Fix CatchWithUnthrownExceptionRule for new $expr()

src/Analyser/NodeScopeResolver.php

@@ -2384,10 +2384,22 @@ static function () use ($expr, $rightResult): MutatingScope {
 			$hasYield = false;
 			$throwPoints = [];
 			if ($expr->class instanceof Expr) {
+				$objectClasses = TypeUtils::getDirectClassNames($scope->getType($expr));
+				if (count($objectClasses) === 1) {
+					$objectExprResult = $this->processExprNode(new New_(new Name($objectClasses[0])), $scope, static function (): void {
+					}, $context->enterDeep());
+					$additionalThrowPoints = $objectExprResult->getThrowPoints();
+				} else {
+					$additionalThrowPoints = [ThrowPoint::createImplicit($scope)];
+				}
+
 				$result = $this->processExprNode($expr->class, $scope, $nodeCallback, $context->enterDeep());
 				$scope = $result->getScope();
 				$hasYield = $result->hasYield();
 				$throwPoints = $result->getThrowPoints();
+				foreach ($additionalThrowPoints as $throwPoint) {
+					$throwPoints[] = $throwPoint;
+				}
 			} elseif ($expr->class instanceof Class_) {
 				$this->reflectionProvider->getAnonymousClassReflection($expr->class, $scope); // populates $expr->class->name
 				$this->processStmtNode($expr->class, $scope, $nodeCallback);

tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleTest.php

@@ -54,4 +54,18 @@ public function testRule(): void
 		]);
 	}
 
+	public function testBug4806(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-4806.php'], [
+			[
+				'Dead catch - ArgumentCountError is never thrown in the try block.',
+				65,
+			],
+			[
+				'Dead catch - Throwable is never thrown in the try block.',
+				119,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Exceptions/data/bug-4806.php

@@ -0,0 +1,124 @@
+<?php
+
+namespace Bug4806;
+
+class NeverThrows
+{
+	/**
+	 * @throws void
+	 */
+	final public function __construct()
+	{
+	}
+}
+
+class HasNoConstructor
+{
+
+}
+
+class MayThrowArgumentCountError
+{
+	/**
+	 * @throws \ArgumentCountError
+	 */
+	public function __construct()
+	{
+		throw new \ArgumentCountError();
+	}
+}
+
+class ImplicitThrow
+{
+
+	public function __construct()
+	{
+
+	}
+
+}
+
+class Foo
+{
+
+	/**
+	 * @param class-string $class
+	 */
+	function createNotSpecified(string $class): object
+	{
+		try {
+			$object = new $class();
+		} catch (\ArgumentCountError $error) {
+
+		}
+
+		return $object;
+	}
+
+	/**
+	 * @param class-string<NeverThrows> $class
+	 */
+	function createNeverThrows(string $class): object
+	{
+		try {
+			$object = new $class();
+		} catch (\ArgumentCountError $throwable) {
+
+		}
+
+		return $object;
+	}
+
+	/**
+	 * @param class-string<MayThrowArgumentCountError> $class
+	 */
+	function createMayThrowArgumentCountError(string $class): object
+	{
+		try {
+			$object = new $class();
+		} catch (\ArgumentCountError $error) {
+
+		}
+
+		return $object;
+	}
+
+	/**
+	 * @param class-string<MayThrowArgumentCountError> $class
+	 */
+	function createMayThrowArgumentCountErrorB(string $class): object
+	{
+		try {
+			$object = new $class();
+		} catch (\Throwable $throwable) {
+
+		}
+
+		return $object;
+	}
+
+	/**
+	 * @param class-string<ImplicitThrow> $class
+	 */
+	function implicitThrow(string $class): void
+	{
+		try {
+			$object = new $class();
+		} catch (\Throwable $throwable) {
+
+		}
+	}
+
+	/**
+	 * @param class-string<HasNoConstructor> $class
+	 */
+	function hasNoConstructor(string $class): void
+	{
+		try {
+			$object = new $class();
+		} catch (\Throwable $throwable) {
+
+		}
+	}
+
+}