MSVC: Silence compiler warning about INFINITY

Contrary to the comment, MSVC does support INFINITY, but
always prints a warning when it's used:

qpainterpath.cpp(3066) : warning C4756: overflow in constant arithmetic

Avoid this by using numeric_limits<T>::infinity.

Change-Id: Ie925b036b807378da5298a275fa108347c24519e
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

1 files changed, 8 insertions, 9 deletions

diff --git a/src/gui/painting/qpainterpath.cpp b/src/gui/painting/qpainterpath.cpp
index 88cf05c646..e2f267d7ee 100644
--- a/src/gui/painting/qpainterpath.cpp
+++ b/src/gui/painting/qpainterpath.cpp
@@ -3057,20 +3057,19 @@ qreal QPainterPath::slopeAtPercent(qreal t) const
     //tangent line
     qreal slope = 0;
 
-#define SIGN(x) ((x < 0)?-1:1)
     if (m1)
         slope = m2/m1;
     else {
-        //windows doesn't define INFINITY :(
-#ifdef INFINITY
-        slope = INFINITY*SIGN(m2);
-#else
-        if (sizeof(qreal) == sizeof(double)) {
-            return 1.79769313486231570e+308;
+        if (std::numeric_limits<qreal>::has_infinity) {
+            slope = (m2  < 0) ? -std::numeric_limits<qreal>::infinity()
+                              : std::numeric_limits<qreal>::infinity();
         } else {
-            return ((qreal)3.40282346638528860e+38);
+            if (sizeof(qreal) == sizeof(double)) {
+                return 1.79769313486231570e+308;
+            } else {
+                return ((qreal)3.40282346638528860e+38);
+            }
         }
-#endif
     }
 
     return slope;