fix: be more careful about ext => rule mapping

See comments about `no-undef`

lib/eslint.mjs

@@ -23,25 +23,74 @@ const legacy = {
   react: legacyReact,
 }
 
-// See https://www.npmjs.com/package/eslint-plugin-html#user-content-settings
+// WARNING: eslint rules from `typescript-eslint`, even the "untyped" rules, assume that your code will be run through
-const htmlExtensions = htmlSettings.getSettings({}).htmlExtensions
+// `tsc` or equivalent for type checking. Using any rule set from `typescript-eslint` will, for example, turn off the
-
+// `no-undef` rule. That makes sense if you'll use TypeScript to catch undefined globals, but it could be dangerous
-// '.html' => '**/*.html'
+// for plain JavaScript.
-const htmlGlobs = htmlExtensions.map(ext => `**/*${ext}`)
+// More information here: https://github.com/typescript-eslint/typescript-eslint/issues/8825#issuecomment-2033315610
-
-const typeScriptExtensions = ['.ts', '.tsx', '.mts', '.cts']
 
 /**
- * Base rules recommended when type information is not available.
+ * Convert an array of file extensions to an array of globs
- * These rules are also safe to use when type information is available.
+ * @param {string[]} extArray - an array of file extensions, like `.foo`
+ * @returns {string[]} an array of globs, like `** /*.foo` (without the space)
  */
-const typeFreeRules = tseslint.config(
+const extArrayToGlobArray = extArray => extArray.map(ext => `**/*${ext}`)
-  eslint.configs.recommended,
-  tseslint.configs.recommended,
-  tseslint.configs.stylistic,
 
+// See https://www.npmjs.com/package/eslint-plugin-html#user-content-settings
+const htmlSettingsDefault = htmlSettings.getSettings({})
+
+const fileExtensions = (x => {
+  x.allScript = [...x.javaScript, ...x.typeScript]
+  return x
+})({
+  html: /** @type {string[]} */ (htmlSettingsDefault.htmlExtensions),
+  javaScript: ['.js', '.jsx', '.mjs', '.cjs'],
+  markdown: ['.md'],
+  typeScript: ['.ts', '.tsx', '.mts', '.cts'],
+  react: ['.jsx', '.tsx'],
+  xml: /** @type {string[]} */ (htmlSettingsDefault.xmlExtensions),
+})
+
+// This explicitly lists each entry so that we can get unused warnings
+const fileGlobs = {
+  allScript: extArrayToGlobArray(fileExtensions.allScript),
+  html: extArrayToGlobArray(fileExtensions.html),
+  javaScript: extArrayToGlobArray(fileExtensions.javaScript),
+  markdown: extArrayToGlobArray(fileExtensions.markdown),
+  react: extArrayToGlobArray(fileExtensions.react),
+  typeScript: extArrayToGlobArray(fileExtensions.typeScript),
+  xml: extArrayToGlobArray(fileExtensions.xml),
+}
+
+/**
+ * Rules for specific file types outside of the core JS/TS rule sets.
+ */
+const miscFileRules = tseslint.config([
+  // eslint-plugin-html
+  {
+    name: 'scratch/miscFileRules[eslint-plugin-html]',
+    files: [...fileGlobs.html, ...fileGlobs.xml],
+    plugins: { html },
+    settings: {
+      'html/html-extensions': fileExtensions.html,
+      'xml/xml-extensions': fileExtensions.xml,
+    },
+  },
+  // eslint-plugin-markdown
+  {
+    name: 'scratch/miscFileRules[eslint-plugin-markdown]',
+    files: fileGlobs.markdown,
+    extends: [markdown.configs.recommended],
+  },
+])
+
+/**
+ * Rules recommended for all script files, whether or not type information is available or checked.
+ */
+const allScriptRules = tseslint.config([
   // eslint-plugin-formatjs
   {
+    name: 'scratch/allScriptRules[eslint-plugin-formatjs]',
     plugins: {
       formatjs,
     },
@@ -49,45 +98,24 @@ const typeFreeRules = tseslint.config(
       'formatjs/no-offset': ['error'],
     },
   },
-  // eslint-plugin-html
-  {
-    files: htmlGlobs,
-    plugins: { html },
-    settings: {
-      'html/html-extensions': htmlExtensions,
-    },
-  },
   // eslint-plugin-import
   {
+    name: 'scratch/allScriptRules[eslint-plugin-import]',
     plugins: importPlugin.flatConfigs.recommended.plugins,
     rules: {
       'import/no-duplicates': 'error', // Forbid duplicate imports
     },
   },
-  // eslint-plugin-jsdoc
-  jsdoc.configs['flat/recommended-error'],
-  {
-    files: ['**/*.ts', '**/*.tsx', '**/*.mts', '**/*.cts'],
-    extends: [jsdoc.configs['flat/recommended-typescript-error']],
-  },
-  {
-    rules: {
-      // If JSDoc comments are present, they must be informative (non-trivial).
-      // For example, the description "The foo." on a variable called "foo" is not informative.
-      // https://github.com/gajus/eslint-plugin-jsdoc/blob/main/docs/rules/informative-docs.md
-      'jsdoc/informative-docs': ['error'],
-
-      // Don't require JSDoc comments. Library authors should consider turning this on for external interfaces.
-      // https://github.com/gajus/eslint-plugin-jsdoc/blob/main/docs/rules/require-jsdoc.md
-      'jsdoc/require-jsdoc': ['off'],
-    },
-  },
   // eslint-plugin-jsx-a11y
-  jsxA11y.flatConfigs.recommended,
+  {
-  // eslint-plugin-markdown
+    name: 'scratch/allScriptRules[eslint-plugin-jsx-a11y]',
-  markdown.configs.recommended,
+    files: fileGlobs.react,
+    extends: [jsxA11y.flatConfigs.recommended],
+  },
   // eslint-plugin-react
   {
+    name: 'scratch/allScriptRules[eslint-plugin-react]',
+    files: fileGlobs.react,
     plugins: {
       react,
     },
@@ -142,27 +170,17 @@ const typeFreeRules = tseslint.config(
   },
   // eslint-plugin-react-hooks
   {
+    name: 'scratch/allScriptRules[eslint-plugin-react-hooks]',
+    files: fileGlobs.react,
     extends: [reactHooks.configs['recommended-latest']],
     rules: {
       // https://github.com/facebook/react/blob/main/packages/eslint-plugin-react-hooks/README.md#advanced-configuration
       'react-hooks/exhaustive-deps': ['error', { additionalHooks: '^useAsync$' }],
     },
   },
-  // typescript-eslint
-  {
-    rules: {
-      // https://typescript-eslint.io/rules/no-non-null-asserted-nullish-coalescing/
-      '@typescript-eslint/no-non-null-asserted-nullish-coalescing': ['error'],
-
-      // https://typescript-eslint.io/rules/no-useless-constructor/
-      '@typescript-eslint/no-useless-constructor': ['error'],
-
-      // https://typescript-eslint.io/rules/no-non-null-assertion
-      '@typescript-eslint/no-non-null-assertion': ['error'],
-    },
-  },
   // @eslint-community/eslint-plugin-eslint-comments
   {
+    name: 'scratch/allScriptRules[eslint-plugin-eslint-comments]',
     extends: [
       // @ts-expect-error This plugin's recommended rules don't quite match the type `tseslint.config` expects.
       eslintComments.recommended,
@@ -174,6 +192,7 @@ const typeFreeRules = tseslint.config(
   },
   // @eslint/js
   {
+    name: 'scratch/allScriptRules[@eslint/js]',
     rules: {
       // https://eslint.org/docs/latest/rules/arrow-body-style
       'arrow-body-style': ['error', 'as-needed'],
@@ -206,17 +225,48 @@ const typeFreeRules = tseslint.config(
       'symbol-description': ['error'],
     },
   },
-)
+])
 
 /**
- * Additional rules recommended when information is available.
+ * Additional rules recommended when type information is not available or checked.
+ */
+const typeFreeRules = tseslint.config([
+  {
+    name: 'scratch/typeFreeRules[base]',
+    extends: [eslint.configs.recommended],
+  },
+  ...allScriptRules,
+  {
+    name: 'scratch/typeFreeRules[eslint-plugin-jsdoc]',
+    extends: [jsdoc.configs['flat/recommended-error']],
+    rules: {
+      // If JSDoc comments are present, they must be informative (non-trivial).
+      // For example, the description "The foo." on a variable called "foo" is not informative.
+      // https://github.com/gajus/eslint-plugin-jsdoc/blob/main/docs/rules/informative-docs.md
+      'jsdoc/informative-docs': ['error'],
+
+      // Don't require JSDoc comments. Library authors should consider turning this on for external interfaces.
+      // https://github.com/gajus/eslint-plugin-jsdoc/blob/main/docs/rules/require-jsdoc.md
+      'jsdoc/require-jsdoc': ['off'],
+    },
+  },
+])
+
+/**
+ * Rules recommended when type information is available and checked. This configuration turns off some rules with the
+ * assumption that other software, such as TypeScript, will flag those problems. For example, the `no-undef` rule is
+ * disabled in this configuration. These rules include `allScriptRules`.
  * These rules require additional configuration.
  * @see https://typescript-eslint.io/getting-started/typed-linting/
  */
-const typeCheckedRules = tseslint.config(
+const typeCheckedRules = tseslint.config([
-  tseslint.configs.recommendedTypeChecked,
-  tseslint.configs.stylisticTypeChecked,
   {
+    name: 'scratch/typeCheckedRules[base]',
+    extends: [
+      eslint.configs.recommended,
+      tseslint.configs.recommendedTypeChecked,
+      tseslint.configs.stylisticTypeChecked,
+    ],
     rules: {
       // https://typescript-eslint.io/rules/no-unnecessary-condition/
       '@typescript-eslint/no-unnecessary-condition': ['error'],
@@ -225,7 +275,43 @@ const typeCheckedRules = tseslint.config(
       '@typescript-eslint/require-await': ['error'],
     },
   },
-)
+  ...allScriptRules,
+  {
+    name: 'scratch/typeCheckedRules[eslint-plugin-jsdoc][1]',
+    extends: [jsdoc.configs['flat/recommended-error']],
+  },
+  {
+    name: 'scratch/typeCheckedRules[eslint-plugin-jsdoc][2]',
+    extends: [jsdoc.configs['flat/recommended-typescript-error']],
+  },
+  {
+    name: 'scratch/typeCheckedRules[eslint-plugin-jsdoc][3]',
+    rules: {
+      // If JSDoc comments are present, they must be informative (non-trivial).
+      // For example, the description "The foo." on a variable called "foo" is not informative.
+      // https://github.com/gajus/eslint-plugin-jsdoc/blob/main/docs/rules/informative-docs.md
+      'jsdoc/informative-docs': ['error'],
+
+      // Don't require JSDoc comments. Library authors should consider turning this on for external interfaces.
+      // https://github.com/gajus/eslint-plugin-jsdoc/blob/main/docs/rules/require-jsdoc.md
+      'jsdoc/require-jsdoc': ['off'],
+    },
+  },
+  // typescript-eslint
+  {
+    name: 'scratch/typeCheckedRules[typescript-eslint]',
+    rules: {
+      // https://typescript-eslint.io/rules/no-non-null-asserted-nullish-coalescing/
+      '@typescript-eslint/no-non-null-asserted-nullish-coalescing': ['error'],
+
+      // https://typescript-eslint.io/rules/no-useless-constructor/
+      '@typescript-eslint/no-useless-constructor': ['error'],
+
+      // https://typescript-eslint.io/rules/no-non-null-assertion
+      '@typescript-eslint/no-non-null-assertion': ['error'],
+    },
+  },
+])
 
 /**
  * Scratch's recommended configuration when type information is not available.
@@ -235,9 +321,10 @@ const recommendedTypeFree = tseslint.config(typeFreeRules, eslintConfigPrettier)
 /**
  * Scratch's recommended configuration when type information is available.
  * These rules require additional configuration.
+ * WARNING: These rules do not specify the `files` property.
  * @see https://typescript-eslint.io/getting-started/typed-linting/
  */
-const recommendedTypeChecked = tseslint.config(typeFreeRules, typeCheckedRules, eslintConfigPrettier)
+const recommendedTypeChecked = tseslint.config(typeCheckedRules, eslintConfigPrettier)
 
 /**
  * Scratch's recommended configuration for general use.
@@ -246,10 +333,22 @@ const recommendedTypeChecked = tseslint.config(typeFreeRules, typeCheckedRules,
  * @see https://typescript-eslint.io/getting-started/typed-linting/
  */
 const recommended = tseslint.config(
-  typeFreeRules,
   {
-    files: typeScriptExtensions,
+    name: 'scratch/recommended',
+  },
+  miscFileRules,
+  {
+    files: fileGlobs.allScript,
+    extends: [typeFreeRules],
+  },
+  {
+    files: fileGlobs.typeScript,
     extends: [typeCheckedRules],
+    languageOptions: {
+      parserOptions: {
+        projectService: true,
+      },
+    },
   },
   eslintConfigPrettier,
 )
@@ -258,4 +357,4 @@ const recommended = tseslint.config(
 export { config } from 'typescript-eslint'
 
 // Our exported configurations
-export { recommended, recommendedTypeChecked, recommendedTypeFree, legacy }
+export { recommended, recommendedTypeChecked, recommendedTypeFree, miscFileRules, legacy }