Reading binary number from wchar as an error, address warnings

Author: TianyiChen

include/nlohmann/detail/input/input_adapters.hpp

@@ -180,12 +180,12 @@ class iterator_input_adapter
     template<class T>
     std::size_t get_elements(T* dest, std::size_t count = 1)
     {
-        auto* ptr = reinterpret_cast<unsigned char*>(dest);
+        auto* ptr = reinterpret_cast<char*>(dest);
         for (std::size_t read_index = 0; read_index < count * sizeof(T); ++read_index)
         {
             if (JSON_HEDLEY_LIKELY(current != end))
             {
-                ptr[read_index] = *current;
+                ptr[read_index] = static_cast<char>(*current);
                 std::advance(current, 1);
             }
             else
@@ -359,15 +359,11 @@ class wide_string_input_adapter
         return utf8_bytes[utf8_bytes_index++];
     }
 
+    // parsing binary with wchar doesn't make sense, but since the parsing mode can be runtime, we need something here
     template<class T>
     std::size_t get_elements(T* dest, std::size_t count = 1)
     {
-        auto* ptr = reinterpret_cast<char*>(dest);
-        for (std::size_t read_index = 0; read_index < count * sizeof(T); ++read_index)
-        {
-            ptr[read_index] = static_cast<char>(get_character());
-        }
-        return count * sizeof(T);
+        JSON_THROW(parse_error::create(112, 1, "wide string type cannot be interpreted as binary data", nullptr));
     }
 
   private:

single_include/nlohmann/json.hpp

@@ -6413,12 +6413,12 @@ class iterator_input_adapter
     template<class T>
     std::size_t get_elements(T* dest, std::size_t count = 1)
     {
-        auto* ptr = reinterpret_cast<unsigned char*>(dest);
+        auto* ptr = reinterpret_cast<char*>(dest);
         for (std::size_t read_index = 0; read_index < count * sizeof(T); ++read_index)
         {
             if (JSON_HEDLEY_LIKELY(current != end))
             {
-                ptr[read_index] = *current;
+                ptr[read_index] = static_cast<char>(*current);
                 std::advance(current, 1);
             }
             else
@@ -6592,15 +6592,11 @@ class wide_string_input_adapter
         return utf8_bytes[utf8_bytes_index++];
     }
 
+    // parsing binary with wchar doesn't make sense, but since the parsing mode can be runtime, we need something here
     template<class T>
     std::size_t get_elements(T* dest, std::size_t count = 1)
     {
-        auto* ptr = reinterpret_cast<char*>(dest);
-        for (std::size_t read_index = 0; read_index < count * sizeof(T); ++read_index)
-        {
-            ptr[read_index] = static_cast<char>(get_character());
-        }
-        return count * sizeof(T);
+        JSON_THROW(parse_error::create(112, 1, "wide string type cannot be interpreted as binary data", nullptr));
     }
 
   private:

tests/src/unit-msgpack.cpp

@@ -1511,10 +1511,18 @@ TEST_CASE("MessagePack")
         SECTION("unexpected end inside int with stream")
         {
             json _;
-            std::string data = {static_cast<char>(0xd2), static_cast<char>(0x12), static_cast<char>(0x34), static_cast<char>(0x56)};
+            const std::string data = {static_cast<char>(0xd2u), static_cast<char>(0x12u), static_cast<char>(0x34u), static_cast<char>(0x56u)};
             CHECK_THROWS_WITH_AS(_ = json::from_msgpack(std::istringstream(data, std::ios::binary)),
                                  "[json.exception.parse_error.110] parse error at byte 5: syntax error while parsing MessagePack number: unexpected end of input", json::parse_error&);
         }
+        SECTION("misuse wchar for binary")
+        {
+            json _;
+            // creates 0xd2 after UTF-8 decoding, triggers get_elements in wide_string_input_adapter for code coverage
+            const std::u32string data = {static_cast<char32_t>(0x0280)};
+            CHECK_THROWS_WITH_AS(_ = json::from_msgpack(data),
+                                 "[json.exception.parse_error.112] parse error at byte 1: wide string type cannot be interpreted as binary data", json::parse_error&);
+        }
 
         SECTION("unsupported bytes")
         {