build: workaround GCC 7.1.1 compilation issue with sanitize flags

Version: gcc (GCC) 7.1.1 20170622 (Red Hat 7.1.1-3)
Flags: -fsanitize=address,undefined

modules/ts/src/cuda_test.cpp

@@ -322,16 +322,20 @@ namespace cvtest
 
         if (m1.size() != m2.size())
         {
-            return AssertionFailure() << "Matrices \"" << expr1 << "\" and \"" << expr2 << "\" have different sizes : \""
-                                      << expr1 << "\" [" << PrintToString(m1.size()) << "] vs \""
-                                      << expr2 << "\" [" << PrintToString(m2.size()) << "]";
+            std::stringstream msg;
+            msg << "Matrices \"" << expr1 << "\" and \"" << expr2 << "\" have different sizes : \""
+                << expr1 << "\" [" << PrintToString(m1.size()) << "] vs \""
+                << expr2 << "\" [" << PrintToString(m2.size()) << "]";
+            return AssertionFailure() << msg.str();
         }
 
         if (m1.type() != m2.type())
         {
-            return AssertionFailure() << "Matrices \"" << expr1 << "\" and \"" << expr2 << "\" have different types : \""
-                                      << expr1 << "\" [" << PrintToString(MatType(m1.type())) << "] vs \""
-                                      << expr2 << "\" [" << PrintToString(MatType(m2.type())) << "]";
+            std::stringstream msg;
+            msg << "Matrices \"" << expr1 << "\" and \"" << expr2 << "\" have different types : \""
+                << expr1 << "\" [" << PrintToString(MatType(m1.type())) << "] vs \""
+                << expr2 << "\" [" << PrintToString(MatType(m2.type())) << "]";
+             return AssertionFailure() << msg.str();
         }
 
         Mat diff;
@@ -343,12 +347,14 @@ namespace cvtest
 
         if (maxVal > eps)
         {
-            return AssertionFailure() << "The max difference between matrices \"" << expr1 << "\" and \"" << expr2
-                                      << "\" is " << maxVal << " at (" << maxLoc.y << ", " << maxLoc.x / m1.channels() << ")"
-                                      << ", which exceeds \"" << eps_expr << "\", where \""
-                                      << expr1 << "\" at (" << maxLoc.y << ", " << maxLoc.x / m1.channels() << ") evaluates to " << printMatVal(m1, maxLoc) << ", \""
-                                      << expr2 << "\" at (" << maxLoc.y << ", " << maxLoc.x / m1.channels() << ") evaluates to " << printMatVal(m2, maxLoc) << ", \""
-                                      << eps_expr << "\" evaluates to " << eps;
+            std::stringstream msg;
+            msg << "The max difference between matrices \"" << expr1 << "\" and \"" << expr2
+                << "\" is " << maxVal << " at (" << maxLoc.y << ", " << maxLoc.x / m1.channels() << ")"
+                << ", which exceeds \"" << eps_expr << "\", where \""
+                << expr1 << "\" at (" << maxLoc.y << ", " << maxLoc.x / m1.channels() << ") evaluates to " << printMatVal(m1, maxLoc) << ", \""
+                << expr2 << "\" at (" << maxLoc.y << ", " << maxLoc.x / m1.channels() << ") evaluates to " << printMatVal(m2, maxLoc) << ", \""
+                << eps_expr << "\" evaluates to " << eps;
+            return AssertionFailure() << msg.str();
         }
 
         return AssertionSuccess();
@@ -469,9 +475,11 @@ namespace cvtest
     {
         if (gold.size() != actual.size())
         {
-            return testing::AssertionFailure() << "KeyPoints size mistmach\n"
-                                               << "\"" << gold_expr << "\" : " << gold.size() << "\n"
-                                               << "\"" << actual_expr << "\" : " << actual.size();
+            std::stringstream msg;
+            msg << "KeyPoints size mistmach\n"
+                << "\"" << gold_expr << "\" : " << gold.size() << "\n"
+                << "\"" << actual_expr << "\" : " << actual.size();
+            return AssertionFailure() << msg.str();
         }
 
         std::sort(actual.begin(), actual.end(), KeyPointLess());
@@ -484,14 +492,16 @@ namespace cvtest
 
             if (!keyPointsEquals(p1, p2))
             {
-                return testing::AssertionFailure() << "KeyPoints differ at " << i << "\n"
-                                                   << "\"" << gold_expr << "\" vs \"" << actual_expr << "\" : \n"
-                                                   << "pt : " << testing::PrintToString(p1.pt) << " vs " << testing::PrintToString(p2.pt) << "\n"
-                                                   << "size : " << p1.size << " vs " << p2.size << "\n"
-                                                   << "angle : " << p1.angle << " vs " << p2.angle << "\n"
-                                                   << "response : " << p1.response << " vs " << p2.response << "\n"
-                                                   << "octave : " << p1.octave << " vs " << p2.octave << "\n"
-                                                   << "class_id : " << p1.class_id << " vs " << p2.class_id;
+                std::stringstream msg;
+                msg << "KeyPoints differ at " << i << "\n"
+                    << "\"" << gold_expr << "\" vs \"" << actual_expr << "\" : \n"
+                    << "pt : " << testing::PrintToString(p1.pt) << " vs " << testing::PrintToString(p2.pt) << "\n"
+                    << "size : " << p1.size << " vs " << p2.size << "\n"
+                    << "angle : " << p1.angle << " vs " << p2.angle << "\n"
+                    << "response : " << p1.response << " vs " << p2.response << "\n"
+                    << "octave : " << p1.octave << " vs " << p2.octave << "\n"
+                    << "class_id : " << p1.class_id << " vs " << p2.class_id;
+                return AssertionFailure() << msg.str();
             }
         }