[RF] additional RooNaNPacker tests

roofit/roofitcore/test/testNaNPacker.cxx

@@ -138,6 +138,59 @@ TEST(RooNaNPacker, PackedNaNPreservedAfterArithmetic)
    EXPECT_TRUE(rnp2.isNaNWithPayload());
    // nothing can harm the PackedNaN
    EXPECT_EQ(rnp.getPayload(), rnp2.getPayload());
+
+   // multiply packed NaN by 0
+   rnp2._payload = 0. * rnp.getNaNWithPayload();
+   EXPECT_TRUE(rnp2.isNaNWithPayload());
+   // PackedNaN pays no mind
+   EXPECT_EQ(rnp.getPayload(), rnp2.getPayload());
+
+   // the following tests have compiler dependent behavior
+   // (note that this behavior was tested for msvc as well, even though this
+   // whole test is currently disabled in msvc)
+#if defined(__clang__) || defined(_MSC_VER)
+   // add packed NaN to regular NaN
+   rnp2._payload = std::numeric_limits<double>::quiet_NaN() + rnp.getNaNWithPayload();
+   // first NaN wins, though! now the payload is gone
+   EXPECT_FALSE(rnp2.isNaNWithPayload());
+   // a quiet NaN has a "payload" of zero
+   EXPECT_EQ(0, rnp2.getPayload());
+
+   // ... other way around
+   rnp2._payload = rnp.getNaNWithPayload() + std::numeric_limits<double>::quiet_NaN();
+   EXPECT_TRUE(rnp2.isNaNWithPayload());
+   // if it comes first, the PackedNaN does survive
+   EXPECT_EQ(rnp.getPayload(), rnp2.getPayload());
+
+   // multiply regular NaN with packed NaN
+   rnp2._payload = rnp.getNaNWithPayload() * std::numeric_limits<double>::quiet_NaN();
+   EXPECT_TRUE(rnp2.isNaNWithPayload());
+   // if it comes first, the PackedNaN does survive
+   EXPECT_EQ(rnp.getPayload(), rnp2.getPayload());
+
+   // ... other way around
+   rnp2._payload = std::numeric_limits<double>::quiet_NaN() * rnp.getNaNWithPayload();
+   // same as with addition: the first NaN wins
+   EXPECT_FALSE(rnp2.isNaNWithPayload());
+   // a quiet NaN has a "payload" of zero
+   EXPECT_EQ(0, rnp2.getPayload());
+#endif // defined(__clang__) || defined(_MSC_VER)
+#if defined(__GNUC__) && !defined(__clang__)
+   // on gcc, a different NaN is preserved than in clang and msvc!
+
+   // add packed NaN to regular NaN
+   rnp2._payload = rnp.getNaNWithPayload() + std::numeric_limits<double>::quiet_NaN();
+   // on gcc, the second NaN wins! now the payload is gone
+   EXPECT_FALSE(rnp2.isNaNWithPayload());
+   // a quiet NaN has a "payload" of zero
+   EXPECT_EQ(0, rnp2.getPayload());
+
+   // ... other way around
+   rnp2._payload = std::numeric_limits<double>::quiet_NaN() + rnp.getNaNWithPayload();
+   EXPECT_TRUE(rnp2.isNaNWithPayload());
+   // if it comes second, the PackedNaN does survive
+   EXPECT_EQ(rnp.getPayload(), rnp2.getPayload());
+#endif // __GNUC__
 }
 
 #endif // !defined(_MSC_VER) || defined(R__ENABLE_BROKEN_WIN_TESTS)