feat: add css.hasGlobal to compile output

.changeset/plenty-hotels-mix.md

@@ -0,0 +1,5 @@
+---
+'svelte': minor
+---
+
+feat: add `hasUnscopedGlobalCss` to `compile` metadata

packages/svelte/src/compiler/phases/2-analyze/css/css-analyze.js

@@ -7,11 +7,13 @@ import { is_keyframes_node } from '../../css.js';
 import { is_global, is_unscoped_pseudo_class } from './utils.js';
 
 /**
+ * We need to use an object for `has_global_unscoped` since state is spread
  * @typedef {Visitors<
  *   AST.CSS.Node,
  *   {
  *     keyframes: string[];
  *     rule: AST.CSS.Rule | null;
+ *     has_unscoped_global: { value: boolean };
  *   }
  * >} CssVisitors
  */
@@ -28,6 +30,30 @@ function is_global_block_selector(simple_selector) {
 	);
 }
 
+/**
+ * @param {import('../types.js').Context["path"]} path
+ * @param {AST.CSS.Rule | null} [rule]
+ * @returns
+ */
+function is_unscoped_global(path, rule) {
+	// remove every at rule or stylesheet and the current rule in case is passed in from `ComplexSelector`
+	const parents = path.filter(
+		(parent) => parent.type !== 'Atrule' && parent.type !== 'StyleSheet' && parent !== rule
+	);
+
+	let unscoped_global = true;
+
+	// no parents means we are on top
+	if (parents.length > 0) {
+		// let's check that everything in the path is not a global block
+		unscoped_global = parents.every((parent) => {
+			return parent.type !== 'Rule' || parent.metadata.is_global_block;
+		});
+	}
+
+	return unscoped_global;
+}
+
 /**
  *
  * @param {Array<AST.CSS.Node>} path
@@ -42,6 +68,9 @@ const css_visitors = {
 		if (is_keyframes_node(node)) {
 			if (!node.prelude.startsWith('-global-') && !is_in_global_block(context.path)) {
 				context.state.keyframes.push(node.prelude);
+			} else if (node.prelude.startsWith('-global-')) {
+				// we don't check if the block.children.length because the keyframe is still added even if empty
+				context.state.has_unscoped_global.value ||= is_unscoped_global(context.path);
 			}
 		}
 
@@ -64,6 +93,13 @@ const css_visitors = {
 						}
 					}
 				}
+
+				if (idx === 0) {
+					context.state.has_unscoped_global.value ||=
+						!!context.state.rule &&
+						context.state.rule.block.children.length > 0 &&
+						is_unscoped_global(context.path, context.state.rule);
+				}
 			}
 		}
 
@@ -174,7 +210,8 @@ const css_visitors = {
 		node.metadata.is_global_block = node.prelude.children.some((selector) => {
 			let is_global_block = false;
 
-			for (const child of selector.children) {
+			for (let i = 0; i < selector.children.length; i++) {
+				const child = selector.children[i];
 				const idx = child.selectors.findIndex(is_global_block_selector);
 
 				if (is_global_block) {
@@ -184,6 +221,12 @@ const css_visitors = {
 
 				if (idx !== -1) {
 					is_global_block = true;
+
+					if (i === 0) {
+						context.state.has_unscoped_global.value ||=
+							node.block.children.length > 0 && is_unscoped_global(context.path);
+					}
+
 					for (let i = idx + 1; i < child.selectors.length; i++) {
 						walk(/** @type {AST.CSS.Node} */ (child.selectors[i]), null, {
 							ComplexSelector(node) {
@@ -283,5 +326,12 @@ const css_visitors = {
  * @param {ComponentAnalysis} analysis
  */
 export function analyze_css(stylesheet, analysis) {
-	walk(stylesheet, { keyframes: analysis.css.keyframes, rule: null }, css_visitors);
+	const css_state = {
+		keyframes: analysis.css.keyframes,
+		rule: null,
+		// we need to use an object since state is spread
+		has_unscoped_global: { value: false }
+	};
+	walk(stylesheet, css_state, css_visitors);
+	analysis.css.has_unscoped_global = css_state.has_unscoped_global.value;
 }

packages/svelte/src/compiler/phases/2-analyze/index.js

@@ -455,7 +455,8 @@ export function analyze_component(root, source, options) {
 						hash
 					})
 				: '',
-			keyframes: []
+			keyframes: [],
+			has_unscoped_global: false
 		},
 		source,
 		undefined_exports: new Map(),

packages/svelte/src/compiler/phases/3-transform/css/index.js

@@ -59,7 +59,8 @@ export function render_stylesheet(source, analysis, options) {
 			// generateMap takes care of calculating source relative to file
 			source: options.filename,
 			file: options.cssOutputFilename || options.filename
-		})
+		}),
+		hasGlobal: analysis.css.has_unscoped_global
 	};
 
 	merge_with_preprocessor_map(css, options, css.map.sources[0]);

packages/svelte/src/compiler/phases/types.d.ts

@@ -73,6 +73,7 @@ export interface ComponentAnalysis extends Analysis {
 		ast: AST.CSS.StyleSheet | null;
 		hash: string;
 		keyframes: string[];
+		has_unscoped_global: boolean;
 	};
 	source: string;
 	undefined_exports: Map<string, Node>;

packages/svelte/src/compiler/types/index.d.ts

@@ -18,6 +18,8 @@ export interface CompileResult {
 		code: string;
 		/** A source map */
 		map: SourceMap;
+		/** Whether or not the CSS includes global rules */
+		hasGlobal: boolean;
 	};
 	/**
 	 * An array of warning objects that were generated during compilation. Each warning has several properties:

packages/svelte/tests/css/samples/global-keyframes/_config.js

@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+	hasGlobal: true
+});

packages/svelte/tests/css/samples/global-with-nesting/_config.js

@@ -1,5 +1,7 @@
 import { test } from '../../test';
 
 export default test({
-	warnings: []
+	warnings: [],
+
+	hasGlobal: false
 });

packages/svelte/tests/css/samples/global/_config.js

@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+	hasGlobal: true
+});

packages/svelte/tests/css/test.ts

@@ -34,6 +34,7 @@ interface CssTest extends BaseTest {
 	compileOptions?: Partial<CompileOptions>;
 	warnings?: Warning[];
 	props?: Record<string, any>;
+	hasGlobal?: boolean;
 }
 
 /**
@@ -78,6 +79,14 @@ const { test, run } = suite<CssTest>(async (config, cwd) => {
 		// assert_html_equal(actual_ssr, expected.html);
 	}
 
+	if (config.hasGlobal !== undefined) {
+		const metadata = JSON.parse(
+			fs.readFileSync(`${cwd}/_output/client/input.svelte.css.json`, 'utf-8')
+		);
+
+		assert.equal(metadata.hasGlobal, config.hasGlobal);
+	}
+
 	const dom_css = fs.readFileSync(`${cwd}/_output/client/input.svelte.css`, 'utf-8').trim();
 	const ssr_css = fs.readFileSync(`${cwd}/_output/server/input.svelte.css`, 'utf-8').trim();
 

packages/svelte/tests/helpers.js

@@ -146,6 +146,10 @@ export async function compile_directory(
 
 			if (compiled.css) {
 				write(`${output_dir}/${file}.css`, compiled.css.code);
+				write(
+					`${output_dir}/${file}.css.json`,
+					JSON.stringify({ hasGlobal: compiled.css.hasGlobal })
+				);
 				if (output_map) {
 					write(`${output_dir}/${file}.css.map`, JSON.stringify(compiled.css.map, null, '\t'));
 				}

packages/svelte/types/index.d.ts

@@ -752,6 +752,8 @@ declare module 'svelte/compiler' {
 			code: string;
 			/** A source map */
 			map: SourceMap;
+			/** Whether or not the CSS includes global rules */
+			hasGlobal: boolean;
 		};
 		/**
 		 * An array of warning objects that were generated during compilation. Each warning has several properties: