next() dynamic return type extension

conf/config.neon

@@ -953,6 +953,11 @@ services:
 		tags:
 			- phpstan.broker.dynamicFunctionReturnTypeExtension
 
+	-
+		class: PHPStan\Type\Php\ArrayNextDynamicReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicFunctionReturnTypeExtension
+
 	-
 		class: PHPStan\Type\Php\ArrayPopFunctionReturnTypeExtension
 		tags:

src/Type/Php/ArrayNextDynamicReturnTypeExtension.php

@@ -0,0 +1,38 @@
+<?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\Constant\ConstantBooleanType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+
+class ArrayNextDynamicReturnTypeExtension implements \PHPStan\Type\DynamicFunctionReturnTypeExtension
+{
+
+	public function isFunctionSupported(FunctionReflection $functionReflection): bool
+	{
+		return $functionReflection->getName() === 'next';
+	}
+
+	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): Type
+	{
+		if (!isset($functionCall->args[0])) {
+			return ParametersAcceptorSelector::selectSingle($functionReflection->getVariants())->getReturnType();
+		}
+
+		$argType = $scope->getType($functionCall->args[0]->value);
+		$iterableAtLeastOnce = $argType->isIterableAtLeastOnce();
+		if ($iterableAtLeastOnce->no()) {
+			return new ConstantBooleanType(false);
+		}
+
+		$valueType = $argType->getIterableValueType();
+
+		return TypeCombinator::union($valueType, new ConstantBooleanType(false));
+	}
+
+}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -431,6 +431,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/closure-types.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5219.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/strval.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/array-next.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/array-next.php

@@ -0,0 +1,77 @@
+<?php
+
+namespace ArrayNext;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	public function doFoo()
+	{
+		$array = [];
+		assertType('false', next($array));
+	}
+
+	/**
+	 * @param int[] $a
+	 */
+	public function doBar(array $a)
+	{
+		assertType('int|false', next($a));
+	}
+
+	/**
+	 * @param non-empty-array<int, string> $a
+	 */
+	public function doBaz(array $a)
+	{
+		assertType('string|false', next($a));
+	}
+
+}
+
+interface HttpClientPoolItem
+{
+	public function isDisabled(): bool;
+}
+
+final class RoundRobinClientPool
+{
+	/**
+	 * @var HttpClientPoolItem[]
+	 */
+	protected $clientPool = [];
+
+	protected function chooseHttpClient(): HttpClientPoolItem
+	{
+		$last = current($this->clientPool);
+		assertType(HttpClientPoolItem::class . '|false', $last);
+
+		do {
+			$client = next($this->clientPool);
+			assertType(HttpClientPoolItem::class . '|false', $client);
+
+			if (false === $client) {
+				$client = reset($this->clientPool);
+				assertType(HttpClientPoolItem::class . '|false', $client);
+
+				if (false === $client) {
+					throw new \Exception();
+				}
+
+				assertType(HttpClientPoolItem::class, $client);
+			}
+
+			assertType(HttpClientPoolItem::class, $client);
+
+			// Case when there is only one and the last one has been disabled
+			if ($last === $client) {
+				assertType(HttpClientPoolItem::class, $client);
+				throw new \Exception();
+			}
+		} while ($client->isDisabled());
+
+		return $client;
+	}
+}

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -1971,4 +1971,12 @@ public function testBug4083(): void
 		$this->analyse([__DIR__ . '/data/bug-4083.php'], []);
 	}
 
+	public function testBug5253(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkNullables = true;
+		$this->checkUnionTypes = true;
+		$this->analyse([__DIR__ . '/data/bug-5253.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-5253.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace Bug5253;
+
+interface HttpClientPoolItem
+{
+	public function isDisabled(): bool;
+}
+
+final class RoundRobinClientPool
+{
+	/**
+	 * @var HttpClientPoolItem[]
+	 */
+	protected $clientPool = [];
+
+	protected function chooseHttpClient(): HttpClientPoolItem
+	{
+		$last = current($this->clientPool);
+
+		do {
+			$client = next($this->clientPool);
+
+			if (false === $client) {
+				$client = reset($this->clientPool);
+
+				if (false === $client) {
+					throw new \Exception();
+				}
+			}
+
+			// Case when there is only one and the last one has been disabled
+			if ($last === $client && $client->isDisabled()) {
+				throw new \Exception();
+			}
+		} while ($client->isDisabled());
+
+		return $client;
+	}
+}