Overview

The zero value of the channel is nil. Hence only declaring a channel creates a nil channel as default zero value of the channel is nil. Below is the result of send and receive operation on a nil channel

•  Sending to a  nil channel blocks forever

•  Receiving from nil channel blocks forever

Let’s see a program for it

Code

package main

import (
	"fmt"
	"time"
)

func main() {
	var ch chan int

	go send(ch)
	<-ch
	time.Sleep(time.Second * 1)
}

func send(ch chan int) {
	fmt.Println("Sending value to channnel start")
	ch <- 1
	fmt.Println("Sending value to channnel finish")
}

Output

Sending value to channnel start
fatal error: all goroutines are asleep - deadlock!
goroutine 1 [chan receive (nil chan)]:
goroutine 18 [chan send (nil chan)]:

In the above program, we are only declaring the channel hence a nil Channel was created since the default 0 value of the channel is nil.  After that, we sent to the channel in send function and received from the channel in the main function.  It results in a deadlock as sending to and receiving from a nil channel block forever.  That is why it  gives below output