backport: Permissions improvements

src/structures/shared/resolvePermissions.js

@@ -0,0 +1,26 @@
+const Permissions = require('../../util/Permissions');
+const Collection = require('../../util/Collection');
+
+module.exports = function resolvePermissions(overwrites, guild) {
+  if (overwrites instanceof Collection || overwrites instanceof Array) {
+    overwrites = overwrites.map(overwrite => {
+      const role = this.client.resolver.resolveRole(guild, overwrite.id);
+      if (role) {
+        overwrite.id = role.id;
+        overwrite.type = 'role';
+      } else {
+        overwrite.id = this.client.resolver.resolveUserID(overwrite.id);
+        overwrite.type = 'member';
+      }
+
+      return {
+        allow: Permissions.resolve(overwrite.allow || overwrite.allowed || 0),
+        deny: Permissions.resolve(overwrite.deny || overwrite.denied || 0),
+        type: overwrite.type,
+        id: overwrite.id,
+      };
+    });
+  }
+
+  return overwrites;
+};