Esbuild throws errors on generic arrow functions in certain cases

[charliematters]

Bug description

We have upgraded esbuild-loader to avoid the node 18 bug in webpack, and suddenly we are getting syntax errors which are not being reported by tsc.

It seems that it can no longer parse this line:

const foo = async <T>(bar:T): Promise<T> => bar

The error thrown is Expected ")" but found ":"

I've added a repo which shows that when that file is consumed from stdin it fails, but passing the filename as an argument works as expected

Minimal reproduction link

https://github.com/charliematters/esbuild-issue

[evanw]

Data from stdin is a raw string without any file extension attached, so esbuild has no information about what type of file it is. In that case, esbuild defaults to assuming the input is JavaScript. You need to specify a different loader if that's not the case (e.g. --loader=ts).

I'm closing this issue because esbuild is working as expected.

[charliematters]

Ah, that makes sense - thanks. Now I just have to apply that to my esbuild-loader config!