🐞 bug report

Affected Package

The issue is caused by package @angular/common.

Description

I18n methods like getLocaleDayNames or getLocaleMonthNames (maybe there are more - haven't checked) always returns the same reference.

Let the code speak for itself:

const dayNames = getLocaleDayNames('en-US', FormStyle.Format, TranslationWidth.Short);
// dayNames = ["Su", "Mo", "Tu", "We", "Th", "Fr", "Sa"]

dayNames.splice(2);
// dayNames = ["Su", "Mo"];

const freshDayNames = getLocaleDayNames('en-US', FormStyle.Format, TranslationWidth.Short);
// freshDayNames = ["Su", "Mo"]; 
// 🙀 🙀 🙀 

This can lead to undesirable behaviour when some third party library modifies locale data.

🔬 Minimal Reproduction

https://stackblitz.com/edit/angular-vbiv7d