goversion.go

package main

import (
	"fmt"
	"runtime/debug"
	"strings"
)

const progname = "goversion"

var version string

func main() {
	fmt.Printf("version from make: %s %s\n", progname, version)

	fmt.Printf("buildinfo: %s %s\n", progname, readBuildInfo())
}

func readBuildInfo() string {
	if info, ok := debug.ReadBuildInfo(); ok {
		// When built with go install ...@version
		version := info.Main.Version
		if version != "(devel)" {
			fmt.Printf("got it from info.Main.Version\n")
			return version
		}

		// Otherwise, use Git commit data.
		fmt.Printf("got it from Git\n")
		sb := strings.Builder{}
		sb.WriteString("devel")
		for _, setting := range info.Settings {
			if strings.HasPrefix(setting.Key, "vcs") {
				sb.WriteString(fmt.Sprintf(" %s=%s", setting.Key, setting.Value))
			}
		}
		version = sb.String()
	}

	return version
}