E0012: Type Already Defined

You tried to define a type with a name that's already in use.

Example

struct Point {
    x: i64,
    y: i64,
}

struct Point {  // Error: type `Point` is already defined in this module
    a: i64,
    b: i64,
}

How to fix

Use a different name for the second type:

struct Point {
    x: i64,
    y: i64,
}

struct Point2D {
    a: i64,
    b: i64,
}