From 25ed41033172dca5f299687b4ed30d5f275d58f8 Mon Sep 17 00:00:00 2001
From: Isaac Nickaein <nickaein.i@gmail.com>
Date: Wed, 19 May 2021 14:21:25 +0430
Subject: [PATCH] use templated is_negative

---
 include/nlohmann/detail/output/serializer.hpp | 17 +++++++++++++++--
 single_include/nlohmann/json.hpp              | 17 +++++++++++++++--
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/include/nlohmann/detail/output/serializer.hpp b/include/nlohmann/detail/output/serializer.hpp
index 865b8904e2..d8f412f65a 100644
--- a/include/nlohmann/detail/output/serializer.hpp
+++ b/include/nlohmann/detail/output/serializer.hpp
@@ -659,6 +659,20 @@ class serializer
         }
     }
 
+    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
 
@@ -701,12 +715,11 @@ class serializer
         // use a pointer to fill the buffer
         auto buffer_ptr = number_buffer.begin();
 
-        const bool is_negative = std::is_same<NumberType, number_integer_t>::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
index a70aaf8cbc..62195a1370 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -16096,6 +16096,20 @@ class serializer
         }
     }
 
+    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
 
@@ -16138,12 +16152,11 @@ class serializer
         // use a pointer to fill the buffer
         auto buffer_ptr = number_buffer.begin();
 
-        const bool is_negative = std::is_same<NumberType, number_integer_t>::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));