Disable signal callback generation in C#

core/object/script_language.h

@@ -256,6 +256,7 @@ public:
 	virtual bool can_inherit_from_file() const { return false; }
 	virtual int find_function(const String &p_function, const String &p_code) const = 0;
 	virtual String make_function(const String &p_class, const String &p_name, const PackedStringArray &p_args) const = 0;
+	virtual bool can_make_function() const { return true; }
 	virtual Error open_in_external_editor(const Ref<Script> &p_script, int p_line, int p_col) { return ERR_UNAVAILABLE; }
 	virtual bool overrides_external_editor() { return false; }
 

core/object/script_language_extension.cpp

@@ -109,6 +109,7 @@ void ScriptLanguageExtension::_bind_methods() {
 	GDVIRTUAL_BIND(_can_inherit_from_file);
 	GDVIRTUAL_BIND(_find_function, "function", "code");
 	GDVIRTUAL_BIND(_make_function, "class_name", "function_name", "function_args");
+	GDVIRTUAL_BIND(_can_make_function);
 	GDVIRTUAL_BIND(_open_in_external_editor, "script", "line", "column");
 	GDVIRTUAL_BIND(_overrides_external_editor);
 

core/object/script_language_extension.h

@@ -373,6 +373,7 @@ public:
 
 	EXBIND2RC(int, find_function, const String &, const String &)
 	EXBIND3RC(String, make_function, const String &, const String &, const PackedStringArray &)
+	EXBIND0RC(bool, can_make_function)
 	EXBIND3R(Error, open_in_external_editor, const Ref<Script> &, int, int)
 	EXBIND0R(bool, overrides_external_editor)
 

doc/classes/ScriptLanguageExtension.xml

@@ -34,6 +34,11 @@
 			<description>
 			</description>
 		</method>
+		<method name="_can_make_function" qualifiers="virtual const">
+			<return type="bool" />
+			<description>
+			</description>
+		</method>
 		<method name="_complete_code" qualifiers="virtual const">
 			<return type="Dictionary" />
 			<param index="0" name="code" type="String" />

editor/connections_dialog.cpp

@@ -178,6 +178,7 @@ void ConnectDialog::_tree_node_selected() {
 		set_dst_method(generate_method_callback_name(source, signal, current));
 	}
 	_update_method_tree();
+	_update_warning_label();
 	_update_ok_enabled();
 }
 
@@ -433,6 +434,23 @@ void ConnectDialog::_update_ok_enabled() {
 	get_ok_button()->set_disabled(false);
 }
 
+void ConnectDialog::_update_warning_label() {
+	Ref<Script> scr = source->get_node(dst_path)->get_script();
+	if (scr.is_null()) {
+		warning_label->set_visible(false);
+		return;
+	}
+
+	ScriptLanguage *language = scr->get_language();
+	if (language->can_make_function()) {
+		warning_label->set_visible(false);
+		return;
+	}
+
+	warning_label->set_text(vformat(TTR("%s: Callback code won't be generated, please add it manually."), language->get_name()));
+	warning_label->set_visible(true);
+}
+
 void ConnectDialog::_notification(int p_what) {
 	switch (p_what) {
 		case NOTIFICATION_ENTER_TREE: {
@@ -617,6 +635,7 @@ void ConnectDialog::init(const ConnectionData &p_cd, const PackedStringArray &p_
 
 void ConnectDialog::popup_dialog(const String p_for_signal) {
 	from_signal->set_text(p_for_signal);
+	warning_label->add_theme_color_override("font_color", warning_label->get_theme_color(SNAME("warning_color"), EditorStringName(Editor)));
 	error_label->add_theme_color_override("font_color", error_label->get_theme_color(SNAME("error_color"), EditorStringName(Editor)));
 	filter_nodes->clear();
 
@@ -694,6 +713,10 @@ ConnectDialog::ConnectDialog() {
 	connect_to_label = Object::cast_to<Label>(vbc_left->get_child(mc->get_index() - 1));
 	vbc_left->add_child(tree);
 
+	warning_label = memnew(Label);
+	vbc_left->add_child(warning_label);
+	warning_label->hide();
+
 	error_label = memnew(Label);
 	error_label->set_text(TTR("Scene does not contain any script."));
 	vbc_left->add_child(error_label);

editor/connections_dialog.h

@@ -134,6 +134,7 @@ private:
 	CheckButton *advanced = nullptr;
 	Vector<Control *> bind_controls;
 
+	Label *warning_label = nullptr;
 	Label *error_label = nullptr;
 
 	void ok_pressed() override;
@@ -155,6 +156,7 @@ private:
 	void _remove_bind();
 	void _advanced_pressed();
 	void _update_ok_enabled();
+	void _update_warning_label();
 
 protected:
 	void _notification(int p_what);

editor/plugins/script_editor_plugin.cpp

@@ -2726,6 +2726,10 @@ void ScriptEditor::_add_callback(Object *p_obj, const String &p_function, const
 	Ref<Script> scr = p_obj->get_script();
 	ERR_FAIL_COND(!scr.is_valid());
 
+	if (!scr->get_language()->can_make_function()) {
+		return;
+	}
+
 	EditorNode::get_singleton()->push_item(scr.ptr());
 
 	for (int i = 0; i < tab_container->get_tab_count(); i++) {

editor/plugins/script_text_editor.cpp

@@ -345,14 +345,19 @@ void ScriptTextEditor::reload_text() {
 }
 
 void ScriptTextEditor::add_callback(const String &p_function, PackedStringArray p_args) {
+	ScriptLanguage *language = script->get_language();
+	if (!language->can_make_function()) {
+		return;
+	}
+
 	String code = code_editor->get_text_editor()->get_text();
-	int pos = script->get_language()->find_function(p_function, code);
+	int pos = language->find_function(p_function, code);
 	code_editor->get_text_editor()->remove_secondary_carets();
 	if (pos == -1) {
 		//does not exist
 		code_editor->get_text_editor()->deselect();
 		pos = code_editor->get_text_editor()->get_line_count() + 2;
-		String func = script->get_language()->make_function("", p_function, p_args);
+		String func = language->make_function("", p_function, p_args);
 		//code=code+func;
 		code_editor->get_text_editor()->set_caret_line(pos + 1);
 		code_editor->get_text_editor()->set_caret_column(1000000); //none shall be that big

modules/mono/csharp_script.cpp

@@ -516,22 +516,11 @@ static String variant_type_to_managed_name(const String &p_var_type_name) {
 }
 
 String CSharpLanguage::make_function(const String &, const String &p_name, const PackedStringArray &p_args) const {
-	// FIXME
-	// - Due to Godot's API limitation this just appends the function to the end of the file
-	// - Use fully qualified name if there is ambiguity
-	String s = "private void " + p_name + "(";
-	for (int i = 0; i < p_args.size(); i++) {
-		const String &arg = p_args[i];
-
-		if (i > 0) {
-			s += ", ";
-		}
-
-		s += variant_type_to_managed_name(arg.get_slice(":", 1)) + " " + escape_csharp_keyword(arg.get_slice(":", 0));
-	}
-	s += ")\n{\n    // Replace with function body.\n}\n";
-
-	return s;
+	// The make_function() API does not work for C# scripts.
+	// It will always append the generated function at the very end of the script. In C#, it will break compilation by
+	// appending code after the final closing bracket (either the class' or the namespace's).
+	// To prevent issues, we have can_make_function() returning false, and make_function() is never implemented.
+	return String();
 }
 #else
 String CSharpLanguage::make_function(const String &, const String &, const PackedStringArray &) const {

modules/mono/csharp_script.h

@@ -439,6 +439,7 @@ public:
 		return -1;
 	}
 	String make_function(const String &p_class, const String &p_name, const PackedStringArray &p_args) const override;
+	virtual bool can_make_function() const override { return false; }
 	virtual String _get_indentation() const;
 	/* TODO? */ void auto_indent_code(String &p_code, int p_from_line, int p_to_line) const override {}
 	/* TODO */ void add_global_constant(const StringName &p_variable, const Variant &p_value) override {}