all: drop golang.org/x/xerrors

The error value wrapping APIs in the standard library's errors package
have been available since Go 1.13, released nearly three years ago.
We now require at least Go 1.16, so we can simplify our code.

Change-Id: I25fb1eede98aece84ad93b19d0542089ffadfe0b
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/536094
Reviewed-by: Roger Peppe <rogpeppe@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Unity-Result: CUEcueckoo <cueckoo@cuelang.org>

Author: mvdan

cue/ast/ident.go

@@ -191,5 +191,5 @@ func LabelName(l Label) (name string, isIdent bool, err error) {
 }
 
 // ErrIsExpression reports whether a label is an expression.
-// This error is never returned directly. Use errors.Is or xerrors.Is.
+// This error is never returned directly. Use errors.Is.
 var ErrIsExpression = errors.New("not a concrete label")

cue/errors/errors.go

@@ -29,7 +29,6 @@ import (
 	"strings"
 
 	"github.com/mpvl/unique"
-	"golang.org/x/xerrors"
 
 	"cuelang.org/go/cue/token"
 )
@@ -43,15 +42,15 @@ func New(msg string) error {
 // Unwrap returns the result of calling the Unwrap method on err, if err
 // implements Unwrap. Otherwise, Unwrap returns nil.
 func Unwrap(err error) error {
-	return xerrors.Unwrap(err)
+	return errors.Unwrap(err)
 }
 
 // Is reports whether any error in err's chain matches target.
 //
 // An error is considered to match a target if it is equal to that target or if
 // it implements a method Is(error) bool such that Is(target) returns true.
 func Is(err, target error) bool {
-	return xerrors.Is(err, target)
+	return errors.Is(err, target)
 }
 
 // As finds the first error in err's chain that matches the type to which target
@@ -64,7 +63,7 @@ func Is(err, target error) bool {
 // The As method should set the target to its value and return true if err
 // matches the type to which target points.
 func As(err error, target interface{}) bool {
-	return xerrors.As(err, target)
+	return errors.As(err, target)
 }
 
 // A Message implements the error interface as well as Message to allow
@@ -119,7 +118,7 @@ type Error interface {
 // by relevance when possible and with duplicates removed.
 func Positions(err error) []token.Pos {
 	e := Error(nil)
-	if !xerrors.As(err, &e) {
+	if !errors.As(err, &e) {
 		return nil
 	}
 
@@ -153,7 +152,7 @@ func (s byPos) Less(i, j int) bool { return comparePos(s[i], s[j]) == -1 }
 
 // Path returns the path of an Error if err is of that type.
 func Path(err error) []string {
-	if e := Error(nil); xerrors.As(err, &e) {
+	if e := Error(nil); errors.As(err, &e) {
 		return e.Path()
 	}
 	return nil
@@ -326,7 +325,7 @@ type list []Error
 
 func (p list) Is(err, target error) bool {
 	for _, e := range p {
-		if xerrors.Is(e, target) {
+		if errors.Is(e, target) {
 			return true
 		}
 	}
@@ -335,7 +334,7 @@ func (p list) Is(err, target error) bool {
 
 func (p list) As(err error, target interface{}) bool {
 	for _, e := range p {
-		if xerrors.As(e, target) {
+		if errors.As(e, target) {
 			return true
 		}
 	}
@@ -567,7 +566,7 @@ func writeErr(w io.Writer, err Error) {
 	}
 
 	for {
-		u := xerrors.Unwrap(err)
+		u := errors.Unwrap(err)
 
 		printed := false
 		msg, args := err.Msg()

encoding/protobuf/util.go

@@ -15,11 +15,11 @@
 package protobuf
 
 import (
+	"fmt"
 	"strings"
 	"text/scanner"
 
 	"github.com/emicklei/proto"
-	"golang.org/x/xerrors"
 
 	"cuelang.org/go/cue/ast"
 	"cuelang.org/go/cue/token"
@@ -28,7 +28,7 @@ import (
 // failf panics with a marked error that can be intercepted upon returning
 // from parsing.
 func failf(pos scanner.Position, format string, args ...interface{}) {
-	panic(protoError{pos, xerrors.Errorf(format, args...)})
+	panic(protoError{pos, fmt.Errorf(format, args...)})
 }
 
 func fail(pos scanner.Position, err error) {

go.mod

@@ -20,7 +20,6 @@ require (
 	golang.org/x/net v0.0.0-20200226121028-0de0cce0169b
 	golang.org/x/text v0.3.7
 	golang.org/x/tools v0.0.0-20200612220849-54c614fe050c
-	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b
 )
 
@@ -35,5 +34,6 @@ require (
 	github.com/pkg/errors v0.8.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	golang.org/x/mod v0.3.1-0.20200828183125-ce943fd02449 // indirect
+	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 // indirect
 	gopkg.in/errgo.v2 v2.1.0 // indirect
 )

go.sum

@@ -40,8 +40,6 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/protocolbuffers/txtpbfmt v0.0.0-20201118171849-f6a6b3f636fc h1:gSVONBi2HWMFXCa9jFdYvYk7IwW/mTLxWOF7rXS4LO0=
 github.com/protocolbuffers/txtpbfmt v0.0.0-20201118171849-f6a6b3f636fc/go.mod h1:KbKfKPy2I6ecOIGA9apfheFv14+P3RSmmQvshofQyMY=
-github.com/rogpeppe/go-internal v1.8.0 h1:FCbCCtXNOY3UtUuHUYaghJg4y7Fd14rXifAYUAtL9R8=
-github.com/rogpeppe/go-internal v1.8.0/go.mod h1:WmiCO8CzOY8rg0OYDC4/i/2WRWAB6poM+XZ2dLUbcbE=
 github.com/rogpeppe/go-internal v1.8.1 h1:geMPLpDpQOgVyCg5z5GoRwLHepNdb71NXb67XFkP+Eg=
 github.com/rogpeppe/go-internal v1.8.1/go.mod h1:JeRgkft04UBgHMgCIwADu4Pn6Mtm5d4nPKWu0nJ5d+o=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=