[DowngradePhp80] Handle infinite loop in array dim fetch on DowngradeMatchToSwitchRector

phpstan.neon

@@ -107,6 +107,7 @@ parameters:
                  - rules/DowngradePhp74/Rector/MethodCall/DowngradeReflectionGetTypeRector.php
                  - rules/DowngradePhp80/Rector/MethodCall/DowngradeReflectionGetAttributesRector.php
                  - rules/DowngradePhp73/Rector/String_/DowngradeFlexibleHeredocSyntaxRector.php
+                 - rules/DowngradePhp80/Rector/Expression/DowngradeMatchToSwitchRector.php
 
         # local attribute key
         - '#Parameter \#2 \$attributeKey of static method Rector\\PhpParser\\NodeTraverser\\SimpleNodeTraverser\:\:decorateWithAttributeValue\(\) expects#'

rules-tests/DowngradePhp80/Rector/Expression/DowngradeMatchToSwitchRector/Fixture/in_array_dim_fetch.php.inc

@@ -0,0 +1,42 @@
+<?php
+
+namespace Rector\Tests\DowngradePhp80\Rector\Expression\DowngradeMatchToSwitchRector\Fixture;
+
+class InArrayDimFetch
+{
+    public function run($c, $n, $v)
+    {
+        $properties[match ($c) {
+            'Error' => 'TypeError',
+            'Exception' => 'ErrorException',
+            default => $c,
+        }][$n] = $v;
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\DowngradePhp80\Rector\Expression\DowngradeMatchToSwitchRector\Fixture;
+
+class InArrayDimFetch
+{
+    public function run($c, $n, $v)
+    {
+        switch ($c) {
+            case 'Error':
+                $match = 'TypeError';
+                break;
+            case 'Exception':
+                $match = 'ErrorException';
+                break;
+            default:
+                $match = $c;
+                break;
+        }
+        $properties[$match][$n] = $v;
+    }
+}
+
+?>

rules/DowngradePhp80/Rector/Expression/DowngradeMatchToSwitchRector.php

@@ -8,6 +8,7 @@
 use PhpParser\Node\Arg;
 use PhpParser\Node\ArrayItem;
 use PhpParser\Node\Expr;
+use PhpParser\Node\Expr\ArrayDimFetch;
 use PhpParser\Node\Expr\ArrowFunction;
 use PhpParser\Node\Expr\Assign;
 use PhpParser\Node\Expr\BinaryOp;
@@ -19,6 +20,7 @@
 use PhpParser\Node\Expr\NullsafeMethodCall;
 use PhpParser\Node\Expr\StaticCall;
 use PhpParser\Node\Expr\Throw_;
+use PhpParser\Node\Expr\Variable;
 use PhpParser\Node\MatchArm;
 use PhpParser\Node\Stmt;
 use PhpParser\Node\Stmt\Break_;
@@ -29,6 +31,7 @@
 use PhpParser\Node\Stmt\Switch_;
 use PhpParser\NodeVisitor;
 use PHPStan\Analyser\Scope;
+use Rector\Naming\Naming\VariableNaming;
 use Rector\NodeTypeResolver\Node\AttributeKey;
 use Rector\Php72\NodeFactory\AnonymousFunctionFactory;
 use Rector\PHPStan\ScopeFetcher;
@@ -44,7 +47,8 @@
 final class DowngradeMatchToSwitchRector extends AbstractRector
 {
     public function __construct(
-        private readonly AnonymousFunctionFactory $anonymousFunctionFactory
+        private readonly AnonymousFunctionFactory $anonymousFunctionFactory,
+        private readonly VariableNaming $variableNaming
     ) {
     }
 
@@ -102,14 +106,37 @@ public function getNodeTypes(): array
     /**
      * @param Echo_|Expression|Return_ $node
      */
-    public function refactor(Node $node): ?Node
+    public function refactor(Node $node): null|Node|array
     {
         /** @var Match_|null $match */
         $match = null;
         $hasChanged = false;
 
         $scope = ScopeFetcher::fetch($node);
 
+        if ($node instanceof Expression
+                && $node->expr instanceof Assign
+                && $node->expr->var instanceof ArrayDimFetch
+                && $node->expr->var->var instanceof ArrayDimFetch
+                && $node->expr->var->var->dim instanceof Match_) {
+            $matchVariable = new Variable($this->variableNaming->createCountedValueName('match', $scope));
+            $expression = new Expression(new Assign($matchVariable, $node->expr->var->var->dim));
+            $expression->setAttribute(AttributeKey::SCOPE, $scope);
+            $refactored = $this->refactor($expression);
+
+            if ($refactored === null) {
+                return null;
+            }
+
+            $node->expr->var->var->dim = $matchVariable;
+
+            $stmts = is_array($refactored)
+                ? $refactored :
+                [$refactored];
+
+            return [...$stmts, $node];
+        }
+
         $this->traverseNodesWithCallable(
             $node,
             function (Node $subNode) use ($node, &$match, &$hasChanged, $scope) {