Treat protected(set) properties as invariant for template variance

protected(set) allows subclasses to write to the property, just like
regular protected properties. Only private(set) truly restricts writes
to the declaring class, so only private(set) should be treated as
covariant.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Rules/Generics/PropertyVarianceRule.php

@@ -58,7 +58,7 @@ public function processNode(Node $node, Scope $scope): array
 
 	private function hasRestrictedWriteAccess(ClassPropertyNode $node): bool
 	{
-		if ($node->isPrivateSet() || $node->isProtectedSet()) {
+		if ($node->isPrivateSet()) {
 			return true;
 		}
 

tests/PHPStan/Rules/Generics/PropertyVarianceRuleTest.php

@@ -162,9 +162,17 @@ public function testBug12964(): void
 				74,
 			],
 			[
-				'Template type X is declared as covariant, but occurs in contravariant position in property Bug12964\E::$b.',
+				'Template type X is declared as covariant, but occurs in invariant position in property Bug12964\E::$a.',
+				82,
+			],
+			[
+				'Template type X is declared as covariant, but occurs in invariant position in property Bug12964\E::$b.',
 				85,
 			],
+			[
+				'Template type X is declared as covariant, but occurs in invariant position in property Bug12964\E::$c.',
+				88,
+			],
 			[
 				'Template type X is declared as covariant, but occurs in invariant position in property Bug12964\E::$d.',
 				91,