ESLint warnings in file that doesn't exist

Description

I’m getting ESLint warnings in a file that doesn’t seem to exist when adding and configuring ESLint using https://www.gatsbyjs.org/packages/gatsby-plugin-eslint/ and https://www.npmjs.com/package/eslint-plugin-react-app.

warn ESLintError:
/Users/mrseanbaines/projects/gatsby-eslint/_this_is_virtual_fs_path_/$virtual/sync-requires.js
  4:30  warning  Unexpected mix of '&&' and '||'  no-mixed-operators
  4:43  warning  Unexpected mix of '&&' and '||'  no-mixed-operators

Steps to reproduce

npx gatsby new gatsby-eslint
cd gatsby-eslint
yarn add -D gatsby-plugin-eslint eslint-loader eslint eslint-plugin-react-app
touch .eslintrc

Add the following to .eslintrc:

{
  "extends": ["plugin:react-app/recommended"]
}

Add the plugin to gatsby-config.js:

  plugins: [
+   `gatsby-plugin-eslint`,
    ...

yarn start

Minimal Reproduction: https://github.com/mrseanbaines/gatsby-eslint

Expected result

No ESLint warnings for files that don’t exist

Actual result

ESLint warnings in file that doesn’t exist

Environment

  System:
    OS: macOS 10.15.6
    CPU: (8) x64 Intel(R) Core(TM) i5-8279U CPU @ 2.40GHz
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 12.17.0 - ~/.nvm/versions/node/v12.17.0/bin/node
    Yarn: 1.22.4 - ~/.yarn/bin/yarn
    npm: 6.14.4 - ~/.nvm/versions/node/v12.17.0/bin/npm
  Languages:
    Python: 2.7.16 - /usr/bin/python
  Browsers:
    Chrome: 84.0.4147.105
    Firefox: 78.0.2
    Safari: 13.1.2
  npmPackages:
    gatsby: ^2.24.26 => 2.24.26 
    gatsby-image: ^2.4.14 => 2.4.14 
    gatsby-plugin-eslint: ^2.0.8 => 2.0.8 
    gatsby-plugin-manifest: ^2.4.21 => 2.4.21 
    gatsby-plugin-offline: ^3.2.21 => 3.2.21 
    gatsby-plugin-react-helmet: ^3.3.10 => 3.3.10 
    gatsby-plugin-sharp: ^2.6.24 => 2.6.24 
    gatsby-source-filesystem: ^2.3.23 => 2.3.23 
    gatsby-transformer-sharp: ^2.5.12 => 2.5.12 

[pieh]

Opened https://github.com/gatsbyjs/gatsby/pull/26356 to fix this the no-mixed-operators problem. Thank you very much @mrseanbaines for the reproduction showcasing the issue.

I do think that using “ignore” options is better overall (as the more custom eslint rules can still cause more warnings/errors as showcased by logs from @bluenex). Seeing that gatsby-plugin-eslint does set some default exclude ( https://github.com/mongkuen/gatsby-plugin-eslint/blob/master/src/gatsby-node.js ), I might either create pull request in the plugin … or adjust the “virtual” file path to contain .cache which should restore behaviours before the switch to virtual modules

[pieh]

I’ll reopen the issue, as the just published hot-fix handles one specific instance of it, but didn’t fix it for all cases (second comment). So this need more involved follow up.