fix: no-unused-keys rule not working when using flat config (#497)

* fix: `no-unused-keys` rule not working when using flat config

* fix

* Create wicked-carpets-sing.md

* test

* fix

* fix

* fix

Author: ota-meshi

Diff for: .changeset/wicked-carpets-sing.md

@@ -0,0 +1,5 @@
+---
+"@intlify/eslint-plugin-vue-i18n": minor
+---
+
+fix: `no-unused-keys` rule not working when using flat config

Diff for: files/empty.json

@@ -2,23 +2,19 @@
  * @fileoverview Collect localization keys
  * @author kazuya kawaguchi (a.k.a. kazupon)
  */
-import type { Linter } from 'eslint'
-import { parseForESLint, AST as VAST } from 'vue-eslint-parser'
-import { readFileSync } from 'fs'
+import { AST as VAST } from 'vue-eslint-parser'
 import { resolve, extname } from 'path'
 import { listFilesToProcess } from './glob-utils'
 import { ResourceLoader } from './resource-loader'
 import { CacheLoader } from './cache-loader'
 import { defineCacheFunction } from './cache-function'
 import debugBuilder from 'debug'
 import type { RuleContext, VisitorKeys } from '../types'
-// @ts-expect-error -- ignore
-import { Legacy } from '@eslint/eslintrc'
 import { getCwd } from './get-cwd'
 import { isStaticLiteral, getStaticLiteralValue } from './index'
-import importFresh from 'import-fresh'
+import type { Parser } from './parser-config-resolver'
+import { buildParserFromConfig } from './parser-config-resolver'
 const debug = debugBuilder('eslint-plugin-vue-i18n:collect-keys')
-const { CascadingConfigArrayFactory } = Legacy
 
 /**
  *
@@ -74,56 +70,20 @@ function getKeyFromI18nComponent(node: VAST.VAttribute) {
   }
 }
 
-function getParser(parser: string | undefined): {
-  parseForESLint?: typeof parseForESLint
-  parse: (code: string, options: unknown) => VAST.ESLintProgram
-} {
-  if (parser) {
-    try {
-      return require(parser)
-    } catch (_e) {
-      // ignore
-    }
-  }
-  return {
-    parseForESLint,
-    parse(code: string, options: unknown) {
-      return parseForESLint(code, options).ast
-    }
-  }
-}
-
 /**
  * Collect the used keys from source code text.
  * @param {string} text
  * @param {string} filename
  * @returns {string[]}
  */
-function collectKeysFromText(
-  text: string,
-  filename: string,
-  getConfigForFile: (filePath: string) => Linter.Config<Linter.RulesRecord>
-) {
+function collectKeysFromText(filename: string, parser: Parser) {
   const effectiveFilename = filename || '<text>'
   debug(`collectKeysFromFile ${effectiveFilename}`)
-  const config = getConfigForFile(effectiveFilename)
-  const parser = getParser(config.parser)
-
-  const parserOptions = Object.assign({}, config.parserOptions, {
-    loc: true,
-    range: true,
-    raw: true,
-    tokens: true,
-    comment: true,
-    eslintVisitorKeys: true,
-    eslintScopeManager: true,
-    filePath: effectiveFilename
-  })
   try {
-    const parseResult =
-      typeof parser.parseForESLint === 'function'
-        ? parser.parseForESLint(text, parserOptions)
-        : { ast: parser.parse(text, parserOptions) }
+    const parseResult = parser(filename)
+    if (!parseResult) {
+      return []
+    }
     return collectKeysFromAST(parseResult.ast, parseResult.visitorKeys)
   } catch (_e) {
     return []
@@ -137,20 +97,7 @@ function collectKeysFromText(
 function collectKeyResourcesFromFiles(fileNames: string[], cwd: string) {
   debug('collectKeysFromFiles', fileNames)
 
-  const configArrayFactory = new CascadingConfigArrayFactory({
-    additionalPluginPool: new Map([
-      ['@intlify/vue-i18n', importFresh('../index')]
-    ]),
-    cwd,
-    async getEslintRecommendedConfig() {
-      return await import('../../files/empty.json')
-    },
-    async getEslintAllConfig() {
-      return await import('../../files/empty.json')
-    },
-    eslintRecommendedPath: require.resolve('../../files/empty.json'),
-    eslintAllPath: require.resolve('../../files/empty.json')
-  })
+  const parser = buildParserFromConfig(cwd)
 
   const results = []
 
@@ -160,21 +107,12 @@ function collectKeyResourcesFromFiles(fileNames: string[], cwd: string) {
 
     results.push(
       new ResourceLoader(resolve(filename), () => {
-        const text = readFileSync(resolve(filename), 'utf8')
-        return collectKeysFromText(text, filename, getConfigForFile)
+        return collectKeysFromText(filename, parser)
       })
     )
   }
 
   return results
-
-  function getConfigForFile(filePath: string) {
-    const absolutePath = resolve(cwd, filePath)
-    return configArrayFactory
-      .getConfigArrayForFile(absolutePath)
-      .extractConfig(absolutePath)
-      .toCompatibleObjectAsConfigFileContent()
-  }
 }
 
 /**

Diff for: lib/utils/collect-keys.ts

@@ -0,0 +1,14 @@
+// @ts-expect-error -- ignore
+import { createSyncFn } from 'synckit'
+import type { ParseResult, Parser } from '.'
+
+const getSync = createSyncFn(require.resolve('./worker'))
+
+/**
+ * Build synchronously parser using the flat config
+ */
+export function buildParserUsingFlatConfig(cwd: string): Parser {
+  return (filePath: string) => {
+    return getSync(cwd, filePath) as ParseResult
+  }
+}

Diff for: lib/utils/parser-config-resolver/build-parser-using-flat-config.ts

@@ -0,0 +1,48 @@
+import type { Parser } from '.'
+// @ts-expect-error -- ignore
+import { Legacy } from '@eslint/eslintrc'
+import path from 'path'
+import { parseByParser } from './parse-by-parser'
+const { CascadingConfigArrayFactory } = Legacy
+
+/**
+ * Build parser using legacy config
+ */
+export function buildParserUsingLegacyConfig(cwd: string): Parser {
+  const configArrayFactory = new CascadingConfigArrayFactory({
+    additionalPluginPool: new Map([
+      ['@intlify/vue-i18n', require('../../index')]
+    ]),
+    cwd,
+    getEslintRecommendedConfig() {
+      return {}
+    },
+    getEslintAllConfig() {
+      return {}
+    }
+  })
+
+  function getConfigForFile(filePath: string) {
+    const absolutePath = path.resolve(cwd, filePath)
+    return configArrayFactory
+      .getConfigArrayForFile(absolutePath)
+      .extractConfig(absolutePath)
+      .toCompatibleObjectAsConfigFileContent()
+  }
+
+  return (filePath: string) => {
+    const config = getConfigForFile(filePath)
+
+    const parserOptions = Object.assign({}, config.parserOptions, {
+      loc: true,
+      range: true,
+      raw: true,
+      tokens: true,
+      comment: true,
+      eslintVisitorKeys: true,
+      eslintScopeManager: true,
+      filePath
+    })
+    return parseByParser(filePath, config.parser, parserOptions)
+  }
+}

Diff for: lib/utils/parser-config-resolver/build-parser-using-legacy-config.ts

@@ -0,0 +1,24 @@
+import { shouldUseFlatConfig } from './should-use-flat-config'
+import type { AST as VAST } from 'vue-eslint-parser'
+import { buildParserUsingLegacyConfig } from './build-parser-using-legacy-config'
+import { buildParserUsingFlatConfig } from './build-parser-using-flat-config'
+
+export type ParseResult = Pick<
+  VAST.ESLintExtendedProgram,
+  'ast' | 'visitorKeys'
+> | null
+export type Parser = (filePath: string) => ParseResult
+
+const parsers: Record<string, undefined | Parser> = {}
+
+export function buildParserFromConfig(cwd: string): Parser {
+  const parser = parsers[cwd]
+  if (parser) {
+    return parser
+  }
+  if (shouldUseFlatConfig(cwd)) {
+    return (parsers[cwd] = buildParserUsingFlatConfig(cwd))
+  }
+
+  return (parsers[cwd] = buildParserUsingLegacyConfig(cwd))
+}

Diff for: lib/utils/parser-config-resolver/index.ts

@@ -0,0 +1,45 @@
+import type { Linter } from 'eslint'
+import { readFileSync } from 'fs'
+import path from 'path'
+import { parseForESLint } from 'vue-eslint-parser'
+import type { ParseResult } from '.'
+
+export function parseByParser(
+  filePath: string,
+  parserDefine: Linter.ParserModule | string | undefined,
+  parserOptions: unknown
+): ParseResult {
+  const parser = getParser(parserDefine, filePath)
+  try {
+    const text = readFileSync(path.resolve(filePath), 'utf8')
+    const parseResult =
+      'parseForESLint' in parser && typeof parser.parseForESLint === 'function'
+        ? parser.parseForESLint(text, parserOptions)
+        : // eslint-disable-next-line @typescript-eslint/no-explicit-any
+          { ast: (parser as any).parse(text, parserOptions) }
+    return parseResult as ParseResult
+  } catch (_e) {
+    return null
+  }
+}
+
+function getParser(
+  parser: Linter.ParserModule | string | undefined,
+  filePath: string
+): Linter.ParserModule {
+  if (parser) {
+    if (typeof parser === 'string') {
+      try {
+        return require(parser)
+      } catch (_e) {
+        // ignore
+      }
+    } else {
+      return parser
+    }
+  }
+  if (filePath.endsWith('.vue')) {
+    return { parseForESLint } as Linter.ParserModule
+  }
+  return require('espree')
+}

Diff for: lib/utils/parser-config-resolver/parse-by-parser.ts

@@ -0,0 +1,66 @@
+/** copied from https://github.com/eslint/eslint/blob/v8.56.0/lib/eslint/flat-eslint.js#L1119 */
+
+import path from 'path'
+import fs from 'fs'
+
+const FLAT_CONFIG_FILENAMES = [
+  'eslint.config.js',
+  'eslint.config.mjs',
+  'eslint.config.cjs'
+]
+/**
+ * Returns whether flat config should be used.
+ * @returns {Promise<boolean>} Whether flat config should be used.
+ */
+export function shouldUseFlatConfig(cwd: string): boolean {
+  // eslint-disable-next-line no-process-env -- ignore
+  switch (process.env.ESLINT_USE_FLAT_CONFIG) {
+    case 'true':
+      return true
+    case 'false':
+      return false
+    default:
+      // If neither explicitly enabled nor disabled, then use the presence
+      // of a flat config file to determine enablement.
+      return Boolean(findFlatConfigFile(cwd))
+  }
+}
+
+/**
+ * Searches from the current working directory up until finding the
+ * given flat config filename.
+ * @param {string} cwd The current working directory to search from.
+ * @returns {string|undefined} The filename if found or `undefined` if not.
+ */
+export function findFlatConfigFile(cwd: string) {
+  return findUp(FLAT_CONFIG_FILENAMES, { cwd })
+}
+
+/** We used https://github.com/sindresorhus/find-up/blob/b733bb70d3aa21b22fa011be8089110d467c317f/index.js#L94 as a reference */
+function findUp(names: string[], options: { cwd: string }) {
+  let directory = path.resolve(options.cwd)
+  const { root } = path.parse(directory)
+  const stopAt = path.resolve(directory, root)
+  // eslint-disable-next-line no-constant-condition -- ignore
+  while (true) {
+    for (const name of names) {
+      const target = path.resolve(directory, name)
+      const stat = fs.existsSync(target)
+        ? fs.statSync(target, {
+            throwIfNoEntry: false
+          })
+        : null
+      if (stat?.isFile()) {
+        return target
+      }
+    }
+
+    if (directory === stopAt) {
+      break
+    }
+
+    directory = path.dirname(directory)
+  }
+
+  return null
+}

Diff for: lib/utils/parser-config-resolver/should-use-flat-config.ts

@@ -0,0 +1,42 @@
+// @ts-expect-error -- ignore
+import { runAsWorker } from 'synckit'
+import { getESLint } from 'eslint-compat-utils/eslint'
+import type { Linter } from 'eslint'
+import type { ParseResult } from '.'
+import { parseByParser } from './parse-by-parser'
+const ESLint = getESLint()
+
+runAsWorker(async (cwd: string, filePath: string): Promise<ParseResult> => {
+  const eslint = new ESLint({ cwd })
+  const config: Linter.FlatConfig = await eslint.calculateConfigForFile(
+    filePath
+  )
+  const languageOptions = config.languageOptions || {}
+  const parserOptions = Object.assign(
+    {
+      sourceType: languageOptions.sourceType || 'module',
+      ecmaVersion: languageOptions.ecmaVersion || 'latest'
+    },
+    languageOptions.parserOptions,
+    {
+      loc: true,
+      range: true,
+      raw: true,
+      tokens: true,
+      comment: true,
+      eslintVisitorKeys: true,
+      eslintScopeManager: true,
+      filePath
+    }
+  )
+
+  const result = parseByParser(filePath, languageOptions.parser, parserOptions)
+  if (!result) {
+    return null
+  }
+
+  return {
+    ast: result.ast,
+    visitorKeys: result?.visitorKeys
+  }
+})