Bundled library contains annotation that Rollup cannot interpret

[blcham]

Bundled SForms library is causing build warning in in Record Manager UI (see warning 2).

Here is the warning:

For now this warning was disabled in Record Manager by commit https://github.com/kbss-cvut/record-manager-ui/pull/116/commits/eaed82ad0a2864513ed1277da736dda91c26d95e .

To test it revert the commit and run npm run build.

[blcham]

@LaChope please investigate ... at least find where the issue is w.r.t. source code.

[blcham]

Some additional notes from https://github.com/shellyear and how it works in record-manager-ui build:

• "node_modules/@kbss-cvut/s-forms/dist/s-forms.modern.js" contains an annotation that Rollup cannot interpret due to the position of the comment.

• PURE*/ annotation is a hint to the minifier that the associated code can be safely removed if it's not being used.

• Invalid annotations are removed and Rollup emits a warning. Valid annotations remain in the code unless their function call or constructor invocation is removed as well.
• related configuration setting for Rollup -- https://rollupjs.org/configuration-options/#treeshake-manualpurefunctions
• similar issue in vue-i18n-next

[LaChope]

I investigated and this appears 194 times in s-forms, so I am not really able to tell what exactly causes it. All I know is that it is caused when bundling s-forms (by microbundle) and that is related to tree shaking (to optimize the bundle).

According to this comment, this is probably linked to its position. IMO, I still think it should be ignored as it does not affect the behavior of the app. We might consider changing of bundler, as microbundle does not seem to be updated (last commit is from 2 years ago).

Additional information from rollup:

• Rollup relies on static analysis to optimize code, including tree shaking to remove unused code. Comments can sometimes interfere with this process, especially if they are placed in a position where Rollup cannot safely determine their impact on the code's purity.
• In most cases, this warning is informational and does not necessarily indicate a critical issue with the code or build process. It's more of a heads-up that Rollup encountered something it couldn't optimize due to the presence of a comment in an unexpected location.

TL-DR: When microbundle bundles s-forms, it generates PURE comment to optimize the bundle (eliminates pure functions), but it is badly placed (not in front of function) so it is removed by rollup.

[blcham]

Maybe we should choose a different library bundler, see:

• 2022/03 -- nice comparison of related tools
• 2021/04 -- not very detailed comparison

After reading links above it seems that Vite is worth to try, maybe see: Create a Component Library Fast🚀(using Vite's library mode)