accounts/abi: fix various issues

The fixed issues include:

(1) If there is no return in a call function, unpack should
return nil error

(2) For some functions which have struct array as parameter,
it will also be detected and generate the struct definition

(3) For event, if it has non-indexed parameter, the parameter
name will also be assigned if empty. Also the internal struct
will be detected and generate struct defition if not exist.

(4) Fix annotation generation in event function

accounts/abi/abi.go

@@ -75,9 +75,6 @@ func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
 
 // Unpack output in v according to the abi specification
 func (abi ABI) Unpack(v interface{}, name string, data []byte) (err error) {
-	if len(data) == 0 {
-		return fmt.Errorf("abi: unmarshalling empty output")
-	}
 	// since there can't be naming collisions with contracts and events,
 	// we need to decide whether we're calling a method or an event
 	if method, ok := abi.Methods[name]; ok {
@@ -94,9 +91,6 @@ func (abi ABI) Unpack(v interface{}, name string, data []byte) (err error) {
 
 // UnpackIntoMap unpacks a log into the provided map[string]interface{}
 func (abi ABI) UnpackIntoMap(v map[string]interface{}, name string, data []byte) (err error) {
-	if len(data) == 0 {
-		return fmt.Errorf("abi: unmarshalling empty output")
-	}
 	// since there can't be naming collisions with contracts and events,
 	// we need to decide whether we're calling a method or an event
 	if method, ok := abi.Methods[name]; ok {

accounts/abi/argument.go

@@ -88,6 +88,13 @@ func (arguments Arguments) isTuple() bool {
 
 // Unpack performs the operation hexdata -> Go format
 func (arguments Arguments) Unpack(v interface{}, data []byte) error {
+	if len(data) == 0 {
+		if len(arguments) != 0 {
+			return fmt.Errorf("abi: unmarshalling empty output")
+		} else {
+			return nil // Nothing to unmarshal, return
+		}
+	}
 	// make sure the passed value is arguments pointer
 	if reflect.Ptr != reflect.ValueOf(v).Kind() {
 		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
@@ -104,11 +111,17 @@ func (arguments Arguments) Unpack(v interface{}, data []byte) error {
 
 // UnpackIntoMap performs the operation hexdata -> mapping of argument name to argument value
 func (arguments Arguments) UnpackIntoMap(v map[string]interface{}, data []byte) error {
+	if len(data) == 0 {
+		if len(arguments) != 0 {
+			return fmt.Errorf("abi: unmarshalling empty output")
+		} else {
+			return nil // Nothing to unmarshal, return
+		}
+	}
 	marshalledValues, err := arguments.UnpackValues(data)
 	if err != nil {
 		return err
 	}
-
 	return arguments.unpackIntoMap(v, marshalledValues)
 }
 

accounts/abi/bind/bind.go

@@ -86,7 +86,7 @@ func Bind(types []string, abis []string, bytecodes []string, fsigs []map[string]
 				if input.Name == "" {
 					normalized.Inputs[j].Name = fmt.Sprintf("arg%d", j)
 				}
-				if _, exist := structs[input.Type.String()]; input.Type.T == abi.TupleTy && !exist {
+				if hasStruct(input.Type) {
 					bindStructType[lang](input.Type, structs)
 				}
 			}
@@ -96,7 +96,7 @@ func Bind(types []string, abis []string, bytecodes []string, fsigs []map[string]
 				if output.Name != "" {
 					normalized.Outputs[j].Name = capitalise(output.Name)
 				}
-				if _, exist := structs[output.Type.String()]; output.Type.T == abi.TupleTy && !exist {
+				if hasStruct(output.Type) {
 					bindStructType[lang](output.Type, structs)
 				}
 			}
@@ -119,14 +119,11 @@ func Bind(types []string, abis []string, bytecodes []string, fsigs []map[string]
 			normalized.Inputs = make([]abi.Argument, len(original.Inputs))
 			copy(normalized.Inputs, original.Inputs)
 			for j, input := range normalized.Inputs {
-				// Indexed fields are input, non-indexed ones are outputs
+				if input.Name == "" {
-				if input.Indexed {
+					normalized.Inputs[j].Name = fmt.Sprintf("arg%d", j)
-					if input.Name == "" {
+				}
-						normalized.Inputs[j].Name = fmt.Sprintf("arg%d", j)
+				if hasStruct(input.Type) {
-					}
+					bindStructType[lang](input.Type, structs)
-					if _, exist := structs[input.Type.String()]; input.Type.T == abi.TupleTy && !exist {
-						bindStructType[lang](input.Type, structs)
-					}
 				}
 			}
 			// Append the event to the accumulator list
@@ -497,6 +494,21 @@ func structured(args abi.Arguments) bool {
 	return true
 }
 
+// hasStruct returns an indicator whether the given type is struct, struct slice
+// or struct array.
+func hasStruct(t abi.Type) bool {
+	switch t.T {
+	case abi.SliceTy:
+		return hasStruct(*t.Elem)
+	case abi.ArrayTy:
+		return hasStruct(*t.Elem)
+	case abi.TupleTy:
+		return true
+	default:
+		return false
+	}
+}
+
 // resolveArgName converts a raw argument representation into a user friendly format.
 func resolveArgName(arg abi.Argument, structs map[string]*tmplStruct) string {
 	var (

accounts/abi/bind/template.go

@@ -483,7 +483,7 @@ var (
 
 		// Parse{{.Normalized.Name}} is a log parse operation binding the contract event 0x{{printf "%x" .Original.ID}}.
 		//
-		// Solidity: {{.Original.String}}
+		// Solidity: {{formatevent .Original $structs}}
 		func (_{{$contract.Type}} *{{$contract.Type}}Filterer) Parse{{.Normalized.Name}}(log types.Log) (*{{$contract.Type}}{{.Normalized.Name}}, error) {
 			event := new({{$contract.Type}}{{.Normalized.Name}})
 			if err := _{{$contract.Type}}.contract.UnpackLog(event, "{{.Original.Name}}", log); err != nil {