C++: Test for overriding existing simple range analysis ranges.

Author: lcartey

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.c

@@ -7,3 +7,8 @@ int test_extensibility_add(int x) {
     return result; // 90 .. 110
   }
 }
+
+int test_overridability_sub(int x) {
+  int result = x - x; // Returns 0 due to custom modeling in QL
+  return result; // 0
+}

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.expected

@@ -2,3 +2,6 @@
 | extensibility.c:5:19:5:19 | x | -10.0 | 2.147483647E9 |
 | extensibility.c:6:38:6:38 | x | -10.0 | 10.0 |
 | extensibility.c:7:12:7:17 | result | 90.0 | 110.0 |
+| extensibility.c:12:16:12:16 | x | -2.147483648E9 | 2.147483647E9 |
+| extensibility.c:12:20:12:20 | x | -2.147483648E9 | 2.147483647E9 |
+| extensibility.c:13:10:13:15 | result | 0.0 | 0.0 |

cpp/ql/test/experimental/library-tests/rangeanalysis/extensibility/extensibility.ql

@@ -25,6 +25,18 @@ class CustomAddFunctionCall extends SimpleRangeAnalysisExpr, FunctionCall {
   override predicate dependsOnChild(Expr child) { child = this.getAnArgument() }
 }
 
+class SelfSub extends SimpleRangeAnalysisExpr, SubExpr {
+  SelfSub() {
+    getLeftOperand().(VariableAccess).getTarget() = getRightOperand().(VariableAccess).getTarget()
+  }
+
+  override float getLowerBounds() { result = 0 }
+
+  override float getUpperBounds() { result = 0 }
+
+  override predicate dependsOnChild(Expr child) { child = this.getAnOperand() }
+}
+
 from VariableAccess expr, float lower, float upper
 where
   lower = lowerBound(expr) and