Revert "encoding/json: implement Is on all errors"

This reverts CL 254537.

Reason for revert: Reason for revert: The recommended way to check for a type of error is errors.As. API changes should also start with a proposal.

Change-Id: I07c37428575e99c80b17525833a61831d10963bb
Reviewed-on: https://go-review.googlesource.com/c/go/+/254857
Trust: Damien Neil <dneil@google.com>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>

1 files changed, 0 insertions, 18 deletions

diff --git a/src/encoding/json/decode.go b/src/encoding/json/decode.go
index 1b006ffb17..86d8a69db7 100644
--- a/src/encoding/json/decode.go
+++ b/src/encoding/json/decode.go
@@ -136,12 +136,6 @@ func (e *UnmarshalTypeError) Error() string {
 	return "json: cannot unmarshal " + e.Value + " into Go value of type " + e.Type.String()
 }
 
-// Is returns true if target is a UnmarshalTypeError.
-func (e *UnmarshalTypeError) Is(target error) bool {
-	_, ok := target.(*UnmarshalTypeError)
-	return ok
-}
-
 // An UnmarshalFieldError describes a JSON object key that
 // led to an unexported (and therefore unwritable) struct field.
 //
@@ -156,24 +150,12 @@ func (e *UnmarshalFieldError) Error() string {
 	return "json: cannot unmarshal object key " + strconv.Quote(e.Key) + " into unexported field " + e.Field.Name + " of type " + e.Type.String()
 }
 
-// Is returns true if target is a UnmarshalFieldError.
-func (e *UnmarshalFieldError) Is(target error) bool {
-	_, ok := target.(*UnmarshalFieldError)
-	return ok
-}
-
 // An InvalidUnmarshalError describes an invalid argument passed to Unmarshal.
 // (The argument to Unmarshal must be a non-nil pointer.)
 type InvalidUnmarshalError struct {
 	Type reflect.Type
 }
 
-// Is returns true if target is a InvalidUnmarshalError.
-func (e *InvalidUnmarshalError) Is(target error) bool {
-	_, ok := target.(*InvalidUnmarshalError)
-	return ok
-}
-
 func (e *InvalidUnmarshalError) Error() string {
 	if e.Type == nil {
 		return "json: Unmarshal(nil)"