Go编译已声明且未使用[重复]

I got some problems with Go, I did have used tag in tag = true

//  project main.go
package main

import (
    "fmt"
)

func main() {
    var m, odd1, odd2, in1, in2 int
    tag := false
    fmt.Scan(&m)
    for i := 0; i < m; i++ {
        fmt.Scan(&in1, &in2)
        odd1 += in1
        odd2 += in2
        if (in1+in2)&1 == 1 {
            tag = true
        }
    }
    if odd1&1 == 0 && odd2&1 == 0 {
        fmt.Print("0")
        return
    }
    if odd1&1 == 0 && odd2&1 == 1 || odd1&1 == 1 && odd2&1 == 0 {
        fmt.Print("1")
        return
    }
    fmt.Print("-1")
}

</div>

'Not used' can be understood as 'has no effect'. While you're assigning true to tag, this is not propagated to the outside nor has any effect on the result of the function.

If you'd use tag in a condition or return it, then the compiler wouldn't complain anymore.

You aren't using tag. You're assigning to it again. Using would mean it's on the right hand side of something: if tag { or if tag && odd1 && 1 == testVal {

_{This is a Christopher Pfohl answer}