SolvedDefinitelyTyped @types/core-js conflicts with typescript/lib/lib.es6.d.ts when @types/core-js is not actually used

A simple reproduce repository: https://github.com/plantain-00/test , after npm i && npm run build, the error is:

node_modules/@types/core-js/index.d.ts(21,14): error TS2300: Duplicate identifier 'PropertyKey'.
node_modules/typescript/lib/lib.es6.d.ts(4133,14): error TS2300: Duplicate identifier 'PropertyKey'.

Expected: no error, because the app.ts is empty. the @types/core-js is used in static/app.ts.

  "devDependencies": {
    "@types/core-js": "^0.9.34",
    "core-js": "^2.4.1",
    "typescript": "^2.0.3"
  }
13 Answers

✔️Accepted Answer

had the similar issue. Added "skipLibCheck": true to compilerOptions in my tsconfig.json and than helped

Other Answers:

@anorborg I did get my situation working using something like this:

  "compilerOptions": {
    "module": "commonjs",
    "target": "es6",
    "moduleResolution": "node",
    "lib": ["es5", "dom"],
    ...
  }

@jefbarn that did work. Basically the the core-js and typescript 2.x es6.d.ts libs are conflicting and that is telling typescript to not use its es6.d.ts. I think the more pure solution is to create some module type definitions for core-js (i.e core-js-es6-object) instead of including the entire core-js definition. I tried to start this locally, but couldn't get local custom types to work. If I have time I will try to figure it out and create a PR for all of the modules.

Bump for attention.

I just created a new project with tsc 2.2.0 using this ts config:

{
  "compilerOptions": {
    "outDir": "./build/",
    "rootDir": "./src/",
    "baseUrl": ".",
    "sourceMap": true,
    "noImplicitAny": false,
    "module": "commonjs",
    "target": "es6"
  },
  "include": [
    "./src/**/*.ts"
  ],
  "compileOnSave": false
}

Which would produce these errors:

node_modules/@types/core-js/index.d.ts(21,14): error TS2300: Duplicate identifier 'PropertyKey'.
node_modules/@types/core-js/index.d.ts(85,5): error TS2687: All declarations of 'name' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(145,5): error TS2403: Subsequent variable declarations must have the same type.  Variable '[Symbol.unscopables]' must be of type '{ copyWithin: boolean; entries: boolean; fill: boolean; find: boolean; findIndex: boolean; keys: ...', but here has type 'any'.
node_modules/@types/core-js/index.d.ts(262,5): error TS2687: All declarations of 'flags' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(276,5): error TS2687: All declarations of 'EPSILON' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(311,5): error TS2687: All declarations of 'MAX_SAFE_INTEGER' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(318,5): error TS2687: All declarations of 'MIN_SAFE_INTEGER' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(457,5): error TS2403: Subsequent variable declarations must have the same type.  Variable '[Symbol.toStringTag]' must be of type '"Symbol"', but here has type 'string'.
node_modules/@types/core-js/index.d.ts(457,5): error TS2687: All declarations of '[Symbol.toStringTag]' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(464,5): error TS2687: All declarations of 'prototype' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(492,5): error TS2687: All declarations of 'hasInstance' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(498,5): error TS2687: All declarations of 'isConcatSpreadable' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(504,5): error TS2687: All declarations of 'iterator' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(510,5): error TS2687: All declarations of 'match' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(516,5): error TS2687: All declarations of 'replace' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(522,5): error TS2687: All declarations of 'search' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(528,5): error TS2687: All declarations of 'species' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(534,5): error TS2687: All declarations of 'split' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(540,5): error TS2687: All declarations of 'toPrimitive' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(546,5): error TS2687: All declarations of 'toStringTag' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(552,5): error TS2687: All declarations of 'unscopables' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(609,5): error TS2403: Subsequent variable declarations must have the same type.  Variable '[Symbol.toStringTag]' must be of type '"Math"', but here has type 'string'.
node_modules/@types/core-js/index.d.ts(609,5): error TS2687: All declarations of '[Symbol.toStringTag]' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(613,5): error TS2403: Subsequent variable declarations must have the same type.  Variable '[Symbol.toStringTag]' must be of type '"JSON"', but here has type 'string'.
node_modules/@types/core-js/index.d.ts(613,5): error TS2687: All declarations of '[Symbol.toStringTag]' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(628,5): error TS2687: All declarations of 'size' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(634,5): error TS2687: All declarations of 'prototype' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(645,5): error TS2687: All declarations of 'size' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(651,5): error TS2687: All declarations of 'prototype' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(656,11): error TS2428: All declarations of 'WeakMap' must have identical type parameters.
node_modules/@types/core-js/index.d.ts(664,27): error TS2344: Type 'K' does not satisfy the constraint 'object'.
node_modules/@types/core-js/index.d.ts(665,53): error TS2344: Type 'K' does not satisfy the constraint 'object'.
node_modules/@types/core-js/index.d.ts(666,5): error TS2687: All declarations of 'prototype' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(680,5): error TS2687: All declarations of 'prototype' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(692,5): error TS2687: All declarations of 'value' must have identical modifiers.
node_modules/@types/core-js/index.d.ts(804,5): error TS2687: All declarations of 'prototype' must have identical modifiers.
node_modules/typescript/lib/lib.es6.d.ts(4199,14): error TS2300: Duplicate identifier 'PropertyKey'.

Changing the target to es5 results in a clean build.

I'm not sure how this issue has recieved so little attention; surely many people are trying to target ES6 with TS and would also run into this?

@jefbarn For non-standard features, I have no solution.
For standard features, I uninstalled @types/core-js, and removed import "core-js";, because core-js is polyfills of ES2015+, so I can use typescript/lib/lib.es6.d.ts instead, the tsconfig.json looks like:

{
    "compilerOptions": {
        "module": "commonjs",
        "target": "es5",
        "lib": [
            "es2015",
            "es5",
            "dom",
            "scripthost"
        ]
    }
}

It seems this issue is still needed, I will reopen this.

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