Propagate "unexpandable" PHIDs to feed notification recipient expansion

Summary:
See PHI466. Ref T13108. Somewhat recently, new rules were added so that "Resigning" from a revision takes you off the default recipient list, even if you're still a member of a project or package that is still a reviewer or subscriber.

However, these rules don't currently apply to the similar expansion which occurs in notifications. If you resign from a revision you may still get some notifications (just not email) if a package or project you're a member of is a reviewer or subscriber.

(Possibly these should eventually share more code, but just get things working for now.)

Test Plan:
  - Created a revision as A.
  - Added B as a reviewer.
  - Added a package B is an owner for as a reviewer.
  - As B, resigned. (Make sure B is also not an explicit subscriber.)
  - Commented on the revision as A.
    - Before: B is included in the expanded notification recipient list.
    - After: B is no longer included in the expanded notification recipient list.

Maniphest Tasks: T13108

Differential Revision: https://secure.phabricator.com/D19244

src/applications/feed/PhabricatorFeedStoryPublisher.php

@@ -12,6 +12,7 @@ final class PhabricatorFeedStoryPublisher extends Phobject {
   private $mailRecipientPHIDs = array();
   private $notifyAuthor;
   private $mailTags = array();
+  private $unexpandablePHIDs = array();
 
   public function setMailTags(array $mail_tags) {
     $this->mailTags = $mail_tags;
@@ -46,6 +47,15 @@ final class PhabricatorFeedStoryPublisher extends Phobject {
     return $this;
   }
 
+  public function setUnexpandablePHIDs(array $unexpandable_phids) {
+    $this->unexpandablePHIDs = $unexpandable_phids;
+    return $this;
+  }
+
+  public function getUnexpandablePHIDs() {
+    return $this->unexpandablePHIDs;
+  }
+
   public function setStoryType($story_type) {
     $this->storyType = $story_type;
     return $this;
@@ -254,10 +264,36 @@ final class PhabricatorFeedStoryPublisher extends Phobject {
   }
 
   private function expandRecipients(array $phids) {
-    return id(new PhabricatorMetaMTAMemberQuery())
+    $expanded_phids = id(new PhabricatorMetaMTAMemberQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withPHIDs($phids)
       ->executeExpansion();
+
+    // Filter out unexpandable PHIDs from the results. The typical case for
+    // this is that resigned reviewers should not be notified just because
+    // they are a member of some project or package reviewer.
+
+    $original_map = array_fuse($phids);
+    $unexpandable_map = array_fuse($this->unexpandablePHIDs);
+
+    foreach ($expanded_phids as $key => $phid) {
+      // We can keep this expanded PHID if it was present originally.
+      if (isset($original_map[$phid])) {
+        continue;
+      }
+
+      // We can also keep it if it isn't marked as unexpandable.
+      if (!isset($unexpandable_map[$phid])) {
+        continue;
+      }
+
+      // If it's unexpandable and we produced it by expanding recipients,
+      // throw it away.
+      unset($expanded_phids[$key]);
+    }
+    $expanded_phids = array_values($expanded_phids);
+
+    return $expanded_phids;
   }
 
   /**

src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php

@@ -3199,6 +3199,11 @@ abstract class PhabricatorApplicationTransactionEditor
     $story_type = $this->getFeedStoryType();
     $story_data = $this->getFeedStoryData($object, $xactions);
 
+    $unexpandable_phids = $this->mailUnexpandablePHIDs;
+    if (!is_array($unexpandable_phids)) {
+      $unexpandable_phids = array();
+    }
+
     id(new PhabricatorFeedStoryPublisher())
       ->setStoryType($story_type)
       ->setStoryData($story_data)
@@ -3207,6 +3212,7 @@ abstract class PhabricatorApplicationTransactionEditor
       ->setRelatedPHIDs($related_phids)
       ->setPrimaryObjectPHID($object->getPHID())
       ->setSubscribedPHIDs($subscribed_phids)
+      ->setUnexpandablePHIDs($unexpandable_phids)
       ->setMailRecipientPHIDs($mailed_phids)
       ->setMailTags($this->getMailTags($object, $xactions))
       ->publish();