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Auto merge of #116494 - compiler-errors:typeck-coinductive-ambig, r=<try>
[crater only] Always make inductive cycles as ambig during typeck r? `@ghost`
2 parents 5257aee + 35865b3 commit d614ed8

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8 files changed

+81
-34
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8 files changed

+81
-34
lines changed

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

Lines changed: 14 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -235,7 +235,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
235235
freshener: infcx.freshener(),
236236
intercrate_ambiguity_causes: None,
237237
query_mode: TraitQueryMode::Standard,
238-
treat_inductive_cycle: TreatInductiveCycleAs::Recur,
238+
treat_inductive_cycle: TreatInductiveCycleAs::Ambig,
239239
}
240240
}
241241

@@ -1619,16 +1619,23 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
16191619
for bound in
16201620
self.tcx().item_bounds(alias_ty.def_id).instantiate(self.tcx(), alias_ty.args)
16211621
{
1622-
// HACK: On subsequent recursions, we only care about bounds that don't
1622+
// HACK: In the initial recursion, we only care about bounds for the
1623+
// `self_ty`. On subsequent recursions, we care about bounds that don't
16231624
// share the same type as `self_ty`. This is because for truly rigid
16241625
// projections, we will never be able to equate, e.g. `<T as Tr>::A`
16251626
// with `<<T as Tr>::A as Tr>::A`.
1626-
if in_parent_alias_type {
1627-
match bound.kind().skip_binder() {
1628-
ty::ClauseKind::Trait(tr) if tr.self_ty() == self_ty => continue,
1629-
ty::ClauseKind::Projection(p) if p.self_ty() == self_ty => continue,
1630-
_ => {}
1627+
match bound.kind().skip_binder() {
1628+
ty::ClauseKind::Trait(tr)
1629+
if (tr.self_ty() == self_ty) ^ !in_parent_alias_type =>
1630+
{
1631+
continue;
1632+
}
1633+
ty::ClauseKind::Projection(p)
1634+
if (p.self_ty() == self_ty) ^ !in_parent_alias_type =>
1635+
{
1636+
continue;
16311637
}
1638+
_ => {}
16321639
}
16331640

16341641
for_each(self, bound, idx)?;

‎tests/ui/associated-type-bounds/bad-bounds-on-assoc-in-trait.stderr

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
error[E0277]: `<Self as Case1>::C` is not an iterator
2+
--> $DIR/bad-bounds-on-assoc-in-trait.rs:25:21
3+
|
4+
LL | type C: Clone + Iterator<Item: Send + Iterator<Item: for<'a> Lam<&'a u8, App: Debug>> + Sync>;
5+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `<Self as Case1>::C` is not an iterator
6+
|
7+
= help: the trait `Iterator` is not implemented for `<Self as Case1>::C`
8+
help: consider further restricting the associated type
9+
|
10+
LL | trait Case1 where <Self as Case1>::C: Iterator {
11+
| ++++++++++++++++++++++++++++++++++
12+
13+
error: aborting due to 1 previous error
14+
15+
For more information about this error, try `rustc --explain E0277`.

‎tests/ui/marker_trait_attr/unsound-overlap.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,7 @@ trait B {}
88
impl<T: A> B for T {}
99
impl<T: B> A for T {}
1010
impl A for &str {}
11+
//~^ ERROR type annotations needed: cannot satisfy `&str: A`
1112
impl<T: A + B> A for (T,) {}
1213
trait TraitWithAssoc {
1314
type Assoc;

‎tests/ui/marker_trait_attr/unsound-overlap.stderr

Lines changed: 18 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,12 +1,27 @@
11
error[E0119]: conflicting implementations of trait `TraitWithAssoc` for type `((&str,),)`
2-
--> $DIR/unsound-overlap.rs:20:1
2+
--> $DIR/unsound-overlap.rs:21:1
33
|
44
LL | impl<T: A> TraitWithAssoc for T {
55
| ------------------------------- first implementation here
66
...
77
LL | impl TraitWithAssoc for ((&str,),) {
88
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `((&str,),)`
99

10-
error: aborting due to 1 previous error
10+
error[E0283]: type annotations needed: cannot satisfy `&str: A`
11+
--> $DIR/unsound-overlap.rs:10:12
12+
|
13+
LL | impl A for &str {}
14+
| ^^^^
15+
|
16+
note: multiple `impl`s satisfying `&str: A` found
17+
--> $DIR/unsound-overlap.rs:9:1
18+
|
19+
LL | impl<T: B> A for T {}
20+
| ^^^^^^^^^^^^^^^^^^
21+
LL | impl A for &str {}
22+
| ^^^^^^^^^^^^^^^
23+
24+
error: aborting due to 2 previous errors
1125

12-
For more information about this error, try `rustc --explain E0119`.
26+
Some errors have detailed explanations: E0119, E0283.
27+
For more information about an error, try `rustc --explain E0119`.

‎tests/ui/specialization/issue-39448.rs

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,7 @@ trait FromA<T> {
2222
}
2323

2424
impl<T: A, U: A + FromA<T>> FromA<T> for U {
25+
//~^ ERROR cycle detected when computing whether impls specialize one another
2526
default fn from(x: T) -> Self {
2627
ToA::to(x)
2728
}
@@ -42,7 +43,7 @@ where
4243

4344
#[allow(dead_code)]
4445
fn foo<T: A, U: A>(x: T, y: U) -> U {
45-
x.foo(y.to()).to() //~ ERROR overflow evaluating the requirement
46+
x.foo(y.to()).to()
4647
}
4748

4849
fn main() {

‎tests/ui/specialization/issue-39448.stderr

Lines changed: 12 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -8,28 +8,21 @@ LL | #![feature(specialization)]
88
= help: consider using `min_specialization` instead, which is more stable and complete
99
= note: `#[warn(incomplete_features)]` on by default
1010

11-
error[E0275]: overflow evaluating the requirement `T: FromA<U>`
12-
--> $DIR/issue-39448.rs:45:13
13-
|
14-
LL | x.foo(y.to()).to()
15-
| ^^
16-
|
17-
note: required for `T` to implement `FromA<U>`
18-
--> $DIR/issue-39448.rs:24:29
11+
error[E0391]: cycle detected when computing whether impls specialize one another
12+
--> $DIR/issue-39448.rs:24:1
1913
|
2014
LL | impl<T: A, U: A + FromA<T>> FromA<T> for U {
21-
| -------- ^^^^^^^^ ^
22-
| |
23-
| unsatisfied trait bound introduced here
24-
note: required for `U` to implement `ToA<T>`
25-
--> $DIR/issue-39448.rs:34:12
15+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
16+
|
17+
= note: ...which requires evaluating trait selection obligation `u16: FromA<u8>`...
18+
= note: ...which again requires computing whether impls specialize one another, completing the cycle
19+
note: cycle used when building specialization graph of trait `FromA`
20+
--> $DIR/issue-39448.rs:20:1
2621
|
27-
LL | impl<T, U> ToA<U> for T
28-
| ^^^^^^ ^
29-
LL | where
30-
LL | U: FromA<T>,
31-
| -------- unsatisfied trait bound introduced here
22+
LL | trait FromA<T> {
23+
| ^^^^^^^^^^^^^^
24+
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
3225

3326
error: aborting due to 1 previous error; 1 warning emitted
3427

35-
For more information about this error, try `rustc --explain E0275`.
28+
For more information about this error, try `rustc --explain E0391`.

‎tests/ui/specialization/issue-39618.rs

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2,8 +2,6 @@
22
// FIXME(JohnTitor): Centril pointed out this looks suspicions, we should revisit here.
33
// More context: https://github.com/rust-lang/rust/pull/69192#discussion_r379846796
44

5-
//@ check-pass
6-
75
#![feature(specialization)] //~ WARN the feature `specialization` is incomplete
86

97
trait Foo {
@@ -19,6 +17,7 @@ impl<T> Bar for T where T: Foo {
1917
}
2018

2119
impl<T> Foo for T where T: Bar {
20+
//~^ ERROR cycle detected when computing whether impls specialize one another
2221
fn foo(&self) {}
2322
}
2423

‎tests/ui/specialization/issue-39618.stderr

Lines changed: 18 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
2-
--> $DIR/issue-39618.rs:7:12
2+
--> $DIR/issue-39618.rs:5:12
33
|
44
LL | #![feature(specialization)]
55
| ^^^^^^^^^^^^^^
@@ -8,5 +8,21 @@ LL | #![feature(specialization)]
88
= help: consider using `min_specialization` instead, which is more stable and complete
99
= note: `#[warn(incomplete_features)]` on by default
1010

11-
warning: 1 warning emitted
11+
error[E0391]: cycle detected when computing whether impls specialize one another
12+
--> $DIR/issue-39618.rs:19:1
13+
|
14+
LL | impl<T> Foo for T where T: Bar {
15+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
16+
|
17+
= note: ...which requires evaluating trait selection obligation `u64: Bar`...
18+
= note: ...which again requires computing whether impls specialize one another, completing the cycle
19+
note: cycle used when building specialization graph of trait `Foo`
20+
--> $DIR/issue-39618.rs:7:1
21+
|
22+
LL | trait Foo {
23+
| ^^^^^^^^^
24+
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
25+
26+
error: aborting due to 1 previous error; 1 warning emitted
1227

28+
For more information about this error, try `rustc --explain E0391`.

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