Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `app/javascript/mastodon/features/compose/components/compose_form.js`:
  Conflict caused because of minor code style change upstream, while glitch-soc
  has different code for handling variable maximum chars.
  Ported the change.
- `app/serializers/initial_state_serializer.rb`:
  Conflict because glitch-soc had two extra attributes where upstream added
  one.
  Added upstream's attribute.

app/serializers/initial_state_serializer.rb

@@ -3,7 +3,8 @@
 class InitialStateSerializer < ActiveModel::Serializer
   attributes :meta, :compose, :accounts,
              :media_attachments, :settings,
-             :max_toot_chars, :poll_limits
+             :max_toot_chars, :poll_limits,
+             :languages
 
   has_one :push_subscription, serializer: REST::WebPushSubscriptionSerializer
 
@@ -76,6 +77,7 @@ class InitialStateSerializer < ActiveModel::Serializer
       store[:me]                = object.current_account.id.to_s
       store[:default_privacy]   = object.visibility || object.current_account.user.setting_default_privacy
       store[:default_sensitive] = object.current_account.user.setting_default_sensitive
+      store[:default_language]  = object.current_account.user.preferred_posting_language
     end
 
     store[:text] = object.text if object.text
@@ -94,6 +96,10 @@ class InitialStateSerializer < ActiveModel::Serializer
     { accept_content_types: MediaAttachment.supported_file_extensions + MediaAttachment.supported_mime_types }
   end
 
+  def languages
+    LanguagesHelper::SUPPORTED_LOCALES.map { |(key, value)| [key, value[0], value[1]] }
+  end
+
   private
 
   def instance_presenter

app/serializers/rest/preferences_serializer.rb

@@ -17,7 +17,7 @@ class REST::PreferencesSerializer < ActiveModel::Serializer
   end
 
   def posting_default_language
-    object.user.setting_default_language.presence
+    object.user.preferred_posting_language
   end
 
   def reading_default_sensitive_media