Subject: bug#63810: closed (Re: bug#63810: 29.0.91; typescript-ts-mode grammar missing the "is" keyword)

From: [email-masked] (GNU bug Tracking System)
Date: Thu, 01 Jun 2023 11:59:02 +0000

Your bug report

#63810: 29.0.91; typescript-ts-mode grammar missing the "is" keyword

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to [email-masked].

-- 
63810: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=63810
GNU Bug Tracking System
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Subject: Re: bug#63810: 29.0.91; typescript-ts-mode grammar missing the "is" keyword
From: Eli Zaretskii <[email-masked]>
To: Theodor Thornhill <[email-masked]>
Cc: [email-masked], [email-masked], [email-masked], [email-masked]
Date: Thu, 01 Jun 2023 14:58:48 +0300
List-Id: <debbugs-submit.debbugs.gnu.org>

> From: Theodor Thornhill <[email-masked]>
> Cc: [email-masked]
> Date: Wed, 31 May 2023 20:51:59 +0200
> 
> Now fixed on emacs-29.

Thanks, closing.

Subject: 29.0.91; typescript-ts-mode grammar missing the "is" keyword
From: Jimmy Yuen Ho Wong <[email-masked]>
To: [email-masked]
Date: Wed, 31 May 2023 08:30:14 +0100
List-Id: <debbugs-submit.debbugs.gnu.org>

Reproduction:

1. C-x C-f test.ts
2. Insert
   ```typescript
   function isFish(pet: Fish | Bird): pet is Fish {
     return (pet as Fish).swim !== undefined;
   }
   ```
3. Observe the `is` keyword isn't highlighted.

Expectation:

TypeScript has a concept called type predicates, which introduces a
keyword called `is`.

[Reference](https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates)