Add C# source generator for a new ScriptPath attribute

This source generator adds a newly introduced attribute,
`ScriptPath` to all classes that:

- Are top-level classes (not inner/nested).
- Have the `partial` modifier.
- Inherit `Godot.Object`.
- The class name matches the file name.

A build error is thrown if the generator finds a class that meets these
conditions but is not declared `partial`, unless the class is annotated
with the `DisableGodotGenerators` attribute.

We also generate an `AssemblyHasScripts` assembly attribute which Godot
uses to get all the script classes in the assembly, eliminating the need
for Godot to search them. We can also avoid searching in assemblies that
don't have this attribute. This will be good for performance in the
future once we support multiple assemblies with Godot script classes.

This is an example of what the generated code looks like:

```
using Godot;
namespace Foo {
	[ScriptPathAttribute("res://Player.cs")]
	// Multiple partial declarations are allowed
	[ScriptPathAttribute("res://Foo/Player.cs")]
	partial class Player {}
}

[assembly:AssemblyHasScripts(new System.Type[] { typeof(Foo.Player) })]
```

The new attributes replace script metadata which we were generating by
determining the namespace of script classes with a very simple parser.
This fixes several issues with the old approach related to parser
errors and conditional compilation.
It also makes the task part of the MSBuild project build, rather than
a separate step executed by the Godot editor.

modules/mono/Directory.Build.props

@@ -0,0 +1,3 @@
+<Project>
+  <Import Project="$(MSBuildThisFileDirectory)\SdkPackageVersions.props" />
+</Project>

modules/mono/SdkPackageVersions.props

@@ -0,0 +1,6 @@
+<Project>
+  <PropertyGroup>
+    <PackageVersion_Godot_NET_Sdk>4.0.0-dev4</PackageVersion_Godot_NET_Sdk>
+    <PackageVersion_Godot_SourceGenerators>4.0.0-dev1</PackageVersion_Godot_SourceGenerators>
+  </PropertyGroup>
+</Project>

modules/mono/build_scripts/godot_net_sdk_build.py

@@ -21,6 +21,18 @@ def build_godot_net_sdk(source, target, env):
     # No need to copy targets. The Godot.NET.Sdk csproj takes care of copying them.
 
 
+def get_nupkgs_versions(props_file):
+    import xml.etree.ElementTree as ET
+
+    tree = ET.parse(props_file)
+    root = tree.getroot()
+
+    return {
+        "Godot.NET.Sdk": root.find("./PropertyGroup/PackageVersion_Godot_NET_Sdk").text.strip(),
+        "Godot.SourceGenerators": root.find("./PropertyGroup/PackageVersion_Godot_SourceGenerators").text.strip(),
+    }
+
+
 def build(env_mono):
     assert env_mono["tools"]
 
@@ -30,14 +42,12 @@ def build(env_mono):
 
     module_dir = os.getcwd()
 
-    package_version_file = os.path.join(
-        module_dir, "editor", "Godot.NET.Sdk", "Godot.NET.Sdk", "Godot.NET.Sdk_PackageVersion.txt"
-    )
-
-    with open(package_version_file, mode="r") as f:
-        version = f.read().strip()
+    nupkgs_versions = get_nupkgs_versions(os.path.join(module_dir, "SdkPackageVersions.props"))
 
-    target_filenames = ["Godot.NET.Sdk.%s.nupkg" % version]
+    target_filenames = [
+        "Godot.NET.Sdk.%s.nupkg" % nupkgs_versions["Godot.NET.Sdk"],
+        "Godot.SourceGenerators.%s.nupkg" % nupkgs_versions["Godot.SourceGenerators"],
+    ]
 
     targets = [os.path.join(nupkgs_dir, filename) for filename in target_filenames]
 

modules/mono/csharp_script.cpp

@@ -31,6 +31,7 @@
 #include "csharp_script.h"
 
 #include <mono/metadata/threads.h>
+#include <mono/metadata/tokentype.h>
 #include <stdint.h>
 
 #include "core/config/project_settings.h"
@@ -1182,46 +1183,56 @@ void CSharpLanguage::reload_assemblies(bool p_soft_reload) {
 }
 #endif
 
-void CSharpLanguage::_load_scripts_metadata() {
-	scripts_metadata.clear();
+void CSharpLanguage::lookup_script_for_class(GDMonoClass *p_class) {
+	if (!p_class->has_attribute(CACHED_CLASS(ScriptPathAttribute))) {
+		return;
+	}
 
-	String scripts_metadata_filename = "scripts_metadata.";
+	MonoObject *attr = p_class->get_attribute(CACHED_CLASS(ScriptPathAttribute));
+	String path = CACHED_FIELD(ScriptPathAttribute, path)->get_string_value(attr);
 
-#ifdef TOOLS_ENABLED
-	scripts_metadata_filename += Engine::get_singleton()->is_editor_hint() ? "editor" : "editor_player";
-#else
-#ifdef DEBUG_ENABLED
-	scripts_metadata_filename += "debug";
-#else
-	scripts_metadata_filename += "release";
-#endif
-#endif
+	dotnet_script_lookup_map[path] = DotNetScriptLookupInfo(
+			p_class->get_namespace(), p_class->get_name(), p_class);
+}
 
-	String scripts_metadata_path = GodotSharpDirs::get_res_metadata_dir().plus_file(scripts_metadata_filename);
+void CSharpLanguage::lookup_scripts_in_assembly(GDMonoAssembly *p_assembly) {
+	if (p_assembly->has_attribute(CACHED_CLASS(AssemblyHasScriptsAttribute))) {
+		MonoObject *attr = p_assembly->get_attribute(CACHED_CLASS(AssemblyHasScriptsAttribute));
+		bool requires_lookup = CACHED_FIELD(AssemblyHasScriptsAttribute, requiresLookup)->get_bool_value(attr);
 
-	if (FileAccess::exists(scripts_metadata_path)) {
-		String old_json;
+		if (requires_lookup) {
+			// This is supported for scenarios where specifying all types would be cumbersome,
+			// such as when disabling C# source generators (for whatever reason) or when using a
+			// language other than C# that has nothing similar to source generators to automate it.
+			MonoImage *image = p_assembly->get_image();
 
-		Error ferr = read_all_file_utf8(scripts_metadata_path, old_json);
+			int rows = mono_image_get_table_rows(image, MONO_TABLE_TYPEDEF);
 
-		ERR_FAIL_COND(ferr != OK);
+			for (int i = 1; i < rows; i++) {
+				// We don't search inner classes, only top-level.
+				MonoClass *mono_class = mono_class_get(image, (i + 1) | MONO_TOKEN_TYPE_DEF);
 
-		Variant old_dict_var;
-		String err_str;
-		int err_line;
-		Error json_err = JSON::parse(old_json, old_dict_var, err_str, err_line);
-		if (json_err != OK) {
-			ERR_PRINT("Failed to parse metadata file: '" + err_str + "' (" + String::num_int64(err_line) + ").");
-			return;
-		}
+				if (!mono_class_is_assignable_from(CACHED_CLASS_RAW(GodotObject), mono_class)) {
+					continue;
+				}
 
-		scripts_metadata = old_dict_var.operator Dictionary();
-		scripts_metadata_invalidated = false;
+				GDMonoClass *current = p_assembly->get_class(mono_class);
+				if (current) {
+					lookup_script_for_class(current);
+				}
+			}
+		} else {
+			// This is the most likely scenario as we use C# source generators
+			MonoArray *script_types = (MonoArray *)CACHED_FIELD(AssemblyHasScriptsAttribute, scriptTypes)->get_value(attr);
 
-		print_verbose("Successfully loaded scripts metadata");
-	} else {
-		if (!Engine::get_singleton()->is_editor_hint()) {
-			ERR_PRINT("Missing scripts metadata file.");
+			int length = mono_array_length(script_types);
+
+			for (int i = 0; i < length; i++) {
+				MonoReflectionType *reftype = mono_array_get(script_types, MonoReflectionType *, i);
+				ManagedType type = ManagedType::from_reftype(reftype);
+				ERR_CONTINUE(!type.type_class);
+				lookup_script_for_class(type.type_class);
+			}
 		}
 	}
 }
@@ -1300,7 +1311,7 @@ void CSharpLanguage::_on_scripts_domain_unloaded() {
 	}
 #endif
 
-	scripts_metadata_invalidated = true;
+	dotnet_script_lookup_map.clear();
 }
 
 #ifdef TOOLS_ENABLED
@@ -3356,45 +3367,34 @@ Error CSharpScript::reload(bool p_keep_state) {
 
 	GD_MONO_SCOPE_THREAD_ATTACH;
 
-	GDMonoAssembly *project_assembly = GDMono::get_singleton()->get_project_assembly();
-
-	if (project_assembly) {
-		const Variant *script_metadata_var = CSharpLanguage::get_singleton()->get_scripts_metadata().getptr(get_path());
-		if (script_metadata_var) {
-			Dictionary script_metadata = script_metadata_var->operator Dictionary()["class"];
-			const Variant *namespace_ = script_metadata.getptr("namespace");
-			const Variant *class_name = script_metadata.getptr("class_name");
-			ERR_FAIL_NULL_V(namespace_, ERR_BUG);
-			ERR_FAIL_NULL_V(class_name, ERR_BUG);
-			GDMonoClass *klass = project_assembly->get_class(namespace_->operator String(), class_name->operator String());
-			if (klass && CACHED_CLASS(GodotObject)->is_assignable_from(klass)) {
-				script_class = klass;
-			}
-		} else {
-			// Missing script metadata. Fallback to legacy method
-			script_class = project_assembly->get_object_derived_class(name);
+	const DotNetScriptLookupInfo *lookup_info =
+			CSharpLanguage::get_singleton()->lookup_dotnet_script(get_path());
+
+	if (lookup_info) {
+		GDMonoClass *klass = lookup_info->script_class;
+		if (klass) {
+			ERR_FAIL_COND_V(!CACHED_CLASS(GodotObject)->is_assignable_from(klass), FAILED);
+			script_class = klass;
 		}
+	}
 
-		valid = script_class != nullptr;
+	valid = script_class != nullptr;
 
-		if (script_class) {
+	if (script_class) {
 #ifdef DEBUG_ENABLED
-			print_verbose("Found class " + script_class->get_full_name() + " for script " + get_path());
+		print_verbose("Found class " + script_class->get_full_name() + " for script " + get_path());
 #endif
 
-			native = GDMonoUtils::get_class_native_base(script_class);
+		native = GDMonoUtils::get_class_native_base(script_class);
 
-			CRASH_COND(native == nullptr);
+		CRASH_COND(native == nullptr);
 
-			update_script_class_info(this);
+		update_script_class_info(this);
 
-			_update_exports();
-		}
-
-		return OK;
+		_update_exports();
 	}
 
-	return ERR_FILE_MISSING_DEPENDENCIES;
+	return OK;
 }
 
 ScriptLanguage *CSharpScript::get_language() const {

modules/mono/csharp_script.h

@@ -66,6 +66,18 @@ TScriptInstance *cast_script_instance(ScriptInstance *p_inst) {
 
 #define CAST_CSHARP_INSTANCE(m_inst) (cast_script_instance<CSharpInstance, CSharpLanguage>(m_inst))
 
+struct DotNetScriptLookupInfo {
+	String class_namespace;
+	String class_name;
+	GDMonoClass *script_class = nullptr;
+
+	DotNetScriptLookupInfo() {} // Required by HashMap...
+
+	DotNetScriptLookupInfo(const String &p_class_namespace, const String &p_class_name, GDMonoClass *p_script_class) :
+			class_namespace(p_class_namespace), class_name(p_class_name), script_class(p_script_class) {
+	}
+};
+
 class CSharpScript : public Script {
 	GDCLASS(CSharpScript, Script);
 
@@ -390,16 +402,15 @@ class CSharpLanguage : public ScriptLanguage {
 
 	int lang_idx = -1;
 
-	Dictionary scripts_metadata;
-	bool scripts_metadata_invalidated = true;
+	HashMap<String, DotNetScriptLookupInfo> dotnet_script_lookup_map;
+
+	void lookup_script_for_class(GDMonoClass *p_class);
 
 	// For debug_break and debug_break_parse
 	int _debug_parse_err_line = -1;
 	String _debug_parse_err_file;
 	String _debug_error;
 
-	void _load_scripts_metadata();
-
 	friend class GDMono;
 	void _on_scripts_domain_unloaded();
 
@@ -436,18 +447,13 @@ class CSharpLanguage : public ScriptLanguage {
 	void reload_assemblies(bool p_soft_reload);
 #endif
 
-	_FORCE_INLINE_ Dictionary get_scripts_metadata_or_nothing() {
-		return scripts_metadata_invalidated ? Dictionary() : scripts_metadata;
-	}
+	_FORCE_INLINE_ ManagedCallableMiddleman *get_managed_callable_middleman() const { return managed_callable_middleman; }
 
-	_FORCE_INLINE_ const Dictionary &get_scripts_metadata() {
-		if (scripts_metadata_invalidated) {
-			_load_scripts_metadata();
-		}
-		return scripts_metadata;
-	}
+	void lookup_scripts_in_assembly(GDMonoAssembly *p_assembly);
 
-	_FORCE_INLINE_ ManagedCallableMiddleman *get_managed_callable_middleman() const { return managed_callable_middleman; }
+	const DotNetScriptLookupInfo *lookup_dotnet_script(const String &p_script_path) const {
+		return dotnet_script_lookup_map.getptr(p_script_path);
+	}
 
 	String get_name() const override;
 

modules/mono/editor/Godot.NET.Sdk/Godot.NET.Sdk.sln

@@ -2,6 +2,12 @@
 Microsoft Visual Studio Solution File, Format Version 12.00
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Godot.NET.Sdk", "Godot.NET.Sdk\Godot.NET.Sdk.csproj", "{31B00BFA-DEA1-42FA-A472-9E54A92A8A5F}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Godot.SourceGenerators", "Godot.SourceGenerators\Godot.SourceGenerators.csproj", "{32D31B23-2A45-4099-B4F5-95B4C8FF7D9F}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Godot.SourceGenerators.Sample", "Godot.SourceGenerators.Sample\Godot.SourceGenerators.Sample.csproj", "{7297A614-8DF5-43DE-9EAD-99671B26BD1F}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "GodotSharp", "..\..\glue\GodotSharp\GodotSharp\GodotSharp.csproj", "{AEBF0036-DA76-4341-B651-A3F2856AB2FA}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -12,5 +18,17 @@ Global
 		{31B00BFA-DEA1-42FA-A472-9E54A92A8A5F}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{31B00BFA-DEA1-42FA-A472-9E54A92A8A5F}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{31B00BFA-DEA1-42FA-A472-9E54A92A8A5F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{32D31B23-2A45-4099-B4F5-95B4C8FF7D9F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{32D31B23-2A45-4099-B4F5-95B4C8FF7D9F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{32D31B23-2A45-4099-B4F5-95B4C8FF7D9F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{32D31B23-2A45-4099-B4F5-95B4C8FF7D9F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{7297A614-8DF5-43DE-9EAD-99671B26BD1F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7297A614-8DF5-43DE-9EAD-99671B26BD1F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7297A614-8DF5-43DE-9EAD-99671B26BD1F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7297A614-8DF5-43DE-9EAD-99671B26BD1F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{AEBF0036-DA76-4341-B651-A3F2856AB2FA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{AEBF0036-DA76-4341-B651-A3F2856AB2FA}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{AEBF0036-DA76-4341-B651-A3F2856AB2FA}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{AEBF0036-DA76-4341-B651-A3F2856AB2FA}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal

modules/mono/editor/Godot.NET.Sdk/Godot.NET.Sdk/Godot.NET.Sdk.csproj

@@ -8,43 +8,33 @@
 
     <PackageId>Godot.NET.Sdk</PackageId>
     <Version>4.0.0</Version>
-    <PackageProjectUrl>https://github.com/godotengine/godot/tree/master/modules/mono/editor/Godot.NET.Sdk</PackageProjectUrl>
+    <PackageVersion>$(PackageVersion_Godot_NET_Sdk)</PackageVersion>
+    <RepositoryUrl>https://github.com/godotengine/godot/tree/master/modules/mono/editor/Godot.NET.Sdk</RepositoryUrl>
+    <PackageProjectUrl>$(RepositoryUrl)</PackageProjectUrl>
     <PackageType>MSBuildSdk</PackageType>
     <PackageTags>MSBuildSdk</PackageTags>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-  </PropertyGroup>
 
-  <PropertyGroup>
-    <NuspecFile>Godot.NET.Sdk.nuspec</NuspecFile>
-    <GenerateNuspecDependsOn>$(GenerateNuspecDependsOn);SetNuSpecProperties</GenerateNuspecDependsOn>
+    <!-- Exclude target framework from the package dependencies as we don't include the build output -->
+    <SuppressDependenciesWhenPacking>true</SuppressDependenciesWhenPacking>
+    <IncludeBuildOutput>false</IncludeBuildOutput>
   </PropertyGroup>
 
-  <Target Name="ReadGodotNETSdkVersion" BeforeTargets="BeforeBuild;BeforeRebuild;CoreCompile">
-    <PropertyGroup>
-      <PackageVersion>$([System.IO.File]::ReadAllText('$(ProjectDir)Godot.NET.Sdk_PackageVersion.txt').Trim())</PackageVersion>
-    </PropertyGroup>
-  </Target>
+  <ItemGroup>
+    <!-- Package Sdk\Sdk.props and Sdk\Sdk.targets file -->
+    <None Include="Sdk\Sdk.props" Pack="true" PackagePath="Sdk" Visible="false" />
+    <None Include="Sdk\Sdk.targets" Pack="true" PackagePath="Sdk" Visible="false" />
+    <!-- SdkPackageVersions.props -->
 
-  <Target Name="SetNuSpecProperties" Condition=" Exists('$(NuspecFile)') " DependsOnTargets="ReadGodotNETSdkVersion">
-    <PropertyGroup>
-      <NuspecProperties>
-        id=$(PackageId);
-        description=$(Description);
-        authors=$(Authors);
-        version=$(PackageVersion);
-        packagetype=$(PackageType);
-        tags=$(PackageTags);
-        projecturl=$(PackageProjectUrl)
-      </NuspecProperties>
-    </PropertyGroup>
-  </Target>
+    <None Include="..\..\..\SdkPackageVersions.props" Pack="true" PackagePath="Sdk" Visible="false" />
+  </ItemGroup>
 
   <Target Name="CopyNupkgToSConsOutputDir" AfterTargets="Pack">
     <PropertyGroup>
       <GodotSourceRootPath>$(SolutionDir)\..\..\..\..\</GodotSourceRootPath>
       <GodotOutputDataDir>$(GodotSourceRootPath)\bin\GodotSharp\</GodotOutputDataDir>
     </PropertyGroup>
-    <Copy SourceFiles="$(OutputPath)$(PackageId).$(PackageVersion).nupkg"
-          DestinationFolder="$(GodotOutputDataDir)Tools\nupkgs\" />
+    <Copy SourceFiles="$(PackageOutputPath)$(PackageId).$(PackageVersion).nupkg" DestinationFolder="$(GodotOutputDataDir)Tools\nupkgs\" />
   </Target>
 </Project>