Mono: Editor and export template dependencies and fixes

- Bundle editor dependencies:
    - 'GodotSharp': Root data directory for the editor
        - 'Tools': Editor dependencies. Only GodotSharp.dll for now.
        - 'Api': Prebuilt GodotSharp and GodotSharpEditor API assemblies.
        - 'Mono': Mono files to bundle with the editor.
            - 'bin': (Optional, not used for now) Mono bin directory.
            - 'etc': Mono configuration files.
            - 'lib': Mono dependency shared libraries.
            - 'lib/mono/4.5': Framework assemblies.
    - Added build option to copy the required files from the mono installation to 'GodotSharp/Mono'. Enable with 'copy_mono_root=yes'. Disabled by default.

- Export template dependencies:
    - 'data_AppName'/'data_Godot':
        - 'Mono': Mono files to bundle with the game.
            - 'etc': Mono configuration files.
            - 'lib': Mono dependency shared libraries.
    - The data directory is generated when compiling and must be bundled with the export templates. In the case of OSX, the data directory must be placed inside the 'osx.zip' export template.
    - In OSX, alternative location for directories (needed for app bundles) are:
        - 'data_AppName/Mono/etc' --> '../Resources/GodotSharp/Mono/etc'
        - 'data_AppName/Mono/lib' --> '../Frameworks/GodotSharp/Mono/lib'

- The editor can bundle prebuilt API assemblies.
    - Generate them with a tools build by running: `--generate-cs-core-api <GodotSharp_OutputDir> --generate-cs-editor-api <GodotSharpEditor_OutputDir> <GodotSharp_OutputDir>/bin/Release/GodotSharp.dll` (This command will be simplified in the future and both projects will be in the same solution)
    - Build the solutions and copy the output files to '#bin/GodotSharp/Api'.
- Fixed API assembly being added twice during the export process.

7 files changed, 238 insertions, 69 deletions

diff --git a/modules/mono/editor/GodotSharpTools/Editor/GodotSharpExport.cs b/modules/mono/editor/GodotSharpTools/Editor/GodotSharpExport.cs
new file mode 100644
index 0000000000..9f0d562ef7
--- /dev/null
+++ b/modules/mono/editor/GodotSharpTools/Editor/GodotSharpExport.cs
@@ -0,0 +1,72 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.CompilerServices;
+
+namespace GodotSharpTools.Editor
+{
+    public static class GodotSharpExport
+    {
+        public static void _ExportBegin(string[] features, bool debug, string path, int flags)
+        {
+            var featureSet = new HashSet<string>(features);
+
+            if (PlatformHasTemplateDir(featureSet))
+            {
+                string templateDirName = "data.mono";
+
+                if (featureSet.Contains("Windows"))
+                {
+                    templateDirName += ".windows";
+                    templateDirName += featureSet.Contains("64") ? ".64" : ".32";
+                }
+                else if (featureSet.Contains("X11"))
+                {
+                    templateDirName += ".x11";
+                    templateDirName += featureSet.Contains("64") ? ".64" : ".32";
+                }
+                else
+                {
+                    throw new NotSupportedException("Target platform not supported");
+                }
+
+                templateDirName += debug ? ".debug" : ".release";
+
+                string templateDirPath = Path.Combine(GetTemplatesDir(), templateDirName);
+
+                if (!Directory.Exists(templateDirPath))
+                    throw new FileNotFoundException("Data template directory not found");
+
+                string outputDir = new FileInfo(path).Directory.FullName;
+
+                string outputDataDir = Path.Combine(outputDir, GetDataDirName());
+
+                Directory.Delete(outputDataDir, recursive: true); // Clean first
+                Directory.CreateDirectory(outputDataDir);
+                
+                foreach (string dir in Directory.GetDirectories(templateDirPath, "*", SearchOption.AllDirectories))
+                {
+                    Directory.CreateDirectory(Path.Combine(outputDataDir, dir.Substring(templateDirPath.Length + 1)));
+                }
+
+                foreach (string file in Directory.GetFiles(templateDirPath, "*", SearchOption.AllDirectories))
+                {
+                    File.Copy(file, Path.Combine(outputDataDir, file.Substring(templateDirPath.Length + 1)));
+                }
+            }
+        }
+
+        public static bool PlatformHasTemplateDir(HashSet<string> featureSet)
+        {
+            // OSX export templates are contained in a zip, so we place
+            // our custom template inside it and let Godot do the rest.
+            return !featureSet.Contains("OSX");
+        }
+
+        [MethodImpl(MethodImplOptions.InternalCall)]
+        extern static string GetTemplatesDir();
+
+        [MethodImpl(MethodImplOptions.InternalCall)]
+        extern static string GetDataDirName();
+    }
+}
diff --git a/modules/mono/editor/GodotSharpTools/GodotSharpTools.csproj b/modules/mono/editor/GodotSharpTools/GodotSharpTools.csproj
index 773e8196f7..fceb732426 100644
--- a/modules/mono/editor/GodotSharpTools/GodotSharpTools.csproj
+++ b/modules/mono/editor/GodotSharpTools/GodotSharpTools.csproj
@@ -41,6 +41,7 @@
     <Compile Include="Project\ProjectUtils.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Utils\OS.cs" />
+    <Compile Include="Editor\GodotSharpExport.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
 </Project>
\ No newline at end of file
diff --git a/modules/mono/editor/csharp_project.cpp b/modules/mono/editor/csharp_project.cpp
index 4764cbe941..6f223b75a3 100644
--- a/modules/mono/editor/csharp_project.cpp
+++ b/modules/mono/editor/csharp_project.cpp
@@ -51,7 +51,7 @@ String generate_core_api_project(const String &p_dir, const Vector<String> &p_fi
 	MonoObject *ret = klass->get_method("GenCoreApiProject", 2)->invoke(NULL, args, &exc);
 
 	if (exc) {
-		GDMonoUtils::debug_unhandled_exception(exc);
+		GDMonoUtils::debug_print_unhandled_exception(exc);
 		ERR_FAIL_V(String());
 	}
 
@@ -72,7 +72,7 @@ String generate_editor_api_project(const String &p_dir, const String &p_core_dll
 	MonoObject *ret = klass->get_method("GenEditorApiProject", 3)->invoke(NULL, args, &exc);
 
 	if (exc) {
-		GDMonoUtils::debug_unhandled_exception(exc);
+		GDMonoUtils::debug_print_unhandled_exception(exc);
 		ERR_FAIL_V(String());
 	}
 
@@ -93,7 +93,7 @@ String generate_game_project(const String &p_dir, const String &p_name, const Ve
 	MonoObject *ret = klass->get_method("GenGameProject", 3)->invoke(NULL, args, &exc);
 
 	if (exc) {
-		GDMonoUtils::debug_unhandled_exception(exc);
+		GDMonoUtils::debug_print_unhandled_exception(exc);
 		ERR_FAIL_V(String());
 	}
 
@@ -114,7 +114,7 @@ void add_item(const String &p_project_path, const String &p_item_type, const Str
 	klass->get_method("AddItemToProjectChecked", 3)->invoke(NULL, args, &exc);
 
 	if (exc) {
-		GDMonoUtils::debug_unhandled_exception(exc);
+		GDMonoUtils::debug_print_unhandled_exception(exc);
 		ERR_FAIL();
 	}
 }
diff --git a/modules/mono/editor/godotsharp_builds.cpp b/modules/mono/editor/godotsharp_builds.cpp
index d397814fa7..8fe6e46b60 100644
--- a/modules/mono/editor/godotsharp_builds.cpp
+++ b/modules/mono/editor/godotsharp_builds.cpp
@@ -249,6 +249,18 @@ bool GodotSharpBuilds::build_api_sln(const String &p_name, const String &p_api_s
 
 bool GodotSharpBuilds::copy_api_assembly(const String &p_src_dir, const String &p_dst_dir, const String &p_assembly_name, APIAssembly::Type p_api_type) {
 
+	// Create destination directory if needed
+	if (!DirAccess::exists(p_dst_dir)) {
+		DirAccess *da = DirAccess::create_for_path(p_dst_dir);
+		Error err = da->make_dir_recursive(p_dst_dir);
+		memdelete(da);
+
+		if (err != OK) {
+			show_build_error_dialog("Failed to create destination directory for the API assemblies. Error: " + itos(err));
+			return false;
+		}
+	}
+
 	String assembly_file = p_assembly_name + ".dll";
 	String assembly_src = p_src_dir.plus_file(assembly_file);
 	String assembly_dst = p_dst_dir.plus_file(assembly_file);
@@ -296,9 +308,9 @@ bool GodotSharpBuilds::make_api_sln(APIAssembly::Type p_api_type) {
 	String api_name = p_api_type == APIAssembly::API_CORE ? API_ASSEMBLY_NAME : EDITOR_API_ASSEMBLY_NAME;
 	String api_build_config = "Release";
 
-	EditorProgress pr("mono_build_release_" + api_name, "Building " + api_name + " solution...", 4);
+	EditorProgress pr("mono_build_release_" + api_name, "Building " + api_name + " solution...", 3);
 
-	pr.step("Generating " + api_name + " solution");
+	pr.step("Generating " + api_name + " solution", 0);
 
 	String core_api_sln_dir = GodotSharpDirs::get_mono_solutions_dir()
 									  .plus_file(_api_folder_name(APIAssembly::API_CORE))
@@ -336,34 +348,19 @@ bool GodotSharpBuilds::make_api_sln(APIAssembly::Type p_api_type) {
 		}
 	}
 
-	pr.step("Building " + api_name + " solution");
+	pr.step("Building " + api_name + " solution", 1);
 
 	if (!GodotSharpBuilds::build_api_sln(api_name, api_sln_dir, api_build_config))
 		return false;
 
-	pr.step("Copying " + api_name + " assembly");
-
-	String res_assemblies_dir = GodotSharpDirs::get_res_assemblies_dir();
-
-	// Create assemblies directory if needed
-	if (!DirAccess::exists(res_assemblies_dir)) {
-		DirAccess *da = DirAccess::create_for_path(res_assemblies_dir);
-		Error err = da->make_dir_recursive(res_assemblies_dir);
-		memdelete(da);
-
-		if (err != OK) {
-			show_build_error_dialog("Failed to create assemblies directory. Error: " + itos(err));
-			return false;
-		}
-	}
+	pr.step("Copying " + api_name + " assembly", 2);
 
 	// Copy the built assembly to the assemblies directory
 	String api_assembly_dir = api_sln_dir.plus_file("bin").plus_file(api_build_config);
+	String res_assemblies_dir = GodotSharpDirs::get_res_assemblies_dir();
 	if (!GodotSharpBuilds::copy_api_assembly(api_assembly_dir, res_assemblies_dir, api_name, p_api_type))
 		return false;
 
-	pr.step("Done");
-
 	return true;
 }
 
@@ -372,15 +369,39 @@ bool GodotSharpBuilds::build_project_blocking(const String &p_config) {
 	if (!FileAccess::exists(GodotSharpDirs::get_project_sln_path()))
 		return true; // No solution to build
 
-	if (!GodotSharpBuilds::make_api_sln(APIAssembly::API_CORE))
-		return false;
+	String editor_prebuilt_api_dir = GodotSharpDirs::get_data_editor_prebuilt_api_dir();
+	String res_assemblies_dir = GodotSharpDirs::get_res_assemblies_dir();
 
-	if (!GodotSharpBuilds::make_api_sln(APIAssembly::API_EDITOR))
-		return false;
+	if (FileAccess::exists(editor_prebuilt_api_dir.plus_file(API_ASSEMBLY_NAME ".dll"))) {
+		EditorProgress pr("mono_copy_prebuilt_api_assemblies",
+				"Copying prebuilt " API_ASSEMBLY_NAME " assemblies...", 1);
+		pr.step("Copying " API_ASSEMBLY_NAME " assembly", 0);
 
-	EditorProgress pr("mono_project_debug_build", "Building project solution...", 2);
+		if (!GodotSharpBuilds::copy_api_assembly(editor_prebuilt_api_dir, res_assemblies_dir,
+					API_ASSEMBLY_NAME, APIAssembly::API_CORE)) {
+			return false;
+		}
+	} else {
+		if (!GodotSharpBuilds::make_api_sln(APIAssembly::API_CORE))
+			return false;
+	}
 
-	pr.step("Building project solution");
+	if (DirAccess::exists(editor_prebuilt_api_dir.plus_file(EDITOR_API_ASSEMBLY_NAME ".dll"))) {
+		EditorProgress pr("mono_copy_prebuilt_api_assemblies",
+				"Copying prebuilt " EDITOR_API_ASSEMBLY_NAME " assemblies...", 1);
+		pr.step("Copying " EDITOR_API_ASSEMBLY_NAME " assembly", 0);
+
+		if (!GodotSharpBuilds::copy_api_assembly(editor_prebuilt_api_dir, res_assemblies_dir,
+					EDITOR_API_ASSEMBLY_NAME, APIAssembly::API_EDITOR)) {
+			return false;
+		}
+	} else {
+		if (!GodotSharpBuilds::make_api_sln(APIAssembly::API_EDITOR))
+			return false;
+	}
+
+	EditorProgress pr("mono_project_debug_build", "Building project solution...", 1);
+	pr.step("Building project solution", 0);
 
 	MonoBuildInfo build_info(GodotSharpDirs::get_project_sln_path(), p_config);
 	if (!GodotSharpBuilds::get_singleton()->build(build_info)) {
@@ -388,8 +409,6 @@ bool GodotSharpBuilds::build_project_blocking(const String &p_config) {
 		return false;
 	}
 
-	pr.step("Done");
-
 	return true;
 }
 
diff --git a/modules/mono/editor/godotsharp_editor.cpp b/modules/mono/editor/godotsharp_editor.cpp
index 3ee38515bf..fca88a7164 100644
--- a/modules/mono/editor/godotsharp_editor.cpp
+++ b/modules/mono/editor/godotsharp_editor.cpp
@@ -197,6 +197,7 @@ void GodotSharpEditor::register_internal_calls() {
 	mono_add_internal_call("GodotSharpTools.Utils.OS::GetPlatformName", (void *)godot_icall_Utils_OS_GetPlatformName);
 
 	GodotSharpBuilds::register_internal_calls();
+	GodotSharpExport::register_internal_calls();
 }
 
 void GodotSharpEditor::show_error_dialog(const String &p_message, const String &p_title) {
diff --git a/modules/mono/editor/godotsharp_export.cpp b/modules/mono/editor/godotsharp_export.cpp
index cd09e6516a..933ede93dc 100644
--- a/modules/mono/editor/godotsharp_export.cpp
+++ b/modules/mono/editor/godotsharp_export.cpp
@@ -30,12 +30,37 @@
 
 #include "godotsharp_export.h"
 
+#include "core/version.h"
+
 #include "../csharp_script.h"
 #include "../godotsharp_defs.h"
 #include "../godotsharp_dirs.h"
+#include "../mono_gd/gd_mono_class.h"
+#include "../mono_gd/gd_mono_marshal.h"
 #include "godotsharp_builds.h"
 
-void GodotSharpExport::_export_file(const String &p_path, const String &p_type, const Set<String> &p_features) {
+static MonoString *godot_icall_GodotSharpExport_GetTemplatesDir() {
+	String current_version = VERSION_FULL_CONFIG;
+	String templates_dir = EditorSettings::get_singleton()->get_templates_dir().plus_file(current_version);
+	return GDMonoMarshal::mono_string_from_godot(ProjectSettings::get_singleton()->globalize_path(templates_dir));
+}
+
+static MonoString *godot_icall_GodotSharpExport_GetDataDirName() {
+	String appname = ProjectSettings::get_singleton()->get("application/config/name");
+	String appname_safe = OS::get_singleton()->get_safe_dir_name(appname);
+	return GDMonoMarshal::mono_string_from_godot("data_" + appname_safe);
+}
+
+void GodotSharpExport::register_internal_calls() {
+	static bool registered = false;
+	ERR_FAIL_COND(registered);
+	registered = true;
+
+	mono_add_internal_call("GodotSharpTools.Editor.GodotSharpExport::GetTemplatesDir", (void *)godot_icall_GodotSharpExport_GetTemplatesDir);
+	mono_add_internal_call("GodotSharpTools.Editor.GodotSharpExport::GetDataDirName", (void *)godot_icall_GodotSharpExport_GetDataDirName);
+}
+
+void GodotSharpExport::_export_file(const String &p_path, const String &p_type, const Set<String> &) {
 
 	if (p_type != CSharpLanguage::get_singleton()->get_type())
 		return;
@@ -56,59 +81,78 @@ void GodotSharpExport::_export_begin(const Set<String> &p_features, bool p_debug
 	// TODO right now there is no way to stop the export process with an error
 
 	ERR_FAIL_COND(!GDMono::get_singleton()->is_runtime_initialized());
-	ERR_FAIL_NULL(GDMono::get_singleton()->get_tools_domain());
+	ERR_FAIL_NULL(TOOLS_DOMAIN);
+	ERR_FAIL_NULL(GDMono::get_singleton()->get_editor_tools_assembly());
 
 	String build_config = p_debug ? "Debug" : "Release";
 
 	ERR_FAIL_COND(!GodotSharpBuilds::build_project_blocking(build_config));
 
-	// Add API assemblies
-
-	String core_api_dll_path = GodotSharpDirs::get_res_assemblies_dir().plus_file(API_ASSEMBLY_NAME ".dll");
-	ERR_FAIL_COND(!_add_assembly(core_api_dll_path, core_api_dll_path));
-
-	String editor_api_dll_path = GodotSharpDirs::get_res_assemblies_dir().plus_file(EDITOR_API_ASSEMBLY_NAME ".dll");
-	ERR_FAIL_COND(!_add_assembly(editor_api_dll_path, editor_api_dll_path));
+	// Add dependency assemblies
 
-	// Add project assembly
+	Map<String, String> dependencies;
 
 	String project_dll_name = ProjectSettings::get_singleton()->get("application/config/name");
 	if (project_dll_name.empty()) {
 		project_dll_name = "UnnamedProject";
 	}
 
-	String project_dll_src_path = GodotSharpDirs::get_res_temp_assemblies_base_dir().plus_file(build_config).plus_file(project_dll_name + ".dll");
-	String project_dll_dst_path = GodotSharpDirs::get_res_assemblies_dir().plus_file(project_dll_name + ".dll");
-	ERR_FAIL_COND(!_add_assembly(project_dll_src_path, project_dll_dst_path));
-
-	// Add dependencies
-
-	MonoDomain *prev_domain = mono_domain_get();
-	MonoDomain *export_domain = GDMonoUtils::create_domain("GodotEngine.ProjectExportDomain");
+	String project_dll_src_dir = GodotSharpDirs::get_res_temp_assemblies_base_dir().plus_file(build_config);
+	String project_dll_src_path = project_dll_src_dir.plus_file(project_dll_name + ".dll");
+	dependencies.insert(project_dll_name, project_dll_src_path);
 
-	ERR_FAIL_COND(!export_domain);
-	ERR_FAIL_COND(!mono_domain_set(export_domain, false));
+	{
+		MonoDomain *export_domain = GDMonoUtils::create_domain("GodotEngine.ProjectExportDomain");
+		ERR_FAIL_NULL(export_domain);
+		_GDMONO_SCOPE_EXIT_DOMAIN_UNLOAD_(export_domain);
 
-	Map<String, String> dependencies;
-	dependencies.insert("mscorlib", GDMono::get_singleton()->get_corlib_assembly()->get_path());
-
-	GDMonoAssembly *scripts_assembly = GDMonoAssembly::load_from(project_dll_name, project_dll_src_path, /* refonly: */ true);
+		_GDMONO_SCOPE_DOMAIN_(export_domain);
 
-	ERR_EXPLAIN("Cannot load refonly assembly: " + project_dll_name);
-	ERR_FAIL_COND(!scripts_assembly);
+		GDMonoAssembly *scripts_assembly = NULL;
+		bool load_success = GDMono::get_singleton()->load_assembly_from(project_dll_name,
+				project_dll_src_dir, &scripts_assembly, /* refonly: */ true);
 
-	Error depend_error = _get_assembly_dependencies(scripts_assembly, dependencies);
+		ERR_EXPLAIN("Cannot load refonly assembly: " + project_dll_name);
+		ERR_FAIL_COND(!load_success);
 
-	GDMono::get_singleton()->finalize_and_unload_domain(export_domain);
-	mono_domain_set(prev_domain, false);
-
-	ERR_FAIL_COND(depend_error != OK);
+		Vector<String> search_dirs;
+		GDMonoAssembly::fill_search_dirs(search_dirs);
+		Error depend_error = _get_assembly_dependencies(scripts_assembly, search_dirs, dependencies);
+		ERR_FAIL_COND(depend_error != OK);
+	}
 
 	for (Map<String, String>::Element *E = dependencies.front(); E; E = E->next()) {
 		String depend_src_path = E->value();
 		String depend_dst_path = GodotSharpDirs::get_res_assemblies_dir().plus_file(depend_src_path.get_file());
 		ERR_FAIL_COND(!_add_assembly(depend_src_path, depend_dst_path));
 	}
+
+	// Mono specific export template extras (data dir)
+
+	GDMonoClass *export_class = GDMono::get_singleton()->get_editor_tools_assembly()->get_class("GodotSharpTools.Editor", "GodotSharpExport");
+	ERR_FAIL_NULL(export_class);
+	GDMonoMethod *export_begin_method = export_class->get_method("_ExportBegin", 4);
+	ERR_FAIL_NULL(export_begin_method);
+
+	MonoArray *features = mono_array_new(mono_domain_get(), CACHED_CLASS_RAW(String), p_features.size());
+	int i = 0;
+	for (const Set<String>::Element *E = p_features.front(); E; E = E->next()) {
+		MonoString *boxed = GDMonoMarshal::mono_string_from_godot(E->get());
+		mono_array_set(features, MonoString *, i, boxed);
+		i++;
+	}
+
+	MonoBoolean debug = p_debug;
+	MonoString *path = GDMonoMarshal::mono_string_from_godot(p_path);
+	uint32_t flags = p_flags;
+	void *args[4] = { features, &debug, path, &flags };
+	MonoException *exc = NULL;
+	export_begin_method->invoke_raw(NULL, args, &exc);
+
+	if (exc) {
+		GDMonoUtils::debug_print_unhandled_exception(exc);
+		ERR_FAIL();
+	}
 }
 
 bool GodotSharpExport::_add_assembly(const String &p_src_path, const String &p_dst_path) {
@@ -125,7 +169,7 @@ bool GodotSharpExport::_add_assembly(const String &p_src_path, const String &p_d
 	return true;
 }
 
-Error GodotSharpExport::_get_assembly_dependencies(GDMonoAssembly *p_assembly, Map<String, String> &r_dependencies) {
+Error GodotSharpExport::_get_assembly_dependencies(GDMonoAssembly *p_assembly, const Vector<String> &p_search_dirs, Map<String, String> &r_dependencies) {
 
 	MonoImage *image = p_assembly->get_image();
 
@@ -134,18 +178,48 @@ Error GodotSharpExport::_get_assembly_dependencies(GDMonoAssembly *p_assembly, M
 		mono_assembly_get_assemblyref(image, i, ref_aname);
 		String ref_name = mono_assembly_name_get_name(ref_aname);
 
-		if (ref_name == "mscorlib" || r_dependencies.find(ref_name))
+		if (r_dependencies.find(ref_name))
 			continue;
 
 		GDMonoAssembly *ref_assembly = NULL;
-		if (!GDMono::get_singleton()->load_assembly(ref_name, ref_aname, &ref_assembly, /* refonly: */ true)) {
-			ERR_EXPLAIN("Cannot load refonly assembly: " + ref_name);
+		String path;
+		bool has_extension = ref_name.ends_with(".dll") || ref_name.ends_with(".exe");
+
+		for (int i = 0; i < p_search_dirs.size(); i++) {
+			const String &search_dir = p_search_dirs[i];
+
+			if (has_extension) {
+				path = search_dir.plus_file(ref_name);
+				if (FileAccess::exists(path)) {
+					GDMono::get_singleton()->load_assembly_from(ref_name.get_basename(), search_dir, ref_aname, &ref_assembly, true);
+					if (ref_assembly != NULL)
+						break;
+				}
+			} else {
+				path = search_dir.plus_file(ref_name + ".dll");
+				if (FileAccess::exists(path)) {
+					GDMono::get_singleton()->load_assembly_from(ref_name, search_dir, ref_aname, &ref_assembly, true);
+					if (ref_assembly != NULL)
+						break;
+				}
+
+				path = search_dir.plus_file(ref_name + ".exe");
+				if (FileAccess::exists(path)) {
+					GDMono::get_singleton()->load_assembly_from(ref_name, search_dir, ref_aname, &ref_assembly, true);
+					if (ref_assembly != NULL)
+						break;
+				}
+			}
+		}
+
+		if (!ref_assembly) {
+			ERR_EXPLAIN("Cannot load assembly (refonly): " + ref_name);
 			ERR_FAIL_V(ERR_CANT_RESOLVE);
 		}
 
 		r_dependencies.insert(ref_name, ref_assembly->get_path());
 
-		Error err = _get_assembly_dependencies(ref_assembly, r_dependencies);
+		Error err = _get_assembly_dependencies(ref_assembly, p_search_dirs, r_dependencies);
 		if (err != OK)
 			return err;
 	}
diff --git a/modules/mono/editor/godotsharp_export.h b/modules/mono/editor/godotsharp_export.h
index b38db9660c..f007016578 100644
--- a/modules/mono/editor/godotsharp_export.h
+++ b/modules/mono/editor/godotsharp_export.h
@@ -43,13 +43,15 @@ class GodotSharpExport : public EditorExportPlugin {
 
 	bool _add_assembly(const String &p_src_path, const String &p_dst_path);
 
-	Error _get_assembly_dependencies(GDMonoAssembly *p_assembly, Map<String, String> &r_dependencies);
+	Error _get_assembly_dependencies(GDMonoAssembly *p_assembly, const Vector<String> &p_search_dirs, Map<String, String> &r_dependencies);
 
 protected:
 	virtual void _export_file(const String &p_path, const String &p_type, const Set<String> &p_features);
 	virtual void _export_begin(const Set<String> &p_features, bool p_debug, const String &p_path, int p_flags);
 
 public:
+	static void register_internal_calls();
+
 	GodotSharpExport();
 	~GodotSharpExport();
 };