chore: using svelte-eslint-parser for style selector parsing (#965)

Author: marekdedic

Diff for: .changeset/itchy-dragons-boil.md

@@ -0,0 +1,5 @@
+---
+'eslint-plugin-svelte': patch
+---
+
+chore: using svelte-eslint-parser for style selector parsing

Diff for: packages/eslint-plugin-svelte/package.json

@@ -64,7 +64,6 @@
     "postcss": "^8.4.49",
     "postcss-load-config": "^3.1.4",
     "postcss-safe-parser": "^7.0.0",
-    "postcss-selector-parser": "^7.0.0",
     "semver": "^7.6.3",
     "svelte-eslint-parser": "^1.0.0-next.6"
   },
@@ -93,6 +92,7 @@
     "less": "^4.2.1",
     "mocha": "^11.0.0",
     "postcss-nested": "^7.0.2",
+    "postcss-selector-parser": "^7.0.0",
     "sass": "^1.81.0",
     "source-map-js": "^1.2.1",
     "stylus": "^0.64.0",

Diff for: packages/eslint-plugin-svelte/src/rules/no-unused-class-name.ts

@@ -10,8 +10,9 @@ import type {
 	SvelteStyleDirective
 } from 'svelte-eslint-parser/lib/ast';
 import type { AnyNode } from 'postcss';
-import { default as selectorParser, type Node as SelectorNode } from 'postcss-selector-parser';
+import type { Node as SelectorNode } from 'postcss-selector-parser';
 import { getSourceCode } from '../utils/compat.js';
+import type { SourceCode } from '../types.js';
 
 export default createRule('no-unused-class-name', {
 	meta: {
@@ -61,7 +62,9 @@ export default createRule('no-unused-class-name', {
 					return;
 				}
 				const classesUsedInStyle =
-					styleContext.status === 'success' ? findClassesInPostCSSNode(styleContext.sourceAst) : [];
+					styleContext.status === 'success'
+						? findClassesInPostCSSNode(styleContext.sourceAst, sourceCode.parserServices)
+						: [];
 				for (const className in classesUsedInTemplate) {
 					if (!allowedClassNames.includes(className) && !classesUsedInStyle.includes(className)) {
 						context.report({
@@ -102,15 +105,17 @@ function findClassesInAttribute(
 /**
  * Extract all class names used in a PostCSS node.
  */
-function findClassesInPostCSSNode(node: AnyNode): string[] {
+function findClassesInPostCSSNode(
+	node: AnyNode,
+	parserServices: SourceCode['parserServices']
+): string[] {
 	if (node.type === 'rule') {
-		let classes = node.nodes.flatMap(findClassesInPostCSSNode);
-		const processor = selectorParser();
-		classes = classes.concat(findClassesInSelector(processor.astSync(node.selector)));
+		let classes = node.nodes.flatMap((node) => findClassesInPostCSSNode(node, parserServices));
+		classes = classes.concat(findClassesInSelector(parserServices.getStyleSelectorAST(node)));
 		return classes;
 	}
 	if ((node.type === 'root' || node.type === 'atrule') && node.nodes !== undefined) {
-		return node.nodes.flatMap(findClassesInPostCSSNode);
+		return node.nodes.flatMap((node) => findClassesInPostCSSNode(node, parserServices));
 	}
 	return [];
 }

Diff for: packages/eslint-plugin-svelte/src/types.ts

@@ -3,8 +3,11 @@ import type { Linter, Rule, SourceCode as ESLintSourceCode } from 'eslint';
 import type { AST, StyleContext, SvelteConfig } from 'svelte-eslint-parser';
 import type { TSESTree } from '@typescript-eslint/types';
 import type { ScopeManager, Scope, Variable } from '@typescript-eslint/scope-manager';
+import type { Rule as StyleRule, Node } from 'postcss';
+import type { Root as SelectorRoot, Node as SelectorNode } from 'postcss-selector-parser';
 import type { ASTNode, ASTNodeWithParent, ASTNodeListener } from './types-for-node.js';
 import type * as TS from 'typescript';
+import type { SourceLocation } from 'svelte-eslint-parser/lib/ast/common.js';
 
 export type { ASTNode, ASTNodeWithParent, ASTNodeListener };
 export interface RuleListener extends ASTNodeListener {
@@ -207,6 +210,10 @@ export interface SourceCode {
 		isSvelteScript?: boolean;
 		getSvelteHtmlAst?: () => unknown;
 		getStyleContext?: () => StyleContext;
+		getStyleSelectorAST: (rule: StyleRule) => SelectorRoot;
+		styleNodeLoc: (node: Node) => Partial<SourceLocation>;
+		styleNodeRange: (node: Node) => [number | undefined, number | undefined];
+		styleSelectorNodeLoc: (node: SelectorNode) => Partial<SourceLocation>;
 		svelteParseContext?: {
 			/**
 			 * Whether to use Runes mode.