2018-11-09 强制使用字段命名方式初始化结构体

// foo.go
package foo

type Config struct {
	_    [0]int
	Name string
	Size int
}

// main.go
package main

import "foo"

func main() {
    //_ = foo.Config{[0]int{}, "bar", 123}
    // doesn't compile
    // 报错信息:implicit assignment of unexported field 'flag' in foo.Config literal

	_ = foo.Config{Name: "bar", Size: 123} // compile okay
}