Is copying mandatory when using value semantics in programming languages?

When using value semantics in a programming language, data copying occurs by default during assignment or value passing. This means that a new copy of the object is created, not a reference to the original.

However, copying is not always physically necessary for all data. Many modern languages and compilers optimize copying operations, for example, by using copy-on-write or compiler-level optimizations.

Example: In Swift, structures have value semantics, and assigning them creates a copy. But if the structure contains reference types, then only the references are copied, not the objects themselves.

struct Point {
    var x: Int
    var y: Int
}

var p1 = Point(x: 1, y: 2)
var p2 = p1  // creates a copy of p1
p2.x = 3
print(p1.x) // 1
print(p2.x) // 3

Thus, copying is logically necessary with value semantics, but the actual implementation can be optimized.