Emitter helper function could be override by user code

Bug Report

🔎 Search Terms

emit, helper

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________

⏯ Playground Link

https://www.typescriptlang.org/play?target=1#code/MYewdgzgLgBA+nApgDyosATCMC8MAUAlLgHwwDeMUAFgE4gDuMYiTAorfbUTAL4CwAKCHAANgEMI2AEIUY43DACMfERKkwAIjBRpMMigOGCAbuNowMilk01ER4CCFGIAdKJABzfBlfjCQA

💻 Code

const __extends = () => { throw new Error() }

class B { a = 1 }
class D extends B {}

var d = new D()
console.log(d.a)

🙁 Actual behavior

Exception

🙂 Expected behavior

console.log(1)

[Kingwl]

We may add a flag what if the flag turns on, tsc will rename the emitted helper name if there are conflicts in a file?

[hardfist]

It really seems like this is the bundler’s fault; there are other scenarios where code taking a dependency on a global could get “blocked” by a hoisted declaration later in the same lexical block. Even mangling is not going to really work here since we would have no way of knowing what other names are in scope since those come from later bundles outside the knowledge of the current compilation.

the bundler comes before compilation , so ts compilation should know all the info about scope name conflict