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Rollup merge of rust-lang#125489 - oli-obk:revert_stuff_2, r=compiler…
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…-errors

Revert problematic opaque type change

fixes rust-lang#124891
fixes rust-lang#125192

reverts rust-lang#123979
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matthiaskrgr authored May 24, 2024
2 parents 54a2bd8 + 526090b commit 1a165ec
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Showing 6 changed files with 138 additions and 37 deletions.
17 changes: 2 additions & 15 deletions compiler/rustc_infer/src/infer/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -957,27 +957,14 @@ impl<'tcx> InferCtxt<'tcx> {
(&ty::Infer(ty::TyVar(a_vid)), &ty::Infer(ty::TyVar(b_vid))) => {
return Err((a_vid, b_vid));
}
// We don't silently want to constrain hidden types here, so we assert that either one side is
// an infer var, so it'll get constrained to whatever the other side is, or there are no opaque
// types involved.
// We don't expect this to actually get hit, but if it does, we now at least know how to write
// a test for it.
(_, ty::Infer(ty::TyVar(_))) => {}
(ty::Infer(ty::TyVar(_)), _) => {}
_ if r_a != r_b && (r_a, r_b).has_opaque_types() => {
span_bug!(
cause.span(),
"opaque types got hidden types registered from within subtype predicate: {r_a:?} vs {r_b:?}"
)
}
_ => {}
}

self.enter_forall(predicate, |ty::SubtypePredicate { a_is_expected, a, b }| {
if a_is_expected {
Ok(self.at(cause, param_env).sub(DefineOpaqueTypes::Yes, a, b))
Ok(self.at(cause, param_env).sub(DefineOpaqueTypes::No, a, b))
} else {
Ok(self.at(cause, param_env).sup(DefineOpaqueTypes::Yes, b, a))
Ok(self.at(cause, param_env).sup(DefineOpaqueTypes::No, b, a))
}
})
}
Expand Down
22 changes: 0 additions & 22 deletions tests/crashes/124891.rs

This file was deleted.

59 changes: 59 additions & 0 deletions tests/ui/impl-trait/lazy_subtyping_of_opaques.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
//! This test checks that we allow subtyping predicates that contain opaque types.
//! No hidden types are being constrained in the subtyping predicate, but type and
//! lifetime variables get subtyped in the generic parameter list of the opaque.

use std::iter;

mod either {
pub enum Either<L, R> {
Left(L),
Right(R),
}

impl<L: Iterator, R: Iterator<Item = L::Item>> Iterator for Either<L, R> {
type Item = L::Item;
fn next(&mut self) -> Option<Self::Item> {
todo!()
}
}
pub use self::Either::{Left, Right};
}

pub enum BabeConsensusLogRef<'a> {
NextEpochData(BabeNextEpochRef<'a>),
NextConfigData,
}

impl<'a> BabeConsensusLogRef<'a> {
pub fn scale_encoding(
&self,
) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
//~^ ERROR is not satisfied
//~| ERROR is not satisfied
//~| ERROR is not satisfied
match self {
BabeConsensusLogRef::NextEpochData(digest) => either::Left(either::Left(
digest.scale_encoding().map(either::Left).map(either::Left),
)),
BabeConsensusLogRef::NextConfigData => either::Right(
// The Opaque type from ``scale_encoding` gets used opaquely here, while the `R`
// generic parameter of `Either` contains type variables that get subtyped and the
// opaque type contains lifetime variables that get subtyped.
iter::once(either::Right(either::Left([1])))
.chain(std::iter::once([1]).map(either::Right).map(either::Right)),
),
}
}
}

pub struct BabeNextEpochRef<'a>(&'a ());

impl<'a> BabeNextEpochRef<'a> {
pub fn scale_encoding(
&self,
) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
std::iter::once([1])
}
}

fn main() {}
21 changes: 21 additions & 0 deletions tests/ui/impl-trait/lazy_subtyping_of_opaques.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
error[E0277]: the trait bound `Either<Either<Map<Map<impl Iterator<Item = impl AsRef<[u8]> + Clone + '_> + Clone + '_, fn(impl AsRef<[u8]> + Clone + '_) -> Either<impl AsRef<[u8]> + Clone + '_, _> {Either::<impl AsRef<[u8]> + Clone + '_, _>::Left}>, fn(Either<impl AsRef<[u8]> + Clone + '_, _>) -> Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>> {Either::<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>::Left}>, _>, std::iter::Chain<std::iter::Once<Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>>, Map<Map<std::iter::Once<[{integer}; 1]>, fn([{integer}; 1]) -> Either<[{integer}; 1], [{integer}; 1]> {Either::<[{integer}; 1], [{integer}; 1]>::Right}>, fn(Either<[{integer}; 1], [{integer}; 1]>) -> Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>> {Either::<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>::Right}>>>: Clone` is not satisfied
--> $DIR/lazy_subtyping_of_opaques.rs:30:10
|
LL | ) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Clone` is not implemented for `Either<Either<Map<Map<impl Iterator<Item = impl AsRef<[u8]> + Clone + '_> + Clone + '_, fn(impl AsRef<[u8]> + Clone + '_) -> Either<impl AsRef<[u8]> + Clone + '_, _> {Either::<impl AsRef<[u8]> + Clone + '_, _>::Left}>, fn(Either<impl AsRef<[u8]> + Clone + '_, _>) -> Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>> {Either::<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>::Left}>, _>, std::iter::Chain<std::iter::Once<Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>>, Map<Map<std::iter::Once<[{integer}; 1]>, fn([{integer}; 1]) -> Either<[{integer}; 1], [{integer}; 1]> {Either::<[{integer}; 1], [{integer}; 1]>::Right}>, fn(Either<[{integer}; 1], [{integer}; 1]>) -> Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>> {Either::<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>::Right}>>>`

error[E0277]: the trait bound `Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>: AsRef<[u8]>` is not satisfied
--> $DIR/lazy_subtyping_of_opaques.rs:30:31
|
LL | ) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `AsRef<[u8]>` is not implemented for `Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>`

error[E0277]: the trait bound `Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>: Clone` is not satisfied
--> $DIR/lazy_subtyping_of_opaques.rs:30:31
|
LL | ) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Clone` is not implemented for `Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>`

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0277`.
30 changes: 30 additions & 0 deletions tests/ui/type-alias-impl-trait/lazy_subtyping_of_opaques.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
#![feature(type_alias_impl_trait)]

//! This test used to ICE rust-lang/rust#124891
//! because we added an assertion for catching cases where opaque types get
//! registered during the processing of subtyping predicates.

type Tait = impl FnOnce() -> ();

fn reify_as_tait() -> Thunk<Tait> {
Thunk::new(|cont| cont)
//~^ ERROR: mismatched types
//~| ERROR: mismatched types
}

struct Thunk<F>(F);

impl<F> Thunk<F> {
fn new(f: F)
where
F: ContFn,
{
todo!();
}
}

trait ContFn {}

impl<F: FnOnce(Tait) -> ()> ContFn for F {}

fn main() {}
26 changes: 26 additions & 0 deletions tests/ui/type-alias-impl-trait/lazy_subtyping_of_opaques.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
error[E0308]: mismatched types
--> $DIR/lazy_subtyping_of_opaques.rs:10:23
|
LL | type Tait = impl FnOnce() -> ();
| ------------------- the found opaque type
...
LL | Thunk::new(|cont| cont)
| ^^^^ expected `()`, found opaque type
|
= note: expected unit type `()`
found opaque type `Tait`

error[E0308]: mismatched types
--> $DIR/lazy_subtyping_of_opaques.rs:10:5
|
LL | fn reify_as_tait() -> Thunk<Tait> {
| ----------- expected `Thunk<_>` because of return type
LL | Thunk::new(|cont| cont)
| ^^^^^^^^^^^^^^^^^^^^^^^ expected `Thunk<_>`, found `()`
|
= note: expected struct `Thunk<_>`
found unit type `()`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0308`.

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