Required virtual method (not?) overriding

[TH3-S4LM0N]

I wanted to take this here before going upstream as they seem confident that it's fixed there (See godotengine/godot#90776).

I'm using Godot 4.3rc1 and trying to implement scripts from Rust with ScriptInstance etc. When trying to add my script (via adding a resource in the editor), the editor immediatly freezes for a second and then prints

ERROR: Required virtual method TroutScript::_has_static_method must be overridden before calling.
   at: _gdvirtual__has_static_method_call (./core/object/script_language_extension.h:102)
ERROR: Required virtual method TroutScript::_get_base_script must be overridden before calling.
   at: _gdvirtual__get_base_script_call (./core/object/script_language_extension.h:55)
ERROR: Required virtual method TroutScript::_get_language must be overridden before calling.
   at: _gdvirtual__get_language_call (./core/object/script_language_extension.h:133)

and quits. TroutScript being just the most basic

#[derive(GodotClass)]
#[class(init, base=ScriptExtension)]
struct TroutScript {
   base: Base<ScriptExtension>
}

I'm led to believe this is a gdext problem and not Godot as godotengine/godot#80275 provides an example of the bug in Lua that runs fine for me with 4.3rc1.

[Bromeon]

We'll likely change the way how we handle required virtual methods: #771

Are those who caused you problems among the methods required in that PR?

[TH3-S4LM0N]

core/object/script_language_extension.h contains

55: EXBIND0R(Ref<Script>, get_base_script)
102: EXBIND1RC(bool, has_static_method, const StringName &)
133: EXBIND0RC(ScriptLanguage *, get_language)

so yes (I don't know what EXBIND does though so correct me if I'm wrong).

[Bromeon]

@TitanNano you probably know this better than me.

The IScriptExtension virtual methods listed above are not marked required in the current special_cases.rs of your PR #771 -- do you think they should be?

[TitanNano]

@Bromeon yes looks that was accidentally clumped together with IScriptLanguageExtension.

[TH3-S4LM0N]

@Bromeon you closed this as completed but #771 hasn't fixed this problem afaik.
All there is now is a lot more required trait methods and less documentation.

A very general version of the example in ScriptInstance: trout_script.rs.txt

Still crashes with

ERROR: Required virtual method MyScript::_has_static_method must be overridden before calling.
   at: _gdvirtual__has_static_method_call (./core/object/script_language_extension.h:102)
ERROR: Required virtual method MyScript::_get_base_script must be overridden before calling.
   at: _gdvirtual__get_base_script_call (./core/object/script_language_extension.h:55)
ERROR: Required virtual method MyScript::_get_language must be overridden before calling.
   at: _gdvirtual__get_language_call (./core/object/script_language_extension.h:133)

when adding the MyScript resource. Also updated to Godot 4.3rc3. If you can get me started on how it works I'm totally willing to fill out the docs for it but I'm not sure where to start.

[TitanNano]

@TH3-S4LM0N apologies for asking this, but are you 100% certain that you recompiled your library and that the editor has loaded the latest version of your library?

All there is now is a lot more required trait methods and less documentation

There shouldn't be less documentation than before. Unfortunately, the engine doesn't even properly document script extensions, so I understand that it's difficult to figure things out.

[TH3-S4LM0N]

@TH3-S4LM0N apologies for asking this, but are you 100% certain that you recompiled your library and that the editor has loaded the latest version of your library?

Yes, I cleaned, updated, and rebuilt the whole cargo project; everything is up to date.

There shouldn't be less documentation than before.

Mostly I was just referring to this function definition example that got removed (although it was already out of date with create_script_instance taking 2 args). Script extensions weren't too confusing to me, I just don't know much about the nitty gritty of how it actually works internally and how gdext and Godot communicate, so I don't know where to look for the disconnect with the virtual method registration/overriding.

[Bromeon]

As a general input, I linked the PR 10 days ago -- if we get feedback and testing during the PR review process, we can incorporate it. I would appreciate if people affected by certain changes took a look while it's in progress, as that reduces the overall amount of work and communication necessary 😉

---

Mostly I was just referring to this function definition example that got removed

This is a fair point, would you mind adding it back?

[TH3-S4LM0N]

As a general input, I linked the PR 10 days ago -- if we get feedback and testing during the PR review process, we can incorporate it. I would appreciate if people affected by certain changes took a look while it's in progress, as that reduces the overall amount of work and communication necessary 😉

I was keeping an eye on it, but saying "this doesn't work" on an unfinished (draft) PR felt unproductive.

[TitanNano]

so I don't know where to look for the disconnect with the virtual method registration/overriding.

@TH3-S4LM0N you can use cargo expand on the module that contains your IScriptExtension implementation. The godot_api macro should generate an implementation of ImplementsGodotVirtual like this:

impl ::godot::obj::cap::ImplementsGodotVirtual for RustScript {
    fn __virtual_call(name: &str) -> ::godot::sys::GDExtensionClassCallVirtual {
        use ::godot::obj::UserClass as _;
        if ::godot::private::is_class_inactive(Self::__config().is_tool) {
            return None;
        }
        match name {
            "_get_global_name" => {
                [...]
            }
            [...]
        }
    }
}

If you don't see an implemented method there, then something is going wrong.