条件编译不起作用

Question

操作系统：linux / amd64
GO：1.5.1

当运行（go run *.go）以下代码时，我收到以下错误，我不明白我做错了什么。我已经阅读了关于构建约束的official doc。不应忽略foo_windows.go吗？

# command-line-arguments
./foo_windows.go:3: hello redeclared in this block
        previous declaration at ./foo_linux.go:3

main.go

package main

import "fmt"

func main() {
    fmt.Println(hello())
}

foo_linux.go

package main

func hello() string {
    return "hello form linux"
}

foo_windows.go

package main

func hello() string {
    return "hello form windows"
}