Respect @throws void on getIterator() when determining foreach Traversable throw points

src/Analyser/NodeScopeResolver.php

@@ -4,6 +4,7 @@
 
 use ArrayAccess;
 use Closure;
+use IteratorAggregate;
 use Override;
 use PhpParser\Comment\Doc;
 use PhpParser\Modifiers;
@@ -1437,8 +1438,9 @@
 				$throwPoints = array_merge($throwPoints, $finalScopeResult->getThrowPoints());
 				$impurePoints = array_merge($impurePoints, $finalScopeResult->getImpurePoints());
 			}
-			if (!(new ObjectType(Traversable::class))->isSuperTypeOf($scope->getType($stmt->expr))->no()) {
-				$throwPoints[] = InternalThrowPoint::createImplicit($scope, $stmt->expr);
+			$traversableThrowPoint = $this->getTraversableForeachThrowPoint($scope, $stmt->expr);
+			if ($traversableThrowPoint !== null) {
+				$throwPoints[] = $traversableThrowPoint;
 			}
 			if ($context->isTopLevel() && $stmt->byRef) {
 				$finalScope = $finalScope->assignExpression(new ForeachValueByRefExpr($stmt->valueVar), new MixedType(), new MixedType());
@@ -4031,6 +4033,37 @@
 		return ['bodyScope' => $bodyScope, 'endScope' => $endScope];
 	}
 
+	private function getTraversableForeachThrowPoint(MutatingScope $scope, Expr $iteratee): ?InternalThrowPoint
+	{
+		$exprType = $scope->getType($iteratee);
+		$traversableType = new ObjectType(Traversable::class);
+
+		if ($traversableType->isSuperTypeOf($exprType)->no()) {
+			return null;
+		}
+
+		$traversablePart = TypeCombinator::intersect($exprType, $traversableType);
+		$iteratorAggregateType = new ObjectType(IteratorAggregate::class);
+
+		if ($iteratorAggregateType->isSuperTypeOf($traversablePart)->yes()
+			&& $traversablePart->hasMethod('getIterator')->yes()) {
+			$method = $traversablePart->getMethod('getIterator', $scope);
+			$throwType = $method->getThrowType();
+			if ($throwType !== null) {
+				if ($throwType->isVoid()->yes()) {
+					return null;
+				}
+				return InternalThrowPoint::createExplicit($scope, $throwType, $iteratee, true);
+			}
+
+			if (!$this->implicitThrows) {
+				return null;
+			}
+		}
+
+		return InternalThrowPoint::createImplicit($scope, $iteratee);
+	}
+
 	/**
 	 * @param callable(Node $node, Scope $scope): void $nodeCallback
 	 */

tests/PHPStan/Analyser/nsrt/bug-6833.php

@@ -0,0 +1,208 @@
+<?php // lint >= 8.0
+
+declare(strict_types=1);
+
+namespace Bug6833;
+
+use PHPStan\TrinaryLogic;
+use function PHPStan\Testing\assertVariableCertainty;
+
+class File
+{
+	public function __construct(private int $id) {}
+	public function getId(): int { return $this->id; }
+}
+
+/**
+ * @implements \IteratorAggregate<int, File>
+ */
+class FileCollection implements \IteratorAggregate
+{
+	/** @var File[] */
+	private array $files = [];
+
+	public function add(File $file): void
+	{
+		$this->files[] = $file;
+	}
+
+	/** @throws void */
+	public function getIterator(): \Iterator
+	{
+		return new \ArrayIterator($this->files);
+	}
+}
+
+function testThrowsVoidOnGetIterator(FileCollection $files): void
+{
+	try {
+		foreach ($files as $file) {
+			echo $file->getId();
+		}
+	} catch (\Throwable) {
+		assertVariableCertainty(TrinaryLogic::createYes(), $file);
+		echo 'Invalid file:' . $file->getId();
+	}
+}
+
+/**
+ * @implements \IteratorAggregate<int, File>
+ */
+class FileCollectionWithoutThrowsVoid implements \IteratorAggregate
+{
+	/** @var File[] */
+	private array $files = [];
+
+	public function getIterator(): \Iterator
+	{
+		return new \ArrayIterator($this->files);
+	}
+}
+
+function testWithoutThrowsVoid(FileCollectionWithoutThrowsVoid $files): void
+{
+	try {
+		foreach ($files as $file) {
+			echo $file->getId();
+		}
+	} catch (\Throwable) {
+		assertVariableCertainty(TrinaryLogic::createMaybe(), $file);
+		echo $file->getId(); // error - getIterator() could throw
+	}
+}
+
+/**
+ * @implements \IteratorAggregate<int, File>
+ */
+class FileCollectionExplicitThrows implements \IteratorAggregate
+{
+	/** @var File[] */
+	private array $files = [];
+
+	/** @throws \RuntimeException */
+	public function getIterator(): \Iterator
+	{
+		return new \ArrayIterator($this->files);
+	}
+}
+
+function testExplicitThrowsMatchingCatch(FileCollectionExplicitThrows $files): void
+{
+	try {
+		foreach ($files as $file) {
+			echo $file->getId();
+		}
+	} catch (\Throwable) {
+		assertVariableCertainty(TrinaryLogic::createMaybe(), $file);
+		echo $file->getId(); // error - getIterator() can throw RuntimeException
+	}
+}
+
+function testExplicitThrowsNonMatchingCatch(FileCollectionExplicitThrows $files): void
+{
+	try {
+		foreach ($files as $file) {
+			if ($file->getId() < 0) {
+				throw new \LogicException('negative');
+			}
+		}
+	} catch (\LogicException) {
+		echo $file->getId(); // no error - RuntimeException doesn't match LogicException catch
+	}
+}
+
+/** @param File[] $files */
+function testArrayForeach(array $files): void
+{
+	try {
+		foreach ($files as $file) {
+			echo $file->getId();
+		}
+	} catch (\Throwable) {
+		assertVariableCertainty(TrinaryLogic::createYes(), $file);
+		echo $file->getId(); // no error - arrays don't call getIterator()
+	}
+}
+
+function testThrowsVoidFinallyScope(FileCollection $files): void
+{
+	try {
+		foreach ($files as $file) {
+			doSomething();
+		}
+	} finally {
+		assertVariableCertainty(TrinaryLogic::createMaybe(), $file);
+	}
+}
+
+/** @param File[]|FileCollection $files */
+function testArrayOrThrowsVoid(array|FileCollection $files): void
+{
+	try {
+		foreach ($files as $file) {
+			echo $file->getId();
+		}
+	} catch (\Throwable) {
+		assertVariableCertainty(TrinaryLogic::createYes(), $file);
+		echo $file->getId(); // no error - array doesn't throw, getIterator() has @throws void
+	}
+}
+
+/** @param File[]|FileCollectionExplicitThrows $files */
+function testArrayOrExplicitThrows(array|FileCollectionExplicitThrows $files): void
+{
+	try {
+		foreach ($files as $file) {
+			echo $file->getId();
+		}
+	} catch (\Throwable) {
+		assertVariableCertainty(TrinaryLogic::createMaybe(), $file);
+		echo $file->getId(); // error - getIterator() can throw RuntimeException
+	}
+}
+
+/** @param File[]|FileCollectionWithoutThrowsVoid $files */
+function testArrayOrNoAnnotation(array|FileCollectionWithoutThrowsVoid $files): void
+{
+	try {
+		foreach ($files as $file) {
+			echo $file->getId();
+		}
+	} catch (\Throwable) {
+		assertVariableCertainty(TrinaryLogic::createMaybe(), $file);
+		echo $file->getId(); // error - getIterator() could throw
+	}
+}
+
+function doSomething(): void {}
+
+/**
+ * @implements \IteratorAggregate<int, File>
+ */
+class MaybeThrowingCollection implements \IteratorAggregate
+{
+	/** @var File[] */
+	private array $files = [];
+
+	public function add(File $file): void
+	{
+		$this->files[] = $file;
+	}
+
+	public function getIterator(): \Iterator
+	{
+		return new \ArrayIterator($this->files);
+	}
+}
+
+function testUnionThrowsMatchingCatch(FileCollectionExplicitThrows|MaybeThrowingCollection $files): void
+{
+	try {
+		foreach ($files as $file) {
+			echo $file->getId();
+		}
+	} catch (\Throwable) {
+		assertVariableCertainty(TrinaryLogic::createMaybe(), $file);
+		echo $file->getId(); // error - getIterator() can throw RuntimeException
+	}
+}

tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php

@@ -1571,4 +1571,59 @@ public function testBug10729(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.0.0')]
+	public function testBug6833(): void
+	{
+		$this->cliArgumentsVariablesRegistered = true;
+		$this->polluteScopeWithLoopInitialAssignments = true;
+		$this->checkMaybeUndefinedVariables = true;
+		$this->polluteScopeWithAlwaysIterableForeach = true;
+		$this->analyse([__DIR__ . '/../../Analyser/nsrt/bug-6833.php'], [
+			[
+				'Variable $file might not be defined.',
+				69,
+			],
+			[
+				'Variable $file might not be defined.',
+				70,
+			],
+			[
+				'Variable $file might not be defined.',
+				96,
+			],
+			[
+				'Variable $file might not be defined.',
+				97,
+			],
+			[
+				'Variable $file might not be defined.',
+				134,
+			],
+			[
+				'Variable $file might not be defined.',
+				159,
+			],
+			[
+				'Variable $file might not be defined.',
+				160,
+			],
+			[
+				'Variable $file might not be defined.',
+				172,
+			],
+			[
+				'Variable $file might not be defined.',
+				173,
+			],
+			[
+				'Variable $file might not be defined.',
+				205,
+			],
+			[
+				'Variable $file might not be defined.',
+				206,
+			],
+		]);
+	}
+
 }