为什么在以下带有defer的golang代码示例中得到0和1

Question

Call to defer produces different results for variables declared in two different ways

package main

import (
    "fmt"
)

func c(i int) int {
    defer func() { i++ }()
    return i
}

func c1() (i int) {
    defer func() { i++ }()
    return i
}

func c2() (i int) {
    defer func() { i++ }()
    return 2
}

func main() {
    fmt.Println(c(0)) // Prints 0
    fmt.Println(c1()) // Prints 1
    fmt.Println(c2()) // Prints 3 Thank you icza
}

https://play.golang.org/p/gfnnCZ--DkH