Attribute Macro into 

#[into]

impl Into for Struct

#[derive(Debug, Default)]
struct Foo {
    field1: i32,
    field3: String,
}

#[into(Foo)]  // no default
//#[into(Foo, default)]  // with default field
struct Bar {
    field1: i32,
    #[into_skip]
    field2: String,
    #[into(self.field3.to_string())]
    field3: i32,
}