Enabling constructor check for class-string variables

src/Rules/Classes/InstantiationRule.php

@@ -17,10 +17,13 @@
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\ShouldNotHappenException;
 use PHPStan\Type\Constant\ConstantStringType;
+use PHPStan\Type\VerbosityLevel;
+use function array_filter;
 use function array_map;
 use function array_merge;
 use function count;
 use function sprintf;
+use function str_starts_with;
 use function strtolower;
 
 /**
@@ -245,6 +248,18 @@ private function getClassNames(Node $node, Scope $scope): array
 
 		$type = $scope->getType($node->class);
 
+		if (str_starts_with($type->describe(VerbosityLevel::precise()), 'class-string')) {
+			$classStringObjectType = $type->getClassStringObjectType();
+
+			return array_map(
+				static fn (string $name): array => [$name, true],
+				array_filter($classStringObjectType->getObjectClassNames(), function (string $name): bool {
+					$reflectionClass = $this->reflectionProvider->getClass($name);
+					return !$reflectionClass->isAbstract() && !$reflectionClass->isInterface();
+				}),
+			);
+		}
+
 		return array_merge(
 			array_map(
 				static fn (ConstantStringType $type): array => [$type->getValue(), true],

tests/PHPStan/Rules/Classes/InstantiationRuleTest.php

@@ -504,4 +504,46 @@ public function testBug11815(): void
 		$this->analyse([__DIR__ . '/data/bug-11815.php'], []);
 	}
 
+	public function testClassString(): void
+	{
+		$this->analyse([__DIR__ . '/data/class-string.php'], [
+			[
+				'Parameter #1 $i of class ClassString\A constructor expects int, string given.',
+				65,
+			],
+			[
+				'Parameter #1 $i of class ClassString\A constructor expects int, string given.',
+				66,
+			],
+			[
+				'Parameter #1 $i of class ClassString\A constructor expects int, string given.',
+				67,
+			],
+			[
+				'Parameter #1 $i of class ClassString\C constructor expects int, string given.',
+				75,
+			],
+			[
+				'Parameter #1 $i of class ClassString\C constructor expects int, string given.',
+				76,
+			],
+			[
+				'Parameter #1 $i of class ClassString\C constructor expects int, string given.',
+				77,
+			],
+			[
+				'Parameter #1 $i of class ClassString\A constructor expects int, string given.',
+				85,
+			],
+			[
+				'Parameter #1 $i of class ClassString\A constructor expects int, string given.',
+				86,
+			],
+			[
+				'Parameter #1 $i of class ClassString\A constructor expects int, string given.',
+				87,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Classes/data/class-string.php

@@ -0,0 +1,87 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace ClassString;
+
+class A
+{
+    public function __construct(public int $i)
+    {
+    }
+}
+
+abstract class B
+{
+    public function __construct(public int $i)
+    {
+    }
+}
+
+class C extends B
+{
+}
+
+interface D
+{
+}
+
+class Foo
+{
+    /**
+     * @return class-string<A>
+     */
+    public static function returnClassStringA(): string
+    {
+        return A::class;
+    }
+
+    /**
+     * @return class-string<B>
+     */
+    public static function returnClassStringB(): string
+    {
+        return B::class;
+    }
+
+    /**
+     * @return class-string<C>
+     */
+    public static function returnClassStringC(): string
+    {
+        return C::class;
+    }
+
+    /**
+     * @return class-string<D>
+     */
+    public static function returnClassStringD(): string
+    {
+        return D::class;
+    }
+}
+
+$classString = Foo::returnClassStringA();
+$error = new (Foo::returnClassStringA())('O_O');
+$error = new ($classString)('O_O');
+$error = new $classString('O_O');
+
+$classString = Foo::returnClassStringB();
+$ok = new (Foo::returnClassStringB())('O_O');
+$ok = new ($classString)('O_O');
+$ok = new $classString('O_O');
+
+$classString = Foo::returnClassStringC();
+$error = new (Foo::returnClassStringC())('O_O');
+$error = new ($classString)('O_O');
+$error = new $classString('O_O');
+
+$classString = Foo::returnClassStringD();
+$ok = new (Foo::returnClassStringD())('O_O');
+$ok = new ($classString)('O_O');
+$ok = new $classString('O_O');
+
+$className = A::class;
+$error = new ($className)('O_O');
+$error = new $className('O_O');
+$error = new A('O_O');