Comments in export default are removed in production mode

[jddxf]

Bug report

What is the current behavior?
Webpack generates output in production mode without minimizers

/* harmony default export */ var src_bar = (Math.abs(0));

for the code below

// ./src/bar.ts
export default /*@__PURE__*/Math.abs(0);

However, if I write code like this

const value = /*@__PURE__*/Math.abs(0);
export default value;

the comment is reserved

var value = /*@__PURE__*/Math.abs(0);
/* harmony default export */ var src_bar = (value);

This behavior brings me some troubles. I have to preprocess my code to split all the inline default exports.

If the current behavior is a bug, please provide the steps to reproduce.

What is the expected behavior?
Perhaps webpack should reserve the comments as below

/* harmony default export */ var src_bar = /*@__PURE__*/(Math.abs(0));

I'm not sure though, since the comments may be considered to belong to the export statement.

Other relevant information:
webpack version: 4.20.1
Related issue: #8039