// main.go

package main

import (
	"fmt"
)

var (
	v0 = constInitCheck()
	v1 = variableInit("v1")
	v2 = variableInit("v2")
)

const (
	c1 = "c1"
	c2 = "c2"
)

func constInitCheck() string {
	if c1 != "" {
		fmt.Println("main: const c1 has been initialized")
	}
	if c1 != "" {
		fmt.Println("main: const c2 has been initialized")
	}
	return ""
}

func variableInit(name string) string {
	fmt.Printf("main: var %s has been initialized\n", name)
	return name
}

func init() {
	fmt.Println("main: first init func invoked")
}

func init() {
	fmt.Println("main: second init func invoked")
}

func main() {
	// do nothing
}

$go run main.go
main: var v1 has been initialized
main: var v2 has been initialized
main: const c1 has been initialized
main: const c2 has been initialized
main: first init func invoked
main: second init func invoked

Within a package, package-level variable initialization proceeds stepwise, with each step selecting the variable earliest in declaration order which has no dependencies on uninitialized variables.

More precisely, a package-level variable is considered ready for initialization if it is not yet initialized and either has no [initialization expression](https://go.dev/ref/spec#Variable_declarations) or its initialization expression has no dependencies on uninitialized variables. Initialization proceeds by repeatedly initializing the next package-level variable that is earliest in declaration order and ready for initialization, until there are no variables ready for initialization.