C++: Tests for PointlessComparison shortcomings

Author: jbj

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

@@ -285,3 +285,33 @@ int widening_cast2(u8 c) {
   else
     return 1;
 }
+
+int unsigned_implicit_conversion(unsigned int ui1) {
+  // These two comparisons are supported by the range analysis because the
+  // implicit signedness conversion is on the constants (0 and 5), not on the
+  // variables (ui1).
+  if (ui1 == 0) {
+    if (ui1 >= 5) { // BAD
+      return 1;
+    }
+  }
+  return 0;
+}
+
+int signedness_cast1(u8 c) {
+  if ((signed char)c == 0) {
+    if (c >= 5) { // BAD [NOT DETECTED]
+      return 1;
+    }
+  }
+  return 0;
+}
+
+int signedness_cast2(signed char c) {
+  if ((u8)c == 0) {
+    if (c >= 5) { // BAD [NOT DETECTED]
+      return 1;
+    }
+  }
+  return 0;
+}

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

@@ -35,5 +35,6 @@
 | PointlessComparison.c:264:12:264:22 | ... >= ... | Comparison is always true because dbl >= 0 and -0 >= - .... |
 | PointlessComparison.c:273:9:273:18 | ... > ... | Comparison is always false because c <= 0. |
 | PointlessComparison.c:283:13:283:19 | ... >= ... | Comparison is always true because c >= 11. |
+| PointlessComparison.c:294:9:294:16 | ... >= ... | Comparison is always false because ui1 <= 0. |
 | RegressionTests.cpp:57:7:57:22 | ... <= ... | Comparison is always true because * ... <= 4294967295. |
 | Templates.cpp:9:10:9:24 | ... <= ... | Comparison is always true because local <= 32767. |