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, 12 deletions

diff --git a/src/encoding/json/encode.go b/src/encoding/json/encode.go
index 8e6b342b59..578d551102 100644
--- a/src/encoding/json/encode.go
+++ b/src/encoding/json/encode.go
@@ -245,12 +245,6 @@ func (e *UnsupportedValueError) Error() string {
 	return "json: unsupported value: " + e.Str
 }
 
-// Is returns true if target is a UnsupportedValueError.
-func (e *UnsupportedValueError) Is(target error) bool {
-	_, ok := target.(*UnsupportedValueError)
-	return ok
-}
-
 // Before Go 1.2, an InvalidUTF8Error was returned by Marshal when
 // attempting to encode a string value with invalid UTF-8 sequences.
 // As of Go 1.2, Marshal instead coerces the string to valid UTF-8 by
@@ -285,12 +279,6 @@ func (e *MarshalerError) Error() string {
 // Unwrap returns the underlying error.
 func (e *MarshalerError) Unwrap() error { return e.Err }
 
-// Is returns true if target is a MarshalerError.
-func (e *MarshalerError) Is(target error) bool {
-	_, ok := target.(*MarshalerError)
-	return ok
-}
-
 var hex = "0123456789abcdef"
 
 // An encodeState encodes JSON into a bytes.Buffer.