Add regression bugs

Author: SplotyCode

tests/PHPStan/Analyser/nsrt/bug-12894.php

@@ -0,0 +1,46 @@
+<?php declare(strict_types = 1);
+
+namespace Bug12894;
+
+/**
+ * @template TValue of object|null
+ */
+interface Dependency {
+	/**
+	 * @return TValue
+	 */
+	public function __invoke(): object|null;
+}
+
+interface DependencyResolver {
+	/**
+	 * @template V of object|null
+	 * @template D of Dependency<V>
+	 *
+	 * @param D $dependency
+	 *
+	 * @return V
+	 */
+	public function resolve(Dependency $dependency): object|null;
+}
+
+/**
+ * @internal
+ */
+class Resolver implements DependencyResolver {
+	public function __construct(
+		/**
+		 * @var Closure(object|null): void
+		 */
+		protected readonly Closure $run,
+	) {
+		// empty
+	}
+
+	public function resolve(Dependency $dependency): object|null {
+		$resolved = $dependency();
+		$result = is_object($resolved) ? 1 : 2;
+		($this->run)($resolved);
+		return $resolved;
+	}
+}

tests/PHPStan/Analyser/nsrt/bug-12989.php

@@ -0,0 +1,17 @@
+<?php declare(strict_types = 1);
+
+namespace Bug12989;
+
+/**
+ * @template T of int|null
+ * @phpstan-param T $b
+ * @phpstan-return int|T
+ */
+function a(?int $b): ?int
+{
+	if ($b === null) {
+		return $b;
+	}
+	return $b;
+}
+