SimplifyUselessVariableRector missing opportunity

[staabm]

Bug Report

I expected SimplifyUselessVariableRector to cleanup this code

Subject	Details
Rector version	e.g. v0.11.5 (invoke vendor/bin/rector --version)

Minimal PHP Code Causing Issue

https://getrector.com/demo/b2fd9fbe-1209-4cbb-a317-fdd49ad2f2b1

Expected Behaviour

<?php

function apcInstalled(): bool
{
    $apcInstalled = false;
-   $apcInstalled = false;
    if (rand(0,1)) {
        return true;
    }

-    return $apcInstalled;
+    return false;
}

[samsonasik]

Since variable may be used in next call, the SideEffectNodeDetector and by-ref param may need to be used to verify.

[staabm]

Alternativly maybe there should be a rector which tests all return expression whether they just return a constant type and replace the return expression with said constant?

[samsonasik]

On method call or user defined function. it clearly should be skipped, as variable can be used via:

global $var;

++$var;

which change behavior, On native function, there is PureFunctionDetector service, that consumed by SideEffectNodeDetector

[samsonasik]

we had MoveVariableDeclarationNearReferenceRector , removed at:

• [CodeQuality] Remove MoveVariableDeclarationNearReferenceRector for too wide domain, not capable on most of real projects rector-src#587

[samsonasik]

I checked the code, it seems the rule is designed to cover Assign in Expression, then use after that, which your use case is out of scope.

we had the MoveVariableDeclarationNearReferenceRector, and due to magical, removed at

• [CodeQuality] Remove MoveVariableDeclarationNearReferenceRector for too wide domain, not capable on most of real projects rector-src#587

on that reasoning, I am closing it :)