json: pass remaining cycle/unsupported-value tests

Author: extemporalgenome

json/codec.go

@@ -309,12 +309,13 @@ func constructSliceCodec(t reflect.Type, seen seenMap) codec {
 	e := t.Elem()
 	s := alignedSize(e)
 
+	var c codec
+
 	if e.Kind() == reflect.Uint8 {
 		// Go 1.7+ behavior: slices of byte types (and aliases) may override the
 		// default encoding and decoding behaviors by implementing marshaler and
 		// unmarshaler interfaces.
 		p := reflect.PointerTo(e)
-		c := codec{}
 
 		switch {
 		case e.Implements(jsonMarshalerType):
@@ -353,11 +354,26 @@ func constructSliceCodec(t reflect.Type, seen seenMap) codec {
 		return c
 	}
 
-	c := constructCodec(e, seen, true)
-	return codec{
-		encode: constructSliceEncodeFunc(s, t, c.encode),
-		decode: constructSliceDecodeFunc(s, t, c.decode),
+	inner := constructCodec(e, seen, true)
+
+	// If encode/decode functions are nil, that means this is a recursive type,
+	// and so we can use delayed binding to define self-referential calls.
+	if inner.encode == nil {
+		inner.encode = func(e encoder, b []byte, p unsafe.Pointer) ([]byte, error) {
+			return c.encode(e, b, p)
+		}
 	}
+
+	if inner.decode == nil {
+		inner.decode = func(d decoder, b []byte, p unsafe.Pointer) ([]byte, error) {
+			return c.decode(d, b, p)
+		}
+	}
+
+	c.encode = constructSliceEncodeFunc(s, t, inner.encode)
+	c.decode = constructSliceDecodeFunc(s, t, inner.decode)
+
+	return c
 }
 
 func constructSliceEncodeFunc(size uintptr, t reflect.Type, encode encodeFunc) encodeFunc {

json/encode.go

@@ -297,7 +297,7 @@ func (e encoder) encodeTime(b []byte, p unsafe.Pointer) ([]byte, error) {
 
 func (e encoder) encodeArray(b []byte, p unsafe.Pointer, n int, size uintptr, t reflect.Type, encode encodeFunc) ([]byte, error) {
 	if shouldCheckForRefCycle(&e) {
-		key := cycleKey{ptr: p}
+		key := cycleKey{ptr: p, len: n}
 		if hasRefCycle(&e, key) {
 			return b, refCycleError(t, p)
 		}