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Weird interaction between specialization and RPITITs #108309
Description
#108203 didn't fully fix this. the bug still persists when using polymorphic indirection via specialization:
#![feature(async_fn_in_trait)]
#![feature(min_specialization)]
struct MyStruct;
trait MyTrait<T> {
async fn foo(_: T);
}
impl<T> MyTrait<T> for MyStruct {
default async fn foo(_: T) {
println!("default");
}
}
impl MyTrait<i32> for MyStruct {
async fn foo(_: i32) {
println!("specialized");
}
}
#[tokio::main]
async fn main() {
MyStruct::foo(42).await;
indirection(42).await;
}
async fn indirection<T>(x: T) {
//explicit type coercion is currently necessary because of https://github.com/rust-lang/rust/issues/67918
<MyStruct as MyTrait<T>>::foo(x).await;
}(note that <MyStruct as MyTrait<i32>>::foo(42).await works just fine, so #67918 probably isn't at fault)
output is
specialized
default
should be
specialized
specialized
Originally commented by @LastExceed em #107002 (comment)
Activity
compiler-errors commentedon Feb 21, 2023
I'll look into this when I actually wake up in a few hours lol
LastExceed commentedon Feb 22, 2023
why does this issue have the
F-return_position_impl_trait_in_traitlabel ?compiler-errors commentedon Feb 22, 2023
Because async fn in trait is just return position impl trait in trait, and the specialization problems are equally as broken with the latter?
Auto merge of rust-lang#115822 - compiler-errors:stabilize-rpitit, r=…