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Revert "Add some extra information to opaque type cycle errors"
This reverts commit 9e98feb, as it caused a performance regression.
1 parent 0d50ab7 commit 6e03965

16 files changed

+24
-421
lines changed

‎compiler/rustc_middle/src/traits/mod.rs

-4
Original file line numberDiff line numberDiff line change
@@ -588,10 +588,6 @@ pub enum SelectionError<'tcx> {
588588
/// Signaling that an error has already been emitted, to avoid
589589
/// multiple errors being shown.
590590
ErrorReporting,
591-
/// Computing an opaque type's hidden type caused an error (e.g. a cycle error).
592-
/// We can thus not know whether the hidden type implements an auto trait, so
593-
/// we should not presume anything about it.
594-
OpaqueTypeAutoTraitLeakageUnknown(DefId),
595591
}
596592

597593
#[derive(Clone, Debug, TypeVisitable, Lift)]

‎compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

+1-45
Original file line numberDiff line numberDiff line change
@@ -30,7 +30,7 @@ use rustc_infer::infer::error_reporting::TypeErrCtxt;
3030
use rustc_infer::infer::{InferOk, TypeTrace};
3131
use rustc_middle::traits::select::OverflowError;
3232
use rustc_middle::traits::solve::Goal;
33-
use rustc_middle::traits::{DefiningAnchor, SelectionOutputTypeParameterMismatch};
33+
use rustc_middle::traits::SelectionOutputTypeParameterMismatch;
3434
use rustc_middle::ty::abstract_const::NotConstEvaluatable;
3535
use rustc_middle::ty::error::{ExpectedFound, TypeError};
3636
use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
@@ -1152,11 +1152,6 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
11521152
}
11531153
}
11541154

1155-
SelectionError::OpaqueTypeAutoTraitLeakageUnknown(def_id) => self.report_opaque_type_auto_trait_leakage(
1156-
&obligation,
1157-
def_id,
1158-
),
1159-
11601155
TraitNotObjectSafe(did) => {
11611156
let violations = self.tcx.object_safety_violations(did);
11621157
report_object_safety_error(self.tcx, span, did, violations)
@@ -1470,12 +1465,6 @@ trait InferCtxtPrivExt<'tcx> {
14701465
terr: TypeError<'tcx>,
14711466
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed>;
14721467

1473-
fn report_opaque_type_auto_trait_leakage(
1474-
&self,
1475-
obligation: &PredicateObligation<'tcx>,
1476-
def_id: DefId,
1477-
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed>;
1478-
14791468
fn report_type_parameter_mismatch_error(
14801469
&self,
14811470
obligation: &PredicateObligation<'tcx>,
@@ -3197,39 +3186,6 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
31973186
)
31983187
}
31993188

3200-
fn report_opaque_type_auto_trait_leakage(
3201-
&self,
3202-
obligation: &PredicateObligation<'tcx>,
3203-
def_id: DefId,
3204-
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
3205-
let name = match self.tcx.opaque_type_origin(def_id.expect_local()) {
3206-
hir::OpaqueTyOrigin::FnReturn(_) | hir::OpaqueTyOrigin::AsyncFn(_) => {
3207-
format!("opaque type")
3208-
}
3209-
hir::OpaqueTyOrigin::TyAlias { .. } => {
3210-
format!("`{}`", self.tcx.def_path_debug_str(def_id))
3211-
}
3212-
};
3213-
let mut err = self.tcx.sess.struct_span_err(
3214-
obligation.cause.span,
3215-
format!("cannot check whether the hidden type of {name} satisfies auto traits"),
3216-
);
3217-
err.span_note(self.tcx.def_span(def_id), "opaque type is declared here");
3218-
match self.defining_use_anchor {
3219-
DefiningAnchor::Bubble | DefiningAnchor::Error => {}
3220-
DefiningAnchor::Bind(bind) => {
3221-
err.span_note(
3222-
self.tcx.def_ident_span(bind).unwrap_or_else(|| self.tcx.def_span(bind)),
3223-
"this item depends on auto traits of the hidden type, \
3224-
but may also be registering the hidden type. \
3225-
This is not supported right now. \
3226-
You can try moving the opaque type and the item that actually registers a hidden type into a new submodule".to_string(),
3227-
);
3228-
}
3229-
};
3230-
err
3231-
}
3232-
32333189
fn report_type_parameter_mismatch_error(
32343190
&self,
32353191
obligation: &PredicateObligation<'tcx>,

‎compiler/rustc_trait_selection/src/traits/select/confirmation.rs

+4-4
Original file line numberDiff line numberDiff line change
@@ -67,7 +67,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
6767
}
6868

6969
AutoImplCandidate => {
70-
let data = self.confirm_auto_impl_candidate(obligation)?;
70+
let data = self.confirm_auto_impl_candidate(obligation);
7171
ImplSource::Builtin(data)
7272
}
7373

@@ -376,12 +376,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
376376
fn confirm_auto_impl_candidate(
377377
&mut self,
378378
obligation: &TraitObligation<'tcx>,
379-
) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
379+
) -> Vec<PredicateObligation<'tcx>> {
380380
debug!(?obligation, "confirm_auto_impl_candidate");
381381

382382
let self_ty = self.infcx.shallow_resolve(obligation.predicate.self_ty());
383-
let types = self.constituent_types_for_ty(self_ty)?;
384-
Ok(self.vtable_auto_impl(obligation, obligation.predicate.def_id(), types))
383+
let types = self.constituent_types_for_ty(self_ty);
384+
self.vtable_auto_impl(obligation, obligation.predicate.def_id(), types)
385385
}
386386

387387
/// See `confirm_auto_impl_candidate`.

‎compiler/rustc_trait_selection/src/traits/select/mod.rs

+4-8
Original file line numberDiff line numberDiff line change
@@ -2271,8 +2271,8 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
22712271
fn constituent_types_for_ty(
22722272
&self,
22732273
t: ty::Binder<'tcx, Ty<'tcx>>,
2274-
) -> Result<ty::Binder<'tcx, Vec<Ty<'tcx>>>, SelectionError<'tcx>> {
2275-
Ok(match *t.skip_binder().kind() {
2274+
) -> ty::Binder<'tcx, Vec<Ty<'tcx>>> {
2275+
match *t.skip_binder().kind() {
22762276
ty::Uint(_)
22772277
| ty::Int(_)
22782278
| ty::Bool
@@ -2336,16 +2336,12 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
23362336
}
23372337

23382338
ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => {
2339-
let ty = self.tcx().type_of(def_id);
2340-
if ty.skip_binder().references_error() {
2341-
return Err(SelectionError::OpaqueTypeAutoTraitLeakageUnknown(def_id));
2342-
}
23432339
// We can resolve the `impl Trait` to its concrete type,
23442340
// which enforces a DAG between the functions requiring
23452341
// the auto trait bounds in question.
2346-
t.rebind(vec![ty.subst(self.tcx(), substs)])
2342+
t.rebind(vec![self.tcx().type_of(def_id).subst(self.tcx(), substs)])
23472343
}
2348-
})
2344+
}
23492345
}
23502346

23512347
fn collect_predicates_for_types(

‎tests/ui/generator/layout-error.rs

-1
Original file line numberDiff line numberDiff line change
@@ -24,6 +24,5 @@ fn main() {
2424
type F = impl Future;
2525
// Check that statics are inhabited computes they layout.
2626
static POOL: Task<F> = Task::new();
27-
//~^ ERROR: cannot check whether the hidden type of `layout_error[b009]::main::F::{opaque#0}` satisfies auto traits
2827
Task::spawn(&POOL, || cb());
2928
}

‎tests/ui/generator/layout-error.stderr

+1-19
Original file line numberDiff line numberDiff line change
@@ -4,24 +4,6 @@ error[E0425]: cannot find value `Foo` in this scope
44
LL | let a = Foo;
55
| ^^^ not found in this scope
66

7-
error: cannot check whether the hidden type of `layout_error[b009]::main::F::{opaque#0}` satisfies auto traits
8-
--> $DIR/layout-error.rs:26:18
9-
|
10-
LL | static POOL: Task<F> = Task::new();
11-
| ^^^^^^^
12-
|
13-
note: opaque type is declared here
14-
--> $DIR/layout-error.rs:24:14
15-
|
16-
LL | type F = impl Future;
17-
| ^^^^^^^^^^^
18-
note: required because it appears within the type `Task<F>`
19-
--> $DIR/layout-error.rs:9:12
20-
|
21-
LL | pub struct Task<F: Future>(F);
22-
| ^^^^
23-
= note: shared static variables must have a type that implements `Sync`
24-
25-
error: aborting due to 2 previous errors
7+
error: aborting due to previous error
268

279
For more information about this error, try `rustc --explain E0425`.

‎tests/ui/impl-trait/auto-trait-leak.rs

+2-4
Original file line numberDiff line numberDiff line change
@@ -3,23 +3,21 @@ use std::rc::Rc;
33

44
fn send<T: Send>(_: T) {}
55

6-
fn main() {}
6+
fn main() {
7+
}
78

89
// Cycles should work as the deferred obligations are
910
// independently resolved and only require the concrete
1011
// return type, which can't depend on the obligation.
1112
fn cycle1() -> impl Clone {
1213
//~^ ERROR cycle detected
13-
//~| ERROR cycle detected
1414
send(cycle2().clone());
15-
//~^ ERROR: cannot check whether the hidden type of opaque type satisfies auto traits
1615

1716
Rc::new(Cell::new(5))
1817
}
1918

2019
fn cycle2() -> impl Clone {
2120
send(cycle1().clone());
22-
//~^ ERROR: cannot check whether the hidden type of opaque type satisfies auto traits
2321

2422
Rc::new(String::from("foo"))
2523
}

‎tests/ui/impl-trait/auto-trait-leak.stderr

+4-87
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
error[E0391]: cycle detected when computing type of `cycle1::{opaque#0}`
2-
--> $DIR/auto-trait-leak.rs:11:16
2+
--> $DIR/auto-trait-leak.rs:12:16
33
|
44
LL | fn cycle1() -> impl Clone {
55
| ^^^^^^^^^^
@@ -11,12 +11,12 @@ LL | send(cycle2().clone());
1111
| ^^^^
1212
= note: ...which requires evaluating trait selection obligation `cycle2::{opaque#0}: core::marker::Send`...
1313
note: ...which requires computing type of `cycle2::{opaque#0}`...
14-
--> $DIR/auto-trait-leak.rs:20:16
14+
--> $DIR/auto-trait-leak.rs:19:16
1515
|
1616
LL | fn cycle2() -> impl Clone {
1717
| ^^^^^^^^^^
1818
note: ...which requires type-checking `cycle2`...
19-
--> $DIR/auto-trait-leak.rs:21:5
19+
--> $DIR/auto-trait-leak.rs:20:5
2020
|
2121
LL | send(cycle1().clone());
2222
| ^^^^
@@ -34,89 +34,6 @@ LL | | Rc::new(String::from("foo"))
3434
LL | | }
3535
| |_^
3636

37-
error[E0391]: cycle detected when computing type of `cycle1::{opaque#0}`
38-
--> $DIR/auto-trait-leak.rs:11:16
39-
|
40-
LL | fn cycle1() -> impl Clone {
41-
| ^^^^^^^^^^
42-
|
43-
note: ...which requires type-checking `cycle1`...
44-
--> $DIR/auto-trait-leak.rs:14:5
45-
|
46-
LL | send(cycle2().clone());
47-
| ^^^^
48-
= note: ...which requires evaluating trait selection obligation `cycle2::{opaque#0}: core::marker::Send`...
49-
note: ...which requires computing type of `cycle2::{opaque#0}`...
50-
--> $DIR/auto-trait-leak.rs:20:16
51-
|
52-
LL | fn cycle2() -> impl Clone {
53-
| ^^^^^^^^^^
54-
note: ...which requires type-checking `cycle2`...
55-
--> $DIR/auto-trait-leak.rs:20:1
56-
|
57-
LL | fn cycle2() -> impl Clone {
58-
| ^^^^^^^^^^^^^^^^^^^^^^^^^
59-
= note: ...which again requires computing type of `cycle1::{opaque#0}`, completing the cycle
60-
note: cycle used when checking item types in top-level module
61-
--> $DIR/auto-trait-leak.rs:1:1
62-
|
63-
LL | / use std::cell::Cell;
64-
LL | | use std::rc::Rc;
65-
LL | |
66-
LL | | fn send<T: Send>(_: T) {}
67-
... |
68-
LL | | Rc::new(String::from("foo"))
69-
LL | | }
70-
| |_^
71-
72-
error: cannot check whether the hidden type of opaque type satisfies auto traits
73-
--> $DIR/auto-trait-leak.rs:21:10
74-
|
75-
LL | send(cycle1().clone());
76-
| ---- ^^^^^^^^^^^^^^^^
77-
| |
78-
| required by a bound introduced by this call
79-
|
80-
note: opaque type is declared here
81-
--> $DIR/auto-trait-leak.rs:11:16
82-
|
83-
LL | fn cycle1() -> impl Clone {
84-
| ^^^^^^^^^^
85-
note: this item depends on auto traits of the hidden type, but may also be registering the hidden type. This is not supported right now. You can try moving the opaque type and the item that actually registers a hidden type into a new submodule
86-
--> $DIR/auto-trait-leak.rs:20:4
87-
|
88-
LL | fn cycle2() -> impl Clone {
89-
| ^^^^^^
90-
note: required by a bound in `send`
91-
--> $DIR/auto-trait-leak.rs:4:12
92-
|
93-
LL | fn send<T: Send>(_: T) {}
94-
| ^^^^ required by this bound in `send`
95-
96-
error: cannot check whether the hidden type of opaque type satisfies auto traits
97-
--> $DIR/auto-trait-leak.rs:14:10
98-
|
99-
LL | send(cycle2().clone());
100-
| ---- ^^^^^^^^^^^^^^^^
101-
| |
102-
| required by a bound introduced by this call
103-
|
104-
note: opaque type is declared here
105-
--> $DIR/auto-trait-leak.rs:20:16
106-
|
107-
LL | fn cycle2() -> impl Clone {
108-
| ^^^^^^^^^^
109-
note: this item depends on auto traits of the hidden type, but may also be registering the hidden type. This is not supported right now. You can try moving the opaque type and the item that actually registers a hidden type into a new submodule
110-
--> $DIR/auto-trait-leak.rs:11:4
111-
|
112-
LL | fn cycle1() -> impl Clone {
113-
| ^^^^^^
114-
note: required by a bound in `send`
115-
--> $DIR/auto-trait-leak.rs:4:12
116-
|
117-
LL | fn send<T: Send>(_: T) {}
118-
| ^^^^ required by this bound in `send`
119-
120-
error: aborting due to 4 previous errors
37+
error: aborting due to previous error
12138

12239
For more information about this error, try `rustc --explain E0391`.

‎tests/ui/impl-trait/issue-103181-2.rs

-2
Original file line numberDiff line numberDiff line change
@@ -24,8 +24,6 @@ where
2424
B: Send, // <- a second bound
2525
{
2626
normalize(broken_fut(), ());
27-
//~^ ERROR: cannot check whether the hidden type of opaque type satisfies auto traits
28-
//~| ERROR: cannot check whether the hidden type of opaque type satisfies auto traits
2927
}
3028

3129
fn main() {}

‎tests/ui/impl-trait/issue-103181-2.stderr

+1-56
Original file line numberDiff line numberDiff line change
@@ -4,61 +4,6 @@ error[E0425]: cannot find value `ident_error` in this scope
44
LL | ident_error;
55
| ^^^^^^^^^^^ not found in this scope
66

7-
error: cannot check whether the hidden type of opaque type satisfies auto traits
8-
--> $DIR/issue-103181-2.rs:26:15
9-
|
10-
LL | normalize(broken_fut(), ());
11-
| --------- ^^^^^^^^^^^^
12-
| |
13-
| required by a bound introduced by this call
14-
|
15-
note: opaque type is declared here
16-
--> $DIR/issue-103181-2.rs:11:23
17-
|
18-
LL | async fn broken_fut() {
19-
| ^
20-
note: this item depends on auto traits of the hidden type, but may also be registering the hidden type. This is not supported right now. You can try moving the opaque type and the item that actually registers a hidden type into a new submodule
21-
--> $DIR/issue-103181-2.rs:20:10
22-
|
23-
LL | async fn iceice<A, B>()
24-
| ^^^^^^
25-
note: required for `impl Future<Output = ()>` to implement `SendFuture`
26-
--> $DIR/issue-103181-2.rs:7:17
27-
|
28-
LL | impl<Fut: Send> SendFuture for Fut {
29-
| ---- ^^^^^^^^^^ ^^^
30-
| |
31-
| unsatisfied trait bound introduced here
32-
note: required by a bound in `normalize`
33-
--> $DIR/issue-103181-2.rs:18:19
34-
|
35-
LL | fn normalize<Fut: SendFuture>(_: Fut, _: Fut::Output) {}
36-
| ^^^^^^^^^^ required by this bound in `normalize`
37-
38-
error: cannot check whether the hidden type of opaque type satisfies auto traits
39-
--> $DIR/issue-103181-2.rs:26:5
40-
|
41-
LL | normalize(broken_fut(), ());
42-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
43-
|
44-
note: opaque type is declared here
45-
--> $DIR/issue-103181-2.rs:11:23
46-
|
47-
LL | async fn broken_fut() {
48-
| ^
49-
note: this item depends on auto traits of the hidden type, but may also be registering the hidden type. This is not supported right now. You can try moving the opaque type and the item that actually registers a hidden type into a new submodule
50-
--> $DIR/issue-103181-2.rs:20:10
51-
|
52-
LL | async fn iceice<A, B>()
53-
| ^^^^^^
54-
note: required for `impl Future<Output = ()>` to implement `SendFuture`
55-
--> $DIR/issue-103181-2.rs:7:17
56-
|
57-
LL | impl<Fut: Send> SendFuture for Fut {
58-
| ---- ^^^^^^^^^^ ^^^
59-
| |
60-
| unsatisfied trait bound introduced here
61-
62-
error: aborting due to 3 previous errors
7+
error: aborting due to previous error
638

649
For more information about this error, try `rustc --explain E0425`.

‎tests/ui/type-alias-impl-trait/auto-trait-leakage3.rs

-2
Original file line numberDiff line numberDiff line change
@@ -6,15 +6,13 @@
66
mod m {
77
pub type Foo = impl std::fmt::Debug;
88
//~^ ERROR: cycle detected when computing type of `m::Foo::{opaque#0}` [E0391]
9-
//~| ERROR: cycle detected when computing type of `m::Foo::{opaque#0}` [E0391]
109

1110
pub fn foo() -> Foo {
1211
22_u32
1312
}
1413

1514
pub fn bar() {
1615
is_send(foo());
17-
//~^ ERROR: cannot check whether the hidden type of `auto_trait_leakage3[211d]::m::Foo::{opaque#0}
1816
}
1917

2018
fn is_send<T: Send>(_: T) {}

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