Disallow newline after `as` after function instantiation

🔎 Search Terms

as newline ASI function type parameters spec difference

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

https://www.typescriptlang.org/play?#code/CYUwxgNghgTiAEAzArgOzAFwJYHtVJxwB4AVAPgAoBKALnhIChRJYFUoBbEAZwAcowCAGLwA3vBAAPXjhgZ4GAJ68EAcxAYMIGPAC88KKkXwAvk3DQ48CBoPc6hxQwY35kvQRzwi8AEzwyOwYhADp1TW0GIA

💻 Code

let x = foo < 2 > as
F.getter

🙁 Actual behavior

It is parsed as

let x = foo<2> as F.getter;

🙂 Expected behavior

It should be parsed as

let x = (foo < 2) > as;
F.getter;

Additional information about the issue

The linked code is valid JavaScript code, and it would be great if tsc could parse as such.

I know that TS is not in general a syntactic superset of JavaScript, but both Babel and SWC already parse this example (when in TS mode) according to JS semantics. We could change our parsers, but it would be better if this ambiguity could be solved in tsc.

cc @kdy1

Riproduci la differenza di parsing utilizzando il TypeScript Playground collegato e l’esempio di codice fornito, quindi traccia il modo in cui il parser TypeScript gestisce as attraverso un ritorno a capo dopo l’istanziazione di una funzione. Il lavoro è completo quando l’esempio segue il parsing JavaScript/ASI previsto e il comportamento di parsing esistente di TypeScript rimane coperto dai test.