Documentation for GDExtension in 4.1 still refers to 4.0

[dcuny]

4.1

Page says it's up to date for 4.1, but still refers to version 4.0

Godot Engine 4.1 documentation in English

The GDExtension tutorial page says that it's currently up to date with 4.1.

However, the "Note" says that "you need to use the 4.0 branch of godot-cpp, which is only compatible with Godot 4.0 and being used here as an example."

The code references the 4.0 version as well:

git submodule add -b 4.0 https://github.com/godotengine/godot-cpp

and

git clone -b 4.0 https://github.com/godotengine/godot-cpp

Additionally, the release notes state there is a binary incompatibility between GDExtensions built in 4.0 vs. 4.1, which requires a small change. I don't see that information referenced on the page, and this "small change" would be helpful to know about before I start trying to port my 4.0 extensions to 4.1, so I can make that change.

[Calinou]

cc @paddy-exe

[dcuny]

In the discussion about what changed between Godot 4.0 and 4.1, there's mention of a "tiny change to the source code":

GDExtensions compiled for Godot 4.0 aren't compatible with Godot 4.1 - a tiny change to the source code is required, and they need to be recompiled. As soon as this PR is merged, I'm planning to make a follow-up PR that adds detailed information on what folks need to do to get their GDExtensions working in 4.1.

It appears the change is in the example_library_init(). This is the 4.0 version:

extern "C" {
// Initialization.
GDExtensionBool GDE_EXPORT example_library_init(const GDExtensionInterface *p_interface, const GDExtensionClassLibraryPtr p_library, GDExtensionInitialization *r_initialization) {
    godot::GDExtensionBinding::InitObject init_obj(p_interface, p_library, r_initialization);

    init_obj.register_initializer(initialize_example_module);
    init_obj.register_terminator(uninitialize_example_module);
    init_obj.set_minimum_library_initialization_level(MODULE_INITIALIZATION_LEVEL_SCENE);

    return init_obj.init();
}

And here's what appears to be the 4.1 version:

extern "C" {
// Initialization.
GDExtensionBool GDE_EXPORT example_library_init(GDExtensionInterfaceGetProcAddress p_get_proc_address, const GDExtensionClassLibraryPtr p_library, GDExtensionInitialization *r_initialization) {
    godot::GDExtensionBinding::InitObject init_obj(p_get_proc_address, p_library, r_initialization);

    init_obj.register_initializer(initialize_example_module);
    init_obj.register_terminator(uninitialize_example_module);
    init_obj.set_minimum_library_initialization_level(MODULE_INITIALIZATION_LEVEL_SCENE);

    return init_obj.init();
}

There are two changes:

1. const GDExtensionInterface *p_interface has been replaced by GDExtensionInterfaceGetProcAddress p_get_proc_address.
2. init_obj now passes p_interface as the first parameter instead of p_get_proc_address.

This should be addressed via a Note on the GDExtention page.

[dsnopek]

I've been working on changes to the "Upgrading from Godot 4.0 to Godot 4.1" page that describes this. When I asked, folks seemed to think that was the right place to put it (as opposed to the GDExtension page). I keep getting sidetracked with other things, but I hope to have the PR for that up soon!

[dsnopek]

I just posted PR #7656 as promised! I'm sure there's ways to improve it - review is welcome :-)