Fix negative zero string conversion

Author: adazem009

src/scratch/value_functions_p.h

@@ -50,7 +50,7 @@ extern "C"
         return v < 0 && std::isinf(v);
     }
 
-    inline long value_convert_int_str(const char *str, int n, bool *ok)
+    inline double value_convert_int_str(const char *str, int n, bool *ok)
     {
         if (ok)
             *ok = false;
@@ -80,7 +80,7 @@ extern "C"
             *ok = true;
 
         if (isNegative)
-            return -ret;
+            return -static_cast<double>(ret); // for negative zero
         else
             return ret;
     }

test/scratch_classes/value_test.cpp

@@ -938,6 +938,15 @@ TEST(ValueTest, ToDouble)
     v = "-0.15";
     ASSERT_EQ(v.toDouble(), -0.15);
 
+    v = "0";
+    ASSERT_EQ(v.toDouble(), 0.0);
+    v = "-0";
+    ASSERT_EQ(v.toDouble(), -0.0);
+    v = "0.0";
+    ASSERT_EQ(v.toDouble(), 0.0);
+    v = "-0.0";
+    ASSERT_EQ(v.toDouble(), -0.0);
+
     v = "+.15";
     ASSERT_EQ(v.toDouble(), 0.15);
     v = ".15";
@@ -2879,6 +2888,11 @@ TEST(ValueTest, StringToDouble)
     ASSERT_EQ(value_stringToDouble("0.15"), 0.15);
     ASSERT_EQ(value_stringToDouble("-0.15"), -0.15);
 
+    ASSERT_EQ(value_stringToDouble("0"), 0.0);
+    ASSERT_EQ(value_stringToDouble("-0"), -0.0);
+    ASSERT_EQ(value_stringToDouble("0.0"), 0.0);
+    ASSERT_EQ(value_stringToDouble("-0.0"), -0.0);
+
     ASSERT_EQ(value_stringToDouble("+.15"), 0.15);
     ASSERT_EQ(value_stringToDouble(".15"), 0.15);
     ASSERT_EQ(value_stringToDouble("-.15"), -0.15);