compiler/rustc_error_codes/src/error_codes/E0107.md

   1 An incorrect number of generic arguments was provided.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0107
   6 struct Foo<T> { x: T }
   7
   8 struct Bar { x: Foo }             // error: wrong number of type arguments:
   9                                   //        expected 1, found 0
  10 struct Baz<S, T> { x: Foo<S, T> } // error: wrong number of type arguments:
  11                                   //        expected 1, found 2
  12
  13 fn foo<T, U>(x: T, y: U) {}
  14 fn f() {}
  15
  16 fn main() {
  17     let x: bool = true;
  18     foo::<bool>(x);                 // error: wrong number of type arguments:
  19                                     //        expected 2, found 1
  20     foo::<bool, i32, i32>(x, 2, 4); // error: wrong number of type arguments:
  21                                     //        expected 2, found 3
  22     f::<'static>();                 // error: wrong number of lifetime arguments
  23                                     //        expected 0, found 1
  24 }
  25 ```
  26
  27 When using/declaring an item with generic arguments, you must provide the exact
  28 same number:
  29
  30 ```
  31 struct Foo<T> { x: T }
  32
  33 struct Bar<T> { x: Foo<T> }               // ok!
  34 struct Baz<S, T> { x: Foo<S>, y: Foo<T> } // ok!
  35
  36 fn foo<T, U>(x: T, y: U) {}
  37 fn f() {}
  38
  39 fn main() {
  40     let x: bool = true;
  41     foo::<bool, u32>(x, 12);              // ok!
  42     f();                                  // ok!
  43 }
  44 ```