🚨 fix warning (code taken from #2736)

nlohmann · Dec 29, 2021 · e113b20 · e113b20
1 parent ae71941
commit e113b20
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Showing 2 changed files with 28 additions and 4 deletions.
diff --git a/include/nlohmann/detail/output/serializer.hpp b/include/nlohmann/detail/output/serializer.hpp
@@ -664,6 +664,19 @@ class serializer
         }
     }
 
+    // templates to avoid warnings about useless casts
+    template <typename NumberType, enable_if_t<std::is_signed<NumberType>::value, int> = 0>
+    bool is_negative_number(NumberType x)
+    {
+        return x < 0;
+    }
+
+    template < typename NumberType, enable_if_t <std::is_unsigned<NumberType>::value, int > = 0 >
+    bool is_negative_number(NumberType /*unused*/)
+    {
+        return false;
+    }
+
     /*!
     @brief dump an integer
 
@@ -707,12 +720,11 @@ class serializer
         // use a pointer to fill the buffer
         auto buffer_ptr = number_buffer.begin(); // NOLINT(llvm-qualified-auto,readability-qualified-auto,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
 
-        const bool is_negative = std::is_signed<NumberType>::value && !(x >= 0); // see issue #755
         number_unsigned_t abs_value;
 
         unsigned int n_chars{};
 
-        if (is_negative)
+        if (is_negative_number(x))
         {
             *buffer_ptr = '-';
             abs_value = remove_sign(static_cast<number_integer_t>(x));

diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
@@ -16707,6 +16707,19 @@ class serializer
         }
     }
 
+    // templates to avoid warnings about useless casts
+    template <typename NumberType, enable_if_t<std::is_signed<NumberType>::value, int> = 0>
+    bool is_negative_number(NumberType x)
+    {
+        return x < 0;
+    }
+
+    template < typename NumberType, enable_if_t <std::is_unsigned<NumberType>::value, int > = 0 >
+    bool is_negative_number(NumberType /*unused*/)
+    {
+        return false;
+    }
+
     /*!
     @brief dump an integer
 
@@ -16750,12 +16763,11 @@ class serializer
         // use a pointer to fill the buffer
         auto buffer_ptr = number_buffer.begin(); // NOLINT(llvm-qualified-auto,readability-qualified-auto,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
 
-        const bool is_negative = std::is_signed<NumberType>::value && !(x >= 0); // see issue #755
         number_unsigned_t abs_value;
 
         unsigned int n_chars{};
 
-        if (is_negative)
+        if (is_negative_number(x))
         {
             *buffer_ptr = '-';
             abs_value = remove_sign(static_cast<number_integer_t>(x));