Query: Ignore search terms consisting of a single dash.

Due to the "exclude" support added in WP 4.4, single dashes were being
converted to "NOT LIKE '%%'" clauses, causing all searches to fail.

Props RomSocial, swissspidy.
Fixes #36195.

git-svn-id: https://develop.svn.wordpress.org/trunk@36989 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/query.php

@@ -2194,8 +2194,8 @@ class WP_Query {
 			else
 				$term = trim( $term, "\"' " );
 
-			// Avoid single A-Z.
+			// Avoid single A-Z and single dashes.
-			if ( ! $term || ( 1 === strlen( $term ) && preg_match( '/^[a-z]$/i', $term ) ) )
+			if ( ! $term || ( 1 === strlen( $term ) && preg_match( '/^[a-z\-]$/i', $term ) ) )
 				continue;
 
 			if ( in_array( call_user_func( $strtolower, $term ), $stopwords, true ) )

tests/phpunit/tests/query/search.php

@@ -126,6 +126,31 @@ class Tests_Query_Search extends WP_UnitTestCase {
 		$this->assertEqualSets( array( $p3 ), $q->posts );
 	}
 
+	/**
+	 * @ticket 36195
+	 */
+	public function test_s_should_not_exclude_for_dashes_between_words() {
+		$p1 = self::factory()->post->create( array(
+			'post_status' => 'publish',
+			'post_content' => 'This post has foo but also bar',
+		) );
+		$p2 = self::factory()->post->create( array(
+			'post_status' => 'publish',
+			'post_content' => 'This post has only bar',
+		) );
+		$p3 = self::factory()->post->create( array(
+			'post_status' => 'publish',
+			'post_content' => 'This post has only foo - bar',
+		) );
+
+		$q = new WP_Query( array(
+			's' => 'foo - bar',
+			'fields' => 'ids',
+		) );
+
+		$this->assertEqualSets( array( $p1, $p3 ), $q->posts );
+	}
+
 	/**
 	 * @ticket 35361
 	 */