string cast might throw exception

Author: canvural

src/Analyser/NodeScopeResolver.php

@@ -3736,6 +3736,12 @@ function (MutatingScope $scope) use ($stmt, $expr, $nodeCallback, $context, $sto
 			$exprType = $scope->getType($expr->expr);
 			$toStringMethod = $scope->getMethodReflection($exprType, '__toString');
 			if ($toStringMethod !== null) {
+				if ($toStringMethod->getThrowType() !== null) {
+					$throwPoints[] = InternalThrowPoint::createExplicit($scope, $toStringMethod->getThrowType(), $expr, false);
+				} else {
+					$throwPoints[] = InternalThrowPoint::createImplicit($scope, $expr);
+				}
+
 				if (!$toStringMethod->hasSideEffects()->no()) {
 					$impurePoints[] = new ImpurePoint(
 						$scope,

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleTest.php

@@ -643,4 +643,9 @@ public function testPropertyHooks(): void
 		]);
 	}
 
+	public function testBug13806(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-13806.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Exceptions/data/bug-13806.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Bug13806;
+
+function doFoo(MyString $myVariable): void
+{
+	try {
+		(string) $myVariable;
+	} catch (\InvalidArgumentException) {
+		// Reported as dead catch, even though the `__toString()` method
+		// in `$myVariable` might throw an exception.
+	}
+}
+
+class MyString {
+	/** @throws \InvalidArgumentException */
+	public function __toString() {
+		throw new \InvalidArgumentException();
+	}
+}