[BUG] wrong return value from async function

[aj3423]

Describe the bug
The code below produces wrong result.

To Reproduce
Steps to reproduce the behavior:

1. code:

async fn fetch_data() -> string {
    return "some data";
}

fn main() {
    let result = await fetch_data();
    
    println "result: {result}";
    return 0;
}

It shows:

result: @

Expected behavior
It shows wrong result:

result: some data

Screenshots

Environment (please complete the following information):

• OS: Fedore 43
• Zen C Version: zc v0.4.2-38-ge4605ce
• Compiler:
  • gcc (GCC) 15.2.1 20260123
  • clang version 21.1.8

Additional context
A discussion in discord, from Alex:

There's a bug in the compiler.
It outputs

    string *res_ptr = malloc(sizeof(string));
    *res_ptr = _impl_fetch_data();
    free(args);
    return (void*)res_ptr; //<----- cast char** to void*
}

It should be outputting

    string res_ptr = malloc(sizeof(string));
    res_ptr = _impl_fetch_data();
    free(args);
    return (void*)res_ptr; //<---- cast char* to void*

[davidscholberg]

@aj3423 the fix for this hasn't been merged yet, so just for future reference it's better to leave these issues open until the fixes land in the main branch.