Merge pull request #2611 from thaJeztah/bump_mapstructure

vendor: mitchellh/mapstructure v1.3.2

vendor.conf

@@ -44,7 +44,7 @@ github.com/matttproud/golang_protobuf_extensions    c12348ce28de40eed0136aa2b644
 github.com/Microsoft/go-winio                       6c72808b55902eae4c5943626030429ff20f3b63 # v0.4.14
 github.com/Microsoft/hcsshim                        5bc557dd210ff2caf615e6e22d398123de77fc11 # v0.8.9
 github.com/miekg/pkcs11                             210dc1e16747c5ba98a03bcbcf728c38086ea357 # v1.0.3
-github.com/mitchellh/mapstructure                   fa473d140ef3c6adf42d6b391fe76707f1f243c8 # v1.0.0
+github.com/mitchellh/mapstructure                   d16e9488127408e67948eb43b6d3fbb9f222da10 # v1.3.2
 github.com/moby/buildkit                            ae7ff7174f73bcb4df89b97e1623b3fb0bfb0a0c
 github.com/moby/sys                                 6154f11e6840c0d6b0dbb23f4125a6134b3013c9 # mountinfo/v0.1.3
 github.com/moby/term                                73f35e472e8f0a3f91347164138ce6bd73b756a9

vendor/github.com/mitchellh/mapstructure/decode_hooks.go

@@ -2,6 +2,8 @@ package mapstructure
 
 import (
 	"errors"
+	"fmt"
+	"net"
 	"reflect"
 	"strconv"
 	"strings"
@@ -115,6 +117,50 @@ func StringToTimeDurationHookFunc() DecodeHookFunc {
 	}
 }
 
+// StringToIPHookFunc returns a DecodeHookFunc that converts
+// strings to net.IP
+func StringToIPHookFunc() DecodeHookFunc {
+	return func(
+		f reflect.Type,
+		t reflect.Type,
+		data interface{}) (interface{}, error) {
+		if f.Kind() != reflect.String {
+			return data, nil
+		}
+		if t != reflect.TypeOf(net.IP{}) {
+			return data, nil
+		}
+
+		// Convert it by parsing
+		ip := net.ParseIP(data.(string))
+		if ip == nil {
+			return net.IP{}, fmt.Errorf("failed parsing ip %v", data)
+		}
+
+		return ip, nil
+	}
+}
+
+// StringToIPNetHookFunc returns a DecodeHookFunc that converts
+// strings to net.IPNet
+func StringToIPNetHookFunc() DecodeHookFunc {
+	return func(
+		f reflect.Type,
+		t reflect.Type,
+		data interface{}) (interface{}, error) {
+		if f.Kind() != reflect.String {
+			return data, nil
+		}
+		if t != reflect.TypeOf(net.IPNet{}) {
+			return data, nil
+		}
+
+		// Convert it by parsing
+		_, net, err := net.ParseCIDR(data.(string))
+		return net, err
+	}
+}
+
 // StringToTimeHookFunc returns a DecodeHookFunc that converts
 // strings to time.Time.
 func StringToTimeHookFunc(layout string) DecodeHookFunc {

vendor/github.com/mitchellh/mapstructure/go.mod

@@ -1 +1,3 @@
 module github.com/mitchellh/mapstructure
+
+go 1.14

vendor/github.com/mitchellh/mapstructure/mapstructure.go

@@ -1,10 +1,150 @@
-// Package mapstructure exposes functionality to convert an arbitrary
+// Package mapstructure exposes functionality to convert one arbitrary
-// map[string]interface{} into a native Go structure.
+// Go type into another, typically to convert a map[string]interface{}
+// into a native Go structure.
 //
 // The Go structure can be arbitrarily complex, containing slices,
 // other structs, etc. and the decoder will properly decode nested
 // maps and so on into the proper structures in the native Go struct.
 // See the examples to see what the decoder is capable of.
+//
+// The simplest function to start with is Decode.
+//
+// Field Tags
+//
+// When decoding to a struct, mapstructure will use the field name by
+// default to perform the mapping. For example, if a struct has a field
+// "Username" then mapstructure will look for a key in the source value
+// of "username" (case insensitive).
+//
+//     type User struct {
+//         Username string
+//     }
+//
+// You can change the behavior of mapstructure by using struct tags.
+// The default struct tag that mapstructure looks for is "mapstructure"
+// but you can customize it using DecoderConfig.
+//
+// Renaming Fields
+//
+// To rename the key that mapstructure looks for, use the "mapstructure"
+// tag and set a value directly. For example, to change the "username" example
+// above to "user":
+//
+//     type User struct {
+//         Username string `mapstructure:"user"`
+//     }
+//
+// Embedded Structs and Squashing
+//
+// Embedded structs are treated as if they're another field with that name.
+// By default, the two structs below are equivalent when decoding with
+// mapstructure:
+//
+//     type Person struct {
+//         Name string
+//     }
+//
+//     type Friend struct {
+//         Person
+//     }
+//
+//     type Friend struct {
+//         Person Person
+//     }
+//
+// This would require an input that looks like below:
+//
+//     map[string]interface{}{
+//         "person": map[string]interface{}{"name": "alice"},
+//     }
+//
+// If your "person" value is NOT nested, then you can append ",squash" to
+// your tag value and mapstructure will treat it as if the embedded struct
+// were part of the struct directly. Example:
+//
+//     type Friend struct {
+//         Person `mapstructure:",squash"`
+//     }
+//
+// Now the following input would be accepted:
+//
+//     map[string]interface{}{
+//         "name": "alice",
+//     }
+//
+// DecoderConfig has a field that changes the behavior of mapstructure
+// to always squash embedded structs.
+//
+// Remainder Values
+//
+// If there are any unmapped keys in the source value, mapstructure by
+// default will silently ignore them. You can error by setting ErrorUnused
+// in DecoderConfig. If you're using Metadata you can also maintain a slice
+// of the unused keys.
+//
+// You can also use the ",remain" suffix on your tag to collect all unused
+// values in a map. The field with this tag MUST be a map type and should
+// probably be a "map[string]interface{}" or "map[interface{}]interface{}".
+// See example below:
+//
+//     type Friend struct {
+//         Name  string
+//         Other map[string]interface{} `mapstructure:",remain"`
+//     }
+//
+// Given the input below, Other would be populated with the other
+// values that weren't used (everything but "name"):
+//
+//     map[string]interface{}{
+//         "name":    "bob",
+//         "address": "123 Maple St.",
+//     }
+//
+// Omit Empty Values
+//
+// When decoding from a struct to any other value, you may use the
+// ",omitempty" suffix on your tag to omit that value if it equates to
+// the zero value. The zero value of all types is specified in the Go
+// specification.
+//
+// For example, the zero type of a numeric type is zero ("0"). If the struct
+// field value is zero and a numeric type, the field is empty, and it won't
+// be encoded into the destination type.
+//
+//     type Source {
+//         Age int `mapstructure:",omitempty"`
+//     }
+//
+// Unexported fields
+//
+// Since unexported (private) struct fields cannot be set outside the package
+// where they are defined, the decoder will simply skip them.
+//
+// For this output type definition:
+//
+//     type Exported struct {
+//         private string // this unexported field will be skipped
+//         Public string
+//     }
+//
+// Using this map as input:
+//
+//     map[string]interface{}{
+//         "private": "I will be ignored",
+//         "Public":  "I made it through!",
+//     }
+//
+// The following struct will be decoded:
+//
+//     type Exported struct {
+//         private: "" // field is left with an empty string (zero value)
+//         Public: "I made it through!"
+//     }
+//
+// Other Configuration
+//
+// mapstructure is highly configurable. See the DecoderConfig struct
+// for other features and options that are supported.
 package mapstructure
 
 import (
@@ -80,6 +220,14 @@ type DecoderConfig struct {
 	//
 	WeaklyTypedInput bool
 
+	// Squash will squash embedded structs.  A squash tag may also be
+	// added to an individual struct field using a tag.  For example:
+	//
+	//  type Parent struct {
+	//      Child `mapstructure:",squash"`
+	//  }
+	Squash bool
+
 	// Metadata is the struct that will contain extra metadata about
 	// the decoding. If this is nil, then no metadata will be tracked.
 	Metadata *Metadata
@@ -224,6 +372,17 @@ func (d *Decoder) Decode(input interface{}) error {
 
 // Decodes an unknown data type into a specific reflection value.
 func (d *Decoder) decode(name string, input interface{}, outVal reflect.Value) error {
+	var inputVal reflect.Value
+	if input != nil {
+		inputVal = reflect.ValueOf(input)
+
+		// We need to check here if input is a typed nil. Typed nils won't
+		// match the "input == nil" below so we check that here.
+		if inputVal.Kind() == reflect.Ptr && inputVal.IsNil() {
+			input = nil
+		}
+	}
+
 	if input == nil {
 		// If the data is nil, then we don't set anything, unless ZeroFields is set
 		// to true.
@@ -237,7 +396,6 @@ func (d *Decoder) decode(name string, input interface{}, outVal reflect.Value) e
 		return nil
 	}
 
-	inputVal := reflect.ValueOf(input)
 	if !inputVal.IsValid() {
 		// If the input value is invalid, then we just set the value
 		// to be the zero value.
@@ -260,8 +418,9 @@ func (d *Decoder) decode(name string, input interface{}, outVal reflect.Value) e
 	}
 
 	var err error
-	inputKind := getKind(outVal)
+	outputKind := getKind(outVal)
-	switch inputKind {
+	addMetaKey := true
+	switch outputKind {
 	case reflect.Bool:
 		err = d.decodeBool(name, input, outVal)
 	case reflect.Interface:
@@ -279,7 +438,7 @@ func (d *Decoder) decode(name string, input interface{}, outVal reflect.Value) e
 	case reflect.Map:
 		err = d.decodeMap(name, input, outVal)
 	case reflect.Ptr:
-		err = d.decodePtr(name, input, outVal)
+		addMetaKey, err = d.decodePtr(name, input, outVal)
 	case reflect.Slice:
 		err = d.decodeSlice(name, input, outVal)
 	case reflect.Array:
@@ -288,12 +447,12 @@ func (d *Decoder) decode(name string, input interface{}, outVal reflect.Value) e
 		err = d.decodeFunc(name, input, outVal)
 	default:
 		// If we reached this point then we weren't able to decode it
-		return fmt.Errorf("%s: unsupported type: %s", name, inputKind)
+		return fmt.Errorf("%s: unsupported type: %s", name, outputKind)
 	}
 
 	// If we reached here, then we successfully decoded SOMETHING, so
 	// mark the key as used if we're tracking metainput.
-	if d.config.Metadata != nil && name != "" {
+	if addMetaKey && d.config.Metadata != nil && name != "" {
 		d.config.Metadata.Keys = append(d.config.Metadata.Keys, name)
 	}
 
@@ -304,9 +463,45 @@ func (d *Decoder) decode(name string, input interface{}, outVal reflect.Value) e
 // value to "data" of that type.
 func (d *Decoder) decodeBasic(name string, data interface{}, val reflect.Value) error {
 	if val.IsValid() && val.Elem().IsValid() {
-		return d.decode(name, data, val.Elem())
+		elem := val.Elem()
+
+		// If we can't address this element, then its not writable. Instead,
+		// we make a copy of the value (which is a pointer and therefore
+		// writable), decode into that, and replace the whole value.
+		copied := false
+		if !elem.CanAddr() {
+			copied = true
+
+			// Make *T
+			copy := reflect.New(elem.Type())
+
+			// *T = elem
+			copy.Elem().Set(elem)
+
+			// Set elem so we decode into it
+			elem = copy
+		}
+
+		// Decode. If we have an error then return. We also return right
+		// away if we're not a copy because that means we decoded directly.
+		if err := d.decode(name, data, elem); err != nil || !copied {
+			return err
+		}
+
+		// If we're a copy, we need to set te final result
+		val.Set(elem.Elem())
+		return nil
 	}
+
 	dataVal := reflect.ValueOf(data)
+
+	// If the input data is a pointer, and the assigned type is the dereference
+	// of that exact pointer, then indirect it so that we can assign it.
+	// Example: *string to string
+	if dataVal.Kind() == reflect.Ptr && dataVal.Type().Elem() == val.Type() {
+		dataVal = reflect.Indirect(dataVal)
+	}
+
 	if !dataVal.IsValid() {
 		dataVal = reflect.Zero(val.Type())
 	}
@@ -323,7 +518,7 @@ func (d *Decoder) decodeBasic(name string, data interface{}, val reflect.Value)
 }
 
 func (d *Decoder) decodeString(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 
 	converted := true
@@ -375,7 +570,7 @@ func (d *Decoder) decodeString(name string, data interface{}, val reflect.Value)
 }
 
 func (d *Decoder) decodeInt(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 	dataType := dataVal.Type()
 
@@ -417,8 +612,9 @@ func (d *Decoder) decodeInt(name string, data interface{}, val reflect.Value) er
 }
 
 func (d *Decoder) decodeUint(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
+	dataType := dataVal.Type()
 
 	switch {
 	case dataKind == reflect.Int:
@@ -450,6 +646,18 @@ func (d *Decoder) decodeUint(name string, data interface{}, val reflect.Value) e
 		} else {
 			return fmt.Errorf("cannot parse '%s' as uint: %s", name, err)
 		}
+	case dataType.PkgPath() == "encoding/json" && dataType.Name() == "Number":
+		jn := data.(json.Number)
+		i, err := jn.Int64()
+		if err != nil {
+			return fmt.Errorf(
+				"error decoding json.Number into %s: %s", name, err)
+		}
+		if i < 0 && !d.config.WeaklyTypedInput {
+			return fmt.Errorf("cannot parse '%s', %d overflows uint",
+				name, i)
+		}
+		val.SetUint(uint64(i))
 	default:
 		return fmt.Errorf(
 			"'%s' expected type '%s', got unconvertible type '%s'",
@@ -460,7 +668,7 @@ func (d *Decoder) decodeUint(name string, data interface{}, val reflect.Value) e
 }
 
 func (d *Decoder) decodeBool(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 
 	switch {
@@ -491,7 +699,7 @@ func (d *Decoder) decodeBool(name string, data interface{}, val reflect.Value) e
 }
 
 func (d *Decoder) decodeFloat(name string, data interface{}, val reflect.Value) error {
-	dataVal := reflect.ValueOf(data)
+	dataVal := reflect.Indirect(reflect.ValueOf(data))
 	dataKind := getKind(dataVal)
 	dataType := dataVal.Type()
 
@@ -595,6 +803,20 @@ func (d *Decoder) decodeMapFromMap(name string, dataVal reflect.Value, val refle
 	// Accumulate errors
 	errors := make([]string, 0)
 
+	// If the input data is empty, then we just match what the input data is.
+	if dataVal.Len() == 0 {
+		if dataVal.IsNil() {
+			if !val.IsNil() {
+				val.Set(dataVal)
+			}
+		} else {
+			// Set to empty allocated value
+			val.Set(valMap)
+		}
+
+		return nil
+	}
+
 	for _, k := range dataVal.MapKeys() {
 		fieldName := fmt.Sprintf("%s[%s]", name, k)
 
@@ -645,27 +867,31 @@ func (d *Decoder) decodeMapFromStruct(name string, dataVal reflect.Value, val re
 		}
 
 		tagValue := f.Tag.Get(d.config.TagName)
-		tagParts := strings.Split(tagValue, ",")
-
-		// Determine the name of the key in the map
 		keyName := f.Name
-		if tagParts[0] != "" {
+
-			if tagParts[0] == "-" {
+		// If Squash is set in the config, we squash the field down.
+		squash := d.config.Squash && v.Kind() == reflect.Struct && f.Anonymous
+		// Determine the name of the key in the map
+		if index := strings.Index(tagValue, ","); index != -1 {
+			if tagValue[:index] == "-" {
 				continue
 			}
-			keyName = tagParts[0]
+			// If "omitempty" is specified in the tag, it ignores empty values.
-		}
+			if strings.Index(tagValue[index+1:], "omitempty") != -1 && isEmptyValue(v) {
-
+				continue
-		// If "squash" is specified in the tag, we squash the field down.
-		squash := false
-		for _, tag := range tagParts[1:] {
-			if tag == "squash" {
-				squash = true
-				break
 			}
-		}
+
-		if squash && v.Kind() != reflect.Struct {
+			// If "squash" is specified in the tag, we squash the field down.
-			return fmt.Errorf("cannot squash non-struct type '%s'", v.Type())
+			squash = !squash && strings.Index(tagValue[index+1:], "squash") != -1
+			if squash && v.Kind() != reflect.Struct {
+				return fmt.Errorf("cannot squash non-struct type '%s'", v.Type())
+			}
+			keyName = tagValue[:index]
+		} else if len(tagValue) > 0 {
+			if tagValue == "-" {
+				continue
+			}
+			keyName = tagValue
 		}
 
 		switch v.Kind() {
@@ -705,12 +931,34 @@ func (d *Decoder) decodeMapFromStruct(name string, dataVal reflect.Value, val re
 	return nil
 }
 
-func (d *Decoder) decodePtr(name string, data interface{}, val reflect.Value) error {
+func (d *Decoder) decodePtr(name string, data interface{}, val reflect.Value) (bool, error) {
+	// If the input data is nil, then we want to just set the output
+	// pointer to be nil as well.
+	isNil := data == nil
+	if !isNil {
+		switch v := reflect.Indirect(reflect.ValueOf(data)); v.Kind() {
+		case reflect.Chan,
+			reflect.Func,
+			reflect.Interface,
+			reflect.Map,
+			reflect.Ptr,
+			reflect.Slice:
+			isNil = v.IsNil()
+		}
+	}
+	if isNil {
+		if !val.IsNil() && val.CanSet() {
+			nilValue := reflect.New(val.Type()).Elem()
+			val.Set(nilValue)
+		}
+
+		return true, nil
+	}
+
 	// Create an element of the concrete (non pointer) type and decode
 	// into that. Then set the value of the pointer to this type.
 	valType := val.Type()
 	valElemType := valType.Elem()
-
 	if val.CanSet() {
 		realVal := val
 		if realVal.IsNil() || d.config.ZeroFields {
@@ -718,16 +966,16 @@ func (d *Decoder) decodePtr(name string, data interface{}, val reflect.Value) er
 		}
 
 		if err := d.decode(name, data, reflect.Indirect(realVal)); err != nil {
-			return err
+			return false, err
 		}
 
 		val.Set(realVal)
 	} else {
 		if err := d.decode(name, data, reflect.Indirect(val)); err != nil {
-			return err
+			return false, err
 		}
 	}
-	return nil
+	return false, nil
 }
 
 func (d *Decoder) decodeFunc(name string, data interface{}, val reflect.Value) error {
@@ -750,35 +998,45 @@ func (d *Decoder) decodeSlice(name string, data interface{}, val reflect.Value)
 	valElemType := valType.Elem()
 	sliceType := reflect.SliceOf(valElemType)
 
-	valSlice := val
+	// If we have a non array/slice type then we first attempt to convert.
-	if valSlice.IsNil() || d.config.ZeroFields {
+	if dataValKind != reflect.Array && dataValKind != reflect.Slice {
-		// Check input type
+		if d.config.WeaklyTypedInput {
-		if dataValKind != reflect.Array && dataValKind != reflect.Slice {
+			switch {
-			if d.config.WeaklyTypedInput {
+			// Slice and array we use the normal logic
-				switch {
+			case dataValKind == reflect.Slice, dataValKind == reflect.Array:
-				// Empty maps turn into empty slices
+				break
-				case dataValKind == reflect.Map:
-					if dataVal.Len() == 0 {
-						val.Set(reflect.MakeSlice(sliceType, 0, 0))
-						return nil
-					}
-					// Create slice of maps of other sizes
-					return d.decodeSlice(name, []interface{}{data}, val)
 
-				case dataValKind == reflect.String && valElemType.Kind() == reflect.Uint8:
+			// Empty maps turn into empty slices
-					return d.decodeSlice(name, []byte(dataVal.String()), val)
+			case dataValKind == reflect.Map:
-				// All other types we try to convert to the slice type
+				if dataVal.Len() == 0 {
-				// and "lift" it into it. i.e. a string becomes a string slice.
+					val.Set(reflect.MakeSlice(sliceType, 0, 0))
-				default:
+					return nil
-					// Just re-try this function with data as a slice.
-					return d.decodeSlice(name, []interface{}{data}, val)
 				}
-			}
+				// Create slice of maps of other sizes
-			return fmt.Errorf(
+				return d.decodeSlice(name, []interface{}{data}, val)
-				"'%s': source data must be an array or slice, got %s", name, dataValKind)
 
+			case dataValKind == reflect.String && valElemType.Kind() == reflect.Uint8:
+				return d.decodeSlice(name, []byte(dataVal.String()), val)
+
+			// All other types we try to convert to the slice type
+			// and "lift" it into it. i.e. a string becomes a string slice.
+			default:
+				// Just re-try this function with data as a slice.
+				return d.decodeSlice(name, []interface{}{data}, val)
+			}
 		}
 
+		return fmt.Errorf(
+			"'%s': source data must be an array or slice, got %s", name, dataValKind)
+	}
+
+	// If the input value is nil, then don't allocate since empty != nil
+	if dataVal.IsNil() {
+		return nil
+	}
+
+	valSlice := val
+	if valSlice.IsNil() || d.config.ZeroFields {
 		// Make a new slice to hold our result, same size as the original data.
 		valSlice = reflect.MakeSlice(sliceType, dataVal.Len(), dataVal.Len())
 	}
@@ -888,10 +1146,29 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 	}
 
 	dataValKind := dataVal.Kind()
-	if dataValKind != reflect.Map {
+	switch dataValKind {
-		return fmt.Errorf("'%s' expected a map, got '%s'", name, dataValKind)
+	case reflect.Map:
-	}
+		return d.decodeStructFromMap(name, dataVal, val)
 
+	case reflect.Struct:
+		// Not the most efficient way to do this but we can optimize later if
+		// we want to. To convert from struct to struct we go to map first
+		// as an intermediary.
+		m := make(map[string]interface{})
+		mval := reflect.Indirect(reflect.ValueOf(&m))
+		if err := d.decodeMapFromStruct(name, dataVal, mval, mval); err != nil {
+			return err
+		}
+
+		result := d.decodeStructFromMap(name, mval, val)
+		return result
+
+	default:
+		return fmt.Errorf("'%s' expected a map, got '%s'", name, dataVal.Kind())
+	}
+}
+
+func (d *Decoder) decodeStructFromMap(name string, dataVal, val reflect.Value) error {
 	dataValType := dataVal.Type()
 	if kind := dataValType.Key().Kind(); kind != reflect.String && kind != reflect.Interface {
 		return fmt.Errorf(
@@ -920,6 +1197,11 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 		field reflect.StructField
 		val   reflect.Value
 	}
+
+	// remainField is set to a valid field set with the "remain" tag if
+	// we are keeping track of remaining values.
+	var remainField *field
+
 	fields := []field{}
 	for len(structs) > 0 {
 		structVal := structs[0]
@@ -932,13 +1214,21 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 			fieldKind := fieldType.Type.Kind()
 
 			// If "squash" is specified in the tag, we squash the field down.
-			squash := false
+			squash := d.config.Squash && fieldKind == reflect.Struct && fieldType.Anonymous
+			remain := false
+
+			// We always parse the tags cause we're looking for other tags too
 			tagParts := strings.Split(fieldType.Tag.Get(d.config.TagName), ",")
 			for _, tag := range tagParts[1:] {
 				if tag == "squash" {
 					squash = true
 					break
 				}
+
+				if tag == "remain" {
+					remain = true
+					break
+				}
 			}
 
 			if squash {
@@ -951,8 +1241,13 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 				continue
 			}
 
-			// Normal struct field, store it away
+			// Build our field
-			fields = append(fields, field{fieldType, structVal.Field(i)})
+			if remain {
+				remainField = &field{fieldType, structVal.Field(i)}
+			} else {
+				// Normal struct field, store it away
+				fields = append(fields, field{fieldType, structVal.Field(i)})
+			}
 		}
 	}
 
@@ -993,9 +1288,6 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 			}
 		}
 
-		// Delete the key we're using from the unused map so we stop tracking
-		delete(dataValKeysUnused, rawMapKey.Interface())
-
 		if !fieldValue.IsValid() {
 			// This should never happen
 			panic("field is not valid")
@@ -1007,6 +1299,9 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 			continue
 		}
 
+		// Delete the key we're using from the unused map so we stop tracking
+		delete(dataValKeysUnused, rawMapKey.Interface())
+
 		// If the name is empty string, then we're at the root, and we
 		// don't dot-join the fields.
 		if name != "" {
@@ -1018,6 +1313,25 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 		}
 	}
 
+	// If we have a "remain"-tagged field and we have unused keys then
+	// we put the unused keys directly into the remain field.
+	if remainField != nil && len(dataValKeysUnused) > 0 {
+		// Build a map of only the unused values
+		remain := map[interface{}]interface{}{}
+		for key := range dataValKeysUnused {
+			remain[key] = dataVal.MapIndex(reflect.ValueOf(key)).Interface()
+		}
+
+		// Decode it as-if we were just decoding this map onto our map.
+		if err := d.decodeMap(name, remain, remainField.val); err != nil {
+			errors = appendErrors(errors, err)
+		}
+
+		// Set the map to nil so we have none so that the next check will
+		// not error (ErrorUnused)
+		dataValKeysUnused = nil
+	}
+
 	if d.config.ErrorUnused && len(dataValKeysUnused) > 0 {
 		keys := make([]string, 0, len(dataValKeysUnused))
 		for rawKey := range dataValKeysUnused {
@@ -1048,6 +1362,24 @@ func (d *Decoder) decodeStruct(name string, data interface{}, val reflect.Value)
 	return nil
 }
 
+func isEmptyValue(v reflect.Value) bool {
+	switch getKind(v) {
+	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
+		return v.Len() == 0
+	case reflect.Bool:
+		return !v.Bool()
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return v.Int() == 0
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return v.Uint() == 0
+	case reflect.Float32, reflect.Float64:
+		return v.Float() == 0
+	case reflect.Interface, reflect.Ptr:
+		return v.IsNil()
+	}
+	return false
+}
+
 func getKind(val reflect.Value) reflect.Kind {
 	kind := val.Kind()