feat(type): support $preserve_keys argument for iterator_to_array()

conf/config.neon

@@ -1361,6 +1361,11 @@ services:
 		tags:
 			- phpstan.typeSpecifier.functionTypeSpecifyingExtension
 
+	-
+		class: PHPStan\Type\Php\IteratorToArrayFunctionReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicFunctionReturnTypeExtension
+
 	-
 		class: PHPStan\Type\Php\IsObjectFunctionTypeSpecifyingExtension
 		tags:

src/Type/Php/ArgumentBasedFunctionReturnTypeExtension.php

@@ -34,7 +34,6 @@ class ArgumentBasedFunctionReturnTypeExtension implements \PHPStan\Type\DynamicF
 		'array_uintersect_assoc' => 0,
 		'array_uintersect_uassoc' => 0,
 		'array_uintersect' => 0,
-		'iterator_to_array' => 0,
 	];
 
 	public function isFunctionSupported(FunctionReflection $functionReflection): bool

src/Type/Php/IteratorToArrayFunctionReturnTypeExtension.php

@@ -0,0 +1,49 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Reflection\ParametersAcceptorSelector;
+use PHPStan\Type\ArrayType;
+use PHPStan\Type\Constant\ConstantBooleanType;
+use PHPStan\Type\DynamicFunctionReturnTypeExtension;
+use PHPStan\Type\IntegerType;
+use PHPStan\Type\Type;
+use function strtolower;
+
+final class IteratorToArrayFunctionReturnTypeExtension implements DynamicFunctionReturnTypeExtension
+{
+
+	public function isFunctionSupported(FunctionReflection $functionReflection): bool
+	{
+		return strtolower($functionReflection->getName()) === 'iterator_to_array';
+	}
+
+	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): Type
+	{
+		$arguments = $functionCall->getArgs();
+
+		if ($arguments === []) {
+			return ParametersAcceptorSelector::selectSingle($functionReflection->getVariants())->getReturnType();
+		}
+
+		$traversableType = $scope->getType($arguments[0]->value);
+		$arrayKeyType = $traversableType->getIterableKeyType();
+
+		if (isset($arguments[1])) {
+			$preserveKeysType = $scope->getType($arguments[1]->value);
+
+			if ($preserveKeysType instanceof ConstantBooleanType && !$preserveKeysType->getValue()) {
+				$arrayKeyType = new IntegerType();
+			}
+		}
+
+		return new ArrayType(
+			$arrayKeyType,
+			$traversableType->getIterableValueType()
+		);
+	}
+
+}

tests/PHPStan/Analyser/data/iterator_to_array.php

@@ -9,10 +9,26 @@
 class Foo
 {
 	/**
-	 * @param Traversable<string, int> $ints
+	 * @param Traversable<string, int> $foo
 	 */
-	public function doFoo(Traversable $ints)
+	public function testDefaultBehavior(Traversable $foo)
 	{
-		assertType('array<string, int>', iterator_to_array($ints));
+		assertType('array<string, int>', iterator_to_array($foo));
+	}
+
+	/**
+	 * @param Traversable<string, string> $foo
+	 */
+	public function testExplicitlyPreserveKeys(Traversable $foo)
+	{
+		assertType('array<string, string>', iterator_to_array($foo, true));
+	}
+
+	/**
+	 * @param Traversable<string, string> $foo
+	 */
+	public function testNotPreservingKeys(Traversable $foo)
+	{
+		assertType('array<int, string>', iterator_to_array($foo, false));
 	}
 }