XMLCodec: fix DecodeValue to return a []byte

pgtype/pgtype_default.go

@@ -91,7 +91,25 @@ func initDefaultMap() {
 	defaultMap.RegisterType(&Type{Name: "varchar", OID: VarcharOID, Codec: TextCodec{}})
 	defaultMap.RegisterType(&Type{Name: "xid", OID: XIDOID, Codec: Uint32Codec{}})
 	defaultMap.RegisterType(&Type{Name: "xid8", OID: XID8OID, Codec: Uint64Codec{}})
-	defaultMap.RegisterType(&Type{Name: "xml", OID: XMLOID, Codec: &XMLCodec{Marshal: xml.Marshal, Unmarshal: xml.Unmarshal}})
+	defaultMap.RegisterType(&Type{Name: "xml", OID: XMLOID, Codec: &XMLCodec{
+		Marshal: xml.Marshal,
+		// xml.Unmarshal does not support unmarshalling into *any. However, XMLCodec.DecodeValue calls Unmarshal with a
+		// *any. Wrap xml.Marshal with a function that copies the data into a new byte slice in this case. Not implementing
+		// directly in XMLCodec.DecodeValue to allow for the unlikely possibility that someone uses an alternative XML
+		// unmarshaler that does support unmarshalling into *any.
+		//
+		// https://github.com/jackc/pgx/issues/2227
+		// https://github.com/jackc/pgx/pull/2228
+		Unmarshal: func(data []byte, v any) error {
+			if v, ok := v.(*any); ok {
+				dstBuf := make([]byte, len(data))
+				copy(dstBuf, data)
+				*v = dstBuf
+				return nil
+			}
+			return xml.Unmarshal(data, v)
+		},
+	}})
 
 	// Range types
 	defaultMap.RegisterType(&Type{Name: "daterange", OID: DaterangeOID, Codec: &RangeCodec{ElementType: defaultMap.oidToType[DateOID]}})

pgtype/xml_test.go

@@ -97,3 +97,32 @@ func TestXMLCodecPointerToPointerToString(t *testing.T) {
 		require.Nil(t, s)
 	})
 }
+
+func TestXMLCodecDecodeValue(t *testing.T) {
+	skipCockroachDB(t, "CockroachDB does not support XML.")
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, _ testing.TB, conn *pgx.Conn) {
+		for _, tt := range []struct {
+			sql      string
+			expected any
+		}{
+			{
+				sql:      `select '<foo>bar</foo>'::xml`,
+				expected: []byte("<foo>bar</foo>"),
+			},
+		} {
+			t.Run(tt.sql, func(t *testing.T) {
+				rows, err := conn.Query(ctx, tt.sql)
+				require.NoError(t, err)
+
+				for rows.Next() {
+					values, err := rows.Values()
+					require.NoError(t, err)
+					require.Len(t, values, 1)
+					require.Equal(t, tt.expected, values[0])
+				}
+
+				require.NoError(t, rows.Err())
+			})
+		}
+	})
+}