[parser] Error with ESLint 6.0.0 pre-releases

[teppeis]

What code were you trying to parse?

module.exports = {
  overrides: [
    {
      files: ["*.ts", "*.tsx"],
      parser: require.resolve("@typescript-eslint/parser")
}

What did you expect to happen?

Able to parse TypeScript files.

What actually happened?

Error: Failed to load parser '@typescript-eslint/parser/dist/parser.js': Cannot find module 'eslint/lib/util/traverser'

Error: Failed to load parser '/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/@typescript-eslint/parser/dist/parser.js' declared in '--config » ../../+typescript.js#overrides[0]': Cannot find module 'eslint/lib/util/traverser'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:582:15)
    at Function.Module._load (internal/modules/cjs/loader.js:508:25)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:22:18)
    at Object.<anonymous> (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/@typescript-eslint/parser/dist/parser.js:7:37)
    at Module._compile (internal/modules/cjs/loader.js:701:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:712:10)
    at Module.load (internal/modules/cjs/loader.js:600:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:539:12)
    at Function.Module._load (internal/modules/cjs/loader.js:531:3)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:22:18)
    at ConfigArrayFactory._loadParser (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:756:29)
    at ConfigArrayFactory._normalizeObjectConfigDataBody (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:549:32)
    at _normalizeObjectConfigDataBody.next (<anonymous>)
    at ConfigArrayFactory._normalizeObjectConfigData (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:490:20)
    at _normalizeObjectConfigData.next (<anonymous>)
    at ConfigArrayFactory._normalizeObjectConfigDataBody (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:580:25)
    at _normalizeObjectConfigDataBody.next (<anonymous>)
    at ConfigArrayFactory._normalizeObjectConfigData (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:490:20)
    at _normalizeObjectConfigData.next (<anonymous>)
    at ConfigArrayFactory._normalizeObjectConfigDataBody (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:544:25)
    at _normalizeObjectConfigDataBody.next (<anonymous>)
    at ConfigArrayFactory._normalizeObjectConfigData (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:490:20)
    at _normalizeObjectConfigData.next (<anonymous>)
    at createConfigArray (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:306:25)
    at ConfigArrayFactory.loadFile (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/config-array-factory.js:381:16)
    at createCLIConfigArray (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/cascading-config-array-factory.js:140:35)
    at new CascadingConfigArrayFactory (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/cascading-config-array-factory.js:199:29)
    at new CLIEngine (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/node_modules/eslint/lib/cli-engine/cli-engine.js:552:36)
    at verify (/Users/teppei/src/github.com/teppeis/eslint-config-teppeis/test/index.js:23:18)

typescript-eslint/packages/parser/src/parser.ts

Line 8 in cca1714

import traverser from 'eslint/lib/util/traverser';

Versions

package	version
@typescript-eslint/parser	1.9.0
TypeScript	3.4.5
ESLint	6.0.0-alpha.2
node	10.15.3
npm	6.9.0

[teppeis]

Related: [indent-new-do-not-use] Error with ESLint 6.0.0-alpha.2 #564

[JamesHenry]

ESLint 6 has moved into the RC phase with rc.0

[JamesHenry]

We could probably temporarily support both ESLint 5 and 6 by converting these imports to requires and wrapping them in a try catch, what do you think @mysticatea? Are there any other changes to watch out for?

[mysticatea]

In ideal, we should not import any private files of ESLint. It's not a part of the public API, so those files can be changed anytime (even if as a patch release).

[ivan-aksamentov]

traverser.js has been moved from lib/util/traverser.js to lib/shared/traverser.js
in commit eslint#219aecb PR eslint#11555

As a quick fix, #614 attempts to monkey-patch this.

[JamesHenry]

FYI this should be fixed by #628