Drop empty constructors during minification

[NullVoxPopuli]

Describe the bug

empty constructor remains in minified output

Input code

import { IS_DEV_MODE } from "debug";

function ifDev(callback: () => void) {
  if (IS_DEV_MODE) {
    callback();
  }
}

export class Foo {
  constructor() {
    ifDev(() => {
      Object.defineProperties({
        hello: {
          enumerable: true,
          get x() { return 1; }
        }
      })
    })
  }
}

Config

{
  "jsc": {
    "parser": {
      "syntax": "typescript",
      "tsx": false
    },
    "target": "es2022",
    "loose": false,
    "minify": {
      "compress": {
        "arguments": false,
        "arrows": true,
        "booleans": true,
        "booleans_as_integers": false,
        "collapse_vars": true,
        "comparisons": true,
        "computed_props": true,
        "conditionals": true,
        "dead_code": true,
        "directives": true,
        "drop_console": false,
        "drop_debugger": true,
        "evaluate": true,
        "expression": false,
        "hoist_funs": false,
        "hoist_props": true,
        "hoist_vars": false,
        "if_return": true,
        "join_vars": true,
        "keep_classnames": false,
        "keep_fargs": true,
        "keep_fnames": false,
        "keep_infinity": false,
        "loops": true,
        "negate_iife": true,
        "properties": true,
        "reduce_funcs": false,
        "reduce_vars": false,
        "side_effects": true,
        "switches": true,
        "typeofs": true,
        "unsafe": false,
        "unsafe_arrows": false,
        "unsafe_comps": false,
        "unsafe_Function": false,
        "unsafe_math": false,
        "unsafe_symbols": false,
        "unsafe_methods": false,
        "unsafe_proto": false,
        "unsafe_regexp": false,
        "unsafe_undefined": false,
        "unused": true,
        "const_to_let": true,
        "pristine_globals": true
      },
      "mangle": false,
    },
    "transform": {
      "constModules": {"globals": {"debug": {"IS_DEV_MODE": "false"}}}
    }
  },
  "module": {
    "type": "es6"
  },
  "minify": false,
  "isModule": true
}

Playground link (or link to the minimal reproduction)

https://play.swc.rs/?version=1.3.94-nightly-20231016.1&code=H4sIAAAAAAAAA01PQWrDMBC8G%2FyHIScZQqFXm%2FbkFHooKRR6Dba8TtTK2rCWQiD474mixPi0w8zszK4ZjiweF3z%2B7OrN7%2B5rW28woRcesOqoDftVlWd51genvWEH09d0Urqxtm30fwlV4O0dJzZdgUue4WaAWoQ9WOC5oooqElOeTTGYzvcDtG3GER%2FMya7ZjV6C9ixqTkjVqfBBAdv2j7R%2F6ag3jr6FjyTe0KhmA3Aga7nEggHIhYGkaS2VuBXReinuyeMceyHkgzi8VvHepzzDqUgozfjRFW4uVnlPAQAA&config=H4sIAAAAAAAAA31VPY%2FbMAzd71cEmjsUGTp0vivQIehQ4FZBsShHV1kyRCqXIPB%2FLy07H5fQ2Sw%2BPlLix%2FPpZbVSH9ion6sTf%2FKhNxkhX85swWMkc2CLomMP2GTfk%2Fp2RglHyJmAUE3DhCgyuQUaWYDr7%2Bv1zFAhJYQzY7Z1Pnp3vM3ZpK7PgHhjYyuHLB1Ewq%2F8GcvpcwQol1v7NqUAJj5BtEHtI0ELWQrcpBBMj6D3JgtRxpua7DFJKUawEFjd59SLeLSefIqc8xG1YKxukgUB8hka8nuQaJyLaRH5ecJ7KmxhW9q29vmODXsTiiEhJxxqS%2Fi2QtRd8kjalSiVcAIXajCBc3Hvmd7pDFRyfOR9JB8XevIPgCsQDGI0HUhxq4fjeVpiu6dMHx2PLB0FnOdbemWElouqvXdCZcfKQCYvdTODLQ2MlW2k68zwQvnQW9DgHM%2BKEBo%2FPTU7Kem46MkJAPfXOGmqJkBftnABHxfiCfyLX0nygM0enaHdMorHbpvCkwQd0C7ZJw7cCkrLcGaVOPTLeIkWeDTAii4FK%2FAoArwAlHSoevkwG7weHFG3IW2vMjE7DBcd7kxs7%2Ff9osWZZc6l3H2VWE67SbaEOgEndU1wUlUf6tfvv%2Fr17V1v%2Fry%2BjWJeo6thGKYEL3MS1dVA19%2FIOEGT%2BP9QV6ezzl%2FuqDxuzsz6rOE%2FQnOQmpIGAAA%3D

SWC Info output

No response

Expected behavior

constructor is removed as it does nothing

Actual behavior

constructor remains

Version

1.3.94-nightly-20231016.1

Additional context

No response

[NullVoxPopuli]

Related:

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

[kdy1]

I don't expect this rule to have a noticeable effect on real-world code.

[NullVoxPopuli]

It compounds for projects that have a lot of class definitions, and is pretty similar to the empty static block removal, yeah?

[kwonoj]

In either case, I really don't think it's worth to separate issue from existing similar variant issues, especially if you already aware those issue exists. Please consolidate your suggestions into existing one.

Core team may evaluate the suggestions, but as noted in original issue we don't track this as high priority at this moment.

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.