);
2829
}
2930

3031
if let Info::Meta(_, v) = meta {
3132
//~^ NOTE: Capturing meta[] -> Immutable
33+
//~| NOTE: Capturing meta[] -> Immutable
3234
//~| NOTE: Capturing meta[(1, 1)] -> ByValue
3335
//~| NOTE: Min Capture meta[] -> ByValue
3436
println!("{:?}", v);

‎tests/ui/closures/2229_closure_analysis/capture-enums.stderr

Lines changed: 18 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@ LL | let c = #[rustc_capture_analysis]
99
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
1010

1111
error[E0658]: attributes on expressions are experimental
12-
--> $DIR/capture-enums.rs:48:13
12+
--> $DIR/capture-enums.rs:50:13
1313
|
1414
LL | let c = #[rustc_capture_analysis]
1515
| ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -34,18 +34,28 @@ note: Capturing point[] -> Immutable
3434
|
3535
LL | if let Info::Point(_, _, str) = point {
3636
| ^^^^^
37+
note: Capturing point[] -> Immutable
38+
--> $DIR/capture-enums.rs:23:41
39+
|
40+
LL | if let Info::Point(_, _, str) = point {
41+
| ^^^^^
3742
note: Capturing point[(2, 0)] -> ByValue
3843
--> $DIR/capture-enums.rs:23:41
3944
|
4045
LL | if let Info::Point(_, _, str) = point {
4146
| ^^^^^
4247
note: Capturing meta[] -> Immutable
43-
--> $DIR/capture-enums.rs:30:35
48+
--> $DIR/capture-enums.rs:31:35
49+
|
50+
LL | if let Info::Meta(_, v) = meta {
51+
| ^^^^
52+
note: Capturing meta[] -> Immutable
53+
--> $DIR/capture-enums.rs:31:35
4454
|
4555
LL | if let Info::Meta(_, v) = meta {
4656
| ^^^^
4757
note: Capturing meta[(1, 1)] -> ByValue
48-
--> $DIR/capture-enums.rs:30:35
58+
--> $DIR/capture-enums.rs:31:35
4959
|
5060
LL | if let Info::Meta(_, v) = meta {
5161
| ^^^^
@@ -67,13 +77,13 @@ note: Min Capture point[] -> ByValue
6777
LL | if let Info::Point(_, _, str) = point {
6878
| ^^^^^
6979
note: Min Capture meta[] -> ByValue
70-
--> $DIR/capture-enums.rs:30:35
80+
--> $DIR/capture-enums.rs:31:35
7181
|
7282
LL | if let Info::Meta(_, v) = meta {
7383
| ^^^^
7484

7585
error: First Pass analysis includes:
76-
--> $DIR/capture-enums.rs:52:5
86+
--> $DIR/capture-enums.rs:54:5
7787
|
7888
LL | / || {
7989
LL | |
@@ -85,13 +95,13 @@ LL | | };
8595
| |_____^
8696
|
8797
note: Capturing point[(2, 0)] -> ByValue
88-
--> $DIR/capture-enums.rs:55:47
98+
--> $DIR/capture-enums.rs:57:47
8999
|
90100
LL | let SingleVariant::Point(_, _, str) = point;
91101
| ^^^^^
92102

93103
error: Min Capture analysis includes:
94-
--> $DIR/capture-enums.rs:52:5
104+
--> $DIR/capture-enums.rs:54:5
95105
|
96106
LL | / || {
97107
LL | |
@@ -103,7 +113,7 @@ LL | | };
103113
| |_____^
104114
|
105115
note: Min Capture point[(2, 0)] -> ByValue
106-
--> $DIR/capture-enums.rs:55:47
116+
--> $DIR/capture-enums.rs:57:47
107117
|
108118
LL | let SingleVariant::Point(_, _, str) = point;
109119
| ^^^^^

‎tests/ui/closures/2229_closure_analysis/match/patterns-capture-analysis.rs

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@ fn test_1_should_capture() {
1414
//~| Min Capture analysis includes:
1515
match variant {
1616
//~^ NOTE: Capturing variant[] -> Immutable
17+
//~| NOTE: Capturing variant[] -> Immutable
1718
//~| NOTE: Min Capture variant[] -> Immutable
1819
Some(_) => {}
1920
_ => {}
@@ -132,6 +133,7 @@ fn test_5_should_capture_multi_variant() {
132133
//~| Min Capture analysis includes:
133134
match variant {
134135
//~^ NOTE: Capturing variant[] -> Immutable
136+
//~| NOTE: Capturing variant[] -> Immutable
135137
//~| NOTE: Min Capture variant[] -> Immutable
136138
MVariant::A => {}
137139
_ => {}
@@ -150,6 +152,7 @@ fn test_7_should_capture_slice_len() {
150152
//~| Min Capture analysis includes:
151153
match slice {
152154
//~^ NOTE: Capturing slice[] -> Immutable
155+
//~| NOTE: Capturing slice[Deref] -> Immutable
153156
//~| NOTE: Min Capture slice[] -> Immutable
154157
[_,_,_] => {},
155158
_ => {}
@@ -162,6 +165,7 @@ fn test_7_should_capture_slice_len() {
162165
//~| Min Capture analysis includes:
163166
match slice {
164167
//~^ NOTE: Capturing slice[] -> Immutable
168+
//~| NOTE: Capturing slice[Deref] -> Immutable
165169
//~| NOTE: Min Capture slice[] -> Immutable
166170
[] => {},
167171
_ => {}
@@ -174,6 +178,7 @@ fn test_7_should_capture_slice_len() {
174178
//~| Min Capture analysis includes:
175179
match slice {
176180
//~^ NOTE: Capturing slice[] -> Immutable
181+
//~| NOTE: Capturing slice[Deref] -> Immutable
177182
//~| NOTE: Min Capture slice[] -> Immutable
178183
[_, .. ,_] => {},
179184
_ => {}

‎tests/ui/closures/2229_closure_analysis/match/patterns-capture-analysis.stderr

Lines changed: 52 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,11 @@ note: Capturing variant[] -> Immutable
1414
|
1515
LL | match variant {
1616
| ^^^^^^^
17+
note: Capturing variant[] -> Immutable
18+
--> $DIR/patterns-capture-analysis.rs:15:15
19+
|
20+
LL | match variant {
21+
| ^^^^^^^
1722

1823
error: Min Capture analysis includes:
1924
--> $DIR/patterns-capture-analysis.rs:12:5
@@ -33,7 +38,7 @@ LL | match variant {
3338
| ^^^^^^^
3439

3540
error: First Pass analysis includes:
36-
--> $DIR/patterns-capture-analysis.rs:30:5
41+
--> $DIR/patterns-capture-analysis.rs:31:5
3742
|
3843
LL | / || {
3944
LL | |
@@ -44,7 +49,7 @@ LL | | };
4449
| |_____^
4550

4651
error: First Pass analysis includes:
47-
--> $DIR/patterns-capture-analysis.rs:49:5
52+
--> $DIR/patterns-capture-analysis.rs:50:5
4853
|
4954
LL | / || {
5055
LL | |
@@ -55,7 +60,7 @@ LL | | };
5560
| |_____^
5661

5762
error: First Pass analysis includes:
58-
--> $DIR/patterns-capture-analysis.rs:63:5
63+
--> $DIR/patterns-capture-analysis.rs:64:5
5964
|
6065
LL | / || {
6166
LL | |
@@ -66,18 +71,18 @@ LL | | };
6671
| |_____^
6772
|
6873
note: Capturing variant[] -> Immutable
69-
--> $DIR/patterns-capture-analysis.rs:66:15
74+
--> $DIR/patterns-capture-analysis.rs:67:15
7075
|
7176
LL | match variant {
7277
| ^^^^^^^
7378
note: Capturing variant[(0, 0)] -> Immutable
74-
--> $DIR/patterns-capture-analysis.rs:66:15
79+
--> $DIR/patterns-capture-analysis.rs:67:15
7580
|
7681
LL | match variant {
7782
| ^^^^^^^
7883

7984
error: Min Capture analysis includes:
80-
--> $DIR/patterns-capture-analysis.rs:63:5
85+
--> $DIR/patterns-capture-analysis.rs:64:5
8186
|
8287
LL | / || {
8388
LL | |
@@ -88,13 +93,13 @@ LL | | };
8893
| |_____^
8994
|
9095
note: Min Capture variant[] -> Immutable
91-
--> $DIR/patterns-capture-analysis.rs:66:15
96+
--> $DIR/patterns-capture-analysis.rs:67:15
9297
|
9398
LL | match variant {
9499
| ^^^^^^^
95100

96101
error: First Pass analysis includes:
97-
--> $DIR/patterns-capture-analysis.rs:83:5
102+
--> $DIR/patterns-capture-analysis.rs:84:5
98103
|
99104
LL | / || {
100105
LL | |
@@ -105,7 +110,7 @@ LL | | };
105110
| |_____^
106111

107112
error: First Pass analysis includes:
108-
--> $DIR/patterns-capture-analysis.rs:95:5
113+
--> $DIR/patterns-capture-analysis.rs:96:5
109114
|
110115
LL | / || {
111116
LL | |
@@ -116,7 +121,7 @@ LL | | };
116121
| |_____^
117122

118123
error: First Pass analysis includes:
119-
--> $DIR/patterns-capture-analysis.rs:108:5
124+
--> $DIR/patterns-capture-analysis.rs:109:5
120125
|
121126
LL | / || {
122127
LL | |
@@ -127,7 +132,7 @@ LL | | };
127132
| |_____^
128133

129134
error: First Pass analysis includes:
130-
--> $DIR/patterns-capture-analysis.rs:130:5
135+
--> $DIR/patterns-capture-analysis.rs:131:5
131136
|
132137
LL | / || {
133138
LL | |
@@ -138,13 +143,18 @@ LL | | };
138143
| |_____^
139144
|
140145
note: Capturing variant[] -> Immutable
141-
--> $DIR/patterns-capture-analysis.rs:133:15
146+
--> $DIR/patterns-capture-analysis.rs:134:15
147+
|
148+
LL | match variant {
149+
| ^^^^^^^
150+
note: Capturing variant[] -> Immutable
151+
--> $DIR/patterns-capture-analysis.rs:134:15
142152
|
143153
LL | match variant {
144154
| ^^^^^^^
145155

146156
error: Min Capture analysis includes:
147-
--> $DIR/patterns-capture-analysis.rs:130:5
157+
--> $DIR/patterns-capture-analysis.rs:131:5
148158
|
149159
LL | / || {
150160
LL | |
@@ -155,13 +165,13 @@ LL | | };
155165
| |_____^
156166
|
157167
note: Min Capture variant[] -> Immutable
158-
--> $DIR/patterns-capture-analysis.rs:133:15
168+
--> $DIR/patterns-capture-analysis.rs:134:15
159169
|
160170
LL | match variant {
161171
| ^^^^^^^
162172

163173
error: First Pass analysis includes:
164-
--> $DIR/patterns-capture-analysis.rs:148:5
174+
--> $DIR/patterns-capture-analysis.rs:150:5
165175
|
166176
LL | / || {
167177
LL | |
@@ -172,13 +182,18 @@ LL | | };
172182
| |_____^
173183
|
174184
note: Capturing slice[] -> Immutable
175-
--> $DIR/patterns-capture-analysis.rs:151:15
185+
--> $DIR/patterns-capture-analysis.rs:153:15
186+
|
187+
LL | match slice {
188+
| ^^^^^
189+
note: Capturing slice[Deref] -> Immutable
190+
--> $DIR/patterns-capture-analysis.rs:153:15
176191
|
177192
LL | match slice {
178193
| ^^^^^
179194

180195
error: Min Capture analysis includes:
181-
--> $DIR/patterns-capture-analysis.rs:148:5
196+
--> $DIR/patterns-capture-analysis.rs:150:5
182197
|
183198
LL | / || {
184199
LL | |
@@ -189,13 +204,13 @@ LL | | };
189204
| |_____^
190205
|
191206
note: Min Capture slice[] -> Immutable
192-
--> $DIR/patterns-capture-analysis.rs:151:15
207+
--> $DIR/patterns-capture-analysis.rs:153:15
193208
|
194209
LL | match slice {
195210
| ^^^^^
196211

197212
error: First Pass analysis includes:
198-
--> $DIR/patterns-capture-analysis.rs:160:5
213+
--> $DIR/patterns-capture-analysis.rs:163:5
199214
|
200215
LL | / || {
201216
LL | |
@@ -206,13 +221,18 @@ LL | | };
206221
| |_____^
207222
|
208223
note: Capturing slice[] -> Immutable
209-
--> $DIR/patterns-capture-analysis.rs:163:15
224+
--> $DIR/patterns-capture-analysis.rs:166:15
225+
|
226+
LL | match slice {
227+
| ^^^^^
228+
note: Capturing slice[Deref] -> Immutable
229+
--> $DIR/patterns-capture-analysis.rs:166:15
210230
|
211231
LL | match slice {
212232
| ^^^^^
213233

214234
error: Min Capture analysis includes:
215-
--> $DIR/patterns-capture-analysis.rs:160:5
235+
--> $DIR/patterns-capture-analysis.rs:163:5
216236
|
217237
LL | / || {
218238
LL | |
@@ -223,13 +243,13 @@ LL | | };
223243
| |_____^
224244
|
225245
note: Min Capture slice[] -> Immutable
226-
--> $DIR/patterns-capture-analysis.rs:163:15
246+
--> $DIR/patterns-capture-analysis.rs:166:15
227247
|
228248
LL | match slice {
229249
| ^^^^^
230250

231251
error: First Pass analysis includes:
232-
--> $DIR/patterns-capture-analysis.rs:172:5
252+
--> $DIR/patterns-capture-analysis.rs:176:5
233253
|
234254
LL | / || {
235255
LL | |
@@ -240,13 +260,18 @@ LL | | };
240260
| |_____^
241261
|
242262
note: Capturing slice[] -> Immutable
243-
--> $DIR/patterns-capture-analysis.rs:175:15
263+
--> $DIR/patterns-capture-analysis.rs:179:15
264+
|
265+
LL | match slice {
266+
| ^^^^^
267+
note: Capturing slice[Deref] -> Immutable
268+
--> $DIR/patterns-capture-analysis.rs:179:15
244269
|
245270
LL | match slice {
246271
| ^^^^^
247272

248273
error: Min Capture analysis includes:
249-
--> $DIR/patterns-capture-analysis.rs:172:5
274+
--> $DIR/patterns-capture-analysis.rs:176:5
250275
|
251276
LL | / || {
252277
LL | |
@@ -257,13 +282,13 @@ LL | | };
257282
| |_____^
258283
|
259284
note: Min Capture slice[] -> Immutable
260-
--> $DIR/patterns-capture-analysis.rs:175:15
285+
--> $DIR/patterns-capture-analysis.rs:179:15
261286
|
262287
LL | match slice {
263288
| ^^^^^
264289

265290
error: First Pass analysis includes:
266-
--> $DIR/patterns-capture-analysis.rs:189:5
291+
--> $DIR/patterns-capture-analysis.rs:194:5
267292
|
268293
LL | / || {
269294
LL | |

‎tests/ui/closures/2229_closure_analysis/only-inhabited-variant.exhaustive_patterns.stderr

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
1+
error[E0499]: cannot borrow `r` as mutable more than once at a time
2+
--> $DIR/only-inhabited-variant.rs:16:17
3+
|
4+
LL | let mut f = || {
5+
| -- first mutable borrow occurs here
6+
LL | let Err((ref mut a, _)) = r;
7+
| - first borrow occurs due to use of `r` in closure
8+
...
9+
LL | let mut g = || {
10+
| ^^ second mutable borrow occurs here
11+
LL |
12+
LL | let Err((_, ref mut b)) = r;
13+
| - second borrow occurs due to use of `r` in closure
14+
...
15+
LL | f();
16+
| - first borrow later used here
17+
18+
error: aborting due to 1 previous error
19+
20+
For more information about this error, try `rustc --explain E0499`.

‎tests/ui/closures/2229_closure_analysis/only-inhabited-variant.normal.stderr

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
1+
error[E0499]: cannot borrow `r` as mutable more than once at a time
2+
--> $DIR/only-inhabited-variant.rs:16:17
3+
|
4+
LL | let mut f = || {
5+
| -- first mutable borrow occurs here
6+
LL | let Err((ref mut a, _)) = r;
7+
| - first borrow occurs due to use of `r` in closure
8+
...
9+
LL | let mut g = || {
10+
| ^^ second mutable borrow occurs here
11+
LL |
12+
LL | let Err((_, ref mut b)) = r;
13+
| - second borrow occurs due to use of `r` in closure
14+
...
15+
LL | f();
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| - first borrow later used here
17+
18+
error: aborting due to 1 previous error
19+
20+
For more information about this error, try `rustc --explain E0499`.

‎tests/ui/closures/2229_closure_analysis/run_pass/multivariant.rs renamed to ‎tests/ui/closures/2229_closure_analysis/only-inhabited-variant.rs

Lines changed: 5 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,9 @@
1-
// Test precise capture of a multi-variant enum (when remaining variants are
2-
// visibly uninhabited).
1+
// This example used to compile, but the fact that it should was never properly
2+
// discussed. With further experience, we concluded that capture precision
3+
// depending on whether some types are inhabited goes too far, introducing a
4+
// bunch of headaches without much benefit.
35
//@ revisions: normal exhaustive_patterns
46
//@ edition:2021
5-
//@ run-pass
67
#![cfg_attr(exhaustive_patterns, feature(exhaustive_patterns))]
78
#![feature(never_type)]
89

@@ -13,6 +14,7 @@ pub fn main() {
1314
*a = 1;
1415
};
1516
let mut g = || {
17+
//~^ ERROR: cannot borrow `r` as mutable more than once at a time
1618
let Err((_, ref mut b)) = r;
1719
*b = 2;
1820
};

‎tests/ui/closures/or-patterns-issue-137467.rs

Lines changed: 159 additions & 0 deletions
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1+
//@ edition:2024
2+
//@ check-pass
3+
4+
const X: u32 = 0;
5+
6+
fn match_literal(x: (u32, u32, u32)) {
7+
let _ = || {
8+
let ((0, a, _) | (_, _, a)) = x;
9+
a
10+
};
11+
}
12+
13+
fn match_range(x: (u32, u32, u32)) {
14+
let _ = || {
15+
let ((0..5, a, _) | (_, _, a)) = x;
16+
a
17+
};
18+
}
19+
20+
fn match_const(x: (u32, u32, u32)) {
21+
let _ = || {
22+
let ((X, a, _) | (_, _, a)) = x;
23+
a
24+
};
25+
}
26+
27+
enum Choice { A, B }
28+
29+
fn match_unit_variant(x: (Choice, u32, u32)) {
30+
let _ = || {
31+
let ((Choice::A, a, _) | (Choice::B, _, a)) = x;
32+
a
33+
};
34+
}
35+
36+
struct Unit;
37+
38+
fn match_unit_struct(mut x: (Unit, u32)) {
39+
let r = &mut x.0;
40+
let _ = || {
41+
let (Unit, a) = x;
42+
a
43+
};
44+
45+
let _ = *r;
46+
}
47+
48+
enum Also { Unit }
49+
50+
fn match_unit_enum(mut x: (Also, u32)) {
51+
let r = &mut x.0;
52+
let _ = || {
53+
let (Also::Unit, a) = x;
54+
a
55+
};
56+
57+
let _ = *r;
58+
}
59+
60+
enum TEnum {
61+
A(u32),
62+
B(u32),
63+
}
64+
65+
enum SEnum {
66+
A { a: u32 },
67+
B { a: u32 },
68+
}
69+
70+
fn match_tuple_enum(x: TEnum) {
71+
let _ = || {
72+
let (TEnum::A(a) | TEnum::B(a)) = x;
73+
a
74+
};
75+
}
76+
77+
fn match_struct_enum(x: SEnum) {
78+
let _ = || {
79+
let (SEnum::A { a } | SEnum::B { a }) = x;
80+
a
81+
};
82+
}
83+
84+
enum TSingle {
85+
A(u32, u32),
86+
}
87+
88+
enum SSingle {
89+
A { a: u32, b: u32 },
90+
}
91+
92+
struct TStruct(u32, u32);
93+
struct SStruct { a: u32, b: u32 }
94+
95+
fn match_struct(mut x: SStruct) {
96+
let r = &mut x.a;
97+
let _ = || {
98+
let SStruct { b, .. } = x;
99+
b
100+
};
101+
102+
let _ = *r;
103+
}
104+
105+
fn match_tuple_struct(mut x: TStruct) {
106+
let r = &mut x.0;
107+
let _ = || {
108+
let TStruct(_, a) = x;
109+
a
110+
};
111+
112+
let _ = *r;
113+
}
114+
115+
fn match_singleton(mut x: SSingle) {
116+
let SSingle::A { a: ref mut r, .. } = x;
117+
let _ = || {
118+
let SSingle::A { b, .. } = x;
119+
b
120+
};
121+
122+
let _ = *r;
123+
}
124+
125+
fn match_tuple_singleton(mut x: TSingle) {
126+
let TSingle::A(ref mut r, _) = x;
127+
let _ = || {
128+
let TSingle::A(_, a) = x;
129+
a
130+
};
131+
132+
let _ = *r;
133+
}
134+
135+
fn match_slice(x: (&[u32], u32, u32)) {
136+
let _ = || {
137+
let (([], a, _) | ([_, ..], _, a)) = x;
138+
a
139+
};
140+
}
141+
142+
// Original testcase, for completeness
143+
enum Camera {
144+
Normal { base_transform: i32 },
145+
Volume { transform: i32 },
146+
}
147+
148+
fn draw_ui(camera: &mut Camera) {
149+
|| {
150+
let (Camera::Normal {
151+
base_transform: _transform,
152+
}
153+
| Camera::Volume {
154+
transform: _transform,
155+
}) = camera;
156+
};
157+
}
158+
159+
fn main() {}

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