Fix iterator_to_array return type with generators

Author: paulbalandan

src/Type/Php/IteratorToArrayFunctionReturnTypeExtension.php

@@ -8,7 +8,9 @@
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\ArrayType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
+use PHPStan\Type\ErrorType;
 use PHPStan\Type\IntegerType;
+use PHPStan\Type\NeverType;
 use PHPStan\Type\Type;
 use function strtolower;
 
@@ -29,7 +31,12 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 		}
 
 		$traversableType = $scope->getType($arguments[0]->value);
-		$arrayKeyType = $traversableType->getIterableKeyType();
+		$arrayKeyType = $traversableType->getIterableKeyType()->toArrayKey();
+
+		if ($arrayKeyType instanceof ErrorType) {
+			return new NeverType(true);
+		}
+
 		$isList = false;
 
 		if (isset($arguments[1])) {

tests/PHPStan/Analyser/nsrt/iterator_to_array.php

@@ -2,6 +2,7 @@
 
 namespace IteratorToArray;
 
+use stdClass;
 use Traversable;
 use function iterator_to_array;
 use function PHPStan\Testing\assertType;
@@ -31,4 +32,33 @@ public function testNotPreservingKeys(Traversable $foo)
 	{
 		assertType('list<string>', iterator_to_array($foo, false));
 	}
+
+	public function testBehaviorOnGenerators(): void
+	{
+		$generator1 = static function (): iterable {
+			yield 0 => 1;
+			yield true => 2;
+			yield 2 => 3;
+			yield null => 4;
+		};
+		$generator2 = static function (): iterable {
+			yield 0 => 1;
+			yield 'a' => 2;
+			yield null => 3;
+			yield true => 4;
+		};
+
+		assertType('array<0|1|2|\'\', 1|2|3|4>', iterator_to_array($generator1()));
+		assertType('array<0|1|\'\'|\'a\', 1|2|3|4>', iterator_to_array($generator2()));
+	}
+
+	public function testOnGeneratorsWithIllegalKeysForArray(): void
+	{
+		$illegalGenerator = static function (): iterable {
+			yield 'a' => 'b';
+			yield new stdClass => 'c';
+		};
+
+		assertType('*NEVER*', iterator_to_array($illegalGenerator()));
+	}
 }