[Feature request] publishConfig overriding support

[cometkim]

Hi 👋

I recently replaced my own rollup configuration with a microbundle and it's much simpler and just works!

However, there is a part that is not supported in the config I used frequently
In the previous config, I was using this in the package.json.

  "main": "./src/index.ts",
  "publishConfig": {
    "main": "./lib/index.js",
    "module": "./lib/index.mjs",
    "browser": "./lib/index.umd.js",
    "types": "./lib/index.d.ts",
    "access": "public"
  },

This pattern is helpful for monorepo tooling. For example, when I run all test suites for an entire package, this helps the test runner resolve monorepo dependency without an additional build step.

[developit]

I might be misunderstanding - how is this different than the existing package.json main/module/browser/unpkg fields we support?

[cometkim]

When using monorepo, with tools like TypeScript, Jest, and whatever else

core
lib -> core

Suppose I have a newly downloaded repository or run git clean -fdx to do a fresh install.

Then, TypeScript cannot resolve the core package when working on lib because the local dependency has not yet been built, and it also fails when running test.

Using the source file in the main field and overriding it in publishConfig can provide a smart separation of local development and publish environments, so can be useful for some monorepo configurations.

I've learned this pattern from https://github.com/yarnpkg/berry

[cometkim]

Obviously, this is optional. And I believe it will not break existing configs.

Can I make a patch for it?

[developit]

Sure, Seems reasonable.