From 35db6d722ba96c1eb94ad1916fe5652ba2db8f2d Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Tue, 5 May 2015 21:58:23 +0000
Subject: [PATCH] In `paginate_links()`, improve handling of custom pagination
 query vars.

Custom pagination query vars, as provided in the 'base' parameter, must be
detected in the current page URL and removed before generating fresh pagination
links. The logic introduced in this changeset ensures that these custom
query vars are properly detected in cases where the 'format' param contains
a `#`.

This is a follow-up to [31203] #30831.

Fixes #31939.

git-svn-id: https://develop.svn.wordpress.org/trunk@32359 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/general-template.php          | 17 ++++++++++++----
 tests/phpunit/tests/general/paginateLinks.php | 20 +++++++++++++++++++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/wp-includes/general-template.php b/src/wp-includes/general-template.php
index f9a529f069..6ed5151a98 100644
--- a/src/wp-includes/general-template.php
+++ b/src/wp-includes/general-template.php
@@ -2659,12 +2659,21 @@ function paginate_links( $args = '' ) {
 	// Merge additional query vars found in the original URL into 'add_args' array.
 	if ( isset( $url_parts[1] ) ) {
 		// Find the format argument.
-		$format_query = parse_url( str_replace( '%_%', $args['format'], $args['base'] ), PHP_URL_QUERY );
-		wp_parse_str( $format_query, $format_arg );
+		$format = explode( '?', str_replace( '%_%', $args['format'], $args['base'] ) );
+		$format_query = isset( $format[1] ) ? $format[1] : '';
+		wp_parse_str( $format_query, $format_args );
+
+		// Find the query args of the requested URL.
+		wp_parse_str( $url_parts[1], $url_query_args );
 
 		// Remove the format argument from the array of query arguments, to avoid overwriting custom format.
-		wp_parse_str( remove_query_arg( array_keys( $format_arg ), $url_parts[1] ), $query_args );
-		$args['add_args'] = array_merge( $args['add_args'], urlencode_deep( $query_args ) );
+		foreach ( $format_args as $format_arg => $format_arg_value ) {
+			if ( isset( $url_query_args[ $format_arg ] ) ) {
+				unset( $url_query_args[ $format_arg ] );
+			}
+		}
+
+		$args['add_args'] = array_merge( $args['add_args'], urlencode_deep( $url_query_args ) );
 	}
 
 	// Who knows what else people pass in $args
diff --git a/tests/phpunit/tests/general/paginateLinks.php b/tests/phpunit/tests/general/paginateLinks.php
index b6c1a32879..ba0b77b87e 100644
--- a/tests/phpunit/tests/general/paginateLinks.php
+++ b/tests/phpunit/tests/general/paginateLinks.php
@@ -311,4 +311,24 @@ EXPECTED;
 
 		$this->assertContains( "<span class='page-numbers current'>3</span>", $links );
 	}
+
+	/**
+	 * @ticket 31939
+	 */
+	public function test_custom_base_query_arg_should_be_stripped_from_current_url_before_generating_pag_links() {
+		// Fake the current URL: example.com?foo
+		$request_uri = $_SERVER['REQUEST_URI'];
+		$_SERVER['REQUEST_URI'] = add_query_arg( 'foo', '', $request_uri );
+
+		$links = paginate_links( array(
+			'base'    => add_query_arg( 'foo', '%_%', home_url() ),
+			'format'  => '%#%',
+			'total'   => 5,
+			'current' => 1,
+			'type'    => 'array',
+		) );
+
+		$page_2_url = home_url() . '?foo=2';
+		$this->assertContains( "<a class='page-numbers' href='$page_2_url'>2</a>", $links );
+	}
 }