C#: Print error when MethodBind call fails

modules/mono/editor/bindings_generator.cpp

@@ -70,6 +70,7 @@
 #define CS_FIELD_MEMORYOWN "memoryOwn"
 #define CS_PARAM_METHODBIND "method"
 #define CS_PARAM_INSTANCE "ptr"
+#define CS_PARAM_CALLER "caller"
 #define CS_SMETHOD_GETINSTANCE "GetPtr"
 #define CS_METHOD_CALL "Call"
 
@@ -87,6 +88,7 @@
 #define C_NS_MONOINTERNALS "GDMonoInternals"
 #define C_METHOD_TIE_MANAGED_TO_UNMANAGED C_NS_MONOINTERNALS "::tie_managed_to_unmanaged"
 #define C_METHOD_UNMANAGED_GET_MANAGED C_NS_MONOUTILS "::unmanaged_get_managed"
+#define C_METHOD_CHECK_CALL_ERROR C_NS_MONOINTERNALS "::check_call_error"
 
 #define C_NS_MONOMARSHAL "GDMonoMarshal"
 #define C_METHOD_MANAGED_TO_VARIANT C_NS_MONOMARSHAL "::mono_object_to_variant"
@@ -774,6 +776,11 @@ void BindingsGenerator::_generate_method_icalls(const TypeInterface &p_itype) {
 			i++;
 		}
 
+		// Collect caller name for MethodBind
+		if (imethod.is_vararg) {
+			im_sig += ", string " CS_PARAM_CALLER;
+		}
+
 		String im_type_out = return_type->im_type_out;
 
 		if (return_type->ret_as_byref_arg) {
@@ -1658,6 +1665,10 @@ Error BindingsGenerator::_generate_cs_method(const BindingsGenerator::TypeInterf
 		}
 	}
 
+	if (p_imethod.is_vararg) {
+		icall_params += ", \"" + p_imethod.cname + "\"";
+	}
+
 	// Generate method
 	{
 		if (!p_imethod.is_virtual && !p_imethod.requires_object_call) {
@@ -2002,6 +2013,11 @@ Error BindingsGenerator::_generate_glue_method(const BindingsGenerator::TypeInte
 		i++;
 	}
 
+	// Collect caller name for MethodBind
+	if (p_imethod.is_vararg) {
+		c_func_sig += ", MonoString* " CS_PARAM_CALLER;
+	}
+
 	if (return_type->ret_as_byref_arg) {
 		c_func_sig += ", ";
 		c_func_sig += return_type->c_type_in;
@@ -2115,6 +2131,15 @@ Error BindingsGenerator::_generate_glue_method(const BindingsGenerator::TypeInte
 			p_output.append(p_imethod.arguments.size() ? C_LOCAL_PTRCALL_ARGS ".ptr()" : "NULL");
 			p_output.append(", total_length, vcall_error);\n");
 
+			p_output.append("#ifdef DEBUG_ENABLED\n");
+			p_output.append("\tVariant instance_variant = Variant(" CS_PARAM_INSTANCE ");\n");
+			p_output.append("\t" C_METHOD_CHECK_CALL_ERROR "(");
+			p_output.append(C_METHOD_MONOSTR_TO_GODOT "(" CS_PARAM_CALLER ")");
+			p_output.append(", &instance_variant, ");
+			p_output.append(p_imethod.arguments.size() ? C_LOCAL_PTRCALL_ARGS ".ptr()" : "NULL");
+			p_output.append(", total_length, vcall_error);\n");
+			p_output.append("#endif // DEBUG_ENABLED\n");
+
 			if (!ret_void) {
 				// See the comment on the C_LOCAL_VARARG_RET declaration
 				if (return_type->cname != name_cache.type_Variant) {

modules/mono/mono_gd/gd_mono_internals.cpp

@@ -139,4 +139,89 @@ void gd_unhandled_exception_event(MonoException *p_exc) {
 	args[0] = p_exc;
 	mono_runtime_invoke(unhandled_exception_method, nullptr, (void **)args, nullptr);
 }
+
+#if DEBUG_ENABLED
+static String _get_var_type(const Variant *p_var) {
+	String basestr;
+
+	if (p_var->get_type() == Variant::OBJECT) {
+		Object *bobj = *p_var;
+		if (!bobj) {
+			if (p_var->is_invalid_object()) {
+				basestr = "previously freed instance";
+			} else {
+				basestr = "null instance";
+			}
+		} else {
+			if (bobj->get_script_instance()) {
+				basestr = bobj->get_class() + " (" + bobj->get_script_instance()->get_script()->get_path().get_file() + ")";
+			} else {
+				basestr = bobj->get_class();
+			}
+		}
+
+	} else {
+		basestr = Variant::get_type_name(p_var->get_type());
+	}
+
+	return basestr;
+}
+
+static String _get_call_where(const String &p_method, const Variant *p_instance, const Variant **argptrs, int argc) {
+	String methodstr = p_method;
+	String basestr = _get_var_type(p_instance);
+
+	if (methodstr == "call") {
+		if (argc >= 1) {
+			methodstr = String(*argptrs[0]) + " (via call)";
+		}
+	} else if (methodstr == "call_recursive" && basestr == "TreeItem") {
+		if (argc >= 1) {
+			methodstr = String(*argptrs[0]) + " (via TreeItem.call_recursive)";
+		}
+	}
+	return "function '" + methodstr + "' in base '" + basestr + "'";
+}
+
+static String _get_call_error(const Variant::CallError &p_err, const String &p_where, const Variant **argptrs) {
+	String err_text;
+
+	if (p_err.error == Variant::CallError::CALL_ERROR_INVALID_ARGUMENT) {
+		int errorarg = p_err.argument;
+		// Handle the Object to Object case separately as we don't have further class details.
+#ifdef DEBUG_ENABLED
+		if (p_err.expected == Variant::OBJECT && argptrs[errorarg]->get_type() == p_err.expected) {
+			err_text = "Invalid type in " + p_where + ". The Object-derived class of argument " + itos(errorarg + 1) + " (" + _get_var_type(argptrs[errorarg]) + ") is not a subclass of the expected argument class.";
+		} else
+#endif // DEBUG_ENABLED
+		{
+			err_text = "Invalid type in " + p_where + ". Cannot convert argument " + itos(errorarg + 1) + " from " + Variant::get_type_name(argptrs[errorarg]->get_type()) + " to " + Variant::get_type_name(p_err.expected) + ".";
+		}
+	} else if (p_err.error == Variant::CallError::CALL_ERROR_TOO_MANY_ARGUMENTS) {
+		err_text = "Invalid call to " + p_where + ". Expected " + itos(p_err.argument) + " arguments.";
+	} else if (p_err.error == Variant::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS) {
+		err_text = "Invalid call to " + p_where + ". Expected " + itos(p_err.argument) + " arguments.";
+	} else if (p_err.error == Variant::CallError::CALL_ERROR_INVALID_METHOD) {
+		err_text = "Invalid call. Nonexistent " + p_where + ".";
+	} else if (p_err.error == Variant::CallError::CALL_ERROR_INSTANCE_IS_NULL) {
+		err_text = "Attempt to call " + p_where + " on a null instance.";
+	} else {
+		err_text = "Bug, call error: #" + itos(p_err.error);
+	}
+
+	return err_text;
+}
+
+void check_call_error(const String &p_method, const Variant *p_instance, const Variant **p_args, int p_arg_count, const Variant::CallError &p_error) {
+	if (p_error.error == Variant::CallError::CALL_OK) {
+		// The call was successful.
+		return;
+	}
+
+	const String &where = _get_call_where(p_method, p_instance, p_args, p_arg_count);
+	ERR_PRINT(_get_call_error(p_error, where, p_args));
+}
+#else
+void check_call_error(const String &p_method, const Variant &p_instance, const Variant **p_args, int p_arg_count, const Variant::CallError &p_error) {}
+#endif
 } // namespace GDMonoInternals

modules/mono/mono_gd/gd_mono_internals.h

@@ -47,6 +47,8 @@ void tie_managed_to_unmanaged(MonoObject *managed, Object *unmanaged);
 void unhandled_exception(MonoException *p_exc);
 
 void gd_unhandled_exception_event(MonoException *p_exc);
+
+void check_call_error(const String &p_method, const Variant *p_instance, const Variant **p_args, int p_arg_count, const Variant::CallError &p_error);
 } // namespace GDMonoInternals
 
 #endif // GD_MONO_INTERNALS_H