Don't show un-completeable results in people/project autocomplete

Summary:
Fixes T10285.

  - If a result (like a milestone) has no primary hashtag, try to fill in a secondary hashtag.
  - If we can't find any hashtag, don't return the result.

This produces these behaviors:

  - By default, you can't autocomplete milestones.
  - If you give one a hashtag, you can.

We might want to give milestones "special" hashtags eventually (like `#xyz/33`) but this fixes the confusing/broken behavior in the UI and we can wait for a better use case for letting you autocomplete milestones, I think.

Also, don't try to cycle hashtags when renaming milestones. This was a little inconsistent before.

Test Plan:
  - Autocompleted normal projects.
  - Autocompleted milestones with explicit hashtags.
  - No autocomplete entry for milestones with no special hashtags.
  - Used normal typeahead to get tag-less milestones to make sure I didn't break anything.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10285

Differential Revision: https://secure.phabricator.com/D15261

src/applications/project/editor/PhabricatorProjectTransactionEditor.php

@@ -169,11 +169,12 @@ final class PhabricatorProjectTransactionEditor
       case PhabricatorProjectTransaction::TYPE_NAME:
         // First, add the old name as a secondary slug; this is helpful
         // for renames and generally a good thing to do.
-        if ($old !== null) {
-          $this->addSlug($object, $old, false);
+        if (!$this->getIsMilestone()) {
+          if ($old !== null) {
+            $this->addSlug($object, $old, false);
+          }
+          $this->addSlug($object, $new, false);
         }
-        $this->addSlug($object, $new, false);
-
         return;
       case PhabricatorProjectTransaction::TYPE_SLUGS:
         $old = $xaction->getOldValue();

src/applications/project/typeahead/PhabricatorProjectDatasource.php

@@ -38,6 +38,8 @@ final class PhabricatorProjectDatasource
       $query->withIsMilestone(false);
     }
 
+    $for_autocomplete = $this->getParameter('autocomplete');
+
     $projs = $this->executeQuery($query);
 
     $projs = mpull($projs, null, 'getPHID');
@@ -58,6 +60,23 @@ final class PhabricatorProjectDatasource
       if (!isset($has_cols[$proj->getPHID()])) {
         continue;
       }
+
+      $slug = $proj->getPrimarySlug();
+      if (!strlen($slug)) {
+        foreach ($proj->getSlugs() as $slug_object) {
+          $slug = $slug_object->getSlug();
+          if (strlen($slug)) {
+            break;
+          }
+        }
+      }
+
+      // If we're building results for the autocompleter and this project
+      // doesn't have any usable slugs, don't return it as a result.
+      if ($for_autocomplete && !strlen($slug)) {
+        continue;
+      }
+
       $closed = null;
       if ($proj->isArchived()) {
         $closed = pht('Archived');
@@ -78,7 +97,6 @@ final class PhabricatorProjectDatasource
         ->setPriorityType('proj')
         ->setClosed($closed);
 
-      $slug = $proj->getPrimarySlug();
       if (strlen($slug)) {
         $proj_result->setAutocomplete('#'.$slug);
       }

src/view/form/control/PhabricatorRemarkupControl.php

@@ -45,7 +45,11 @@ final class PhabricatorRemarkupControl extends AphrontFormTextAreaControl {
     $root_id = celerity_generate_unique_node_id();
 
     $user_datasource = new PhabricatorPeopleDatasource();
-    $proj_datasource = new PhabricatorProjectDatasource();
+    $proj_datasource = id(new PhabricatorProjectDatasource())
+      ->setParameters(
+        array(
+          'autocomplete' => 1,
+        ));
 
     Javelin::initBehavior(
       'phabricator-remarkup-assist',