Merge pull request #2244 from matthewbauer/tag-cbor

include/nlohmann/detail/output/binary_writer.hpp

@@ -279,6 +279,12 @@ class binary_writer
 
             case value_t::binary:
             {
+                if (j.m_value.binary->has_subtype())
+                {
+                    write_number(static_cast<std::uint8_t>(0xd8));
+                    write_number(j.m_value.binary->subtype());
+                }
+
                 // step 1: write control byte and the binary array size
                 const auto N = j.m_value.binary->size();
                 if (N <= 0x17)

single_include/nlohmann/json.hpp

@@ -12795,6 +12795,12 @@ class binary_writer
 
             case value_t::binary:
             {
+                if (j.m_value.binary->has_subtype())
+                {
+                    write_number(static_cast<std::uint8_t>(0xd8));
+                    write_number(j.m_value.binary->subtype());
+                }
+
                 // step 1: write control byte and the binary array size
                 const auto N = j.m_value.binary->size();
                 if (N <= 0x17)

test/src/unit-cbor.cpp

@@ -2503,6 +2503,8 @@ TEST_CASE("examples from RFC 7049 Appendix A")
         std::vector<uint8_t> expected((std::istreambuf_iterator<char>(f_bin)),
                                       std::istreambuf_iterator<char>());
         CHECK(j == json::binary(expected));
+
+        CHECK(json::to_cbor(json::binary(std::vector<uint8_t> {}, 0x42)) == std::vector<uint8_t> {0xd8, 0x42, 0x40});
     }
 
     SECTION("arrays")