no-function-expression and generic functions in TSX

[astorije]

While the following is supported by the language:

function foo<T>(x: T): T { return x; }

The following is not:

const foo = <T>(x: T) => x; // ERROR : unclosed `T` tag

no-function-expression encourages to use arrow functions, which can lead to the following to make the linter pass (or disable the linter on a case-by-case basis):

const foo = <T extends {}>(x: T) => x;

Which isn't great. See https://stackoverflow.com/questions/32308370/what-is-the-syntax-for-typescript-arrow-functions-with-generics

Similarly to the fact that function expressions that contain a this reference are allowed and will not create a failure, it would be nice if function expressions that have a generic type were allowed.

Thoughts?

[JoshuaKGoldberg]

The following is not:

const foo = <T>(x: T) => x; // ERROR : unclosed `T` tag

Are you on the latest TypeScript? That works fine for me on typescriptlang.org/play (link). Seems like that SO answer is outdated now?

[astorije]

Yes, latest TypeScript, but I believe this is a limitation of TSX. So the exclusion could be generic function in a TSX file.

[JoshuaKGoldberg]

TSX

Ah! I'd missed that. Yes, agreed, this is a bug. +1 to excluding these generic functions in TSX files.