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// build-pass
// edition:2018
type BoxFuture<T> = std::pin::Pin<Box<dyn std::future::Future<Output=T>>>;
fn main() {
f();
}
async fn f() {
run("dependency").await;
}
struct InMemoryStorage;
struct User<'dep> {
dep: &'dep str,
}
impl<'a> StorageRequest<InMemoryStorage> for SaveUser<'a> {
fn execute(&self) -> BoxFuture<Result<(), String>> {
todo!()
}
}
trait Storage {
type Error;
}
impl Storage for InMemoryStorage {
type Error = String;
}
trait StorageRequestReturnType {
type Output;
}
trait StorageRequest<S: Storage>: StorageRequestReturnType {
fn execute(
&self,
) -> BoxFuture<Result<<Self as StorageRequestReturnType>::Output, <S as Storage>::Error>>;
}
struct SaveUser<'a> {
name: &'a str,
}
impl<'a> StorageRequestReturnType for SaveUser<'a> {
type Output = ();
}
impl<'dep> User<'dep> {
async fn save<S>(self)
where
S: Storage,
for<'a> SaveUser<'a>: StorageRequest<S>,
{
SaveUser { name: "Joe" }
.execute()
.await;
}
}
async fn run<S>(dep: &str)
where
S: Storage,
for<'a> SaveUser<'a>: StorageRequest<S>,
for<'a> SaveUser<'a>: StorageRequestReturnType,
{
User { dep }.save().await;
}
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