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()));
+}
 }