Support "extends" tsconfig directive

[raythurnvoid]

Is your feature request related to a problem? Please describe.
svelte-preprocess seems to not follows the extends directive provided in a tsconfig.

Describe the solution you'd like
Using typescript.parseJsonConfigFileContent should do the trick.

How important is this feature to you?
It's not blocking, since i could implement my custom tsconfig file reader, but it would be nice to have this feature built-in.

[kaisermann]

Hey @raythurnevoid 👋

If I'm not mistaken, the parseJsonConfigFileContent needs a valid ParseConfigHost, which is a bit too much for this IMO. Can you check if #302 would be enough?

[raythurnvoid]

Thank you for the reply!
Unfortunately it's not enough :(.
There are two main issues, it's not recursive and require will break with comments in tsconfig.json (which "@tsconfig/svelte/tsconfig.json" has).

Actually also ts-loader takes advantage of parseJsonConfigFileContent; it woud allow you to avoid much custom code with the confidence of it working in all occasions.
I know you need ParseConfigHost but you can easily overcome this by passing the sys object exposed under "typescript" package as achieved by ts-loader.

Don't know if it is of any help, i show you what i came up so far. It doesn't use parseJsonConfigFileContent since i have to pass a compilerOptions object in the same format of a regular tsconfig.json to the svelte-loader, and parseJsonConfigFileContent unfortunately doesn't provide it. The problem of my implementation is that it doesn't work with globally installed node_modules and neither with node_modules present in parent folders of the cwd.

[kaisermann]

@raythurnevoid Thanks for the reference links! I will take a look at them and see what I come up with.