Fix failed build with compile flag: -Werror=float-equal (#741)

Author: artem-sharipov

Diff for: src/unity.c

@@ -337,10 +337,12 @@ void UnityPrintFloat(const UNITY_DOUBLE input_number)
     static const int sig_digits = 9;
     static const UNITY_INT32 min_scaled = 100000000;
     static const UNITY_INT32 max_scaled = 1000000000;
+    static const UNITY_DOUBLE epsilon = UNITY_DOUBLE_PRECISION;
 #else
     static const int sig_digits = 7;
     static const UNITY_INT32 min_scaled = 1000000;
     static const UNITY_INT32 max_scaled = 10000000;
+    static const UNITY_DOUBLE epsilon = UNITY_FLOAT_PRECISION;
 #endif
 
     UNITY_DOUBLE number = input_number;
@@ -353,7 +355,7 @@ void UnityPrintFloat(const UNITY_DOUBLE input_number)
     }
 
     /* handle zero, NaN, and +/- infinity */
-    if (number == 0.0f)
+    if (UNITY_ABS(number) < epsilon)
     {
         UnityPrint("0");
     }
@@ -420,7 +422,7 @@ void UnityPrintFloat(const UNITY_DOUBLE input_number)
 
 #ifndef UNITY_ROUND_TIES_AWAY_FROM_ZERO
         /* round to even if exactly between two integers */
-        if ((n & 1) && (((UNITY_DOUBLE)n - number) == 0.5f))
+        if ((n & 1) && (UNITY_ABS((UNITY_DOUBLE)n - number - 0.5f) < epsilon))
             n--;
 #endif
 

Diff for: src/unity_internals.h

@@ -259,8 +259,14 @@ typedef UNITY_FLOAT_TYPE UNITY_FLOAT;
 #ifndef UNITY_IS_NAN
 #ifndef isnan
 /* NaN is the only floating point value that does NOT equal itself.
- * Therefore if n != n, then it is NaN. */
-#define UNITY_IS_NAN(n) ((n != n) ? 1 : 0)
+ * Therefore if n != n, then it is NaN.
+ *
+ * Another way to define NaN is to check whether the number belongs
+ * simultaneously to the set of negative and positive numbers, including 0.
+ * Therefore if ((n >= 0) == (n < 0)), then it is NaN.
+ * This implementation will not cause an error with the compilation flag:
+ * -Werror=float-equal */
+#define UNITY_IS_NAN(n) ((((n) >= 0.0f) == ((n) < 0.0f)) ? 1 : 0)
 #else
 #define UNITY_IS_NAN(n) isnan(n)
 #endif
@@ -276,6 +282,11 @@ typedef UNITY_FLOAT_TYPE UNITY_FLOAT;
 #endif
 #endif
 
+/* Calculates the absolute value of the given number */
+#ifndef UNITY_ABS
+  #define UNITY_ABS(n) (((n) < 0) ? -(n) : (n))
+#endif
+
 #endif
 
 /*-------------------------------------------------------