C#: Update ConstantCondition.ql

Author: hvitved

csharp/ql/src/Bad Practices/Control-Flow/ConstantCondition.ql

@@ -35,7 +35,23 @@ class ConstantBooleanCondition extends ConstantCondition {
 
   override predicate isWhiteListed() {
     // E.g. `x ?? false`
-    this.(BoolLiteral) = any(NullCoalescingExpr nce).getRightOperand()
+    this.(BoolLiteral) = any(NullCoalescingExpr nce).getRightOperand() or
+    // No need to flag logical operations when the operands are constant
+    isConstantCondition(this.(LogicalNotExpr).getOperand(), _) or
+    this =
+      any(LogicalAndExpr lae |
+        isConstantCondition(lae.getAnOperand(), false)
+        or
+        isConstantCondition(lae.getLeftOperand(), true) and
+        isConstantCondition(lae.getRightOperand(), true)
+      ) or
+    this =
+      any(LogicalOrExpr loe |
+        isConstantCondition(loe.getAnOperand(), true)
+        or
+        isConstantCondition(loe.getLeftOperand(), false) and
+        isConstantCondition(loe.getRightOperand(), false)
+      )
   }
 }
 
@@ -51,7 +67,8 @@ class ConstantIfCondition extends ConstantBooleanCondition {
     or
     // It is a common pattern to use a local constant/constant field to control
     // whether code parts must be executed or not
-    this instanceof AssignableRead
+    this instanceof AssignableRead and
+    not this instanceof ParameterRead
   }
 }
 

csharp/ql/test/query-tests/Bad Practices/Control-Flow/ConstantCondition/ConstantCondition.cs

@@ -106,6 +106,15 @@ string M5(object o)
             _ => o.ToString() // GOOD
         };
     }
+
+    void M6(bool b1, bool b2) {
+        if (!b1)
+            return;
+        if (!b2)
+            return;
+        if (b1 && b2) // BAD
+            return;
+    }
 }
 
 class Assertions

csharp/ql/test/query-tests/Bad Practices/Control-Flow/ConstantCondition/ConstantCondition.expected

@@ -8,6 +8,8 @@
 | ConstantCondition.cs:66:18:66:18 | 3 | Pattern always matches. |
 | ConstantCondition.cs:77:18:77:20 | access to type Int32 | Pattern never matches. |
 | ConstantCondition.cs:97:13:97:13 | _ | Pattern always matches. |
+| ConstantCondition.cs:115:13:115:14 | access to parameter b1 | Condition always evaluates to 'true'. |
+| ConstantCondition.cs:115:19:115:20 | access to parameter b2 | Condition always evaluates to 'true'. |
 | ConstantConditionBad.cs:5:16:5:20 | ... > ... | Condition always evaluates to 'false'. |
 | ConstantConditionalExpressionCondition.cs:11:22:11:34 | ... == ... | Condition always evaluates to 'true'. |
 | ConstantConditionalExpressionCondition.cs:12:21:12:25 | false | Condition always evaluates to 'false'. |