Incorrect behavior of ChangeSwitchToMatchRector in if/else block

[sylbru]

Bug Report

Subject	Details
Rector version	last dev-master
Installed as	composer dependency

Minimal PHP Code Causing Issue

See https://getrector.org/demo/b0d8696f-23ae-44b1-afb3-9c5ce9443bdf

<?php

function f(int $param, bool $flag): string
{
    if (!$flag) {
        $value = "A";
    } else {
        switch ($param) {
            case 1:
                $value = "B";
                break;
            case 2:
                $value = "C";
                break;
            default:
                $value = "D";
                break;
        }
    }
    
    return $value;
}

Responsible rules

• ChangeSwitchToMatchRector

Expected Behavior

The rule should not touch anything outside the initial switch statement. Here it’s removing the $value = "A"; instruction in the other branch of the if/else block. This means that if I call this function with (99, false), it will have an undefined return value, where it should have returned "A" before running Rector.

By the way, but this is an unrelated issue, I think it’s dangerous to advertise this as a part of a simple automatic upgrade for PHP 8, as the switch->match conversion will likely introduce some bugs because of the strict comparison being used in match.