Decorator output is inconsistent

[vjeux]

In this example, the decorator is not wrapped in a Decorator node:

class Person {
  @inject leftLeg: Leg;
}

==>

node.decorators = [ {type: 'Identifier'} ];

In this example, it is wrapped in a TSDecorator node, instead of Decorator node:

@dec enum E {}

==>

node.decorators = [ {type: 'TSDecorator', expression: {type: 'Identifier'}} ];

It would be nice if decorators arrays was always wrapped in a Decorator node (without TS prefix). This way it would work out of the box with babylon decorators.

I have a workaround in prettier, but I'd rather it be fixed inside of this project: prettier/prettier#1509

[soda0289]

Thanks for the report.
We can make this change. We should be following the estree spec:
https://github.com/estree/estree/blob/master/experimental/decorators.md

Typescript also allows decorators on method parameters but should still be using the same node type in all cases.

[vjeux]

Thanks for being super responsive!

[JamesHenry]

Nice to see you over this side @vjeux 😉

Just FYI @dec enum E {} is semantically invalid TypeScript, there are currently no examples of decorators outside of a class context in TS. But regardless, I agree that the AST should be consistent, even when the semantics are incorrect. The raw TypeScript AST definitely is in this case.

I'll submit a PR for this tomorrow.

[vjeux]

We're running prettier on all the typescript tests and looking at where it crashes. So expect a lot of crazy edge cases uncovered!

[vjeux]

vscode uses a lot of decorators and right now prettier is crashing because of the inconsistency fyi.