[no-shadow] enum shadowing when there's nothing else in parent scope?

[mikemaccana]

I have the following file, twith this as it's only contents:

export enum ProjectOrderByType {
  featuredAt = "featuredAt",
  updatedAt = "updatedAt",
  createdAt = "createdAt",
}

Which fails with:

'ProjectOrderByType' is already declared in the upper scope.

I have read related issues like #2629 and understand this is a charge in eslint v4 https://github.com/typescript-eslint/typescript-eslint/releases/tag/v4.0.0

However I do not understand what is being shadowed here - there is nothing else except the export in the parent scope.

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have read the FAQ and my problem is not listed.

Repro

See above

Versions

package	version
@typescript-eslint/eslint-plugin	4.6.0
@typescript-eslint/parser	4.6.0
TypeScript	3.9.7
ESLint	7.12.1
node	v12.18.3

Config:

module.exports = {
  // Generated with 'npx tslint-to-eslint-config'. See this commit log for the output!
  env: {
    es6: true,
    node: true,
  },
  parser: "@typescript-eslint/parser",
  parserOptions: {
    project: "tsconfig.json",
    sourceType: "module",
  },
  plugins: ["@typescript-eslint", "import", "prefer-arrow"],
  rules: {
    "@typescript-eslint/adjacent-overload-signatures": "error",
    "@typescript-eslint/array-type": "error",
    "@typescript-eslint/ban-types": "error",
    // This warns on typeorm migrations
    "@typescript-eslint/class-name-casing": "off",
    "@typescript-eslint/consistent-type-assertions": "off",
    // This triggers too many warnings but we may wish to enable in future
    "@typescript-eslint/explicit-member-accessibility": "off",
    "@typescript-eslint/indent": "off",
    "@typescript-eslint/member-delimiter-style": [
      "off",
      {
        multiline: {
          delimiter: "none",
          requireLast: true,
        },
        singleline: {
          delimiter: "semi",
          requireLast: false,
        },
      },
    ],
    "@typescript-eslint/no-empty-function": "error",
    "@typescript-eslint/no-empty-interface": "error",
    "@typescript-eslint/no-explicit-any": "off",
    "@typescript-eslint/no-misused-new": "error",
    "@typescript-eslint/no-namespace": "error",
    "@typescript-eslint/no-parameter-properties": "off",
    "@typescript-eslint/no-this-alias": "error",
    "@typescript-eslint/no-use-before-define": "off",
    "@typescript-eslint/no-var-requires": "error",
    "@typescript-eslint/prefer-for-of": "error",
    "@typescript-eslint/prefer-function-type": "error",
    "@typescript-eslint/prefer-namespace-keyword": "error",
    "@typescript-eslint/quotes": "off",
    "@typescript-eslint/semi": ["off", null],
    "@typescript-eslint/triple-slash-reference": "error",
    "@typescript-eslint/ban-types": "off",
    "@typescript-eslint/type-annotation-spacing": "off",
    "@typescript-eslint/unified-signatures": "error",
    "arrow-parens": ["off", "as-needed"],
    // Google places, Stripe and third party APIs want snake_case
    // We may wish to enable this in future
    camelcase: "off",
    "comma-dangle": "off",
    complexity: "off",
    "constructor-super": "error",
    "dot-notation": "error",
    "eol-last": "off",
    eqeqeq: ["error", "smart"],
    "guard-for-in": "error",
    "id-blacklist": [
      "error",
      "any",
      "Number",
      "number",
      "String",
      "string",
      "Boolean",
      "boolean",
      "Undefined",
      "undefined",
    ],
    "id-match": "error",
    "import/no-extraneous-dependencies": [
      "error",
      {
        devDependencies: false,
      },
    ],
    "import/no-internal-modules": "error",
    "import/order": "error",
    "linebreak-style": "off",
    "max-classes-per-file": "error",
    "max-len": "off",
    "new-parens": "off",
    "newline-per-chained-call": "off",
    "no-bitwise": "error",
    "no-caller": "error",
    "no-cond-assign": "error",
    "no-console": "error",
    "no-debugger": "error",
    "no-duplicate-case": "error",
    "no-duplicate-imports": "error",
    "no-empty": "error",
    "no-eval": "error",
    "no-extra-bind": "error",
    "no-extra-semi": "off",
    "no-fallthrough": "off",
    "no-invalid-this": "off",
    "no-irregular-whitespace": "off",
    "no-multiple-empty-lines": "off",
    "no-new-func": "error",
    "no-new-wrappers": "error",
    "no-redeclare": "error",
    "no-return-await": "error",
    "no-sequences": "error",
    "no-shadow": [
      "error",
      {
        hoist: "all",
      },
    ],
    "no-sparse-arrays": "error",
    "no-template-curly-in-string": "error",
    "no-throw-literal": "error",
    "no-trailing-spaces": "off",
    "no-undef-init": "error",
    // Some of our APIs use leading underscores, however we might wish to change this in future
    "no-underscore-dangle": "off",
    "no-unsafe-finally": "error",
    "no-unused-expressions": "error",
    "no-unused-labels": "error",
    "no-var": "error",
    "object-shorthand": "error",
    "one-var": ["error", "never"],
    // This plugin will warn if 'function' is used anytime outside an Object's prototype
    "prefer-arrow/prefer-arrow-functions": "off",
    "prefer-const": "error",
    "prefer-object-spread": "error",
    "quote-props": "off",
    radix: "error",
    // "warn" as this needs a lot of fixes (and eslint can't do them for us)
    // https://github.com/eslint/eslint/issues/11924
    // But please do fix these (and change to "error" when we're done!)
    "sort-imports": ["warn", {
      // We seperate groups into libraries, current directory, other directories
      "allowSeparatedGroups": true,
      "ignoreCase": true
    }],
    "space-before-function-paren": "off",
    "space-in-parens": ["off", "never"],
    "spaced-comment": "error",
    "use-isnan": "error",
    "valid-typeof": "off",
  },
  overrides: [
    {
      files: ["src/tasks/*/*.ts"],
      rules: {
        "no-console": "off",
      },
    },
  ],
};

[mikemaccana]

Also from reading the discussion I saw @oigewan mentioned

If it gets accepted, I can do a follow-up PR which will add an option to the no-shadow rule which will ignore enum members with documentation recommending that the new rule is enabled if the no-shadow option ignoring enum members is enabled.

Did that new option get created?

[bradzacher]

you skipped the config section of the template.
please don't skip sections of the template. The template is there so that people can respond to you without having to waste time asking for more information.

What config are you using?

Are you using @typescript-eslint/no-shadow or no-shadow?
If it's the latter - then it's expected it's broken - it doesn't understand TS enums.

[mikemaccana]

@bradzacher Config added. Got it - we're using no-shadow, I'll move to @typescript-eslint/no-shadow

[mikemaccana]

(btw, looks like no-shadow worked in previous versions of eslint / typescript-eslint

[bradzacher]

"worked" is a strong word.

It worked for JS use cases.
It didn't work well for anything TS-specific.

The way it sort-of-worked was via a hacky, haphazardly patched scope analyser.
This hack was built mostly to stop the rules from reporting false-positives, and didn't do much to cover the many (and much more insidious) false-negatives.

You can read more in #1856 and in the changes made in #2039.