[heft] heft-typescript-plugin - error with an array at the extends property

[diabhoil]

Summary

I am trying to extend my tsconfig.json with a rig config and a custom config from a multi project repo. So my tsconfig.json looks something like this:

{
  "extends": [
    "./node_modules/@microsoft/spfx-web-build-rig/profiles/default/tsconfig-base.json",
    "../../tsconfig.base.json"
  ]
}

When I am trying to build the project, this fails somewhere in the heft-typescript-plugin:

The schema for TypeScript allows this syntax. The schema in the heft-typescript-plugin does not.

Repro steps

I am working with a SPFx setup which is using heft since version 1.22.
So the easiest way would be to

1. Create a SPFx project
2. Change the tsconfig to include an array

But a simple heft typescript project should work too.

Details

What do you think is the cause of this problem? see above
How do you think we should fix this? extend the schema for allowing arrays

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question	Answer
@rushstack/heft version?	1.1.2
Operating system?	windows / linux (wsl)
Would you consider contributing a PR?	Maybe
Node.js version (node -v)?	22.17.0

[iclanton]

extends arrays aren't currently supported by Heft. We could do the work to add support for this, but the semantics get pretty complicated pretty quickly. This isn't just the schema not allowing extends arrays, @rushstack/heft-config-file would need to support this as well.

Can you have your tsconfig.base.json extend @microsoft/spfx-web-build-rig/profiles/default/tsconfig-base.json instead of providing an array in your project's tsconfig?

[diabhoil]

@iclanton we tried but that is not working.
If we do it, then we get problems with the relative paths defined in the rig tsconfig. To handle that problem, we either have to copy contents of the rig config to our tsconfig to correct the path errors. Or - we have to reference the rig config from project node_modules folder. But that is not working for our project structure either.

Our project structure is having multiple projects on the same level and we want to share a tsconfig between these projects.
So if we reference the extend path in the shared tsconfig lying in the root folder, to one node_modules folder of a subproject the subproject might work, but the other projects are not.

So I guess we have to continue to just extend all the projects tsconfig.json with settings ;)