Closed
Description
The following code results in an ICE on stable, beta, and nightly
#![feature(fn_traits)]
#![feature(unboxed_closures)]
trait T0<'a, A> {
type O;
}
struct L<T> {
f: T,
}
impl<'a, A, T> T0<'a, A> for L<T>
where
T: FnMut<A>,
{
type O = T::Output;
}
trait T1: for<'r> Ty<'r> {
fn m<'a, B: Ty<'a>, F>(&self, f: F) -> ()
where
F: for<'r> T0<'r, (<Self as Ty<'r>>::V,), O = <B as Ty<'r>>::V>,
{
unimplemented!();
}
}
trait Ty<'a> {
type V;
}
fn main() {
let v = ().m(L{ f : |x|{drop(x)} } );
}
impl<'a> Ty<'a> for () {
type V = &'a u8;
}
impl T1 for () {}Errors:
Compiling playground v0.0.1 (/playground)
error[E0554]: #![feature] may not be used on the stable release channel
--> src/main.rs:1:1
|
1 | #![feature(fn_traits)]
| ^^^^^^^^^^^^^^^^^^^^^^
error[E0554]: #![feature] may not be used on the stable release channel
--> src/main.rs:2:1
|
2 | #![feature(unboxed_closures)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0271]: type mismatch resolving `for<'r> <L<[closure@src/main.rs:33:25: 33:37]> as T0<'r, (<() as Ty<'r>>::V,)>>::O == <_ as Ty<'r>>::V`
--> src/main.rs:33:16
|
33 | let v = ().m(L{ f : |x|{drop(x)} } );
| ^ expected (), found associated type
|
= note: expected type `()`
found type `<_ as Ty<'_>>::V`
error: internal compiler error: src/librustc/infer/lexical_region_resolve/mod.rs:632: collect_error_for_expanding_node() could not find error for var '_#5r in universe U8, lower_bounds=[
RegionAndOrigin(RePlaceholder(Placeholder { universe: U7, name: BrNamed(crate0:DefIndex(1:20), 'r) }),Subtype(TypeTrace(ObligationCause { span: src/main.rs:33:16: 33:17, body_id: HirId { owner: DefIndex(0:12), local_id: 22 }, code: ImplDerivedObligation(DerivedObligationCause { parent_trait_ref: Binder(<L<[closure@src/main.rs:33:25: 33:37]> as T0<'r, (<() as Ty<'r>>::V,)>>), parent_code: MiscObligation }) }))),
RegionAndOrigin(RePlaceholder(Placeholder { universe: U7, name: BrNamed(crate0:DefIndex(1:20), 'r) }),Subtype(TypeTrace(ObligationCause { span: src/main.rs:33:16: 33:17, body_id: HirId { owner: DefIndex(0:12), local_id: 22 }, code: ImplDerivedObligation(DerivedObligationCause { parent_trait_ref: Binder(<L<[closure@src/main.rs:33:25: 33:37]> as T0<'r, (<() as Ty<'r>>::V,)>>), parent_code: MiscObligation }) }))),
], upper_bounds=[
RegionAndOrigin(RePlaceholder(Placeholder { universe: U7, name: BrNamed(crate0:DefIndex(1:20), 'r) }),Subtype(TypeTrace(ObligationCause { span: src/main.rs:33:16: 33:17, body_id: HirId { owner: DefIndex(0:12), local_id: 22 }, code: ImplDerivedObligation(DerivedObligationCause { parent_trait_ref: Binder(<L<[closure@src/main.rs:33:25: 33:37]> as T0<'r, (<() as Ty<'r>>::V,)>>), parent_code: MiscObligation }) }))),
RegionAndOrigin(RePlaceholder(Placeholder { universe: U7, name: BrNamed(crate0:DefIndex(1:20), 'r) }),Subtype(TypeTrace(ObligationCause { span: src/main.rs:33:16: 33:17, body_id: HirId { owner: DefIndex(0:12), local_id: 22 }, code: ImplDerivedObligation(DerivedObligationCause { parent_trait_ref: Binder(<L<[closure@src/main.rs:33:25: 33:37]> as T0<'r, (<() as Ty<'r>>::V,)>>), parent_code: MiscObligation }) }))),
]
--> src/main.rs:33:16
|
33 | let v = ().m(L{ f : |x|{drop(x)} } );
| ^
thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:570:9
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
error: aborting due to 4 previous errors
Some errors occurred: E0271, E0554.
For more information about an error, try `rustc --explain E0271`.
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: rustc 1.35.0 (3c235d560 2019-05-20) running on x86_64-unknown-linux-gnu
note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type bin
note: some of the compiler flags provided by cargo are hidden
error: Could not compile `playground`.
To learn more, run the command again with --verbose.