XRegExp pattern fails when using IE11 (polyfills-es5)

[psmyrdek]

🐞 bug report

Affected Package

@angular/core

Is this a regression?

Yes - works fine on 8.x

Description

🔬 Minimal Reproduction

Create a fresh project (Angular 9.1) and replace main.ts with the following content:
https://gist.github.com/psmyrdek/a32ed781830f1c69472c0580123330ef

It works on Chrome, Firefox, etc. but it doesn't work on IE11. Everything is fine if we're on 8.x

🔥 Exception or Error

🌍 Your Environment

Angular Version:

Angular CLI: 9.1.0
Node: 12.16.1
OS: darwin x64

Angular: 9.1.0
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.901.0
@angular-devkit/build-angular     0.901.0
@angular-devkit/build-optimizer   0.901.0
@angular-devkit/build-webpack     0.901.0
@angular-devkit/core              9.1.0
@angular-devkit/schematics        9.1.0
@ngtools/webpack                  9.1.0
@schematics/angular               9.1.0
@schematics/update                0.901.0
rxjs                              6.5.4
typescript                        3.8.3
webpack                           4.42.0

we're also relying on xregexp@4.3.0

[psmyrdek]

I'm aware that it probably has nothing with Angular itself, but rather with Angular build pipe (babel, core-js, etc.). All in all, we noticed it right after upgrading to 9.1 so I want to ask for some guidance.

[psmyrdek]

Testing the same pattern using "@angular/cli": "8.0.6" () and "@angular/cli": "9.1.0" and for sure there are some changes in RegExp polyfill.

In both cases, I'm trying to translate the same pattern and I see a different output in console:

Works fine -"@angular/cli": "8.0.6" with core-js@3.0.1 and @babel/runtime-corejs3@7.9.2:

Breaks on -"@angular/cli": "9.1.6" with core-js@3.6.4 and @babel/runtime-corejs3@7.9.2:

And the base is:

XRegExp('(^((?=[uuuuuuuuu\\sxxxxxxxxx\\p{L}\\p{N}\\p{P}\\p{S}\\p{M}/])[^;\\\\<>{}])*$)|(^$)')

(u and x chars introduced only to see how the \s behaves)

UPDATE: Can confirm that "@angular/cli": "9.1.6" with core-js@3.0.1 works fine 🤔

[alan-agius4]

Closing as this is ok it actionable by the Angular tooling team.

We’ll consume the fix once the core-ha team addressed the problem.

[angular-automatic-lock-bot]

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