Menus: Add current_page_parent for CPT archive on singular views

Author: pi-20

src/wp-includes/nav-menu-template.php

@@ -394,6 +394,13 @@ function _wp_menu_item_classes_by_context( &$menu_items ) {
 	$front_page_id          = (int) get_option( 'page_on_front' );
 	$privacy_policy_page_id = (int) get_option( 'wp_page_for_privacy_policy' );
 
+	$public_custom_post_types = get_post_types(
+		array(
+			'public'   => true,
+			'_builtin' => false,
+		)
+	);
+
 	foreach ( (array) $menu_items as $key => $menu_item ) {
 
 		$menu_items[ $key ]->current = false;
@@ -526,6 +533,15 @@ function _wp_menu_item_classes_by_context( &$menu_items ) {
 			}
 		}
 
+		// If a public custom post type single is being viewed, the archive menu item is a logical parent (#38836).
+		if ( is_singular( $public_custom_post_types ) ) {
+			$post_type = get_post_type();
+
+			if ( $post_type === $menu_item->object && 'post_type_archive' === $menu_item->type ) {
+				$classes[] = 'current_page_parent';
+			}
+		}
+
 		// Back-compat with wp_page_menu(): add "current_page_parent" to static home page link for any non-page query.
 		if ( ! empty( $home_page_id ) && 'post_type' === $menu_item->type
 			&& empty( $wp_query->is_page ) && $home_page_id === (int) $menu_item->object_id

tests/phpunit/tests/post/nav-menu.php

@@ -1392,4 +1392,103 @@ public function test_wp_update_nav_menu_item_with_post_date() {
 		$post = get_post( $menu_item_id );
 		$this->assertEqualsWithDelta( strtotime( gmdate( 'Y-m-d H:i:s' ) ), strtotime( $post->post_date ), 2, 'The dates should be equal' );
 	}
+
+	/**
+	 * Post type archive menu items should receive current_page_parent on public CPT single views.
+	 *
+	 * @ticket 38836
+	 */
+	public function test_post_type_archive_menu_item_gets_current_page_parent_on_public_cpt_single() {
+		$page_id = self::factory()->post->create(
+			array(
+				'post_type'  => 'page',
+				'post_title' => 'Test Page',
+			)
+		);
+
+		register_post_type(
+			'cpt38836',
+			array(
+				'public'      => true,
+				'has_archive' => true,
+			)
+		);
+
+		$cpt_id = self::factory()->post->create(
+			array(
+				'post_type'   => 'cpt38836',
+				'post_name'   => 'cpt-name',
+				'post_status' => 'publish',
+			)
+		);
+
+		wp_update_nav_menu_item(
+			$this->menu_id,
+			0,
+			array(
+				'menu-item-type'      => 'post_type_archive',
+				'menu-item-object'    => 'cpt38836',
+				'menu-item-status'    => 'publish',
+			)
+		);
+
+		wp_update_nav_menu_item(
+			$this->menu_id,
+			0,
+			array(
+				'menu-item-type'      => 'post_type',
+				'menu-item-object'    => 'page',
+				'menu-item-object-id' => $page_id,
+				'menu-item-status'    => 'publish',
+			)
+		);
+
+		$this->go_to( get_permalink( $cpt_id ) );
+
+		$menu_items = wp_get_nav_menu_items( $this->menu_id );
+		_wp_menu_item_classes_by_context( $menu_items );
+
+		$this->assertContains( 'current_page_parent', $menu_items[0]->classes, 'Archive item should be marked parent on CPT single.' );
+		$this->assertNotContains( 'current_page_parent', $menu_items[1]->classes, 'Unrelated page item should not get the class.' );
+	}
+
+	/**
+	 * Non-public CPT singles should not add current_page_parent to the archive menu item.
+	 *
+	 * @ticket 38836
+	 */
+	public function test_post_type_archive_menu_item_is_not_current_page_parent_for_non_public_cpt_single() {
+		register_post_type(
+			'cpt38836b',
+			array(
+				'has_archive' => true,
+			)
+		);
+
+		$cpt_id = self::factory()->post->create(
+			array(
+				'post_type'   => 'cpt38836b',
+				'post_name'   => 'cpt-name',
+				'post_status' => 'publish',
+			)
+		);
+
+		wp_update_nav_menu_item(
+			$this->menu_id,
+			0,
+			array(
+				'menu-item-type'      => 'post_type_archive',
+				'menu-item-object'    => 'cpt38836b',
+				'menu-item-status'    => 'publish',
+			)
+		);
+
+		$this->go_to( get_permalink( $cpt_id ) );
+
+		$menu_items = wp_get_nav_menu_items( $this->menu_id );
+		_wp_menu_item_classes_by_context( $menu_items );
+
+		$cpt_archive_classes = $menu_items[0]->classes;
+		$this->assertNotContains( 'current_page_parent', $cpt_archive_classes );
+	}
 }