These callbacks are used for marshaling by callables and generic Godot
collections.
C# generics don't support specialization the way C++ templates do.
I knew NativeAOT could optimize away many type checks when the types
are known at compile time, but I didn't trust the JIT would do as good
a job, so I initially went with cached function pointers.
Well, it turns out the JIT is also very good at optimizing in this
scenario, so I'm changing the methods to do the conversion directly,
rather than returning a function pointer for the conversion.
The methods were moved to `VariantUtils`, and were renamed from
`GetFromVariantCallback/GetToVariantCallback` to `ConvertTo/CreateFrom`.
The new implementation looks like it goes through many `if` checks
at runtime to find the right branch for the type, but in practice it
works pretty much like template specialization. The JIT only generates
code for the relevant branch. Together with inlining, the result is
very close or the same as doing the conversion manually:
```cs
godot_variant variant;
int foo = variant.Int;
int bar = VariantUtils.ConvertTo<int>(variant);
```
If the type is a generic Godot collection, the conversion still goes
through a function pointer call.
The new code happens to be much shorter as well, with the file going
from 1057 lines to 407.
Side note: `Variant.cs` was mistakenly created in the wrong folder,
so I moved it to the `Core` folder.
This allows using generic Godot collections as type arguments for other
generic Godot collections. This also allows generic Godot collections
as parameter or return type in dynamic Callable invocations.
We aim to make the C# API reflection-free, mainly for concerns about
performance, and to be able to target NativeAOT in refletion-free mode,
which reduces the binary size.
One of the main usages of reflection still left was the dynamic
invokation of callable delegates, and for some time I wasn't sure
I would find an alternative solution that I'd be happy with.
The new solution uses trampoline functions to invoke the delegates:
```
static void Trampoline(object delegateObj, NativeVariantPtrArgs args, out godot_variant ret)
{
if (args.Count != 1)
throw new ArgumentException($"Callable expected 1 arguments but received {args.Count}.");
string res = ((Func<int, string>)delegateObj)(
VariantConversionCallbacks.GetToManagedCallback<int>()(args[0])
);
ret = VariantConversionCallbacks.GetToVariantCallback<string>()(res);
}
Callable.CreateWithUnsafeTrampoline((int num) => "Foo" + num, &Trampoline);
```
Of course, this is too much boilerplate for user code. To improve this,
the `Callable.From` methods were added. These are overloads that take
`Action` and `Func` delegates, which covers the most common use cases:
lambdas and method groups:
```
// Lambda
Callable.From((int num) => "Foo" + num);
// Method group
string AppendNum(int num) => "Foo" + num;
Callable.From(AppendNum);
```
Unfortunately, due to limitations in the C# language, implicit
conversions from delegates to `Callable` are not supported.
`Callable.From` does not support custom delegates. These should be
uncommon, but the Godot C# API actually uses them for event signals.
As such, the bindings generator was updated to generate trampoline
functions for event signals. It was also optimized to use `Action`
instead of a custom delegate for parameterless signals, which removes
the need for the trampoline functions for those signals.
The change to reflection-free invokation removes one of the last needs
for `ConvertVariantToManagedObjectOfType`. The only remaining usage is
from calling script constructors with parameters from the engine
(`CreateManagedForGodotObjectScriptInstance`). Once that one is made
reflection-free, `ConvertVariantToManagedObjectOfType` can be removed.
We use collectible AssemblyLoadContexts as that's the only way to allow
reloading assemblies after building. However, collectible assemblies
have some restrictions:
- https://learn.microsoft.com/en-us/dotnet/framework/reflection-and-codedom/collectible-assemblies#restrictions-on-collectible-assemblies
Those restrictions can cause issues with third-party code, such as some
mocking libraries.
In order to work around this problem, we're going to load assemblies
as collectible only in Godot editor, and not when running games.
These issues will still exist in the editor, but this will be enough
for some users.
- Use `long` and `double` types since signals currently only support 64-bit types.
- Fix bug for checking if the type name is a class registered in ClassDB.
Ensures that the versions always match the Godot version, albeit following
SemVer 2.0 so inserting a dot between "beta" and the build number.
For "stable" status, we omit the suffix as this would be interpreted as a
pre-release build too.
So we have:
| Godot version | Nupkg version |
| -------------- | -------------- |
| 4.0.0-beta | 4.0.0-beta |
| 4.0.0-beta2 | 4.0.0-beta.2 |
| 4.0.0-rc1 | 4.0.0-rc.1 |
| 4.0.0-stable | 4.0.0 |
Android was the last platform to still attempt to disable RTTI (for binary
size), but both the Android editor and now the ICU library used by templates
need RTTI.
There could still be the possibility to support this for non-ICU template
builds (i.e. without the TextServerAdvanced module), but since this isn't one
of the build configurations we test regularly it's pretty risky to keep this
option only for that specific use case. And our code is already littered with
`dynamic_cast`s which weren't guarded with `!defined(NO_SAFE_CAST)`.
If the delegate target is an Object, the connected signal will be registered in that object instead of the middleman. So when that object is destroyed, the signal will be properly disconnected.
Implements https://github.com/godotengine/godot-proposals/issues/3371.
New `target` presets
====================
The `tools` option is removed and `target` changes to use three new presets,
which match the builds users are familiar with. These targets control the
default optimization level and enable editor-specific and debugging code:
- `editor`: Replaces `tools=yes target=release_debug`.
* Defines: `TOOLS_ENABLED`, `DEBUG_ENABLED`, `-O2`/`/O2`
- `template_debug`: Replaces `tools=no target=release_debug`.
* Defines: `DEBUG_ENABLED`, `-O2`/`/O2`
- `template_release`: Replaces `tools=no target=release`.
* Defines: `-O3`/`/O2`
New `dev_build` option
======================
The previous `target=debug` is now replaced by a separate `dev_build=yes`
option, which can be used in combination with either of the three targets,
and changes the following:
- `dev_build`: Defines `DEV_ENABLED`, disables optimization (`-O0`/`/0d`),
enables generating debug symbols, does not define `NDEBUG` so `assert()`
works in thirdparty libraries, adds a `.dev` suffix to the binary name.
Note: Unlike previously, `dev_build` defaults to off so that users who
compile Godot from source get an optimized and small build by default.
Engine contributors should now set `dev_build=yes` in their build scripts or
IDE configuration manually.
Changed binary names
====================
The name of generated binaries and object files are changed too, to follow
this format:
`godot.<platform>.<target>[.dev][.double].<arch>[.<extra_suffix>][.<ext>]`
For example:
- `godot.linuxbsd.editor.dev.arm64`
- `godot.windows.template_release.double.x86_64.mono.exe`
Be sure to update your links/scripts/IDE config accordingly.
More flexible `optimize` and `debug_symbols` options
====================================================
The optimization level and whether to generate debug symbols can be further
specified with the `optimize` and `debug_symbols` options. So the default
values listed above for the various `target` and `dev_build` combinations
are indicative and can be replaced when compiling, e.g.:
`scons p=linuxbsd target=template_debug dev_build=yes optimize=debug`
will make a "debug" export template with dev-only code enabled, `-Og`
optimization level for GCC/Clang, and debug symbols. Perfect for debugging
complex crashes at runtime in an exported project.
Ensures the `push_nupkgs_local` argument in build_assemblies.py is an
absolute path so the argument can be
given as a relative path and it will be converted.
- Creates a `Godot.Offline.Config` file to configurate NuGet with
Godot's fallback folder. This is easier because now we can assume we can
override the entire file since user config will likely be in the default
`NuGet.Config` file or an additional `*.config` file.
- Ensure the NuGet fallback folder is created at the same time it is
added to the NuGet configuration so future builds don't fail.
- Add `GodotSharp` and `GodotSharpEditor` packages to the fallback folder.
- Add `.nupkg.metadata` file to packages in fallback folder.
- Refer to `Godot.SourceGenerators` using the specific non-floating version
since floating versions don't seem to work with fallbackPackageFolders.
We want to replace libnethost as it gives us issues with some compilers.
Our implementation tries to mimic libnethost's hostfxr_resolver search
logic. We try to use the same function names for easier comparing in
case we need to update this in the future.
Scripts that are instantiated at some point will always be recreated
if they ever become placeholders to prevent non-tool scripts
instantiated manually by users to become placeholders, if they
do become placeholders due to errors that prevent instantiation
(such as a missing parameterless constructor) these scripts
will also be recreated replacing the temporary placeholder.
If a script is marked as a tool but becomes a non-tool script
in a rebuild, the script will become a placeholder and will
no longer be considered applicable to be replaced by an instance
since the user explicitly removed the Tool attribute.
Since the list of signals in `CSharpScript::event_signals` retrieved
from calling `ScriptManagerBridge.UpdateScriptClassInfo` already
includes the signals from base scripts there is no need to iterate the
hierarchy again on `CSharpInstance::connect_event_signals`.
When the C# bindings generator finds a type without meta assume the type
refers to the 64-bit version of the type:
- `float` is converted to `double`
- `int` is converted to `long`
