Is possible to load C++ class? I got an `undefined symbol` error when trying this.

[mojerro]

I'm trying to load c++ class using this, but it's hard for me to finish it.

fn main() {
    let res = call_dynamic();

    println!("Hello, world! {:?}", res);
}

fn call_dynamic() -> Result<char, Box<dyn std::error::Error>> {
    unsafe {
        let lib = libloading::Library::new("./lib/thosttraderapi_se.so")?;
        let func: libloading::Symbol<unsafe extern "C" fn() -> char> = lib.get(b"CThostFtdcTraderApi::GetApiVersion()")?;
        Ok(func())
    }
}

nm -g --defined-only -C mylib.so

00000000001c238a T CThostFtdcTraderApi::GetApiVersion()
00000000001c2342 T CThostFtdcTraderApi::CreateFtdcTraderApi(char const*)
00000000001d1b8e W CThostFtdcTraderApi::CThostFtdcTraderApi()
00000000001d1b8e W CThostFtdcTraderApi::CThostFtdcTraderApi()
00000000001caadc W CThostFtdcTraderApi::~CThostFtdcTraderApi()
00000000001caadc W CThostFtdcTraderApi::~CThostFtdcTraderApi()

[nagisa]

It is possible. Given your code/nm output, it does seem like the symbol you’re attempting to load is mangled, and nm is demangling it for you. libloading does not automatically mangle or demangle symbols for you as described in the documentation for Library::get. What you want is probably gonna start with a _Z and will never contain ::. Invoke nm --no-demangle to get actual symbols that are usable with libloading.

Make sure that the calling convention used on the C++ side and on the Rust side match.

Hope you can get it to work :)

[mojerro]

o, I got it, I need to run nm -g --defined-only mylib.so to let it work