Minifier should preserve classes with a side effect in a static block

[kdy1]

Describe the bug

Minifier currently removes static block if a class is not used

Found by #5578

Input code

"use strict";
let getFoo;
class Foo {
    static #foo = 42;
    static{
        getFoo = ()=>this.#foo;
    }
}
expect(getFoo()).toBe(42);

Config

{
  "jsc": {
    "parser": {
      "syntax": "ecmascript"
    },
    "target": "es2022",
    "minify": {
      "compress": {
        "arguments": false,
        "arrows": true,
        "booleans": true,
        "booleans_as_integers": false,
        "collapse_vars": true,
        "comparisons": true,
        "computed_props": false,
        "conditionals": true,
        "dead_code": true,
        "directives": false,
        "drop_console": false,
        "drop_debugger": true,
        "evaluate": false,
        "expression": false,
        "hoist_funs": false,
        "hoist_props": false,
        "hoist_vars": false,
        "if_return": true,
        "join_vars": false,
        "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
    },
    "loose": false
  },
  "minify": false
}

Playground link

https://play.swc.rs/?version=1.2.241&code=H4sIAAAAAAAAA02LMQqAMBAE%2B3vFoU3SWAS7oIWF%2F5BwakCIeCsI4t%2BNpHGqZZitThVWHDGg8rQJeBGMKXkK26TKefJNnFFMiIHrOZuOW%2Bd%2FthQf5Z0DY7sea9TmO5T2oYfk2iXAlMxY2yANYlpn%2FQvXyVYQigAAAA%3D%3D&config=H4sIAAAAAAAAA22TTZLjIAyF7%2BJ1FlNZ9gHmGhQB4dADkguJdFxdffcWcYxjZ3Z%2Bn%2FVAf3wPn%2ByGj%2B9hsoWhtC%2BeUex9%2BBjAZcuuxEmGn9MgtowgDfP5z%2Fk8nIYcMYa5WRzlqQBz%2B9awmgFFRbCJ4aSk0JdKKVXVhSiBxTdtLJuIAiOUzeooJTsxmJst3dFusyUy4Q5VAW%2BmQtOrHX2USKhyDfVgvXHkoYNYwEm8webzeorGIGtqe%2BjhUsexNWoxw82mamWLgvujE3pnR1eKLCZU5APaJ7uwpdAnisEUkFpwve6TIu5D%2FgFoqskyo81w4EGH0QtfyH%2BiIgadpMydJnrktdgQRq3PxBh6x1reUCRCDyrgq4NWo9sOf8Jduhw9GAhBO97N%2FBXFXbfDZJ6AQpfaNxu2Bi%2FSrEu1p20P3uBfzUpeB%2FLk2cr1yHjOF0pvR2SQK%2Fk3rI0QOsKiK3yfjrSiB20z%2BJcflZtcNxh1%2BkImtUe29lk3Qj1mTHTpK6xvMVsc%2B2b%2BPAbGL3J9mIv%2BBWHfBxnjAwAA

Expected behavior

It should not be removed

Actual behavior

No response

Version

1.2.241

Additional context

No response

[hyf0]

I wonder what fix would you accept?

1. If a class has any static field, we just leave it as it is.
2. Do more delegate analyzing for the static fields, only compress it if there are no side effects.

I found the solution 2 is kind of hard for your mentioned case. It could not simply call extract_class_side_effect to it and extract the statement getFoo = ()=>this.#foo;, because the block reference this.#foo.

[kdy1]

I think 1 is fine

[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.