Remove extraneous table join in get_adjacent_post().

Since [29248], a table join has not been necessary to process the
`$excluded_terms` parameter of `get_adjacent_post()`. Aside from adding extra
overhead, this join meant that post records that don't have any corresponding
rows in `wp_term_relationships` were erroneously excluded from results.

Fixes #32833.

git-svn-id: https://develop.svn.wordpress.org/trunk@34088 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/link-template.php

@@ -1492,9 +1492,6 @@ function get_adjacent_post( $in_same_term = false, $excluded_terms = '', $previo
 	$where = '';
 
 	if ( $in_same_term || ! empty( $excluded_terms ) ) {
-		$join = " INNER JOIN $wpdb->term_relationships AS tr ON p.ID = tr.object_id INNER JOIN $wpdb->term_taxonomy tt ON tr.term_taxonomy_id = tt.term_taxonomy_id";
-		$where = $wpdb->prepare( "AND tt.taxonomy = %s", $taxonomy );
-
 		if ( ! empty( $excluded_terms ) && ! is_array( $excluded_terms ) ) {
 			// back-compat, $excluded_terms used to be $excluded_terms with IDs separated by " and "
 			if ( false !== strpos( $excluded_terms, ' and ' ) ) {
@@ -1508,6 +1505,9 @@ function get_adjacent_post( $in_same_term = false, $excluded_terms = '', $previo
 		}
 
 		if ( $in_same_term ) {
+			$join .= " INNER JOIN $wpdb->term_relationships AS tr ON p.ID = tr.object_id INNER JOIN $wpdb->term_taxonomy tt ON tr.term_taxonomy_id = tt.term_taxonomy_id";
+			$where .= $wpdb->prepare( "AND tt.taxonomy = %s", $taxonomy );
+
 			if ( ! is_object_in_taxonomy( $post->post_type, $taxonomy ) )
 				return '';
 			$term_array = wp_get_object_terms( $post->ID, $taxonomy, array( 'fields' => 'ids' ) );

tests/phpunit/tests/link.php

@@ -257,6 +257,73 @@ class Tests_Link extends WP_UnitTestCase {
 		$this->assertEmpty( get_adjacent_post( false, array(), false ) );
 	}
 
+	/**
+	 * @ticket 32833
+	 */
+	public function test_get_adjacent_post_excluded_terms() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$t = $this->factory->term->create( array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		$p1 = $this->factory->post->create( array( 'post_date' => '2015-08-27 12:00:00' ) );
+		$p2 = $this->factory->post->create( array( 'post_date' => '2015-08-26 12:00:00' ) );
+		$p3 = $this->factory->post->create( array( 'post_date' => '2015-08-25 12:00:00' ) );
+
+		wp_set_post_terms( $p2, array( $t ), 'wptests_tax' );
+
+		// Fake current page.
+		$_post = isset( $GLOBALS['post'] ) ? $GLOBALS['post'] : null;
+		$GLOBALS['post'] = get_post( $p1 );
+
+		$found = get_adjacent_post( false, array( $t ), true, 'wptests_tax' );
+
+		if ( ! is_null( $_post ) ) {
+			$GLOBALS['post'] = $_post;
+		} else {
+			unset( $GLOBALS['post'] );
+		}
+
+		// Should skip $p2, which belongs to $t.
+		$this->assertEquals( $p3, $found->ID );
+	}
+
+	/**
+	 * @ticket 32833
+	 */
+	public function test_get_adjacent_post_excluded_terms_should_not_require_posts_to_have_terms_in_any_taxonomy() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$t = $this->factory->term->create( array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		$p1 = $this->factory->post->create( array( 'post_date' => '2015-08-27 12:00:00' ) );
+		$p2 = $this->factory->post->create( array( 'post_date' => '2015-08-26 12:00:00' ) );
+		$p3 = $this->factory->post->create( array( 'post_date' => '2015-08-25 12:00:00' ) );
+
+		wp_set_post_terms( $p2, array( $t ), 'wptests_tax' );
+
+		// Make sure that $p3 doesn't have the 'Uncategorized' category.
+		wp_delete_object_term_relationships( $p3, 'category' );
+
+		// Fake current page.
+		$_post = isset( $GLOBALS['post'] ) ? $GLOBALS['post'] : null;
+		$GLOBALS['post'] = get_post( $p1 );
+
+		$found = get_adjacent_post( false, array( $t ), true, 'wptests_tax' );
+
+		if ( ! is_null( $_post ) ) {
+			$GLOBALS['post'] = $_post;
+		} else {
+			unset( $GLOBALS['post'] );
+		}
+
+		// Should skip $p2, which belongs to $t.
+		$this->assertEquals( $p3, $found->ID );
+	}
+
 	public function test_wp_make_link_relative_with_http_scheme() {
 		$link = 'http://example.com/this-is-a-test-http-url/';
 		$relative_link = wp_make_link_relative( $link );