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

What part of core-js is needed that isn't included in lib.es6? Couldn't you simply not install @types/core-js?

@aciccarello core-js and @types/core-js is used by frontend in static/app.ts, this part works well

There are 2 tsconfig.json, one for backend(es6, error happens here), and the other one for frontend(es5, no error, works well),

@plantain-00 Did you figure this out?
I'm having a similar issue, where I want to use some of the non-standard features of core-js (Dictionaries), but the types conflict with typescripts library.

@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.

I am having this issue using @types\core-js and targeting ES6

@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?

@wyqydsyq core.js and ES6 both define a lot of the same definitions. Either don't include @types/core.js or set "lib": ["es5", "dom"], in your tsconfig

I am also getting the similar kind of conflict.

1>c:\Program Files (x86)\Microsoft SDKs\TypeScript\2.6\lib.es2015.iterable.d.ts(203,11): error TS2300: Build:Duplicate identifier 'Promise'.
1>c:\Program Files (x86)\Microsoft SDKs\TypeScript\2.6\lib.es2015.promise.d.ts(223,13): error TS2300: Build:Duplicate identifier 'Promise'.
1>c:\Program Files (x86)\Microsoft SDKs\TypeScript\2.6\lib.es2015.symbol.wellknown.d.ts(168,11): error TS2300: Build:Duplicate identifier 'Promise'.
1>c:\Program Files (x86)\Microsoft SDKs\TypeScript\2.6\lib.es5.d.ts(1292,11): error TS2300: Build:Duplicate identifier 'Promise'.
1>c:\users\username\node_modules\@types\es6-promise\index.d.ts(11,15): error TS2300: Build:Duplicate identifier 'Promise'.
1>c:\users\username\node_modules\@types\es6-promise\index.d.ts(42,19): error TS2300: Build:Duplicate identifier 'Promise'.

tsconfig: -

{
"compilerOptions": {
"target": "es5",
"module": "commonjs",
"moduleResolution": "node",
"sourceMap": true,
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
"lib": [ "es2015", "dom" ],
"noImplicitAny": true,
"suppressImplicitAnyIndexErrors": true,
"noStrictGenericChecks": true
}
}

Package.Json:

{
  "name": "angular-quickstart",
  "version": "1.0.0",
  "description": "QuickStart package.json from the documentation, supplemented with testing support",
  "scripts": {
    "build": "tsc -p src/",
    "build:watch": "tsc -p src/ -w",
    "build:e2e": "tsc -p e2e/",
    "serve": "lite-server -c=bs-config.json",
    "serve:e2e": "lite-server -c=bs-config.e2e.json",
    "prestart": "npm run build",
    "start": "concurrently \"npm run build:watch\" \"npm run serve\"",
    "pree2e": "npm run build:e2e",
    "e2e": "concurrently \"npm run serve:e2e\" \"npm run protractor\" --kill-others --success first",
    "preprotractor": "webdriver-manager update",
    "protractor": "protractor protractor.config.js",
    "pretest": "npm run build",
    "test": "concurrently \"npm run build:watch\" \"karma start karma.conf.js\"",
    "pretest:once": "npm run build",
    "test:once": "karma start karma.conf.js --single-run",
    "lint": "tslint ./src/**/*.ts -t verbose"
  },
  "keywords": [],
  "author": "",
  "license": "MIT",
  "dependencies": {
    "@angular/common": "~4.3.4",
    "@angular/compiler": "~4.3.4",
    "@angular/core": "~4.3.4",
    "@angular/forms": "~4.3.4",
    "@angular/http": "~4.3.4",
    "@angular/platform-browser": "~4.3.4",
    "@angular/platform-browser-dynamic": "~4.3.4",
    "@angular/router": "~4.3.4",
    "angular-in-memory-web-api": "~0.3.0",
    "systemjs": "0.19.40",
    "core-js": "^2.4.1",
    "rxjs": "5.0.1",
    "zone.js": "^0.8.4"
  },
  "devDependencies": {
    "concurrently": "^3.2.0",
    "lite-server": "^2.2.2",
    "typescript": "2.6.0",
    "canonical-path": "0.0.2",
    "tslint": "^3.15.1",
    "lodash": "^4.16.4",
    "jasmine-core": "~2.4.1",
    "karma": "^1.3.0",
    "karma-chrome-launcher": "^2.0.0",
    "karma-cli": "^1.0.1",
    "karma-jasmine": "^1.0.2",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~4.0.14",
    "rimraf": "^2.5.4",
    "@types/node": "^6.0.46",
    "@types/jasmine": "2.5.36"
  },
  "repository": {}
}

npm 5.5.1
node 8.9.1

Any workaround?

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

Hi

./node_modules/@types/core-js/index.d.ts:1461:36 - error TS2339: Property 'for' does not exist on type 'SymbolConstructor'.

1461 const _for: typeof core.Symbol.for;
~~~

../node_modules/@types/core-js/index.d.ts:1465:43 - error TS2339: Property 'hasInstance' does not exist on type 'SymbolConstructor'.

1465 const hasInstance: typeof core.Symbol.hasInstance;
~~~

../node_modules/@types/core-js/index.d.ts:1469:50 - error TS2339: Property 'isConcatSpreadable' does not exist on type 'SymbolConstructor'.

1469 const isConcatSpreadable: typeof core.Symbol.isConcatSpreadable;
~~~~~~

../node_modules/@types/core-js/index.d.ts:1477:38 - error TS2339: Property 'keyFor' does not exist on type 'SymbolConstructor'.

1477 const keyFor: typeof core.Symbol.keyFor;
~~

../node_modules/@types/core-js/index.d.ts:1481:37 - error TS2339: Property 'match' does not exist on type 'SymbolConstructor'.

1481 const match: typeof core.Symbol.match;
~

../node_modules/@types/core-js/index.d.ts:1485:39 - error TS2339: Property 'replace' does not exist on type 'SymbolConstructor'.

1485 const replace: typeof core.Symbol.replace;
~~~

../node_modules/@types/core-js/index.d.ts:1489:38 - error TS2339: Property 'search' does not exist on type 'SymbolConstructor'.

1489 const search: typeof core.Symbol.search;
~~

../node_modules/@types/core-js/index.d.ts:1493:39 - error TS2339: Property 'species' does not exist on type 'SymbolConstructor'.

1493 const species: typeof core.Symbol.species;
~~~

../node_modules/@types/core-js/index.d.ts:1497:37 - error TS2339: Property 'split' does not exist on type 'SymbolConstructor'.

1497 const split: typeof core.Symbol.split;
~

../node_modules/@types/core-js/index.d.ts:1501:43 - error TS2339: Property 'toPrimitive' does not exist on type 'SymbolConstructor'.

1501 const toPrimitive: typeof core.Symbol.toPrimitive;
~~~

../node_modules/@types/core-js/index.d.ts:1505:43 - error TS2339: Property 'toStringTag' does not exist on type 'SymbolConstructor'.

1505 const toStringTag: typeof core.Symbol.toStringTag;
~~~

../node_modules/@types/core-js/index.d.ts:1509:43 - error TS2339: Property 'unscopables' does not exist on type 'SymbolConstructor'.

1509 const unscopables: typeof core.Symbol.unscopables;
~~~

../node_modules/@types/core-js/index.d.ts:2272:36 - error TS2339: Property 'for' does not exist on type 'SymbolConstructor'.

2272 const _for: typeof core.Symbol.for;
~~~

../node_modules/@types/core-js/index.d.ts:2276:43 - error TS2339: Property 'hasInstance' does not exist on type 'SymbolConstructor'.

2276 const hasInstance: typeof core.Symbol.hasInstance;
~~~

../node_modules/@types/core-js/index.d.ts:2280:50 - error TS2339: Property 'isConcatSpreadable' does not exist on type 'SymbolConstructor'.

2280 const isConcatSpreadable: typeof core.Symbol.isConcatSpreadable;
~~~~~~

../node_modules/@types/core-js/index.d.ts:2288:38 - error TS2339: Property 'keyFor' does not exist on type 'SymbolConstructor'.

2288 const keyFor: typeof core.Symbol.keyFor;
~~

../node_modules/@types/core-js/index.d.ts:2292:37 - error TS2339: Property 'match' does not exist on type 'SymbolConstructor'.

2292 const match: typeof core.Symbol.match;
~

../node_modules/@types/core-js/index.d.ts:2296:39 - error TS2339: Property 'replace' does not exist on type 'SymbolConstructor'.

2296 const replace: typeof core.Symbol.replace;
~~~

../node_modules/@types/core-js/index.d.ts:2300:38 - error TS2339: Property 'search' does not exist on type 'SymbolConstructor'.

2300 const search: typeof core.Symbol.search;
~~

../node_modules/@types/core-js/index.d.ts:2304:39 - error TS2339: Property 'species' does not exist on type 'SymbolConstructor'.

2304 const species: typeof core.Symbol.species;
~~~

../node_modules/@types/core-js/index.d.ts:2308:37 - error TS2339: Property 'split' does not exist on type 'SymbolConstructor'.

2308 const split: typeof core.Symbol.split;
~

../node_modules/@types/core-js/index.d.ts:2312:43 - error TS2339: Property 'toPrimitive' does not exist on type 'SymbolConstructor'.

2312 const toPrimitive: typeof core.Symbol.toPrimitive;
~~~

../node_modules/@types/core-js/index.d.ts:2316:43 - error TS2339: Property 'toStringTag' does not exist on type 'SymbolConstructor'.

2316 const toStringTag: typeof core.Symbol.toStringTag;
~~~

../node_modules/@types/core-js/index.d.ts:2320:43 - error TS2339: Property 'unscopables' does not exist on type 'SymbolConstructor'.

2320 const unscopables: typeof core.Symbol.unscopables;
~~~

This is the error i am getting

my tsconfig
{
"compileOnSave": false,
"compilerOptions": {
"baseUrl": "",
"outDir": "./dist/out-tsc",
"sourceMap": true,
"declaration": false,
"downlevelIteration": true,
"experimentalDecorators": true,
"module": "es6",
"moduleResolution": "node",
"importHelpers": true,
"target": "es5",
"typeRoots": [
"node_modules/@types"
],
"lib": [
"es5",
"es2015",
"es2017",
"dom",
"scripthost"
],
},
"angularCompilerOptions": {
"fullTemplateTypeCheck": true,
"strictInjectionParameters": true
}
}
help me to solve the issue