Switch to the standard errors API, that was introduced in 1.13 (#273)

* Switch to the standard errors API, that was introduced in 1.13

* Fix linter errors 🤦‍

* Remove withStackError

* fix: freeze go version to 1.17, since 1.18 introduced generics, which are not supported by linters yet

* fix: freeze go version to 1.17, since 1.18 introduced generics, which are not supported by linters yet

bin/go

@@ -1 +1 @@
-.go@latest.pkg
+.go-1.17.pkg

bin/gofmt

@@ -1 +1 @@
-.go@latest.pkg
+.go-1.17.pkg

callbacks.go

@@ -4,8 +4,6 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
-
-	"github.com/pkg/errors"
 )
 
 type bindings map[reflect.Type]func() (reflect.Value, error)
@@ -35,7 +33,7 @@ func (b bindings) addProvider(provider interface{}) error {
 	pv := reflect.ValueOf(provider)
 	t := pv.Type()
 	if t.Kind() != reflect.Func || t.NumIn() != 0 || t.NumOut() != 2 || t.Out(1) != reflect.TypeOf((*error)(nil)).Elem() {
-		return errors.Errorf("%T must be a function with the signature func()(T, error)", provider)
+		return fmt.Errorf("%T must be a function with the signature func()(T, error)", provider)
 	}
 	rt := pv.Type().Out(0)
 	b[rt] = func() (reflect.Value, error) {

context.go

@@ -1,14 +1,13 @@
 package kong
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"reflect"
 	"sort"
 	"strconv"
 	"strings"
-
-	"github.com/pkg/errors"
 )
 
 // Path records the nodes and parsed values from the current command-line.
@@ -209,9 +208,8 @@ func (c *Context) Validate() error { // nolint: gocyclo
 			desc = node.Path()
 		}
 		if validate := isValidatable(value); validate != nil {
-			err := validate.Validate()
+			if err := validate.Validate(); err != nil {
-			if err != nil {
+				return fmt.Errorf("%s: %w", desc, err)
-				return errors.Wrap(err, desc)
 			}
 		}
 	}
@@ -558,7 +556,7 @@ func (c *Context) Resolve() error {
 			for _, resolver := range resolvers {
 				s, err := resolver.Resolve(c, path, flag)
 				if err != nil {
-					return errors.Wrap(err, flag.ShortSummary())
+					return fmt.Errorf("%s: %w", flag.ShortSummary(), err)
 				}
 				if s == nil {
 					continue
@@ -683,8 +681,9 @@ func (c *Context) parseFlag(flags []*Flag, match string) (err error) {
 		}
 		err := flag.Parse(c.scan, c.getValue(flag.Value))
 		if err != nil {
-			if e, ok := errors.Cause(err).(*expectedError); ok && e.token.InferredType().IsAny(FlagToken, ShortFlagToken) {
+			var expected *expectedError
-				return errors.Errorf("%s; perhaps try %s=%q?", err, flag.ShortSummary(), e.token)
+			if errors.As(err, &expected) && expected.token.InferredType().IsAny(FlagToken, ShortFlagToken) {
+				return fmt.Errorf("%s; perhaps try %s=%q?", err.Error(), flag.ShortSummary(), expected.token)
 			}
 			return err
 		}
@@ -888,7 +887,7 @@ func checkEnum(value *Value, target reflect.Value) error {
 		return nil
 
 	case reflect.Map, reflect.Struct:
-		return errors.Errorf("enum can only be applied to a slice or value")
+		return errors.New("enum can only be applied to a slice or value")
 
 	default:
 		enumSlice := value.EnumSlice()

error.go

@@ -8,5 +8,5 @@ type ParseError struct {
 	Context *Context
 }
 
-// Cause returns the original cause of the error.
+// Unwrap returns the original cause of the error.
-func (p *ParseError) Cause() error { return p.error }
+func (p *ParseError) Unwrap() error { return p.error }

go.mod

@@ -3,7 +3,6 @@ module github.com/alecthomas/kong
 require (
 	github.com/alecthomas/repr v0.0.0-20210801044451-80ca428c5142
 	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/pkg/errors v0.9.1
 	github.com/stretchr/testify v1.7.0
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -3,8 +3,6 @@ github.com/alecthomas/repr v0.0.0-20210801044451-80ca428c5142/go.mod h1:2kn6fqh/
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
-github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

kong.go

@@ -1,6 +1,7 @@
 package kong
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -378,13 +379,14 @@ func (k *Kong) FatalIfErrorf(err error, args ...interface{}) {
 		msg = fmt.Sprintf(args[0].(string), args[1:]...) + ": " + err.Error()
 	}
 	// Maybe display usage information.
-	if err, ok := err.(*ParseError); ok {
+	var parseErr *ParseError
+	if errors.As(err, &parseErr) {
 		switch k.usageOnError {
 		case fullUsage:
-			_ = k.help(k.helpOptions, err.Context)
+			_ = k.help(k.helpOptions, parseErr.Context)
 			fmt.Fprintln(k.Stdout)
 		case shortUsage:
-			_ = k.shortHelp(k.helpOptions, err.Context)
+			_ = k.shortHelp(k.helpOptions, parseErr.Context)
 			fmt.Fprintln(k.Stdout)
 		}
 	}

kong_test.go

@@ -2,11 +2,11 @@ package kong_test
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"strings"
 	"testing"
 
-	"github.com/pkg/errors"
 	"github.com/stretchr/testify/require"
 
 	"github.com/alecthomas/kong"

mapper.go

@@ -3,6 +3,7 @@ package kong
 import (
 	"encoding"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"math/bits"
@@ -12,8 +13,6 @@ import (
 	"strconv"
 	"strings"
 	"time"
-
-	"github.com/pkg/errors"
 )
 
 var (
@@ -295,14 +294,14 @@ func (boolMapper) Decode(ctx *DecodeContext, target reflect.Value) error {
 				target.SetBool(false)
 
 			default:
-				return errors.Errorf("bool value must be true, 1, yes, false, 0 or no but got %q", v)
+				return fmt.Errorf("bool value must be true, 1, yes, false, 0 or no but got %q", v)
 			}
 
 		case bool:
 			target.SetBool(v)
 
 		default:
-			return errors.Errorf("expected bool but got %q (%T)", token.Value, token.Value)
+			return fmt.Errorf("expected bool but got %q (%T)", token.Value, token.Value)
 		}
 	} else {
 		target.SetBool(true)
@@ -322,12 +321,12 @@ func durationDecoder() MapperFunc {
 		case string:
 			d, err = time.ParseDuration(v)
 			if err != nil {
-				return errors.Errorf("expected duration but got %q: %s", v, err)
+				return fmt.Errorf("expected duration but got %q: %v", v, err)
 			}
 		case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, float32, float64:
 			d = reflect.ValueOf(v).Convert(reflect.TypeOf(time.Duration(0))).Interface().(time.Duration) // nolint: forcetypeassert
 		default:
-			return errors.Errorf("expected duration but got %q", v)
+			return fmt.Errorf("expected duration but got %q", v)
 		}
 		target.Set(reflect.ValueOf(d))
 		return nil
@@ -368,11 +367,11 @@ func intDecoder(bits int) MapperFunc { // nolint: dupl
 			sv = fmt.Sprintf("%v", v)
 
 		default:
-			return errors.Errorf("expected an int but got %q (%T)", t, t.Value)
+			return fmt.Errorf("expected an int but got %q (%T)", t, t.Value)
 		}
 		n, err := strconv.ParseInt(sv, 10, bits)
 		if err != nil {
-			return errors.Errorf("expected a valid %d bit int but got %q", bits, sv)
+			return fmt.Errorf("expected a valid %d bit int but got %q", bits, sv)
 		}
 		target.SetInt(n)
 		return nil
@@ -394,11 +393,11 @@ func uintDecoder(bits int) MapperFunc { // nolint: dupl
 			sv = fmt.Sprintf("%v", v)
 
 		default:
-			return errors.Errorf("expected an int but got %q (%T)", t, t.Value)
+			return fmt.Errorf("expected an int but got %q (%T)", t, t.Value)
 		}
 		n, err := strconv.ParseUint(sv, 10, bits)
 		if err != nil {
-			return errors.Errorf("expected a valid %d bit uint but got %q", bits, sv)
+			return fmt.Errorf("expected a valid %d bit uint but got %q", bits, sv)
 		}
 		target.SetUint(n)
 		return nil
@@ -415,7 +414,7 @@ func floatDecoder(bits int) MapperFunc {
 		case string:
 			n, err := strconv.ParseFloat(v, bits)
 			if err != nil {
-				return errors.Errorf("expected a float but got %q (%T)", t, t.Value)
+				return fmt.Errorf("expected a float but got %q (%T)", t, t.Value)
 			}
 			target.SetFloat(n)
 
@@ -429,7 +428,7 @@ func floatDecoder(bits int) MapperFunc {
 			target.Set(reflect.ValueOf(v))
 
 		default:
-			return errors.Errorf("expected an int but got %q (%T)", t, t.Value)
+			return fmt.Errorf("expected an int but got %q (%T)", t, t.Value)
 		}
 		return nil
 	}
@@ -447,7 +446,7 @@ func mapDecoder(r *Registry) MapperFunc {
 			t := ctx.Scan.Pop()
 			// If decoding a flag, we need an argument.
 			if t.IsEOL() {
-				return errors.Errorf("unexpected EOL")
+				return errors.New("unexpected EOL")
 			}
 			switch v := t.Value.(type) {
 			case string:
@@ -457,7 +456,7 @@ func mapDecoder(r *Registry) MapperFunc {
 				for _, m := range v {
 					err := jsonTranscode(m, target.Addr().Interface())
 					if err != nil {
-						return errors.WithStack(err)
+						return err
 					}
 				}
 				return nil
@@ -466,7 +465,7 @@ func mapDecoder(r *Registry) MapperFunc {
 				return jsonTranscode(v, target.Addr().Interface())
 
 			default:
-				return errors.Errorf("invalid map value %q (of type %T)", t, t.Value)
+				return fmt.Errorf("invalid map value %q (of type %T)", t, t.Value)
 			}
 		} else {
 			tokens := ctx.Scan.PopWhile(func(t Token) bool { return t.IsValue() })
@@ -480,7 +479,7 @@ func mapDecoder(r *Registry) MapperFunc {
 			}
 			parts := strings.SplitN(token, "=", 2)
 			if len(parts) != 2 {
-				return errors.Errorf("expected \"<key>=<value>\" but got %q", token)
+				return fmt.Errorf("expected \"<key>=<value>\" but got %q", token)
 			}
 			key, value := parts[0], parts[1]
 
@@ -488,7 +487,7 @@ func mapDecoder(r *Registry) MapperFunc {
 			if typ := ctx.Value.Tag.Type; typ != "" {
 				parts := strings.Split(typ, ":")
 				if len(parts) != 2 {
-					return errors.Errorf("type:\"\" on map field must be in the form \"[<keytype>]:[<valuetype>]\"")
+					return errors.New("type:\"\" on map field must be in the form \"[<keytype>]:[<valuetype>]\"")
 				}
 				keyTypeName, valueTypeName = parts[0], parts[1]
 			}
@@ -497,14 +496,14 @@ func mapDecoder(r *Registry) MapperFunc {
 			keyDecoder := r.ForNamedType(keyTypeName, el.Key())
 			keyValue := reflect.New(el.Key()).Elem()
 			if err := keyDecoder.Decode(ctx.WithScanner(keyScanner), keyValue); err != nil {
-				return errors.Errorf("invalid map key %q", key)
+				return fmt.Errorf("invalid map key %q", key)
 			}
 
 			valueScanner := Scan(value)
 			valueDecoder := r.ForNamedType(valueTypeName, el.Elem())
 			valueValue := reflect.New(el.Elem()).Elem()
 			if err := valueDecoder.Decode(ctx.WithScanner(valueScanner), valueValue); err != nil {
-				return errors.Errorf("invalid map value %q", value)
+				return fmt.Errorf("invalid map value %q", value)
 			}
 
 			target.SetMapIndex(keyValue, valueValue)
@@ -522,7 +521,7 @@ func sliceDecoder(r *Registry) MapperFunc {
 			t := ctx.Scan.Pop()
 			// If decoding a flag, we need an argument.
 			if t.IsEOL() {
-				return errors.Errorf("unexpected EOL")
+				return errors.New("unexpected EOL")
 			}
 			switch v := t.Value.(type) {
 			case string:
@@ -541,13 +540,13 @@ func sliceDecoder(r *Registry) MapperFunc {
 		}
 		childDecoder := r.ForNamedType(ctx.Value.Tag.Type, el)
 		if childDecoder == nil {
-			return errors.Errorf("no mapper for element type of %s", target.Type())
+			return fmt.Errorf("no mapper for element type of %s", target.Type())
 		}
 		for !childScanner.Peek().IsEOL() {
 			childValue := reflect.New(el).Elem()
 			err := childDecoder.Decode(ctx.WithScanner(childScanner), childValue)
 			if err != nil {
-				return errors.WithStack(err)
+				return err
 			}
 			target.Set(reflect.Append(target, childValue))
 		}
@@ -561,7 +560,7 @@ func pathMapper(r *Registry) MapperFunc {
 			return sliceDecoder(r)(ctx, target)
 		}
 		if target.Kind() != reflect.String {
-			return errors.Errorf("\"path\" type must be applied to a string not %s", target.Type())
+			return fmt.Errorf("\"path\" type must be applied to a string not %s", target.Type())
 		}
 		var path string
 		err := ctx.Scan.PopValueInto("file", &path)
@@ -607,7 +606,7 @@ func existingFileMapper(r *Registry) MapperFunc {
 			return sliceDecoder(r)(ctx, target)
 		}
 		if target.Kind() != reflect.String {
-			return errors.Errorf("\"existingfile\" type must be applied to a string not %s", target.Type())
+			return fmt.Errorf("\"existingfile\" type must be applied to a string not %s", target.Type())
 		}
 		var path string
 		err := ctx.Scan.PopValueInto("file", &path)
@@ -621,7 +620,7 @@ func existingFileMapper(r *Registry) MapperFunc {
 				return err
 			}
 			if stat.IsDir() {
-				return errors.Errorf("%q exists but is a directory", path)
+				return fmt.Errorf("%q exists but is a directory", path)
 			}
 		}
 		target.SetString(path)
@@ -635,7 +634,7 @@ func existingDirMapper(r *Registry) MapperFunc {
 			return sliceDecoder(r)(ctx, target)
 		}
 		if target.Kind() != reflect.String {
-			return errors.Errorf("\"existingdir\" must be applied to a string not %s", target.Type())
+			return fmt.Errorf("\"existingdir\" must be applied to a string not %s", target.Type())
 		}
 		var path string
 		err := ctx.Scan.PopValueInto("file", &path)
@@ -648,7 +647,7 @@ func existingDirMapper(r *Registry) MapperFunc {
 			return err
 		}
 		if !stat.IsDir() {
-			return errors.Errorf("%q exists but is not a directory", path)
+			return fmt.Errorf("%q exists but is not a directory", path)
 		}
 		target.SetString(path)
 		return nil
@@ -666,7 +665,7 @@ func counterMapper() MapperFunc {
 			case string:
 				n, err := strconv.ParseInt(v, 10, 64)
 				if err != nil {
-					return errors.Errorf("expected a counter but got %q (%T)", t, t.Value)
+					return fmt.Errorf("expected a counter but got %q (%T)", t, t.Value)
 				}
 				target.SetInt(n)
 
@@ -674,7 +673,7 @@ func counterMapper() MapperFunc {
 				target.Set(reflect.ValueOf(v))
 
 			default:
-				return errors.Errorf("expected a counter but got %q (%T)", t, t.Value)
+				return fmt.Errorf("expected a counter but got %q (%T)", t, t.Value)
 			}
 			return nil
 		}
@@ -690,7 +689,7 @@ func counterMapper() MapperFunc {
 			target.SetFloat(target.Float() + 1)
 
 		default:
-			return errors.Errorf("type:\"counter\" must be used with a numeric field")
+			return fmt.Errorf("type:\"counter\" must be used with a numeric field")
 		}
 		return nil
 	}
@@ -705,7 +704,7 @@ func urlMapper() MapperFunc {
 		}
 		url, err := url.Parse(urlStr)
 		if err != nil {
-			return errors.WithStack(err)
+			return err
 		}
 		target.Set(reflect.ValueOf(url))
 		return nil
@@ -775,7 +774,7 @@ func (f *NamedFileContentFlag) Decode(ctx *DecodeContext) error { // nolint: rev
 	filename = ExpandPath(filename)
 	data, err := ioutil.ReadFile(filename) // nolint: gosec
 	if err != nil {
-		return errors.Errorf("failed to open %q: %s", filename, err)
+		return fmt.Errorf("failed to open %q: %v", filename, err)
 	}
 	f.Contents = data
 	f.Filename = filename
@@ -799,7 +798,7 @@ func (f *FileContentFlag) Decode(ctx *DecodeContext) error { // nolint: revive
 	filename = ExpandPath(filename)
 	data, err := ioutil.ReadFile(filename) // nolint: gosec
 	if err != nil {
-		return errors.Errorf("failed to open %q: %s", filename, err)
+		return fmt.Errorf("failed to open %q: %v", filename, err)
 	}
 	*f = data
 	return nil
@@ -808,7 +807,10 @@ func (f *FileContentFlag) Decode(ctx *DecodeContext) error { // nolint: revive
 func jsonTranscode(in, out interface{}) error {
 	data, err := json.Marshal(in)
 	if err != nil {
-		return errors.WithStack(err)
+		return err
 	}
-	return errors.Wrapf(json.Unmarshal(data, out), "%#v -> %T", in, out)
+	if err = json.Unmarshal(data, out); err != nil {
+		return fmt.Errorf("%#v -> %T: %v", in, out, err)
+	}
+	return nil
 }

model.go

@@ -7,8 +7,6 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
-
-	"github.com/pkg/errors"
 )
 
 // A Visitable component in the model.
@@ -335,7 +333,7 @@ func (v *Value) Parse(scan *Scanner, target reflect.Value) (err error) {
 	}
 	err = v.Mapper.Decode(&DecodeContext{Value: v, Scan: scan}, target)
 	if err != nil {
-		return errors.Wrap(err, v.ShortSummary())
+		return fmt.Errorf("%s: %w", v.ShortSummary(), err)
 	}
 	v.Set = true
 	return nil

options.go

@@ -1,6 +1,8 @@
 package kong
 
 import (
+	"errors"
+	"fmt"
 	"io"
 	"os"
 	"os/user"
@@ -8,8 +10,6 @@ import (
 	"reflect"
 	"regexp"
 	"strings"
-
-	"github.com/pkg/errors"
 )
 
 // An Option applies optional changes to the Kong application.
@@ -344,7 +344,7 @@ func IgnoreFields(regexes ...string) Option {
 
 			re, err := regexp.Compile(r)
 			if err != nil {
-				return errors.Wrap(err, "unable to compile regex")
+				return fmt.Errorf("unable to compile regex: %v", err)
 			}
 
 			k.ignoreFields = append(k.ignoreFields, re)
@@ -380,7 +380,7 @@ func Configuration(loader ConfigurationLoader, paths ...string) Option {
 
 			resolver, err := k.LoadConfig(path)
 			if err != nil {
-				return errors.Wrap(err, path)
+				return fmt.Errorf("%s: %v", path, err)
 			}
 			if resolver != nil {
 				k.resolvers = append(k.resolvers, resolver)