Multiselect box on registration page does not show error if required

[dcrabill]

In bp-xprofile-template.php on line 385, the string '[]' gets added to the field name for the multiselect box. I'm not sure why it's necessary to indicate it's an array, but it breaks the error message functionality.

If the multiselect box is required but the user does not complete it, then the error is correctly placed in $bp->signup->errors, but under the field name only (without the '[]' appended). The error never shows on the page, but the user is still prevented from signing up.

[boonebgorges]

It does seem odd that we need the []. The original ticket is here: ​http://buddypress.trac.wordpress.org/ticket/2173

I'm going to need to research it more to determine the best course of action. Moving to 1.8 in the meantime.

[boonebgorges]

In 7122:

Introduces bp_get_the_profile_field_errors_action()

This convenience function concatenates an action name for use in rendering the
errors associated with a given xprofile field during registration.

Previously, the action name was concatenated inline, using the _field_name_
value. This caused problems in the case of multiselect fields, which have a
field name appended with '[]' for other reasons. See #2173

Fixes #4978