Add UI test for missing argument in args_into

[NiwakaDev]

This PR addresses #11 and Introduces a compile error when using missing argument in args_into.

Here's an example:

#[swift_bridge::bridge]
mod ffi {
    extern "Rust" {
        #[swift_bridge(args_into = (arg, arg_typo))]
        fn some_function(arg: u8);
    }
}

error: arg_typo: Unknown argument
       Could not find "arg_typo" in "fn some_function(arg : u8)".
 --> tests/ui/args-into-argument-not-found.rs:7:42
  |
7 |         #[swift_bridge(args_into = (arg, arg_typo))]
  |                                          ^^^^^^^^

[chinedufn]

Thanks a lot for working on this. Great stuff.

A few minor requests then looks good to me!

[chinedufn]

Maybe:

format!(r#"Argument "{}" was not found in the "fn {}(..)""#, missing_arg, func.sig.ident.to_token_stream().to_string());

Argument "foo" was not found in "fn some_function(..)".

[chinedufn]

Can we also match on &errors[0] and confirm that it is an ArgsIntoArgNotFound error?

[chinedufn]

i.e. something like:

        assert_eq!(errors.len(), 1);
        match &errors[0] {
            ParseError::ArgsIntoArgNotFound {
                func: _,
                missing_arg,
            } => {
                assert_eq!(missing_arg, "bar")
            }
            _ => panic!(),
        };

[chinedufn]

This will panic if you use args_into on a method:

#[swift_bridge::bridge]
mod ffi {
    extern "Rust" {
        type SomeType;
        #[swift_bridge(args_into = (foo))]
        fn some_function(&self);
    }
}

[chinedufn]

Maybe:

                    if let Some(ref args) = attributes.args_into {
                        let mut func_sig_args = HashSet::with_capacity(args.len());
                        for fn_arg in func.sig.inputs.iter() {
                            match fn_arg {
                                FnArg::Receiver(_) => {}
                                FnArg::Typed(pat_ty) => {
                                    let fn_arg_name = pat_ty.pat.to_token_stream().to_string();
                                    func_sig_args.insert(fn_arg_name);
                                }
                            }
                        }

                        for arg in args.iter() {
                            let arg_name = arg.to_token_stream().to_string();

                            if !func_sig_args.contains(&arg_name) {
                                self.errors.push(ParseError::ArgsIntoArgNotFound {
                                    func: func.clone(),
                                    missing_arg: arg.clone(),
                                })
                            }
                        }
                    }

[chinedufn]

Can we add a second extern "Rust" block here that uses a method?

Maybe something like:

extern "Rust" {
    type SomeType;

    #[swift_bridge(args_into = (arg, arg_typo))]
    fn some_method(&self, arg: u8);
}

[NiwakaDev]

Addressed your review!

[chinedufn]

Thanks!