minifier: invalid function handling in switch statement

[hyp3rflow]

Describe the bug

Even if the function in switch statement has some expressions; like console.log("hi"), the minified result remains unchanged.

Input code

const k = (() => {
    switch (1) { 
        case 0: 
            function x() {}
        default:
            x(); 
    } 
})();

Config

No response

Playground link (or link to the minimal reproduction)

https://play.swc.rs/?version=1.4.11&code=H4sIAAAAAAAAA1WMvQqAIBSFd5%2FijLrVati7iClJoYNKgfjuXQuKvu38mhhSxgYFzgXUjMpApMNns4KPAhW30zE6WQzyMzquBJN9DDjpoLY3W6zTZc%2FyV6bO9MwbWBOk2AWJvP1RggAAAA%3D%3D&config=H4sIAAAAAAAAA32UO3LjMAyG%2B5zCozrFjostcoDtcgYOLYIyvSShIUDHmozvvtDDj40hdRI%2B%2FAAJgPh%2B2%2B2aE7XNx%2B5bPuWnt4Wg3P%2FFQkNmexFLA22y1JbQc%2FN%2BoycakbeRYDJdZ9KwLR3wpKL9r%2F1%2BUTQRkeCmWGwp5OCH55wtpr4A0ZNNrBKyJshM%2F%2BsXVvBrBFzqs%2F2AGMHmDWIsmZAZOiha4BZjtD2BOduiRBlPaksg1FKMsDI40xfsVZ5d4IBZcr5SB9aZFh0oKBRoOZxBk0kukWWS6yn3mbCDQ%2B26qc8%2F1HC2sVpWcsJlaomcVol6xEBsfM1aCWe4UoMZLsX9qQzeFOBa8qvuhCGv9OQvgFQgWqJsE2hxJw8v87Sm9pvKkL2MLA8Kl%2FnWbpmhk6KaELxS2bEyUDho3SzgagtjZVvtOAteKR8FBwa8l1lRQtNX4PaoJeWhB%2FQKkP5ar03VDMz9Fa7w8UFs4D9yS9YHbPFIlo%2FrlIZ0wLiRIAEf0W04SCsY13GRLXHp13nNDmQ0wKkulSbwugTkATCaOO3Ll9mQ5yERTRfx8FgTi8P1voeTzd3jvc%2Br%2BG1xaBK6OsFlyY%2F9nVfz7%2BbhdNvC94M3gT5vyjns9R%2F7ntJqMQYAAA%3D%3D

SWC Info output

No response

Expected behavior

maybe

let k = void 0;

Actual behavior

let k = void (void 0)();

which results in calling undefined ((void 0) is not a function)

Version

1.4.11

Additional context

No response

[yazaldefilimone]

Hello @kdy1, @magic-akari

could you help me send my first pr?

[kdy1]

@yazaldefilimone The code for the optimizer that uses variable data lives at https://github.com/swc-project/swc/tree/1839980185a5771f8e51fe6912438a08f2ed2fc2/crates/swc_ecma_minifier/src/compress/optimize and the code for variable analyzer lives at https://github.com/swc-project/swc/tree/1839980185a5771f8e51fe6912438a08f2ed2fc2/crates/swc_ecma_usage_analyzer/src/analyzer

Both the optimizer and analyzer use the visitor pattern, and you can follow visitor methods to understand the flow.

The visitor visits all fields of each types, and you can see the types at https://rustdoc.swc.rs/swc_ecma_ast/