Hot Reloading is not supported

[puzzir]

System information

Godot Engine v4.2.2.stable.official.15073afe3
Microsoft Windows NT 10.0.19045.0

Issue description

Godot editor crashes with error while recompiling library.

Steps to reproduce:

1. Сompile the code and run Godot (with gd command).

package main

import (
	"grow.graphics/gd"
	"grow.graphics/gd/gdextension"
)

type NewLabel struct {
	gd.Class[NewLabel, gd.Label]
}

func main() {
	godot, ok := gdextension.Link()
	if !ok {
		return
	}
	gd.Register[NewLabel](godot)
}

2. Add a new object "NewLabel" in the Godot editor via "Add Chid Node".

3. With the editor running, recompile the library.

gd build

or

go build -o ./graphics/windows_amd64.dll -buildmode=c-shared

Then Godot editor crashes with error:

ERROR: Cannot get class ''.          
   at: (core/object/class_db.cpp:407)
panic: runtime.link/mmm error: use after free                                                                                
                                                                                                                             
goroutine 17 [running, locked to thread]:                                                                                    
grow.graphics/gd/gdextension.linkCGO.func80({{0x7ff85b0b2cf8?, 0xc0006c2000?}, 0x7ff85c4cc240?}, {{}, {0x6?, 0xc000624a50?}})
        D:/Golang/GOPATH/pkg/mod/grow.graphics/gd@v0.0.0-20240615231848-e0bdc0378103/gdextension/gdextension_interface.go:1755 +0x70
grow.graphics/gd.Engine(...)
        D:/Golang/GOPATH/pkg/mod/grow.graphics/gd@v0.0.0-20240615231848-e0bdc0378103/classdb.go:3643
grow.graphics/gd.(*instanceImplementation).Notification(0xc0001fa270, 0x3ea, 0xf8?)
        D:/Golang/GOPATH/pkg/mod/grow.graphics/gd@v0.0.0-20240615231848-e0bdc0378103/register_class.go:446 +0x63
grow.graphics/gd/gdextension.notification_func(0x0?, 0x3ea, 0x0)
        D:/Golang/GOPATH/pkg/mod/grow.graphics/gd@v0.0.0-20240615231848-e0bdc0378103/gdextension/gdextension_interface.go:2464 +0xa3
exit status 2

[Splizard]

I'm not sure how solvable this is, Go doesn't strictly support dlclose when compiled to a shared library, so you get these weird inconsistent issues when you reload the extension. In my case, it works sometimes, other times, Godot will crash.

[Ullanar]

Same here! But editor just closes silently. Without any additional logs

[Splizard]

The idea I've got for hot reloading is to use Go plugins on supported platforms, we can just reload the plugin and hot swap it with the code running in the loaded shared library. Issue is.. Go plugins are not available on windows, so I'm not quite sure how to get hot reloading working on it.

[Splizard]

Maybe WASM I guess

EDIT: the web port shows this is feasible but it will take some work to create yet another startup layer for WASM hot-reloading. We will probably also want to re-use WASM for console support, so I think this is the way to go here. Maybe we can support plugins on Linux/Mac too but then we will be maintaining four different startup adapters.