src/librustc_error_codes/error_codes/E0049.md

   1 An attempted implementation of a trait method has the wrong number of type or
   2 const parameters.
   3
   4 Erroneous code example:
   5
   6 ```compile_fail,E0049
   7 trait Foo {
   8     fn foo<T: Default>(x: T) -> Self;
   9 }
  10
  11 struct Bar;
  12
  13 // error: method `foo` has 0 type parameters but its trait declaration has 1
  14 // type parameter
  15 impl Foo for Bar {
  16     fn foo(x: bool) -> Self { Bar }
  17 }
  18 ```
  19
  20 For example, the `Foo` trait has a method `foo` with a type parameter `T`,
  21 but the implementation of `foo` for the type `Bar` is missing this parameter.
  22 To fix this error, they must have the same type parameters:
  23
  24 ```
  25 trait Foo {
  26     fn foo<T: Default>(x: T) -> Self;
  27 }
  28
  29 struct Bar;
  30
  31 impl Foo for Bar {
  32     fn foo<T: Default>(x: T) -> Self { // ok!
  33         Bar
  34     }
  35 }
  36 ```