[DeadCode] Fix known array type in empty if foreach (#2432)

phpstan.neon

@@ -722,3 +722,6 @@ parameters:
         - '#Method "refactorPhpDoc\(\)" returns bool type, so the name should start with is/has/was#'
 
         - '#Cognitive complexity for "Rector\\Renaming\\Rector\\FileWithoutNamespace\\PseudoNamespaceToNamespaceRector\:\:refactorStmts\(\)" is 11, keep it under 10#'
+
+        # resolve later with configurable types
+        - '#On passing a constant, the method should have an enum type\. See https\://phpstan\.org/writing\-php\-code/phpdoc\-types\#literals\-and\-constants#'

rules-tests/DeadCode/Rector/If_/RemoveUnusedNonEmptyArrayBeforeForeachRector/Fixture/property_foreach.php.inc

@@ -0,0 +1,45 @@
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\If_\RemoveUnusedNonEmptyArrayBeforeForeachRector\Fixture;
+
+final class PropertyForeach
+{
+    private $items = [];
+
+    public function __construct(array $items)
+    {
+        $this->items = $items;
+    }
+
+    public function run()
+    {
+        if ($this->items) {
+            foreach ($this->items as $item) {
+            }
+        }
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\If_\RemoveUnusedNonEmptyArrayBeforeForeachRector\Fixture;
+
+final class PropertyForeach
+{
+    private $items = [];
+
+    public function __construct(array $items)
+    {
+        $this->items = $items;
+    }
+
+    public function run()
+    {
+        foreach ($this->items as $item) {
+        }
+    }
+}
+
+?>

rules/DeadCode/Rector/If_/RemoveUnusedNonEmptyArrayBeforeForeachRector.php

@@ -8,6 +8,7 @@
 use PhpParser\Node\Expr\Variable;
 use PhpParser\Node\Stmt\Foreach_;
 use PhpParser\Node\Stmt\If_;
+use PHPStan\Type\ArrayType;
 use Rector\Core\NodeManipulator\IfManipulator;
 use Rector\Core\Php\ReservedKeywordAnalyzer;
 use Rector\Core\Rector\AbstractRector;
@@ -121,6 +122,12 @@ private function isUselessBeforeForeachCheck(If_ $if): bool
             return true;
         }
 
+        // we know it's an array
+        $condType = $this->getType($if->cond);
+        if ($condType instanceof ArrayType) {
+            return true;
+        }
+
         return $this->countManipulator->isCounterHigherThanOne($if->cond, $foreachExpr);
     }
 }