Error code E0107
An incorrect number of generic arguments was provided.
Erroneous code example:
struct Foo<T> { x: T } struct Bar { x: Foo } // error: wrong number of type arguments: // expected 1, found 0 struct Baz<S, T> { x: Foo<S, T> } // error: wrong number of type arguments: // expected 1, found 2 fn foo<T, U>(x: T, y: U) {} fn f() {} fn main() { let x: bool = true; foo::<bool>(x); // error: wrong number of type arguments: // expected 2, found 1 foo::<bool, i32, i32>(x, 2, 4); // error: wrong number of type arguments: // expected 2, found 3 f::<'static>(); // error: wrong number of lifetime arguments // expected 0, found 1 }
When using/declaring an item with generic arguments, you must provide the exact same number:
struct Foo<T> { x: T } struct Bar<T> { x: Foo<T> } // ok! struct Baz<S, T> { x: Foo<S>, y: Foo<T> } // ok! fn foo<T, U>(x: T, y: U) {} fn f() {} fn main() { let x: bool = true; foo::<bool, u32>(x, 12); // ok! f(); // ok! }