No more class chaining since 5.15.1 (class C extends class B extends class A)

[VandeurenGlenn]

Bug report or Feature request?
One of the two ^^

Version (complete output of terser -V or specific git commit)
v5.15.1
Complete CLI command or minify() options used

{
    mangle: false,
    keep_classnames: true,
    ecma: 6
}

terser input

class A  {
  constructor() {
    console.log('super')
  }
}

class B extends A {
  constructor() {
    super()
  }
}

class C extends B {
  constructor() {
    super()
  }
}

export { C as default } 

terser output or error

class A {constructor(){console.log('super')}}class B extends A{constructor(){super()}}class C extendsB{constructor(){super}}

Expected result

class C extends class B extends class A {constructor(){console.log('super')}}{constructor(){super()}}{constructor(){super()}}

[fabiosantoscode]

Classes aren't inlined anymore in some cases to prevent them being created multiple times and then being !== from themselves after a compilation (eg #1267).

It's really tricky to analyze whether something will be executed multiple times (and specializing that for Extends), so I think this is a good trade-off for less scoping bugs, assuming it doesn't increase source code size a lot.

[VandeurenGlenn]

@fabiosantoscode Thanks for the answer, only problem here is that if I try to put the result as text in a 'new Function(code)'
It fails now, I tried multiple ways like adding semicolon after each class etc but no success, only seems to work when the classes are inlined, any ideas?

[fabiosantoscode]

Try returning the class you want the function to return. You'll need to add the bare_returns parse option so Terser doesn't think the return outside a function is a syntax error.

[VandeurenGlenn]

Thanks, I missed the bare_returns option

edit: realized I don't need that option since I do a regex check for exported es and replace it with a return etc https://github.com/ArteonToken/monorepo/blob/main/scripts/create-genesis.js#L13
So just made it so it returns the (desired) class now.
I couldn't seem to figure out the return before (while experimenting in devconsole)
so after you said try to return I tried again and relalized a newline (\n) at the end of the code (for the rest no newlines) was causing the problem.

Thanks for the time!

edit2: so, realised something else 😅 shouldn't Terser remove that newline?