mutable boxed types

[clegaard]

What is the correct way to declare a mutable boxed type a function signature using #[ffi_export]?

Compiling with macro produces an error for the following piece of code:

#[ffi_export]
pub fn fmi2FreeInstance(mut slave: Option<repr_c::Box<Slave>>) {
    match slave.as_mut() {
        Some(s) => {
            s.rpc.fmi2FreeInstance();
            drop(slave)
        }
        None => {}
    }
}

244 | pub fn fmi2FreeInstance(mut slave: Option<repr_c::Box<Slave>>) {
    |                             ^^^^^ no rules expected this token in macro call

Without the macro the code compiles.

[danielhenrymantilla]

Not yet supported, but soon (say, in 2-3 weeks)! In the meantime, you'll need to do:

  #[ffi_export]
- pub fn fmi2FreeInstance(mut slave: Option<repr_c::Box<Slave>>) {
+ pub fn fmi2FreeInstance(    slave: Option<repr_c::Box<Slave>>) {
+     let mut slave = slave;
      match slave.as_mut() {
          Some(s) => {
              s.rpc.fmi2FreeInstance();
              drop(slave)
          }
          None => {}
      }
  }

[clegaard]

I see. I did not realize that it was possible to get a mutable "alias" to the boxed value inside the function.
Thank you for the quick response :)