why does eslint require await for synchronous request and reply methods in VS code?

[budarin]

💬 Question here

here the code:

eslint error:

Your Environment

• node version: 18
• fastify version: 4.9.2
• os: any
• VS Code: 1.72.2

[Uzlopak]

Seems to be, that typescript thinks that it is a promise and not a sync function.

Can you provide a repo with that issue?

[budarin]

I'll try to make a demo repo from our project

[budarin]

@Uzlopak here is it

[Uzlopak]

LOL, that project has half of the npm registry as dependencies ;).

Ok it is because FastifyReply has a .then-method with two parameters

https://github.com/fastify/fastify/blob/68914519a3fd65ce65ba8db8962940eecf7f0fc8/types/reply.d.ts#L63

so eslint assumes it is a a Promise.

https://github.com/typescript-eslint/typescript-eslint/blob/0be356bae50156ba159c70d570b030e6d94afcb1/packages/eslint-plugin/src/rules/no-floating-promises.ts#L184

It is an issue of eslint and not of Fastify.

[budarin]

I wanted to keep the system in the state it is in for investigation :)

But they will rightly object to me that everything that has the 'then' method is a Promise and what should I do in this situation?

[Uzlopak]

You mean with "they" your colleagues?

Well sorry, but it is what it is. I dont know how we could fix it on our side to get that false positive fixed. It is an issue of eslint, as it is ducktyping it too wide.

What you can do is to add a local patch and remove the then-method in reply.d.ts

[jsumners]

everything that has the 'then' method is a Promise

Not so. Such things are thennables.

As covered in fastify/fastify#4246, it's out of our control.

[budarin]

ok, I created an issue in eslint