From 02b3d43fd4661271e6e8dc8940d84cb2ba352fe0 Mon Sep 17 00:00:00 2001
From: Luca Beldi <v.ronin@yahoo.it>
Date: Wed, 22 Aug 2018 08:21:01 +0100
Subject: _q_interpolate<T> is unsafe with unsigned template arguments

_q_interpolate<T> subtracts 2 arguments of type T,
for unsigned types this can cause wrapping around

Task-number: QTBUG-57925
Change-Id: Iffa59f413579a3d5de8cb728fe71443d8e8a04aa
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
---
 src/corelib/animation/qvariantanimation_p.h | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

(limited to 'src/corelib/animation')

diff --git a/src/corelib/animation/qvariantanimation_p.h b/src/corelib/animation/qvariantanimation_p.h
index 37318a5339..9f0f2e3030 100644
--- a/src/corelib/animation/qvariantanimation_p.h
+++ b/src/corelib/animation/qvariantanimation_p.h
@@ -58,6 +58,8 @@
 
 #include "private/qabstractanimation_p.h"
 
+#include <type_traits>
+
 #ifndef QT_NO_ANIMATION
 
 QT_BEGIN_NAMESPACE
@@ -104,7 +106,17 @@ public:
 };
 
 //this should make the interpolation faster
-template<typename T> inline T _q_interpolate(const T &f, const T &t, qreal progress)
+template<typename T>
+typename std::enable_if<std::is_unsigned<T>::value, T>::type
+_q_interpolate(const T &f, const T &t, qreal progress)
+{
+    return T(f + t * progress - f * progress);
+}
+
+// the below will apply also to all non-arithmetic types
+template<typename T>
+typename std::enable_if<!std::is_unsigned<T>::value, T>::type
+_q_interpolate(const T &f, const T &t, qreal progress)
 {
     return T(f + (t - f) * progress);
 }
-- 
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