Useless constructor not removed during minification

[NullVoxPopuli]

Playground link: https://esbuild.github.io/try/#dAAwLjE5LjUAewogIG1pbmlmeTogdHJ1ZQp9AGNsYXNzIEJhciB7fQpleHBvcnQgY2xhc3MgRm9vIGV4dGVuZHMgQmFyIHsKICBjb25zdHJ1Y3RvcigpIHsKICAgIHN1cGVyKC4uLmFyZ3VtZW50cykKICB9Cn0

Expected

class r{}export class Foo extends r{}

Actual

class r{}export class Foo extends r{constructor(){super(...arguments)}}

related to: #3463

[NullVoxPopuli]

Related:

• Drop constructor() if it contains only super() with same arguments swc-project/swc#7336
• Drop empty constructors during minification swc-project/swc#8177
• empty constructor is not removed during minification #3463
• Useless constructor not removed during minification #3464
• Useless contsructor not removed terser/terser#1467
• empty constructor not removed terser/terser#1468

[bakkot]

Those are not semantically equivalent. The latter observably uses ArrayIteratorPrototype; the former does not.

For example, if you run Array.prototype.values().__proto__.next = function(){ throw 'no'; } first, and new Foo after, only the latter will throw.

(In some browsers the former will still throw because they have not yet implemented tc39/ecma262#2216.)

[NullVoxPopuli]

why would someone do that to all their iterators? 🤔
assuming people aren't trying to run prototype injection attacks against themselves, it's basically the same as

https://esbuild.github.io/try/#dAAwLjE5LjUAewogIG1pbmlmeTogdHJ1ZQp9AGNsYXNzIEJhciB7fQpleHBvcnQgY2xhc3MgRm9vIGV4dGVuZHMgQmFyIHsKICBjb25zdHJ1Y3Rvcihmb28sIGJhcikgewogICAgc3VwZXIoZm9vLCBiYXIpCiAgfQp9

which would be:

code

class Bar {}
export class Foo extends Bar {
  constructor(foo, bar) {
    super(foo, bar)
  }
}

actual

class c{}export class Foo extends c{constructor(o,r){super(o,r)}}

expected

class c{}export class Foo extends c{}