query_posts() problem with multiple tags since 3.1 update

[joshstauffer]

When I upgraded to 3.1 this query stopped working.

Does NOT return any results in 3.1:

query_posts( 'cat=8&tag=featured+hotels-and-motels' );

Returns expected results in 3.1:

$args = array (
	'cat' => 8,
	'tag_slug__and' => 'featured+hotels-and-motels',
);
query_posts( $args );

​Another user with similar experience.

3.1.1 for investigation.

Caused by [17272], which added back the old processing, but didn't skip the new, global, processing.

Also, since [17489], the terms are doubled.

I don't know if we can do it at this point, but having all taxonomies support '+' and ',' might be nice.

Re doubling:

The trouble is that after each call to parse_query(), 'tag_slug__and' and 'tag_slug__in' are populated again, without being reset.

Two ways of going about this:

• Reset them using $wp_query->query. This is the easiest way, but is a potential source of future bugs.

• Don't manipulate them at all; parse 'cat' and 'tag' directly into tax_query.

Actually, the first approach will cause bugs: say, if someone were to set 'category__and' on 'pre_get_posts', so nevermind that.

As per IRC convo confirming that the issue I reference here and in ​Support Forum is a related issue with failure of 'category__and' since 3.1 update.

array_unique() for tag_slug_*. Untested.

Can we not do array_unique() on those like we do everywhere else?

I guess that will have to do.

So, for 'category', include_children is false. That's expected, since 'cat' is lame.

But, for 'post_tag', include_children is set to true. That shouldn't be.

Nevermind that last comment; include_children is ignored unless the taxonomy is hierarchical.

I resolved my issue by changing the query to use an Advanced Taxonomy Query. Details are on the ​support forum.

(In [17500]) Don't double process the tag query var. Props scribu. fixes #16730 for trunk

(In [17501]) Don't double process the tag query var. Props scribu. fixes #16730 for 3.1

Could we also get 16730.diff​ in?