From 1721af83d153f77ee989fc5ae04b112b5d738f07 Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Sat, 1 Jul 2017 11:45:09 +0000
Subject: [PATCH] Taxonomy: Ignore cached term value when it doesn't match the
 queried taxonomy.

When a cache entry is found that matches the requested `$term_id`, but
doesn't match an explicitly provided `$taxonomy`, that cache entry
should be ignored.

Props GunGeekATX.
Fixes #40671.

git-svn-id: https://develop.svn.wordpress.org/trunk@40979 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/class-wp-term.php   |  3 +++
 tests/phpunit/tests/term/wpTerm.php | 15 +++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/wp-includes/class-wp-term.php b/src/wp-includes/class-wp-term.php
index acd0124172..76d74e060c 100644
--- a/src/wp-includes/class-wp-term.php
+++ b/src/wp-includes/class-wp-term.php
@@ -136,6 +136,9 @@ final class WP_Term {
 
 		// If there isn't a cached version, hit the database.
 		if ( ! $_term || ( $taxonomy && $taxonomy !== $_term->taxonomy ) ) {
+			// Any term found in the cache is not a match, so don't use it.
+			$_term = false;
+
 			// Grab all matching terms, in case any are shared between taxonomies.
 			$terms = $wpdb->get_results( $wpdb->prepare( "SELECT t.*, tt.* FROM $wpdb->terms AS t INNER JOIN $wpdb->term_taxonomy AS tt ON t.term_id = tt.term_id WHERE t.term_id = %d", $term_id ) );
 			if ( ! $terms ) {
diff --git a/tests/phpunit/tests/term/wpTerm.php b/tests/phpunit/tests/term/wpTerm.php
index 9154633f1e..5ccbc8beb2 100644
--- a/tests/phpunit/tests/term/wpTerm.php
+++ b/tests/phpunit/tests/term/wpTerm.php
@@ -68,4 +68,19 @@ class Tests_Term_WpTerm extends WP_UnitTestCase {
 
 		$this->assertSame( 1, $found->term_id );
 	}
+
+	/**
+	 * @ticket 40671
+	 */
+	public function test_get_instance_should_respect_taxonomy_when_term_id_is_found_in_cache() {
+		global $wpdb;
+
+		register_taxonomy( 'wptests_tax2', 'post' );
+
+		// Ensure that cache is primed.
+		WP_Term::get_instance( self::$term_id, 'wptests_tax' );
+
+		$found = WP_Term::get_instance( self::$term_id, 'wptests_tax2' );
+		$this->assertFalse( $found );
+	}
 }