Merge branch 'develop' of https://github.com/nlohmann/json into issue2824

README.md

@@ -1612,6 +1612,7 @@ The library supports **Unicode input** as follows:
 - Invalid surrogates (e.g., incomplete pairs such as `\uDEAD`) will yield parse errors.
 - The strings stored in the library are UTF-8 encoded. When using the default string type (`std::string`), note that its length/size functions return the number of stored bytes rather than the number of characters or glyphs.
 - When you store strings with different encodings in the library, calling [`dump()`](https://nlohmann.github.io/json/api/basic_json/dump/) may throw an exception unless `json::error_handler_t::replace` or `json::error_handler_t::ignore` are used as error handlers.
+- To store wide strings (e.g., `std::wstring`), you need to convert them to a a UTF-8 encoded `std::string` before, see [an example](https://json.nlohmann.me/home/faq/#wide-string-handling).
 
 ### Comments in JSON
 

doc/mkdocs/docs/home/faq.md

@@ -44,7 +44,7 @@ for objects.
 
 !!! question
 
-	- Can you add an option to ignore trailing commas?
+	Can you add an option to ignore trailing commas?
 
 This library does not support any feature which would jeopardize interoperability.
 
@@ -70,6 +70,45 @@ The library supports **Unicode input** as follows:
 In most cases, the parser is right to complain, because the input is not UTF-8 encoded. This is especially true for Microsoft Windows where Latin-1 or ISO 8859-1 is often the standard encoding.
 
 
+### Wide string handling
+
+!!! question
+
+    Why are wide strings (e.g., `std::wstring`) dumped as arrays of numbers?
+
+As described [above](#parse-errors-reading-non-ascii-characters), the library assumes UTF-8 as encoding.  To store a wide string, you need to change the encoding.
+
+!!! example
+
+    ```cpp
+    #include <codecvt> // codecvt_utf8
+    #include <locale>  // wstring_convert
+    
+    // encoding function
+    std::string to_utf8(std::wstring& wide_string)
+    {
+        static std::wstring_convert<std::codecvt_utf8<wchar_t>> utf8_conv;
+        return utf8_conv.to_bytes(wide_string);
+    }
+    
+    json j;
+    std::wstring ws = L"車B1234 こんにちは";
+    
+    j["original"] = ws;
+    j["encoded"] = to_utf8(ws);
+    
+    std::cout << j << std::endl;
+    ```
+    
+    The result is:
+    
+    ```json
+    {
+      "encoded": "車B1234 こんにちは",
+      "original": [36554, 66, 49, 50, 51, 52, 32, 12371, 12435, 12395, 12385, 12399]
+    }
+    ```
+
 ## Exceptions
 
 ### Parsing without exceptions

include/nlohmann/detail/conversions/to_chars.hpp

@@ -1066,6 +1066,8 @@ char* to_chars(char* first, const char* last, FloatType value)
         *first++ = '-';
     }
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
     if (value == 0) // +-0
     {
         *first++ = '0';
@@ -1074,6 +1076,7 @@ char* to_chars(char* first, const char* last, FloatType value)
         *first++ = '0';
         return first;
     }
+#pragma GCC diagnostic pop
 
     JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10);
 

include/nlohmann/detail/output/binary_writer.hpp

@@ -1525,6 +1525,8 @@ class binary_writer
 
     void write_compact_float(const number_float_t n, detail::input_format_t format)
     {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
         if (static_cast<double>(n) >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
                 static_cast<double>(n) <= static_cast<double>((std::numeric_limits<float>::max)()) &&
                 static_cast<double>(static_cast<float>(n)) == static_cast<double>(n))
@@ -1541,6 +1543,7 @@ class binary_writer
                                 : get_msgpack_float_prefix(n));
             write_number(n);
         }
+#pragma GCC diagnostic pop
     }
 
   public:

include/nlohmann/json.hpp

@@ -6278,6 +6278,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     */
     friend bool operator==(const_reference lhs, const_reference rhs) noexcept
     {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
         const auto lhs_type = lhs.type();
         const auto rhs_type = rhs.type();
 
@@ -6342,6 +6344,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         }
 
         return false;
+#pragma GCC diagnostic pop
     }
 
     /*!

single_include/nlohmann/json.hpp

@@ -14826,6 +14826,8 @@ class binary_writer
 
     void write_compact_float(const number_float_t n, detail::input_format_t format)
     {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
         if (static_cast<double>(n) >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
                 static_cast<double>(n) <= static_cast<double>((std::numeric_limits<float>::max)()) &&
                 static_cast<double>(static_cast<float>(n)) == static_cast<double>(n))
@@ -14842,6 +14844,7 @@ class binary_writer
                                 : get_msgpack_float_prefix(n));
             write_number(n);
         }
+#pragma GCC diagnostic pop
     }
 
   public:
@@ -15982,6 +15985,8 @@ char* to_chars(char* first, const char* last, FloatType value)
         *first++ = '-';
     }
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
     if (value == 0) // +-0
     {
         *first++ = '0';
@@ -15990,6 +15995,7 @@ char* to_chars(char* first, const char* last, FloatType value)
         *first++ = '0';
         return first;
     }
+#pragma GCC diagnostic pop
 
     JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10);
 
@@ -23364,6 +23370,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     */
     friend bool operator==(const_reference lhs, const_reference rhs) noexcept
     {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
         const auto lhs_type = lhs.type();
         const auto rhs_type = rhs.type();
 
@@ -23428,6 +23436,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         }
 
         return false;
+#pragma GCC diagnostic pop
     }
 
     /*!

test/src/unit-cbor.cpp

@@ -28,7 +28,6 @@ SOFTWARE.
 */
 
 #include "doctest_compatibility.h"
-DOCTEST_GCC_SUPPRESS_WARNING("-Wfloat-equal")
 
 #include <nlohmann/json.hpp>
 using nlohmann::json;

test/src/unit-constructor1.cpp

@@ -28,7 +28,6 @@ SOFTWARE.
 */
 
 #include "doctest_compatibility.h"
-DOCTEST_GCC_SUPPRESS_WARNING("-Wfloat-equal")
 
 #define JSON_TESTS_PRIVATE
 #include <nlohmann/json.hpp>

test/src/unit-readme.cpp

@@ -28,7 +28,6 @@ SOFTWARE.
 */
 
 #include "doctest_compatibility.h"
-DOCTEST_GCC_SUPPRESS_WARNING("-Wfloat-equal")
 
 #include <nlohmann/json.hpp>
 using nlohmann::json;

test/src/unit-reference_access.cpp

@@ -28,7 +28,6 @@ SOFTWARE.
 */
 
 #include "doctest_compatibility.h"
-DOCTEST_GCC_SUPPRESS_WARNING("-Wfloat-equal")
 
 #include <nlohmann/json.hpp>
 using nlohmann::json;

test/src/unit-regression1.cpp

@@ -28,7 +28,6 @@ SOFTWARE.
 */
 
 #include "doctest_compatibility.h"
-DOCTEST_GCC_SUPPRESS_WARNING("-Wfloat-equal")
 
 // for some reason including this after the json header leads to linker errors with VS 2017...
 #include <locale>

test/src/unit-regression2.cpp

@@ -28,7 +28,6 @@ SOFTWARE.
 */
 
 #include "doctest_compatibility.h"
-DOCTEST_GCC_SUPPRESS_WARNING("-Wfloat-equal")
 
 // for some reason including this after the json header leads to linker errors with VS 2017...
 #include <locale>