Cleanup

lib/Database.php

@@ -932,7 +932,7 @@ class Database {
     }
 
     /** Returns the time at which any of a user's subscriptions (or a specific subscription) was last refreshed, as a DateTimeImmutable object */
-    public function subscriptionRefreshed(string $user, int $id = null): ?\DateTimeInterface {
+    public function subscriptionRefreshed(string $user, int $id = null): ?\DateTimeImmutable {
         if (!Arsse::$user->authorize($user, __FUNCTION__)) {
             throw new User\ExceptionAuthz("notAuthorized", ["action" => __FUNCTION__, "user" => $user]);
         }

lib/Feed.php

@@ -390,7 +390,7 @@ class Feed {
         return $offset;
     }
 
-    protected function computeLastModified(): ?\DateTimeInterface {
+    protected function computeLastModified(): ?\DateTimeImmutable {
         if (!$this->modified) {
             return $this->lastModified; // @codeCoverageIgnore
         }

lib/Misc/Date.php

@@ -21,19 +21,19 @@ class Date {
         return $out;
     }
 
-    public static function normalize($date, string $inFormat = null): ?\DateTimeInterface {
+    public static function normalize($date, string $inFormat = null): ?\DateTimeImmutable {
         return ValueInfo::normalize($date, ValueInfo::T_DATE, $inFormat);
     }
 
-    public static function add($interval, $date = "now"): ?\DateTimeInterface {
+    public static function add($interval, $date = "now"): ?\DateTimeImmutable {
         return self::modify("add", $interval, $date);
     }
 
-    public static function sub($interval, $date = "now"): ?\DateTimeInterface {
+    public static function sub($interval, $date = "now"): ?\DateTimeImmutable {
         return self::modify("sub", $interval, $date);
     }
 
-    protected static function modify(string $func, $interval, $date): ?\DateTimeInterface {
+    protected static function modify(string $func, $interval, $date): ?\DateTimeImmutable {
         $date = self::normalize($date);
         $interval = (!$interval instanceof \DateInterval) ? ValueInfo::normalize($interval, ValueInfo::T_INTERVAL) : $interval;
         return $date ? $date->$func($interval) : null;