结构声明样式之间的句法/语义差异

Question

Any difference between these two declarations?

type Foo = struct {
    F string `zoom:"1"`
}

and

type Foo struct {
    F string `zoom:"1"`
}

they both compile and seem to work the same.

Answer 1

The 2nd one, it's an example of struct declaration.

type Foo struct {
    F string `zoom:"1"`
}

---

And the 1st one, it is usage example of go1.9 new feature: type aliases.

A new type Foo is created. It's an alias of an anonymous struct.

type Foo = struct {
    F string `zoom:"1"`
}

The type aliases syntax can be used to define a struct. In example above, it's generating an equivalent result like type Foo struct.

But, the original purpose of type alias is to make an alias from defined type.

In example below, a new type called Bar is created and it's an alias of Foo struct.

type Foo struct {
    F string `zoom:"1"`
}
type Bar = Foo