🚑 fix for #1021

include/nlohmann/detail/exceptions.hpp

@@ -301,6 +301,7 @@ Exceptions have ids 5xx.
 name / id                      | example message | description
 ------------------------------ | --------------- | -------------------------
 json.exception.other_error.501 | unsuccessful: {"op":"test","path":"/baz", "value":"bar"} | A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.
+json.exception.other_error.502 | type for number_float_t is not supported | The template type for a number is not supported for the binary serialization in CBOR, MessagePack or UBJSON.
 
 @sa @ref exception for the base class of the library exceptions
 @sa @ref parse_error for exceptions indicating a parse error

include/nlohmann/detail/output/binary_writer.hpp

@@ -149,9 +149,19 @@ class binary_writer
                 break;
             }
 
-            case value_t::number_float: // Double-Precision Float
+            case value_t::number_float:
             {
-                oa->write_character(static_cast<CharType>(0xFB));
+                switch (sizeof(typename BasicJsonType::number_float_t))
+                {
+                    case 4:  // Single-Precision Float
+                        oa->write_character(static_cast<CharType>(0xFA));
+                        break;
+                    case 8:  // Double-Precision Float
+                        oa->write_character(static_cast<CharType>(0xFB));
+                        break;
+                    default:
+                        JSON_THROW(other_error::create(502, "type for number_float_t is not supported"));
+                }
                 write_number(j.m_value.number_float);
                 break;
             }
@@ -409,9 +419,19 @@ class binary_writer
                 break;
             }
 
-            case value_t::number_float: // float 64
+            case value_t::number_float:
             {
-                oa->write_character(static_cast<CharType>(0xCB));
+                switch (sizeof(typename BasicJsonType::number_float_t))
+                {
+                    case 4:  // float 32
+                        oa->write_character(static_cast<CharType>(0xCA));
+                        break;
+                    case 8:  // float 64
+                        oa->write_character(static_cast<CharType>(0xCB));
+                        break;
+                    default:
+                        JSON_THROW(other_error::create(502, "type for number_float_t is not supported"));
+                }
                 write_number(j.m_value.number_float);
                 break;
             }
@@ -712,7 +732,17 @@ class binary_writer
     {
         if (add_prefix)
         {
-            oa->write_character(static_cast<CharType>('D'));  // float64
+            switch (sizeof(typename BasicJsonType::number_float_t))
+            {
+                case 4:  // float 32
+                    oa->write_character(static_cast<CharType>('d'));
+                    break;
+                case 8:  // float 64
+                    oa->write_character(static_cast<CharType>('D'));
+                    break;
+                default:
+                    JSON_THROW(other_error::create(502, "type for number_float_t is not supported"));
+            }
         }
         write_number(n);
     }
@@ -892,7 +922,15 @@ class binary_writer
             }
 
             case value_t::number_float:
-                return 'D';
+                switch (sizeof(typename BasicJsonType::number_float_t))
+                {
+                    case 4:  // float 32
+                        return 'd';
+                    case 8:  // float 64
+                        return 'D';
+                    default:
+                        JSON_THROW(other_error::create(502, "type for number_float_t is not supported"));
+                }
 
             case value_t::string:
                 return 'S';

single_include/nlohmann/json.hpp

@@ -794,6 +794,7 @@ Exceptions have ids 5xx.
 name / id                      | example message | description
 ------------------------------ | --------------- | -------------------------
 json.exception.other_error.501 | unsuccessful: {"op":"test","path":"/baz", "value":"bar"} | A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.
+json.exception.other_error.502 | type for number_float_t is not supported | The template type for a number is not supported for the binary serialization in CBOR, MessagePack or UBJSON.
 
 @sa @ref exception for the base class of the library exceptions
 @sa @ref parse_error for exceptions indicating a parse error
@@ -6357,9 +6358,19 @@ class binary_writer
                 break;
             }
 
-            case value_t::number_float: // Double-Precision Float
+            case value_t::number_float:
             {
-                oa->write_character(static_cast<CharType>(0xFB));
+                switch (sizeof(typename BasicJsonType::number_float_t))
+                {
+                    case 4:  // Single-Precision Float
+                        oa->write_character(static_cast<CharType>(0xFA));
+                        break;
+                    case 8:  // Double-Precision Float
+                        oa->write_character(static_cast<CharType>(0xFB));
+                        break;
+                    default:
+                        JSON_THROW(other_error::create(502, "type for number_float_t is not supported"));
+                }
                 write_number(j.m_value.number_float);
                 break;
             }
@@ -6617,9 +6628,19 @@ class binary_writer
                 break;
             }
 
-            case value_t::number_float: // float 64
+            case value_t::number_float:
             {
-                oa->write_character(static_cast<CharType>(0xCB));
+                switch (sizeof(typename BasicJsonType::number_float_t))
+                {
+                    case 4:  // float 32
+                        oa->write_character(static_cast<CharType>(0xCA));
+                        break;
+                    case 8:  // float 64
+                        oa->write_character(static_cast<CharType>(0xCB));
+                        break;
+                    default:
+                        JSON_THROW(other_error::create(502, "type for number_float_t is not supported"));
+                }
                 write_number(j.m_value.number_float);
                 break;
             }
@@ -6920,7 +6941,17 @@ class binary_writer
     {
         if (add_prefix)
         {
-            oa->write_character(static_cast<CharType>('D'));  // float64
+            switch (sizeof(typename BasicJsonType::number_float_t))
+            {
+                case 4:  // float 32
+                    oa->write_character(static_cast<CharType>('d'));
+                    break;
+                case 8:  // float 64
+                    oa->write_character(static_cast<CharType>('D'));
+                    break;
+                default:
+                    JSON_THROW(other_error::create(502, "type for number_float_t is not supported"));
+            }
         }
         write_number(n);
     }
@@ -7100,7 +7131,15 @@ class binary_writer
             }
 
             case value_t::number_float:
-                return 'D';
+                switch (sizeof(typename BasicJsonType::number_float_t))
+                {
+                    case 4:  // float 32
+                        return 'd';
+                    case 8:  // float 64
+                        return 'D';
+                    default:
+                        JSON_THROW(other_error::create(502, "type for number_float_t is not supported"));
+                }
 
             case value_t::string:
                 return 'S';

test/src/unit-regression.cpp

@@ -114,6 +114,13 @@ struct nocopy
 };
 }
 
+/////////////////////////////////////////////////////////////////////
+// for #1021
+/////////////////////////////////////////////////////////////////////
+
+using float_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int32_t, std::uint32_t, float>;
+
+
 TEST_CASE("regression tests")
 {
     SECTION("issue #60 - Double quotation mark is not parsed correctly")
@@ -1597,4 +1604,15 @@ TEST_CASE("regression tests")
         auto j = json::parse(geojsonExample, cb, true);
         CHECK(j == json());
     }
+
+    SECTION("issue #1021 - to/from_msgpack only works with standard typization")
+    {
+        float_json j = 1000.0;
+        CHECK(float_json::from_cbor(float_json::to_cbor(j)) == j);
+        CHECK(float_json::from_msgpack(float_json::to_msgpack(j)) == j);
+        CHECK(float_json::from_ubjson(float_json::to_ubjson(j)) == j);
+
+        float_json j2 = {1000.0, 2000.0, 3000.0};
+        CHECK(float_json::from_ubjson(float_json::to_ubjson(j2, true, true)) == j2);
+    }
 }