Fix phpstan/phpstan#12964: Support for covariant templates in interface properties in 8.4

src/Rules/Generics/PropertyVarianceRule.php

@@ -45,7 +45,7 @@ public function processNode(Node $node, Scope $scope): array
 			return [];
 		}
 
-		$variance = $node->isReadOnly() || $node->isReadOnlyByPhpDoc()
+		$variance = $node->isReadOnly() || $node->isReadOnlyByPhpDoc() || $this->isEffectivelyReadOnly($node)
 			? TemplateTypeVariance::createCovariant()
 			: TemplateTypeVariance::createInvariant();
 
@@ -56,4 +56,24 @@ public function processNode(Node $node, Scope $scope): array
 		);
 	}
 
+	private function isEffectivelyReadOnly(ClassPropertyNode $node): bool
+	{
+		if ($node->isPrivateSet() || $node->isProtectedSet()) {
+			return true;
+		}
+
+		$hooks = $node->getHooks();
+		if ($hooks === []) {
+			return false;
+		}
+
+		foreach ($hooks as $hook) {
+			if ($hook->name->name === 'set') {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
 }

tests/PHPStan/Rules/Generics/PropertyVarianceRuleTest.php

@@ -137,4 +137,63 @@ public function testBug13049(): void
 		$this->analyse([__DIR__ . '/data/bug-13049.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.4')]
+	public function testBug12964(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-12964.php'], [
+			[
+				'Template type X is declared as covariant, but occurs in contravariant position in property Bug12964\C::$b.',
+				51,
+			],
+			[
+				'Template type X is declared as covariant, but occurs in invariant position in property Bug12964\C::$d.',
+				57,
+			],
+			[
+				'Template type X is declared as contravariant, but occurs in covariant position in property Bug12964\D::$a.',
+				65,
+			],
+			[
+				'Template type X is declared as contravariant, but occurs in covariant position in property Bug12964\D::$c.',
+				71,
+			],
+			[
+				'Template type X is declared as contravariant, but occurs in invariant position in property Bug12964\D::$d.',
+				74,
+			],
+			[
+				'Template type X is declared as covariant, but occurs in contravariant position in property Bug12964\E::$b.',
+				85,
+			],
+			[
+				'Template type X is declared as covariant, but occurs in invariant position in property Bug12964\E::$d.',
+				91,
+			],
+			[
+				'Template type X is declared as covariant, but occurs in contravariant position in property Bug12964\F::$b.',
+				103,
+			],
+			[
+				'Template type X is declared as covariant, but occurs in invariant position in property Bug12964\F::$d.',
+				109,
+			],
+			[
+				'Template type X is declared as contravariant, but occurs in covariant position in property Bug12964\G::$a.',
+				118,
+			],
+			[
+				'Template type X is declared as contravariant, but occurs in covariant position in property Bug12964\G::$c.',
+				124,
+			],
+			[
+				'Template type X is declared as contravariant, but occurs in invariant position in property Bug12964\G::$d.',
+				127,
+			],
+			[
+				'Template type X is declared as covariant, but occurs in invariant position in property Bug12964\H::$a.',
+				136,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Generics/data/bug-12964.php

@@ -0,0 +1,137 @@
+<?php // lint >= 8.4
+
+declare(strict_types = 1);
+
+namespace Bug12964;
+
+/** @template-contravariant T */
+interface In {
+}
+
+/** @template-covariant T */
+interface Out {
+}
+
+/** @template T */
+interface Invariant {
+}
+
+/**
+ * @template-covariant T
+ */
+interface A
+{
+	/**
+	 * @var T
+	 */
+	public mixed $b { get; }
+}
+
+/**
+ * @template-covariant T
+ */
+final class B
+{
+	/**
+	 * @param T $data
+	 */
+	public function __construct(
+		public private(set) mixed $data,
+	) {}
+}
+
+/**
+ * @template-covariant X
+ */
+class C {
+	/** @var X */
+	public private(set) mixed $a;
+
+	/** @var In<X> */
+	public private(set) mixed $b;
+
+	/** @var Out<X> */
+	public private(set) mixed $c;
+
+	/** @var Invariant<X> */
+	public private(set) mixed $d;
+}
+
+/**
+ * @template-contravariant X
+ */
+class D {
+	/** @var X */
+	public private(set) mixed $a;
+
+	/** @var In<X> */
+	public private(set) mixed $b;
+
+	/** @var Out<X> */
+	public private(set) mixed $c;
+
+	/** @var Invariant<X> */
+	public private(set) mixed $d;
+}
+
+/**
+ * @template-covariant X
+ */
+class E {
+	/** @var X */
+	public protected(set) mixed $a;
+
+	/** @var In<X> */
+	public protected(set) mixed $b;
+
+	/** @var Out<X> */
+	public protected(set) mixed $c;
+
+	/** @var Invariant<X> */
+	public protected(set) mixed $d;
+}
+
+/**
+ * @template-covariant X
+ */
+interface F
+{
+	/** @var X */
+	public mixed $a { get; }
+
+	/** @var In<X> */
+	public mixed $b { get; }
+
+	/** @var Out<X> */
+	public mixed $c { get; }
+
+	/** @var Invariant<X> */
+	public mixed $d { get; }
+}
+
+/**
+ * @template-contravariant X
+ */
+interface G
+{
+	/** @var X */
+	public mixed $a { get; }
+
+	/** @var In<X> */
+	public mixed $b { get; }
+
+	/** @var Out<X> */
+	public mixed $c { get; }
+
+	/** @var Invariant<X> */
+	public mixed $d { get; }
+}
+
+/**
+ * @template-covariant X
+ */
+interface H
+{
+	/** @var X */
+	public mixed $a { get; set; }
+}