Trying to compare two values ​​of type V with Go generics doesn't work

php Editor Apple found that in Go language, two values ​​of type V cannot be directly compared when using generics. This means that comparisons cannot be made simply using == or != as you can with strings or integers. This is because generics are implemented differently and cannot directly compare values. In this case, we need to use a custom comparison function or method to perform the comparison operation to achieve the functionality we require. This is a detail to pay attention to, especially when writing code involving generics.

Question content

go version: go1.21rc2

I'm writing a function in go using generics that takes a value and returns true/false if the value is in a map.

In version 1 below, I don't understand why two values ​​cannot be compared when their type is any? But after converting to any in version 2, it works now... I guess I'm missing something obvious, but I don't quite understand it.

Version 1 (not working):

func invalues[m ~map[k]v, k comparable, v any](m m, v v) bool {
    for _, x := range maps.values(m) {
        if x == v {
            return true
        }
    }
    return false
}

Version 2 (Working):

func InValues[M ~map[K]V, K comparable, V any](m M, v V) bool {
    for _, x := range maps.Values(m) {
        if any(x) == any(v) {
            return true
        }
    }
    return false
}

Solution

V needs to be comparable to allow ==.
Converting to any then compares effectively because it uses non-generic == between any, which is always allowed.

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