Editor: Handle nested array block gap values properly.

Guard against non-scalar (nested array) `blockGap` values in
`wp_sanitize_block_gap_value()` before passing them to `preg_match()`,
which requires a string subject. A malformed axial gap value such as
`blockGap.top` being `array( '1rem' )` previously triggered an uncaught
`TypeError`, breaking front-end rendering and REST API responses.

Includes a direct unit test for `wp_sanitize_block_gap_value()` and a
data provider case in `Tests_Block_Supports_Layout` covering rendering
with a malformed axial block gap.

Developed in WordPress#12604.

Ports WordPress/gutenberg#80464 to Core.

Props tyxla, ramonopoly.
Fixes #65667.

git-svn-id: https://develop.svn.wordpress.org/trunk@62801 602fd350-edb4-49c9-b593-d223f7449a82

Author: tyxla

src/wp-includes/block-supports/layout.php

@@ -86,7 +86,7 @@ function wp_get_layout_container_values( $layout ) {
 function wp_sanitize_block_gap_value( $gap_value ) {
 	if ( is_array( $gap_value ) ) {
 		foreach ( $gap_value as $key => $value ) {
-			$gap_value[ $key ] = $value && preg_match( '%[\\\(&=}]|/\*%', $value ) ? null : $value;
+			$gap_value[ $key ] = ! is_scalar( $value ) || ( $value && preg_match( '%[\\\(&=}]|/\*%', (string) $value ) ) ? null : $value;
 		}
 
 		return $gap_value;

tests/phpunit/tests/block-supports/layout.php

@@ -82,6 +82,26 @@ public function filter_set_theme_root() {
 		return $this->theme_root;
 	}
 
+	/**
+	 * @ticket 65667
+	 *
+	 * @covers ::wp_sanitize_block_gap_value
+	 */
+	public function test_sanitize_block_gap_value_rejects_nested_array_values() {
+		$this->assertSame(
+			array(
+				'top'  => null,
+				'left' => '2rem',
+			),
+			wp_sanitize_block_gap_value(
+				array(
+					'top'  => array( '1rem' ),
+					'left' => '2rem',
+				)
+			)
+		);
+	}
+
 	/**
 	 * @ticket 55505
 	 */
@@ -235,6 +255,32 @@ public function data_layout_support_flag_renders_classnames_on_wrapper() {
 				),
 				'expected_output' => '<div class="wp-block-group is-layout-flow wp-block-group-is-layout-flow"></div>',
 			),
+			'single wrapper block layout with malformed axial block gap' => array(
+				'args'            => array(
+					'block_content' => '<div class="wp-block-group"></div>',
+					'block'         => array(
+						'blockName'    => 'core/group',
+						'attrs'        => array(
+							'layout' => array(
+								'type' => 'default',
+							),
+							'style'  => array(
+								'spacing' => array(
+									'blockGap' => array(
+										'top' => array( '1rem' ),
+									),
+								),
+							),
+						),
+						'innerBlocks'  => array(),
+						'innerHTML'    => '<div class="wp-block-group"></div>',
+						'innerContent' => array(
+							'<div class="wp-block-group"></div>',
+						),
+					),
+				),
+				'expected_output' => '<div class="wp-block-group is-layout-flow wp-block-group-is-layout-flow"></div>',
+			),
 			'single wrapper block layout with constrained type' => array(
 				'args'            => array(
 					'block_content' => '<div class="wp-block-group"></div>',