🚨 fixed more compiler warnings

include/nlohmann/detail/conversions/to_json.hpp

@@ -247,7 +247,7 @@ void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
 
 template<typename BasicJsonType, typename T,
          enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
-void to_json(BasicJsonType& j, std::valarray<T> arr)
+void to_json(BasicJsonType& j, const std::valarray<T>& arr)
 {
     external_constructor<value_t::array>::construct(j, std::move(arr));
 }

include/nlohmann/detail/input/json_sax.hpp

@@ -405,11 +405,9 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
 
     bool end_object() override
     {
-        bool keep = true;
         if (ref_stack.back())
         {
-            keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back());
-            if (not keep)
+            if (not callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back()))
             {
                 // discard object
                 *ref_stack.back() = discarded;

include/nlohmann/detail/input/lexer.hpp

@@ -1173,7 +1173,7 @@ scan_number_done:
             {
                 // escape control characters
                 char cs[9];
-                snprintf(cs, 9, "<U+%.4hhX>", c);
+                snprintf(cs, 9, "<U+%.4hhX>", static_cast<unsigned char>(c));
                 result += cs;
             }
             else

include/nlohmann/detail/iterators/primitive_iterator.hpp

@@ -87,7 +87,7 @@ class primitive_iterator_t
     primitive_iterator_t const operator++(int) noexcept
     {
         auto result = *this;
-        m_it++;
+        ++m_it;
         return result;
     }
 
@@ -100,7 +100,7 @@ class primitive_iterator_t
     primitive_iterator_t const operator--(int) noexcept
     {
         auto result = *this;
-        m_it--;
+        --m_it;
         return result;
     }
 

single_include/nlohmann/json.hpp

@@ -1520,7 +1520,7 @@ void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
 
 template<typename BasicJsonType, typename T,
          enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
-void to_json(BasicJsonType& j, std::valarray<T> arr)
+void to_json(BasicJsonType& j, const std::valarray<T>& arr)
 {
     external_constructor<value_t::array>::construct(j, std::move(arr));
 }
@@ -3165,7 +3165,7 @@ scan_number_done:
             {
                 // escape control characters
                 char cs[9];
-                snprintf(cs, 9, "<U+%.4hhX>", c);
+                snprintf(cs, 9, "<U+%.4hhX>", static_cast<unsigned char>(c));
                 result += cs;
             }
             else
@@ -3746,11 +3746,9 @@ class json_sax_dom_callback_parser : public json_sax<BasicJsonType>
 
     bool end_object() override
     {
-        bool keep = true;
         if (ref_stack.back())
         {
-            keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back());
-            if (not keep)
+            if (not callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back()))
             {
                 // discard object
                 *ref_stack.back() = discarded;