Unsupported syntax for async arrow functions with multiline generic parameters

[seralexeev]

First of all, thank you for your work on ts-blank-space. I've migrated all my projects to use it, and everything works great. It has been a breath of fresh air in the complex world of building TypeScript projects in monorepos.

I wanted to share an edge case I encountered. I understand that this is an edge case that can be resolved by suppressing Prettier or changing a method expression to a method declaration. I don't think this case can be fixed by changing anything in ts-blank-space.

I studied the unsupported_syntax.md and didn't find this case documented. I believe it would be helpful to add it to the documentation.

Problem Description:

Consider the following async arrow function with generic parameters:

const fn = async <T>() => null;

After transformation with ts-blank-space, I get:

const fn = async () => null;

Which is syntactically correct.

However, if the function contains a large list of generic parameters, Prettier may move the parameters to new lines:

const fn = async <
    T,
    U,
    V
>() => null;

After transformation with ts-blank-space, I get:

const fn = async



 () => null;

This code is syntactically incorrect and leads to a runtime error:

Uncaught SyntaxError: Malformed arrow function parameter list

Since this is not an error in ts-blank-space but an example of code that is not supported by design, I think it would be helpful to add it to the documentation under unsupported syntax.

[acutmore]

Hi @seralexeev!

First of all, thank you for your work on ts-blank-space. I've migrated all my projects to use it, and everything works great. It has been a breath of fresh air in the complex world of building TypeScript projects in monorepos

I'm really pleased to hear this 😀

Thank you so much for finding this issue. I think this is a bug, and it can be supported. The output can be:

const fn = async (



  ) => null;

Moving the opening paren up to where the generic type began. This is similar to how a multi-line return type is fixed up.

[acutmore]

I've raised #19. should be an easy fix. I'll look into this today.

[seralexeev]

Hey @acutmore. Thanks for the super quick response and your effort 🔥

[acutmore]

@seralexeev the fix is available in [email protected].

Thanks again for the report!