A new list isn't created for function calls with rest arguments with lists

[MaryamZi]

Based on the following example, it seems like we are not always creating a new list? IMO, we need to create a new list always (also in-line with the spec) because it can result in unintentional updates like in the example.

E.g.,

import ballerina/io;

int[] arr = [1, 2];

public function main() {
    fn(...getArr());
    io:println(arr); // updated to [1,2,4] on 2201.4.0
}

function getArr() returns int[] => arr;

function fn(int... x) {
    x.push(4);
}

Btw, just to add, the rest argument doesn't have to be just for the rest param, it can provide arguments for other params also.

[int, int...] arr = [1, 2];

public function main() {
    fn(...getArr()); // valid
}

function getArr() returns [int, int...] => arr;

function fn(int a, int... x) {
}

Originally posted by @MaryamZi in #40040 (comment)