Decorator wrapped around declare or abstract fields are failing since 0.19.8

[rodrigofuentes]

The issue I'm facing is decorated declare or abstract fields are causing an Error: Decorators are not valid here. After some inspection it seems that esbuild supported this until version 0.19.8

Is this no longer supported?

Code example:

function log(target: any, key: string): void {
  console.log(`Logging ${key} function`)
}

abstract class ExampleClass {
  @log
  abstract prop1: string

  @log
  prop2: boolean = true
}

class ExampleClass2 extends ExampleClass {
  prop1: string = "world"
}

Esbuild result:

✘ [ERROR] Decorators are not valid here

    entry.ts:6:2:
      6 │   @log
        ╵   ^

Some playground links:

Working esbuild-playground on version 0.19.7

typescript-playground

[evanw]

There are two problems here:

1. Using decorators like this is legacy TypeScript-specific behavior that requires you to set "experimentalDecorators": true in your tsconfig.json file. You can do this on esbuild's command line with --tsconfig-raw='{"compilerOptions":{"experimentalDecorators":true}}' like this.

2. This currently only works for declare fields, not for abstract fields. This is an esbuild bug that I can fix (I didn't think about the abstract case).

[rodrigofuentes]

@evanw abstract support would be awesome thanks.