IteratorAggregate - read key and value type from generics if getItera…

…tor() doesn't have PHPDoc type

src/Type/ObjectType.php

@@ -525,11 +525,14 @@ public function getIterableKeyType(): Type
 		}
 
 		if ($this->isInstanceOf(\IteratorAggregate::class)->yes()) {
-			return RecursionGuard::run($this, static function () use ($classReflection): Type {
+			$keyType = RecursionGuard::run($this, static function () use ($classReflection): Type {
 				return ParametersAcceptorSelector::selectSingle(
 					$classReflection->getNativeMethod('getIterator')->getVariants()
 				)->getReturnType()->getIterableKeyType();
 			});
+			if (!$keyType instanceof MixedType || $keyType->isExplicitMixed()) {
+				return $keyType;
+			}
 		}
 
 		if ($this->isInstanceOf(\Traversable::class)->yes()) {
@@ -558,11 +561,14 @@ public function getIterableValueType(): Type
 		}
 
 		if ($this->isInstanceOf(\IteratorAggregate::class)->yes()) {
-			return RecursionGuard::run($this, static function () use ($classReflection): Type {
+			$valueType = RecursionGuard::run($this, static function () use ($classReflection): Type {
 				return ParametersAcceptorSelector::selectSingle(
 					$classReflection->getNativeMethod('getIterator')->getVariants()
 				)->getReturnType()->getIterableValueType();
 			});
+			if (!$valueType instanceof MixedType || $valueType->isExplicitMixed()) {
+				return $valueType;
+			}
 		}
 
 		if ($this->isInstanceOf(\Traversable::class)->yes()) {

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -4893,13 +4893,13 @@ public function dataForeachObjectType(): array
 			],
 			[
 				__DIR__ . '/data/foreach/object-type.php',
-				'*ERROR*',
+				'mixed',
 				'$keyFromRecursiveAggregate',
 				"'insideThirdForeach'",
 			],
 			[
 				__DIR__ . '/data/foreach/object-type.php',
-				'*ERROR*',
+				'mixed',
 				'$valueFromRecursiveAggregate',
 				"'insideThirdForeach'",
 			],
@@ -10726,6 +10726,11 @@ public function dataBug4398(): array
 		return $this->gatherAssertTypes(__DIR__ . '/data/bug-4398.php');
 	}
 
+	public function dataBug4415(): array
+	{
+		return $this->gatherAssertTypes(__DIR__ . '/data/bug-4415.php');
+	}
+
 	/**
 	 * @param string $file
 	 * @return array<string, mixed[]>
@@ -10937,6 +10942,7 @@ private function gatherAssertTypes(string $file): array
 	 * @dataProvider dataVarAboveDeclare
 	 * @dataProvider dataClosureReturnType
 	 * @dataProvider dataBug4398
+	 * @dataProvider dataBug4415
 	 * @param string $assertType
 	 * @param string $file
 	 * @param mixed ...$args

tests/PHPStan/Analyser/data/bug-4415.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Bug4415;
+
+use function PHPStan\Analyser\assertType;
+
+/**
+ * @implements \IteratorAggregate<int, string>
+ */
+class Foo implements \IteratorAggregate
+{
+
+	public function getIterator(): \Iterator
+	{
+
+	}
+
+}
+
+function (Foo $foo): void {
+	foreach ($foo as $k => $v) {
+		assertType('int', $k);
+		assertType('string', $v);
+	}
+};

tests/PHPStan/Rules/Methods/MissingMethodReturnTypehintRuleTest.php

@@ -63,4 +63,15 @@ public function testArrayTypehintWithoutNullInPhpDoc(): void
 		$this->analyse([__DIR__ . '/../../Analyser/data/array-typehint-without-null-in-phpdoc.php'], []);
 	}
 
+	public function testBug4415(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-4415.php'], [
+			[
+				'Method Bug4415Rule\CategoryCollection::getIterator() return type has no value type specified in iterable type Iterator.',
+				76,
+				"Consider adding something like <fg=cyan>Iterator<Foo></> to the PHPDoc.\nYou can turn off this check by setting <fg=cyan>checkMissingIterableValueType: false</> in your <fg=cyan>%configurationFile%</>.",
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-4415.php

@@ -0,0 +1,87 @@
+<?php
+
+namespace Bug4415Rule;
+
+/**
+ * @template T
+ * @extends \IteratorAggregate<T>
+ */
+interface CollectionInterface extends \IteratorAggregate
+{
+	/**
+	 * @param T $item
+	 */
+	public function has($item): bool;
+
+	/**
+	 * @return self<T>
+	 */
+	public function sort(): self;
+}
+
+/**
+ * @template T
+ * @extends CollectionInterface<T>
+ */
+interface MutableCollectionInterface extends CollectionInterface
+{
+	/**
+	 * @param T $item
+	 * @phpstan-return self<T>
+	 */
+	public function add($item): self;
+}
+
+/**
+ * @extends CollectionInterface<Category>
+ */
+interface CategoryCollectionInterface extends CollectionInterface
+{
+	public function has($item): bool;
+
+	/**
+	 * @phpstan-return \Iterator<Category>
+	 */
+	public function getIterator(): \Iterator;
+}
+
+/**
+ * @extends MutableCollectionInterface<Category>
+ */
+interface MutableCategoryCollectionInterface extends CategoryCollectionInterface, MutableCollectionInterface
+{
+}
+
+class CategoryCollection implements MutableCategoryCollectionInterface
+{
+	/** @var array<Category> */
+	private array $categories = [];
+
+	public function add($item): self
+	{
+		$this->categories[$item->getName()] = $item;
+		return $this;
+	}
+
+	public function has($item): bool
+	{
+		return isset($this->categories[$item->getName()]);
+	}
+
+	public function sort(): self
+	{
+		return $this;
+	}
+
+	public function getIterator(): \Iterator
+	{
+		return new \ArrayIterator($this->categories);
+	}
+}
+
+class Category {
+	public function getName(): string
+	{
+		return '';
+	}
+}