[3.x] Improve PHP 8.4+ support by avoiding implicitly nullable types

This changeset improves PHP 8.4+ support by avoiding implicitly nullable types as discussed in reactphp/promise#260.

I'm planning to add native types to the public API and introduce PHPStan in follow-up PRs.

Once merged, we should apply similar changes to all our upcoming v3 components. On top of this, we should backport similar changes to the v1 branch.

Builds on top of #182, #222 and reactphp/promise#260

src/Query/TcpTransportExecutor.php

@@ -135,7 +135,7 @@ class TcpTransportExecutor implements ExecutorInterface
      * @param string         $nameserver
      * @param ?LoopInterface $loop
      */
-    public function __construct($nameserver, LoopInterface $loop = null)
+    public function __construct($nameserver, ?LoopInterface $loop = null)
     {
         if (\strpos($nameserver, '[') === false && \substr_count($nameserver, ':') >= 2 && \strpos($nameserver, '://') === false) {
             // several colons, but not enclosed in square brackets => enclose IPv6 address in square brackets

src/Query/TimeoutExecutor.php

@@ -12,7 +12,12 @@ final class TimeoutExecutor implements ExecutorInterface
     private $loop;
     private $timeout;
 
-    public function __construct(ExecutorInterface $executor, $timeout, LoopInterface $loop = null)
+    /**
+     * @param ?ExecutorInterface $executor
+     * @param float|int $timeout
+     * @param ?LoopInterface $loop
+     */
+    public function __construct(?ExecutorInterface $executor, $timeout, ?LoopInterface $loop = null)
     {
         $this->executor = $executor;
         $this->loop = $loop ?: Loop::get();

src/Query/UdpTransportExecutor.php

@@ -99,7 +99,7 @@ final class UdpTransportExecutor implements ExecutorInterface
      * @param string         $nameserver
      * @param ?LoopInterface $loop
      */
-    public function __construct($nameserver, LoopInterface $loop = null)
+    public function __construct($nameserver, ?LoopInterface $loop = null)
     {
         if (\strpos($nameserver, '[') === false && \substr_count($nameserver, ':') >= 2 && \strpos($nameserver, '://') === false) {
             // several colons, but not enclosed in square brackets => enclose IPv6 address in square brackets

src/Resolver/Factory.php

@@ -36,7 +36,7 @@ final class Factory
      * @throws \InvalidArgumentException for invalid DNS server address
      * @throws \UnderflowException when given DNS Config object has an empty list of nameservers
      */
-    public function create($config, LoopInterface $loop = null)
+    public function create($config, ?LoopInterface $loop = null)
     {
         $executor = $this->decorateHostsFileExecutor($this->createExecutor($config, $loop ?: Loop::get()));
 
@@ -59,7 +59,7 @@ public function create($config, LoopInterface $loop = null)
      * @throws \InvalidArgumentException for invalid DNS server address
      * @throws \UnderflowException when given DNS Config object has an empty list of nameservers
      */
-    public function createCached($config, LoopInterface $loop = null, CacheInterface $cache = null)
+    public function createCached($config, ?LoopInterface $loop = null, ?CacheInterface $cache = null)
     {
         // default to keeping maximum of 256 responses in cache unless explicitly given
         if (!($cache instanceof CacheInterface)) {