Core-js: failed to compile after 3.0.0 update

[blondie63]

I've a Ionic 4 working project with latest plugins (angular 7.2.10 etc etc), this is my package.json
"dependencies": {
"@angular/common": "^7.2.10",
"@angular/core": "^7.2.10",
"@angular/forms": "^7.2.10",
"@angular/http": "^7.2.10",
"@angular/platform-browser": "^7.2.10",
"@angular/platform-browser-dynamic": "^7.2.10",
"@angular/pwa": "^0.13.6",
"@angular/router": "^7.2.10",
"@angular/service-worker": "7.2.10",
"@capacitor/cli": "^1.0.0-beta.19",
"@capacitor/core": "1.0.0-beta.19",
"@ionic-native/core": "^5.3.0",
"@ionic-native/splash-screen": "^5.3.0",
"@ionic-native/status-bar": "^5.3.0",
"@ionic/angular": "^4.1.1",
"angular-pipes": "^9.0.2",
"cordova-android": "^8.0.0",
"cordova-ios": "5.0.0",
"cordova-plugin-device": "^2.0.2",
"cordova-plugin-ionic-keyboard": "^2.1.3",
"cordova-plugin-ionic-webview": "^4.0.0",
"cordova-plugin-splashscreen": "^5.0.2",
"cordova-plugin-statusbar": "^2.4.2",
"cordova-plugin-whitelist": "^1.3.3",
"core-js": "^3.0.0",
"dayjs": "1.8.10",
"google-libphonenumber": "^3.2.2",
"rxjs": "~6.4.0",
"zone.js": "~0.8.29"
},
"devDependencies": {
"@angular-devkit/architect": "~0.13.6",
"@angular-devkit/build-angular": "~0.13.6",
"@angular-devkit/core": "~7.3.6",
"@angular-devkit/schematics": "~7.3.6",
"@angular/cli": "~7.3.6",
"@angular/compiler": "~7.2.10",
"@angular/compiler-cli": "^7.2.10",
"@angular/language-service": "~7.2.10",
"@commitlint/cli": "^7.5.2",
"@commitlint/config-conventional": "^7.5.0",
"@ionic/angular-toolkit": "~1.4.1",
"@ionic/lab": "1.0.24",
"@types/node": "~11.11.4",
"codelyzer": "5.0.0-beta.1",
"husky": "^1.3.1",
"pre-commit": "^1.2.2",
"ts-node": "~8.0.3",
"tslint": "~5.14.0",
"typescript": "~3.2.4"

After upgrade to core-js 3.0.0 i've a failed to compile error:
[ng] ERROR in ./node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/jit-polyfills.js
[ng] Module not found: Error: Can't resolve 'core-js/es7/reflect' in '/Users/mauro/Documents/_projects/Ionic Apps/Ionic4_tests/ionic4-full-starter-app-1.2/node_modules/@angular-devkit/build-angular/src/angular-cli-files/models'
[ng] ERROR in ./src/polyfills.ts
[ng] Module not found: Error: Can't resolve 'core-js/es7/reflect' in '/Users/mauro/Documents/_projects/Ionic Apps/Ionic4_tests/ionic4-full-starter-app-1.2/src'

Some help ?

[nicolo-ribaudo]

I think that that dependency is importing core-js but it isn't specified in their dependencies.

[nicolo-ribaudo]

Tracked at https://github.com/angular/angular-cli/issues/13954, duplicate of https://github.com/zloirock/core-js/issues/412

[blondie63]

Really i've created my project with cmd like this:
ionic start corejs3-test tabs
And ionic add corejs as dependencie, i'm not using directly, so maybe you are right and this is a problem of Angular.. it's better to stay on core-js 2.6.5 untile Angular start to use v3.0.0
Do you agree?

[nicolo-ribaudo]

The problem is not that angular doesn't use core-js@3: is that they are using core-js@2 without listing it in their dependencies. As soon as their fix that but, you can use core-js@3 in your project.