The array_push and array_unshift functions require at least 2 arguments. Requirement about second argument was relevant until version 5.6, because the code array_push($array) really does not make sense. But with argument unpacking syntax we can use spread operator for array union:

array_push($array, ...$values);
array_unshift($array, ...$values);

If the addition list length is not predefined then we should explicitly check the case when this list is emptiness to avoid the warning message, or prepend the expression with @-operator. Actually the functions work well with single argument, they just do not change it. The warning is completely redundant and explicit checking negates the benefit (code size reducing) gained with the spread operator.

For example, relevant array methods push and unshift in the JavaScript work this way:

"use strict";
var array = [1,2,3]
var values = []
array.push(...values)
array.unshift(...values)
// no error messages, both methods just return 3, array is still [1,2,3]

Adding multiple elements to an array is a very common operation. This patch just will make it a little more convenient.

Unfortunately, it may cause the minor BC break for return value. Currently both functions returns NULL when second argument is not passed. With this patch in this case they will return the length of array passed as first argument. Do I need to create RFC for such a small change?