From dd811c3f5c836a098ba5c6f2025d1bfe7727785d Mon Sep 17 00:00:00 2001
From: phpstan-bot <79867460+phpstan-bot@users.noreply.github.com>
Date: Tue, 31 Mar 2026 15:17:53 +0000
Subject: [PATCH] Fix sealed class-string match exhaustiveness for generic
 sealed hierarchies

- GenericObjectType::changeSubtractedType() now delegates to parent's sealed
  type logic, returning NeverType when all allowed subtypes are subtracted
- This fixes match expressions on $foo::class reporting "unhandled values"
  for generic @phpstan-sealed class hierarchies
- New regression test in tests/PHPStan/Rules/Comparison/data/bug-14412.php

Closes https://github.com/phpstan/phpstan/issues/14412
---
 phpstan-baseline.neon                         |  2 +-
 src/Type/Generic/GenericObjectType.php        |  8 +++
 .../Comparison/MatchExpressionRuleTest.php    |  6 ++
 .../Rules/Comparison/data/bug-14412.php       | 57 +++++++++++++++++++
 4 files changed, 72 insertions(+), 1 deletion(-)
 create mode 100644 tests/PHPStan/Rules/Comparison/data/bug-14412.php

diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index e925137b245..67dabae8fea 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -1134,7 +1134,7 @@ parameters:
 		-
 			rawMessage: 'Doing instanceof PHPStan\Type\ObjectType is error-prone and deprecated. Use Type::isObject() or Type::getObjectClassNames() instead.'
 			identifier: phpstanApi.instanceofType
-			count: 1
+			count: 2
 			path: src/Type/Generic/GenericObjectType.php
 
 		-
diff --git a/src/Type/Generic/GenericObjectType.php b/src/Type/Generic/GenericObjectType.php
index 10b516355d0..63a10119e8a 100644
--- a/src/Type/Generic/GenericObjectType.php
+++ b/src/Type/Generic/GenericObjectType.php
@@ -405,6 +405,14 @@ protected function recreate(string $className, array $types, ?Type $subtractedTy
 
 	public function changeSubtractedType(?Type $subtractedType): Type
 	{
+		$result = parent::changeSubtractedType($subtractedType);
+
+		// Parent handles sealed type exhaustiveness (returning NeverType when all
+		// allowed subtypes are subtracted, or a single remaining subtype).
+		if (!$result instanceof ObjectType || $result->getClassName() !== $this->getClassName()) {
+			return $result;
+		}
+
 		return new self($this->getClassName(), $this->types, $subtractedType, null, $this->variances);
 	}
 
diff --git a/tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php b/tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php
index 85b8364a323..1f7880fc2a9 100644
--- a/tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/MatchExpressionRuleTest.php
@@ -453,6 +453,12 @@ public function testBug12241(): void
 		$this->analyse([__DIR__ . '/data/bug-12241.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.0')]
+	public function testBug14412(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14412.php'], []);
+	}
+
 	#[RequiresPhp('>= 8.0')]
 	public function testBug13029(): void
 	{
diff --git a/tests/PHPStan/Rules/Comparison/data/bug-14412.php b/tests/PHPStan/Rules/Comparison/data/bug-14412.php
new file mode 100644
index 00000000000..35266e75cec
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/bug-14412.php
@@ -0,0 +1,57 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug14412;
+
+/**
+ * @template-covariant T
+ * @phpstan-sealed BarCov|BazCov
+ */
+abstract class FooCov {}
+
+/**
+ * @template-covariant T
+ * @extends FooCov<T>
+ */
+final class BarCov extends FooCov {}
+
+/**
+ * @template-covariant T
+ * @extends FooCov<T>
+ */
+final class BazCov extends FooCov {}
+
+/** @param FooCov<string> $foo */
+function testTemplateCovariant(FooCov $foo): string {
+	return match ($foo::class) {
+		BarCov::class => 'bar',
+		BazCov::class => 'baz',
+	};
+}
+
+/**
+ * @template T
+ * @phpstan-sealed BarInv|BazInv
+ */
+abstract class FooInv {}
+
+/**
+ * @template T
+ * @extends FooInv<T>
+ */
+final class BarInv extends FooInv {}
+
+/**
+ * @template T
+ * @extends FooInv<T>
+ */
+final class BazInv extends FooInv {}
+
+/** @param FooInv<covariant string> $foo */
+function testCovariantParam(FooInv $foo): string {
+	return match ($foo::class) {
+		BarInv::class => 'bar',
+		BazInv::class => 'baz',
+	};
+}