From 23a53beb7e6c9a4948637203c908aecf10663501 Mon Sep 17 00:00:00 2001
From: Scott Taylor <scott.c.taylor@mac.com>
Date: Wed, 4 Jun 2014 17:50:15 +0000
Subject: [PATCH] After [28613], also kill queries that explicityly pass empty
 arrays to `category__in`, `tag__in`, `tag_slug__in`, and `author__in` to
 `WP_Query`.

Adds unit tests.
Fixes #28099.

Built from https://develop.svn.wordpress.org/trunk@28664


git-svn-id: http://core.svn.wordpress.org/trunk@28482 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/query.php | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/wp-includes/query.php b/wp-includes/query.php
index d523bcc351..d060b7e3b6 100644
--- a/wp-includes/query.php
+++ b/wp-includes/query.php
@@ -1830,6 +1830,8 @@ class WP_Query {
 				'field' => 'term_id',
 				'include_children' => false
 			);
+		} elseif ( isset( $this->query['category__in'] ) ) {
+			$q['category__in'] = false;
 		}
 
 		if ( ! empty($q['category__not_in']) ) {
@@ -1887,6 +1889,8 @@ class WP_Query {
 				'taxonomy' => 'post_tag',
 				'terms' => $q['tag__in']
 			);
+		} elseif ( isset( $this->query['tag__in'] ) ) {
+			$q['tag__in'] = false;
 		}
 
 		if ( !empty($q['tag__not_in']) ) {
@@ -1914,6 +1918,8 @@ class WP_Query {
 				'terms' => $q['tag_slug__in'],
 				'field' => 'slug'
 			);
+		} elseif ( isset( $this->query['tag_slug__in'] ) ) {
+			$q['tag_slug__in'] = false;
 		}
 
 		if ( !empty($q['tag_slug__and']) ) {
@@ -2500,6 +2506,13 @@ class WP_Query {
 			$where .= $clauses['where'];
 		}
 
+		// If *__in is passed to WP_Query as an empty array, don't return results
+		foreach ( array( 'category', 'tag', 'tag_slug' ) as $in ) {
+			if ( isset( $q["{$in}__in"] ) && false === $q["{$in}__in"] ) {
+				$where = " AND 1=0 $where";
+			}
+		}
+
 		if ( $this->is_tax ) {
 			if ( empty($post_type) ) {
 				// Do a fully inclusive search for currently registered post types of queried taxonomies
@@ -2591,6 +2604,9 @@ class WP_Query {
 		} elseif ( ! empty( $q['author__in'] ) ) {
 			$author__in = implode( ',', array_map( 'absint', array_unique( (array) $q['author__in'] ) ) );
 			$where .= " AND {$wpdb->posts}.post_author IN ($author__in) ";
+		} elseif ( isset( $this->query['author__in'] ) ) {
+			$author__in = 0;
+			$where .= ' AND 1=0 ';
 		}
 
 		// Author stuff for nice URLs