src/test/ui/traits/trait-suggest-deferences-multiple-1.rs

   1 use std::ops::{Deref, DerefMut};
   2
   3 trait Happy {}
   4 struct LDM;
   5 impl Happy for &mut LDM {}
   6
   7 struct Foo(LDM);
   8 struct Bar(Foo);
   9 struct Baz(Bar);
  10 impl Deref for Foo {
  11     type Target = LDM;
  12     fn deref(&self) -> &Self::Target {
  13         &self.0
  14     }
  15 }
  16 impl Deref for Bar {
  17     type Target = Foo;
  18     fn deref(&self) -> &Self::Target {
  19         &self.0
  20     }
  21 }
  22 impl Deref for Baz {
  23     type Target = Bar;
  24     fn deref(&self) -> &Self::Target {
  25         &self.0
  26     }
  27 }
  28 impl DerefMut for Foo {
  29     fn deref_mut(&mut self) -> &mut Self::Target {
  30         &mut self.0
  31     }
  32 }
  33 impl DerefMut for Bar {
  34     fn deref_mut(&mut self) -> &mut Self::Target {
  35         &mut self.0
  36     }
  37 }
  38 impl DerefMut for Baz {
  39     fn deref_mut(&mut self) -> &mut Self::Target {
  40         &mut self.0
  41     }
  42 }
  43
  44
  45 fn foo<T>(_: T) where T: Happy {}
  46
  47 fn main() {
  48     // Currently the compiler doesn't try to suggest dereferences for situations
  49     // where DerefMut involves. So this test is meant to ensure compiler doesn't
  50     // generate incorrect help message.
  51     let mut baz = Baz(Bar(Foo(LDM)));
  52     foo(&mut baz);
  53     //~^ ERROR the trait bound `&mut Baz: Happy` is not satisfied
  54 }