[rojer@nbd /tmp]$ find foobar/
foobar/
foobar/go.mod
foobar/foo
foobar/foo/foo.go
foobar/bar
foobar/bar/bar.go
[rojer@nbd /tmp]$ cat foobar/foo/foo.go
package main

import (
        "foobar/bar"
)

func main() {
        // Test unused method elimination.
        var b bar.Interface
        b = bar.Bar{}
        b.UsedInterfaceMethod()
}
[rojer@nbd /tmp]$ cat foobar/bar/bar.go 
package bar

import "fmt"

type Interface interface {
        UsedInterfaceMethod()
        UnusedInterfaceMethod()
}

type Bar struct{}

func (Bar) UsedInterfaceMethod() {
        fmt.Println("one")
}

// This method is unused but cannot be eliminated yet.
// https://github.com/golang/go/issues/38685
func (Bar) UnusedInterfaceMethod() {
        fmt.Println("two")
}

// This method is unused and should be eliminated.
func (Bar) UnusedNonInterfaceMethod() {
        fmt.Println("three")
}

[rojer@nbd /tmp/foobar/foo]$ GOROOT=/home/rojer/go/go-git /home/rojer/go/go-git/bin/go build 
[rojer@nbd /tmp/foobar/foo]$ GOROOT=/home/rojer/go/go-git /home/rojer/go/go-git/bin/go tool nm -size foo | grep foobar/bar
  497080        187 T foobar/bar.(*Bar).UnusedInterfaceMethod
  497140        187 T foobar/bar.(*Bar).UsedInterfaceMethod
  535e20         32 D foobar/bar..inittask
  496fe0        138 T foobar/bar.Bar.UsedInterfaceMethod
  4da288         40 R go.itab.foobar/bar.Bar,foobar/bar.Interface