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Mangling non-main-entry-export names

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
javascript, rollup
Domain
build-system, tooling

Research direction

Start by running the two-module example in _prepare.mjs and main.mjs through microbundle with the supplied mangle.json. Inspect how the main entry point and its re-exported names affect mangling of _stringifyCallback and _prepare; done means determining whether either name can be safely mangled and capturing the resulting behavior.

Written by the indexing model from the issue text.

Description

needs more info

Suppose I have the following two files:
_prepare.mjs

const _stringifyCallback = (_, value) => {
  if (!value.isSJS) return value;
  return `${value.type}__sjs`;
};

const _prepare = (schema) => {
  const _preparedString = JSON.stringify(schema, _stringifyCallback);
  const _preparedSchema = JSON.parse(_preparedString);

  return {
    _preparedString,
    _preparedSchema,
  };
};

export { _prepare };

and

main.mjs, which is the entry point.

import { _prepare } from './_prepare.mjs'

function a() { _prepare({}); }
function b() { /* do other stuff */ }

export { a, b }

This results in the following minification:

const _stringifyCallback=(e,r)=>r.t?`${r.type}__sjs`:r,_prepare=e=>{const r=JSON.stringify(e,_stringifyCallback);return{_:r,p:JSON.parse(r)}};function a(){_prepare({})};function b(){};export{a,b};

However, when monitoring closely _stringifyCallback could be mangled, but is not, and also _prepare could be mangled, since it is not exported from the main entry point.
Is there a way to achieve at least one of the mangling?

The following mangle.json did not change anything (I tested a lot):

{
  "minify": {
    "mangle": {
      "toplevel": true,
      "properties": true,
      "keep_fnames": false
    },
    "compress": {
      "keep_fnames": false,
      "reduce_funcs": false,
      "passes": 2
    },
    "toplevel": true
  }
}
Dominant language
JavaScript
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