block.json: Allow passing filename as variations field

src/wp-includes/blocks.php

@@ -385,6 +385,7 @@ function get_block_metadata_i18n_schema() {
  * @since 6.3.0 Added `selectors` field.
  * @since 6.4.0 Added support for `blockHooks` field.
  * @since 6.5.0 Added support for `allowedBlocks`, `viewScriptModule`, and `viewStyle` fields.
+ * @since 6.7.0 Allow PHP filename as `variations` argument.
  *
  * @param string $file_or_folder Path to the JSON file with metadata definition for
  *                               the block or path to the folder where the `block.json` file is located.
@@ -522,6 +523,34 @@ function register_block_type_from_metadata( $file_or_folder, $args = array() ) {
 		}
 	}
 
+	// If `variations` is a string, it's the name of a PHP file that
+	// generates the variations.
+	if ( ! empty( $metadata['variations'] ) && is_string( $metadata['variations'] ) ) {
+		$variations_path = wp_normalize_path(
+			realpath(
+				dirname( $metadata['file'] ) . '/' .
+				remove_block_asset_path_prefix( $metadata['variations'] )
+			)
+		);
+		if ( $variations_path ) {
+			/**
+			 * Generates the list of block variations.
+			 *
+			 * @since 6.7.0
+			 *
+			 * @return string Returns the list of block variations.
+			 */
+			$settings['variation_callback'] = static function () use ( $variations_path ) {
+				$variations = require $variations_path;
+				return $variations;
+			};
+			// The block instance's `variations` field is only allowed to be an array
+			// (of known block variations). We unset it so that the block instance will
+			// provide a getter that returns the result of the `variation_callback` instead.
+			unset( $settings['variations'] );
+		}
+	}
+
 	$settings = array_merge( $settings, $args );
 
 	$script_fields = array(

tests/phpunit/data/blocks/notice/variations.php

@@ -0,0 +1,10 @@
+<?php
+
+return array(
+	array(
+		'name'        => 'warning',
+		'title'       => 'warning',
+		'description' => 'Shows warning.',
+		'keywords'    => array( 'warning' ),
+	),
+);

tests/phpunit/tests/blocks/register.php

@@ -957,6 +957,37 @@ public function data_register_block_registers_with_args_override_returns_false_w
 		);
 	}
 
+	/**
+	 * Tests registering a block with variations from a PHP file.
+	 *
+	 * @ticket 61280
+	 *
+	 * @covers ::register_block_type_from_metadata
+	 */
+	public function test_register_block_type_from_metadata_with_variations_php_file() {
+		$filter_metadata_registration = static function ( $metadata ) {
+			$metadata['variations'] = 'file:./variations.php';
+			return $metadata;
+		};
+
+		add_filter( 'block_type_metadata', $filter_metadata_registration, 10, 2 );
+		$result = register_block_type_from_metadata(
+			DIR_TESTDATA . '/blocks/notice'
+		);
+		remove_filter( 'block_type_metadata', $filter_metadata_registration );
+
+		$this->assertInstanceOf( 'WP_Block_Type', $result, 'The block was not registered' );
+
+		$this->assertIsCallable( $result->variation_callback, 'The variation callback hasn\'t been set' );
+		$expected_variations = require DIR_TESTDATA . '/blocks/notice/variations.php';
+		$this->assertSame(
+			$expected_variations,
+			call_user_func( $result->variation_callback ),
+			'The variation callback hasn\'t been set correctly'
+		);
+		$this->assertSame( $expected_variations, $result->variations, 'The block variations are incorrect' );
+	}
+
 	/**
 	 * Tests that the function returns the registered block when the `block.json`
 	 * is found in the fixtures directory.