Mockgen can't handle interface in current package other files

Suppose I have two files:

bar.go
```
package current
```

type Bar interface{}

2.  foo.go

package current

type Foo interface { Bar error }

Running `mockgen -destination current_mock.go -package current -source=foo.go` gives
2021/12/23 21:37:55 Loading input failed: foo.go:4:2: unknown embedded interface Bar

23  .  .  .  .  .  Type: *ast.InterfaceType {
24  .  .  .  .  .  .  Interface: /home/work/go/src/github.com/golang/mock/foo.go:3:10
25  .  .  .  .  .  .  Methods: *ast.FieldList {
26  .  .  .  .  .  .  .  Opening: /home/work/go/src/github.com/golang/mock/foo.go:3:20
27  .  .  .  .  .  .  .  List: []*ast.Field (len = 2) {
28  .  .  .  .  .  .  .  .  0: *ast.Field {
29  .  .  .  .  .  .  .  .  .  Type: *ast.Ident {
30  .  .  .  .  .  .  .  .  .  .  NamePos: /home/work/go/src/github.com/golang/mock/foo.go:4:2
31  .  .  .  .  .  .  .  .  .  .  Name: "Bar"
32  .  .  .  .  .  .  .  .  .  }
33  .  .  .  .  .  .  .  .  }
34  .  .  .  .  .  .  .  .  1: *ast.Field {
35  .  .  .  .  .  .  .  .  .  Type: *ast.Ident {
36  .  .  .  .  .  .  .  .  .  .  NamePos: /home/work/go/src/github.com/golang/mock/foo.go:5:2
37  .  .  .  .  .  .  .  .  .  .  Name: "error"
38  .  .  .  .  .  .  .  .  .  }
39  .  .  .  .  .  .  .  .  }
40  .  .  .  .  .  .  .  }
41  .  .  .  .  .  .  .  Closing: /home/work/go/src/github.com/golang/mock/foo.go:6:1
42  .  .  .  .  .  .  }
43  .  .  .  .  .  .  Incomplete: false
44  .  .  .  .  .  }


result `Bar` like `error`

golang / mock

Mockgen can't handle interface in current package other files #606