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use std::ops::{Deref, DerefMut};
trait Happy {}
struct LDM;
impl Happy for &mut LDM {}
struct Foo(LDM);
struct Bar(Foo);
struct Baz(Bar);
impl Deref for Foo {
type Target = LDM;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl Deref for Bar {
type Target = Foo;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl Deref for Baz {
type Target = Bar;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl DerefMut for Foo {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
impl DerefMut for Bar {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
impl DerefMut for Baz {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
fn foo<T>(_: T) where T: Happy {}
fn main() {
// Currently the compiler doesn't try to suggest dereferences for situations
// where DerefMut involves. So this test is meant to ensure compiler doesn't
// generate incorrect help message.
let mut baz = Baz(Bar(Foo(LDM)));
foo(&mut baz);
//~^ ERROR the trait bound `&mut Baz: Happy` is not satisfied
}
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