Register block style early.

src/wp-admin/includes/upgrade.php

@@ -654,6 +654,8 @@ function wp_upgrade() {
 			update_site_meta( get_current_blog_id(), 'db_last_updated', microtime() );
 		}
 
+		delete_transient( 'wp_core_block_css_files' );
+
 		/**
 		 * Fires after a site is fully upgraded.
 		 *

src/wp-includes/blocks.php

@@ -186,6 +186,20 @@ function register_block_style_handle( $metadata, $field_name, $index = 0 ) {
 		return false;
 	}
 
+	$style_handle = $metadata[ $field_name ];
+	if ( is_array( $style_handle ) ) {
+		if ( empty( $style_handle[ $index ] ) ) {
+			return false;
+		}
+		$style_handle = $style_handle[ $index ];
+	}
+
+	$style_handle_name = generate_block_asset_handle( $metadata['name'], $field_name, $index );
+	// If the style handle is already registered, skip re-registering.
+	if ( wp_style_is( $style_handle_name, 'registered' ) ) {
+		return $style_handle_name;
+	}
+
 	static $wpinc_path_norm = '';
 	if ( ! $wpinc_path_norm ) {
 		$wpinc_path_norm = wp_normalize_path( realpath( ABSPATH . WPINC ) );
@@ -197,14 +211,6 @@ function register_block_style_handle( $metadata, $field_name, $index = 0 ) {
 		return false;
 	}
 
-	$style_handle = $metadata[ $field_name ];
-	if ( is_array( $style_handle ) ) {
-		if ( empty( $style_handle[ $index ] ) ) {
-			return false;
-		}
-		$style_handle = $style_handle[ $index ];
-	}
-
 	$style_path      = remove_block_asset_path_prefix( $style_handle );
 	$is_style_handle = $style_handle === $style_path;
 	// Allow only passing style handles for core blocks.
@@ -246,10 +252,9 @@ function register_block_style_handle( $metadata, $field_name, $index = 0 ) {
 		$style_uri = false;
 	}
 
-	$style_handle = generate_block_asset_handle( $metadata['name'], $field_name, $index );
-	$version      = ! $is_core_block && isset( $metadata['version'] ) ? $metadata['version'] : false;
-	$result       = wp_register_style(
-		$style_handle,
+	$version = ! $is_core_block && isset( $metadata['version'] ) ? $metadata['version'] : false;
+	$result  = wp_register_style(
+		$style_handle_name,
 		$style_uri,
 		array(),
 		$version
@@ -259,7 +264,7 @@ function register_block_style_handle( $metadata, $field_name, $index = 0 ) {
 	}
 
 	if ( $has_style_file ) {
-		wp_style_add_data( $style_handle, 'path', $style_path_norm );
+		wp_style_add_data( $style_handle_name, 'path', $style_path_norm );
 
 		if ( $is_core_block ) {
 			$rtl_file = str_replace( "{$suffix}.css", "-rtl{$suffix}.css", $style_path_norm );
@@ -268,13 +273,13 @@ function register_block_style_handle( $metadata, $field_name, $index = 0 ) {
 		}
 
 		if ( is_rtl() && file_exists( $rtl_file ) ) {
-			wp_style_add_data( $style_handle, 'rtl', 'replace' );
-			wp_style_add_data( $style_handle, 'suffix', $suffix );
-			wp_style_add_data( $style_handle, 'path', $rtl_file );
+			wp_style_add_data( $style_handle_name, 'rtl', 'replace' );
+			wp_style_add_data( $style_handle_name, 'suffix', $suffix );
+			wp_style_add_data( $style_handle_name, 'path', $rtl_file );
 		}
 	}
 
-	return $style_handle;
+	return $style_handle_name;
 }
 
 /**
@@ -320,7 +325,7 @@ function register_block_type_from_metadata( $file_or_folder, $args = array() ) {
 	 */
 	static $core_blocks_meta;
 	if ( ! $core_blocks_meta ) {
-		$core_blocks_meta = require_once ABSPATH . WPINC . '/blocks/blocks-json.php';
+		$core_blocks_meta = require ABSPATH . WPINC . '/blocks/blocks-json.php';
 	}
 
 	$metadata_file = ( ! str_ends_with( $file_or_folder, 'block.json' ) ) ?

src/wp-includes/blocks/index.php

@@ -12,6 +12,92 @@
 require BLOCKS_PATH . 'widget-group.php';
 require BLOCKS_PATH . 'require-dynamic-blocks.php';
 
+/**
+ * Registers core block style handles.
+ *
+ * While {@see register_block_style_handle()} is typically used for that, the way it is
+ * implemented is inefficient for core block styles. Registering those style handles here
+ * avoids unnecessary logic and filesystem lookups in the other function.
+ *
+ * @since 6.3.0
+ */
+function register_core_block_style_handles() {
+	if ( ! wp_should_load_separate_core_block_assets() ) {
+		return;
+	}
+
+	static $core_blocks_meta;
+	if ( ! $core_blocks_meta ) {
+		$core_blocks_meta = require ABSPATH . WPINC . '/blocks/blocks-json.php';
+	}
+
+	$includes_url  = includes_url();
+	$includes_path = ABSPATH . WPINC . '/';
+	$suffix        = wp_scripts_get_suffix();
+	$wp_styles     = wp_styles();
+	$style_fields  = array(
+		'style'       => 'style',
+		'editorStyle' => 'editor',
+	);
+
+	/*
+	 * Ignore transient cache when the development mode is set to 'core'. Why? To avoid interfering with
+	 * the core developer's workflow.
+	 */
+	if ( 'core' !== wp_get_development_mode() ) {
+		$transient_name = 'wp_core_block_css_files';
+		$files          = get_transient( $transient_name );
+		if ( ! $files ) {
+			$files = glob( __DIR__ . '/**/**.css' );
+			set_transient( $transient_name, $files );
+		}
+	} else {
+		$files = glob( __DIR__ . '/**/**.css' );
+	}
+
+	foreach ( $core_blocks_meta as $name => $schema ) {
+		/** This filter is documented in wp-includes/blocks.php */
+		$schema = apply_filters( 'block_type_metadata', $schema );
+
+		// Backfill these properties similar to `register_block_type_from_metadata()`.
+		if ( ! isset( $schema['style'] ) ) {
+			$schema['style'] = "wp-block-{$name}";
+		}
+		if ( ! isset( $schema['editorStyle'] ) ) {
+			$schema['editorStyle'] = "wp-block-{$name}-editor";
+		}
+
+		foreach ( $style_fields as $style_field => $filename ) {
+			$style_handle = $schema[ $style_field ];
+			if ( is_array( $style_handle ) ) {
+				continue;
+			}
+
+			$style_path = "blocks/{$name}/{$filename}{$suffix}.css";
+			$path       = $includes_path . $style_path;
+
+			if ( ! in_array( $path, $files, true ) ) {
+				$wp_styles->add(
+					$style_handle,
+					false
+				);
+				continue;
+			}
+
+			$wp_styles->add( $style_handle, $includes_url . $style_path );
+			$wp_styles->add_data( $style_handle, 'path', $path );
+
+			$rtl_file = str_replace( "{$suffix}.css", "-rtl{$suffix}.css", $path );
+			if ( is_rtl() && in_array( $rtl_file, $files, true ) ) {
+				$wp_styles->add_data( $style_handle, 'rtl', 'replace' );
+				$wp_styles->add_data( $style_handle, 'suffix', $suffix );
+				$wp_styles->add_data( $style_handle, 'path', $rtl_file );
+			}
+		}
+	}
+}
+add_action( 'init', 'register_core_block_style_handles', 9 );
+
 /**
  * Registers core block types using metadata files.
  * Dynamic core blocks are registered separately.

tests/phpunit/tests/blocks/register.php

@@ -397,6 +397,7 @@ public function data_register_block_style_handle_uses_correct_core_stylesheet()
 	 */
 	public function test_handle_passed_register_block_style_handle() {
 		$metadata = array(
+			'name'  => 'test-block',
 			'style' => 'test-style-handle',
 		);
 		$result   = register_block_style_handle( $metadata, 'style' );
@@ -406,6 +407,7 @@ public function test_handle_passed_register_block_style_handle() {
 
 	public function test_handles_passed_register_block_style_handles() {
 		$metadata = array(
+			'name'  => 'test-block',
 			'style' => array( 'test-style-handle', 'test-style-handle-2' ),
 		);
 
@@ -523,6 +525,26 @@ public function test_success_register_block_style_handle_in_theme() {
 		$this->assertFalse( wp_styles()->get_data( $expected_style_handle, 'rtl' ) );
 	}
 
+	/**
+	 * @ticket 58528
+	 *
+	 * @covers ::register_block_style_handle
+	 */
+	public function test_success_register_block_style_handle_exists() {
+		$expected_style_handle = 'block-theme-example-block-editor-style';
+		wp_register_style( $expected_style_handle, false );
+		switch_theme( 'block-theme' );
+
+		$metadata = array(
+			'file'        => wp_normalize_path( get_theme_file_path( 'blocks/example-block/block.json' ) ),
+			'name'        => 'block-theme/example-block',
+			'editorStyle' => 'file:./editor-style.css',
+		);
+		$result   = register_block_style_handle( $metadata, 'editorStyle' );
+
+		$this->assertSame( $expected_style_handle, $result );
+	}
+
 	/**
 	 * Tests that the function returns false when the `block.json` is not found
 	 * in the WordPress core.

tests/phpunit/tests/blocks/registerCoreBlockStyleHandles.php

@@ -0,0 +1,124 @@
+<?php
+
+/**
+ * Tests for block style handles.
+ *
+ * @package WordPress
+ * @subpackage Blocks
+ *
+ * @since 6.3.0
+ *
+ * @group blocks
+ *
+ * @covers ::register_core_block_style_handles
+ */
+class Tests_Blocks_registerCoreBlockStyleHandles extends WP_UnitTestCase {
+
+	/**
+	 * @var WP_Styles
+	 */
+	private $old_wp_styles;
+
+	/**
+	 * @var string
+	 */
+	private $includes_url;
+
+	const STYLE_FIELDS = array(
+		'style'       => 'style',
+		'editorStyle' => 'editor',
+	);
+
+	public function set_up() {
+		parent::set_up();
+
+		$this->old_wp_styles = $GLOBALS['wp_styles'];
+
+		$this->includes_url = includes_url();
+
+		remove_action( 'wp_default_styles', 'wp_default_styles' );
+
+		if ( empty( $GLOBALS['wp_styles'] ) ) {
+			$GLOBALS['wp_styles'] = null;
+		}
+	}
+
+	public function tear_down() {
+		$GLOBALS['wp_styles'] = $this->old_wp_styles;
+
+		add_action( 'wp_default_styles', 'wp_default_styles' );
+
+		parent::tear_down();
+	}
+
+	/**
+	 * @ticket 58528
+	 *
+	 * @dataProvider data_block_data
+	 */
+	public function test_wp_should_load_separate_core_block_assets_false( $name, $schema ) {
+		register_core_block_style_handles();
+
+		foreach ( self::STYLE_FIELDS as $style_field => $filename ) {
+			$style_handle = $schema[ $style_field ];
+			if ( is_array( $style_handle ) ) {
+				continue;
+			}
+
+			$this->assertArrayNotHasKey( $style_handle, $GLOBALS['wp_styles']->registered, 'The key should not exist, as this style should not be registered' );
+		}
+	}
+
+
+	/**
+	 * @ticket 58528
+	 *
+	 * @dataProvider data_block_data
+	 */
+	public function test_wp_should_load_separate_core_block_assets_true( $name, $schema ) {
+		add_filter( 'should_load_separate_core_block_assets', '__return_true' );
+		register_core_block_style_handles();
+
+		$wp_styles = $GLOBALS['wp_styles'];
+
+		foreach ( self::STYLE_FIELDS as $style_field => $filename ) {
+			$style_handle = $schema[ $style_field ];
+			if ( is_array( $style_handle ) ) {
+				continue;
+			}
+
+			$this->assertArrayHasKey( $style_handle, $wp_styles->registered, 'The key should exist, as this style should be registered' );
+			if ( false === $wp_styles->registered[ $style_handle ]->src ) {
+				$this->assertEmpty( $wp_styles->registered[ $style_handle ]->extra, 'If source is false, not style path should be set' );
+			} else {
+				$this->assertStringContainsString( $this->includes_url, $wp_styles->registered[ $style_handle ]->src, 'Source of style should contain the includes url' );
+				$this->assertNotEmpty( $wp_styles->registered[ $style_handle ]->extra, 'The path of the style should exist' );
+				$this->assertArrayHasKey( 'path', $wp_styles->registered[ $style_handle ]->extra, 'The path key of the style should exist in extra array' );
+				$this->assertNotEmpty( $wp_styles->registered[ $style_handle ]->extra['path'], 'The path key of the style should not be empty' );
+			}
+		}
+	}
+
+
+	public function data_block_data() {
+		$core_blocks_meta = require ABSPATH . WPINC . '/blocks/blocks-json.php';
+
+		// Remove this blocks for now, as they are registered elsewhere.
+		unset( $core_blocks_meta['archives'] );
+		unset( $core_blocks_meta['widget-group'] );
+
+		$data = array();
+		foreach ( $core_blocks_meta as $name => $schema ) {
+			if ( ! isset( $schema['style'] ) ) {
+				$schema['style'] = "wp-block-$name";
+			}
+			if ( ! isset( $schema['editorStyle'] ) ) {
+				$schema['editorStyle'] = "wp-block-{$name}-editor";
+			}
+
+			$data[ $name ] = array( $name, $schema );
+		}
+
+		return $data;
+	}
+}