Why Can I Use Value Receivers with sync.WaitGroup\'s Pointer Methods?

Why Does sync.WaitGroup Work with Value Receivers?

The sync.WaitGroup type offers an empty method set, meaning it has no methods defined directly on its type. However, it has methods with pointer receivers. This raises the question of why these methods can be called on value receivers.

The answer lies in the Go language specification. Specifically, if a variable is addressable and its method set includes a method with a pointer receiver, the syntax x.m() is shorthand for (&x).m().

In the given example:

var wg sync.WaitGroup

wg.Add(1)
wg.Done()

This is an example of using a value receiver for pointer methods. The compiler automatically generates the equivalent code:

(&wg).Add(1)
(&wg).Done()

This allows the use of value receivers even though the actual method implementations require pointer receivers.

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