Incorrect const A declaration after a class B extends A is moved and becomes unnamed during minification

[goto-bus-stop]

Bug report or Feature request?
Bug report.

Version (complete output of terser -V or specific git commit)

terser 4.6.9

According to git bisect, this regressed in 0e40b8d.

Complete CLI command or minify() options used

terser input.js --compress --beautify

terser input

(function () {
    const HtmlContent = require('./html-content.js')
    class BreadcrumbPanel extends HtmlContent {}
    module.exports = BreadcrumbPanel
}())

From my tests, it seems to only happen with a combination of factors:

• The HtmlContent variable is used in a class's extends node
• The class that it is used in (BreadcrumbPanel) is named
• The class that it is used in (BreadcrumbPanel) becomes anonymous during minification, and/or the class that it is used in is moved during minification (to module.exports = class {})

For example, using the HtmlContent value in these patterns do not have this bug:

console.log(HtmlContent)

const BreadcrumbPanel = class extends HtmlContent {}

module.exports = class BreadcrumbPanel extends HtmlContent {}

terser output or error
The initializer is separated from the const declaration by a semicolon, which is invalid:

!function() {
    const HtmlContent;
    require("./html-content.js");
    module.exports = class extends HtmlContent {};
}();

Expected result

!function() {
    const HtmlContent = require("./html-content.js");
    module.exports = class extends HtmlContent {};
}();

[fabiosantoscode]

Nasty! I'll have a look right away.

[200Puls]

I think I encountered the same issue. This happens since 4.6.8.

Chrome Console says: Uncaught SyntaxError: Missing initializer in const declaration

{const e;Wt(t);return class extends e{

I havent looked up the source as it occurs in a library I use (Polymer)

[goto-bus-stop]

That does the trick 🎉 Thanks for the quick fix @fabiosantoscode!

[fabiosantoscode]

I'm waiting for the functional tests to ship 4.6.10

[Haprog]

Thanks a lot for the quick fix!