| 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 |
| } |
