Fix: import gdnative prelude in lib.rs template

[aclave1]

The default lib.rs template has a compiler error with newer versions of the gdnative library. Importing the Variant type is now required to run the godot_init macro. I decided to include the prelude instead of just importing Variant to hopefully prevent these API changes from breaking things in future versions.

Test Plan:

ftw new test
cd test
ftw build

Error Output:

error[E0433]: failed to resolve: use of undeclared type `Variant`
  --> rust\src\lib.rs:13:1
   |
13 | godot_init!(init);
   | ^^^^^^^^^^^^^^^^^ not found in this scope
   |
   = note: this error originates in the macro `$crate::godot_nativescript_init` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider importing this struct
   |
4  | use gdnative::core_types::Variant;
   |

For more information about this error, try `rustc --explain E0433`.
error: could not compile `example` due to 2 previous errors
 ERROR: The system cannot find the file specified. (os error 2)
Error: ()

lib.rs

mod game;
mod spinning_cube;

use gdnative::prelude::{godot_init, InitHandle};

// Function that registers all exposed classes to Godot
fn init(handle: InitHandle) {
    handle.add_class::<game::Game>();
    handle.add_class::<spinning_cube::SpinningCube>();
}

// macros that create the entry-points of the dynamic library.
godot_init!(init);

[macalimlim]

Hi @aclave1,

Thank you for filing this issue, may I know what target, rust version, ftw version and the operating system you are running ftw on? Based on my initial test, I seem to don't get the error that you are getting. Please see screenshot below.

I'm on NixOS, x86_64-unknown-linux-gnu target, rust v1.64.0 and ftw v0.10.0

Mike

[aclave1]

I'm on windows 11, target is x86_64-pc-windows-msvc, rust 1.63.0, ftw 0.10.0. One thing I see from your logs is the usage of gdnative v0.11.0. The version of gdnative that mine is using is 0.10.1. This is a project generated by ftw new. Maybe my local copy of godot-rust-template is cached?

edit: I haven't verified yet, but godot-rust/gdnative#954 mentions this issue. We can probably close this issue, sorry! I need to figure out how to update the template that ftw is using.