enable updating custom version files with changeset version

[dominikg]

Affected Packages

changesets/cli , version command

Problem

sometimes a package wants to export it's version. To do that, it needs to include something like

// version.js , autogenerated, do not modify
export const VERSION = '1.2.3';

// index.js
export VERSION from './version.js'

in it's output.

But version.js can only be updated after changeset version has bumped package.json. Leading to a situation where the version value in package.json and version.js is different until a separate generate-version-js script has been run.

If for whatever reason these two go out of sync, there could be a release where the VERSION export does not correctly reflect the version of package.json, which would be very confusing at best and lead to hard to track errors at worst.

Proposed solution

improve the version command allow updating other files with the bumped verison. This could be other files like documentation too.

One workaround could be to use a custom version arg with the @changeset/action, but this ties it to github actions.

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Background: we are moving svelte to a pnpm monorepo with changesets and need to export the version in unbundled esm.

[dominikg]

Looks like with commit: false option which is the default, it is possible to do this after changeset version and before commiting. The changeset action allows to pass a custom version script so with a bit of scripting effort this is achievable today.

Still would be nice to have something builtin.