6.4.0 and current git fail to compile with latest Vala versions (0.55+)

[decathorpe]

libgdata.vapi:2038.3-2038.27: warning: Creation method of abstract class cannot be public.
 2038 | 		public Parsable.from_json (GLib.Type parsable_type, string json, int length) throws GLib.Error;
      | 		^~~~~~~~~~~~~~~~~~~~~~~~~                                                                      
libgdata.vapi:2041.3-2041.26: warning: Creation method of abstract class cannot be public.
 2041 | 		public Parsable.from_xml (GLib.Type parsable_type, string xml, int length) throws GLib.Error;
      | 		^~~~~~~~~~~~~~~~~~~~~~~~                                                                     
../src/Composer/ComposerWidget.vala:69.49-79.5: error: value is less accessible than constant `Mail.ComposerWidget.ACTION_ENTRIES'
   69 |     public const ActionEntry[] ACTION_ENTRIES = {
      |                                                 ^
   70 |         {ACTION_ADD_ATTACHMENT, on_add_attachment },
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   71 |         {ACTION_BOLD, on_edit_action, "s", "''" },
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   72 |         {ACTION_ITALIC, on_edit_action, "s", "''" },
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   73 |         {ACTION_UNDERLINE, on_edit_action, "s", "''" },
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   74 |         {ACTION_STRIKETHROUGH, on_edit_action, "s", "''" },
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   75 |         {ACTION_INSERT_LINK, on_insert_link_clicked, },
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   76 |         {ACTION_REMOVE_FORMAT, on_remove_format },
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   77 |         {ACTION_DISCARD, on_discard },
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   78 |         {ACTION_SEND, on_send }
      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   79 |     };
      | ~~~~~ 
Compilation failed: 1 error(s), 2 warning(s)

[decathorpe]

Thanks for fixing it so quickly!