fix: set processor for flat config, prefer context.languageOptions.parserOptions (#593)

Author: JounQin

.changeset/new-pumpkins-remain.md

@@ -0,0 +1,5 @@
+---
+"eslint-plugin-mdx": patch
+---
+
+fix: set `processor` for flat config

.changeset/purple-terms-agree.md

@@ -0,0 +1,5 @@
+---
+"eslint-plugin-mdx": patch
+---
+
+fix: prefer `context.languageOptions.parserOptions` over `context.parserOptions`

packages/eslint-plugin-mdx/src/configs/flat.ts

@@ -2,15 +2,14 @@ import type { Linter } from 'eslint'
 import * as eslintMdx from 'eslint-mdx'
 
 import * as mdx from '../index.js'
+import { remark } from '../processors/remark.js'
 
 import { codeBlocks } from './code-blocks.js'
 
 // eslint-disable-next-line sonarjs/deprecation
 export const flat: Linter.FlatConfig = {
   files: ['**/*.{md,mdx}'],
   languageOptions: {
-    sourceType: 'module',
-    ecmaVersion: 'latest',
     parser: eslintMdx,
     globals: {
       React: false,
@@ -19,6 +18,7 @@ export const flat: Linter.FlatConfig = {
   plugins: {
     mdx,
   },
+  processor: remark,
   rules: {
     'mdx/remark': 'warn',
     'no-unused-expressions': 'error',

packages/eslint-plugin-mdx/src/rules/remark.ts

@@ -28,14 +28,17 @@ export const remark: Rule.RuleModule = {
     // eslint-disable-next-line sonarjs/deprecation -- FIXME: ESLint 8.40+ required
     const sourceCode = context.getSourceCode()
 
+    /* istanbul ignore next */
     const {
       extensions,
       markdownExtensions,
       ignoreRemarkConfig,
       remarkConfigPath,
-    } =
+    } = {
       // eslint-disable-next-line sonarjs/deprecation -- FIXME: ESLint 8.40+ required
-      context.parserOptions as ParserOptions
+      ...context.parserOptions,
+      ...context.languageOptions?.parserOptions,
+    } as ParserOptions
 
     const isMdx = [...DEFAULT_EXTENSIONS, ...(extensions || [])].includes(
       extname,