src/test/run-pass/methods/method-projection.rs

   1 // run-pass
   2 // Test that we can use method notation to call methods based on a
   3 // projection bound from a trait. Issue #20469.
   4
   5 ///////////////////////////////////////////////////////////////////////////
   6
   7
   8 trait MakeString {
   9     fn make_string(&self) -> String;
  10 }
  11
  12 impl MakeString for isize {
  13     fn make_string(&self) -> String {
  14         format!("{}", *self)
  15     }
  16 }
  17
  18 impl MakeString for usize {
  19     fn make_string(&self) -> String {
  20         format!("{}", *self)
  21     }
  22 }
  23
  24 ///////////////////////////////////////////////////////////////////////////
  25
  26 trait Foo {
  27     type F: MakeString;
  28
  29     fn get(&self) -> &Self::F;
  30 }
  31
  32 fn foo<F:Foo>(f: &F) -> String {
  33     f.get().make_string()
  34 }
  35
  36 ///////////////////////////////////////////////////////////////////////////
  37
  38 struct SomeStruct {
  39     field: isize,
  40 }
  41
  42 impl Foo for SomeStruct {
  43     type F = isize;
  44
  45     fn get(&self) -> &isize {
  46         &self.field
  47     }
  48 }
  49
  50 ///////////////////////////////////////////////////////////////////////////
  51
  52 struct SomeOtherStruct {
  53     field: usize,
  54 }
  55
  56 impl Foo for SomeOtherStruct {
  57     type F = usize;
  58
  59     fn get(&self) -> &usize {
  60         &self.field
  61     }
  62 }
  63
  64 fn main() {
  65     let x = SomeStruct { field: 22 };
  66     assert_eq!(foo(&x), format!("22"));
  67
  68     let x = SomeOtherStruct { field: 44 };
  69     assert_eq!(foo(&x), format!("44"));
  70 }