C++: Tests for -0.0 in range analysis

Author: jbj

cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/PointlessComparison.expected

@@ -50,4 +50,7 @@
 | PointlessComparison.cpp:43:6:43:29 | ... >= ... | Comparison is always true because ... >> ... >= 140737488355327.5. |
 | PointlessComparison.cpp:44:6:44:28 | ... >= ... | Comparison is always true because ... >> ... >= 140737488355327.5. |
 | RegressionTests.cpp:57:7:57:22 | ... <= ... | Comparison is always true because * ... <= 4294967295. |
+| RegressionTests.cpp:89:7:89:14 | ... == ... | Comparison is always false because val <= -0. |
+| RegressionTests.cpp:107:7:107:14 | ... == ... | Comparison is always false because val <= -0. |
+| RegressionTests.cpp:116:7:116:14 | ... == ... | Comparison is always false because val <= -0. |
 | Templates.cpp:9:10:9:24 | ... <= ... | Comparison is always true because local <= 32767. |

cpp/ql/test/query-tests/Likely Bugs/Arithmetic/PointlessComparison/RegressionTests.cpp

@@ -79,4 +79,40 @@ int containsIfDef(int x) {
 #endif
 
   return result >= 0;
-}
+}
+
+void negativeZero1(int val) {
+  if (val >= 0)
+  {
+    val = -val;
+  }
+  if (val == 0) // GOOD [FALSE POSITIVE]
+    ;
+}
+
+void negativeZero2(int val) {
+  if (val >= 0)
+  {
+    val = 0 - val;
+  }
+  if (val == 0) // GOOD
+    ;
+}
+
+void negativeZero3(int val) {
+  if (val >= 0)
+  {
+    val *= -1;
+  }
+  if (val == 0) // GOOD [FALSE POSITIVE]
+    ;
+}
+
+void negativeZero4(int val) {
+  if (val >= 0)
+  {
+    val = val * -1;
+  }
+  if (val == 0) // GOOD [FALSE POSITIVE]
+    ;
+}