Introduction

Hello there ! first of all thanks for the great work, using preconstruct was very smooth and helped me a lot to understand multi-entrypoint import both in esm/cjs

Related PR #618

The issue

Right now unless I'm mistaken, will only be computed the package/tsconfig.json.
This could be a bottleneck when working with composite TypeScript projects ( aka solution style TypeScript configuration ) or when having a dedicated tsconfig json file for build etc.

// tsconfig.json
{
   // ...
  "files": [],
  "include": [],
  "references": [
    {
      "path": "./tsconfig.lib.json"
    },
    {
      "path": "./tsconfig.spec.json"
    }
  ]
}

Actual

In this way, from my understanding of the preconstruct the current "stick to tsconfig.json" behavior is implied by the

// cli/src/rollup-plugins/typescript-declarations/common.ts

export async function getProgram(dirname: string, pkgName: string, ts: TS) {
  let configFileName = ts.findConfigFile(dirname, ts.sys.fileExists);

Which has this signature

  function findConfigFile(searchPath, fileExists, configName = "tsconfig.json") {

Suggestion

Adding a new configuration option tsConfigFilename under a typescript configuration object in Preconstruct's config:

{
  "preconstruct": {
    "typescript": {
      "tsConfigFilename": "tsconfig.build.json"
    }
  }
}

Related pull-request

Created this #618 in order to give more context and consistency to this issue
Tests might not be the most idiomatic and such could also be the configuration naming 😅 let me know !

As always any suggestions are welcomed !
Have a great day !