Merge pull request #16403 from geoffw0/qhelp1

C++: Improve qhelp for IncorrectNotOperatorUsage.

Author: geoffw0

cpp/ql/src/Likely Bugs/Likely Typos/IncorrectNotOperatorUsage.cpp

@@ -2,19 +2,18 @@
 
 void f_warning(int i)
 {
-    // The usage of the logical not operator in this case is unlikely to be correct
+    // BAD: the usage of the logical not operator in this case is unlikely to be correct
     // as the output is being used as an operator for a bit-wise and operation
-    if (i & !FLAGS) 
+    if (i & !FLAGS)
     {
         // code
     }
 }
 
-
 void f_fixed(int i)
 {
-    if (i & ~FLAGS) // Changing the logical not operator for the bit-wise not operator would fix this logic
+    if (i & ~FLAGS) // GOOD: Changing the logical not operator for the bit-wise not operator would fix this logic
     {
         // code
     }
-}
+}

cpp/ql/src/Likely Bugs/Likely Typos/IncorrectNotOperatorUsage.qhelp

@@ -16,7 +16,13 @@
 <p>Carefully inspect the flagged expressions. Consider the intent in the code logic, and decide whether it is necessary to change the not operator.</p>
 </recommendation>
 
-<example><sample src="IncorrectNotOperatorUsage.cpp" /></example>
+<example>
+<p>Here is an example of this issue and how it can be fixed:</p>
+
+<sample src="IncorrectNotOperatorUsage.cpp" />
+
+<p>In other cases, particularly when the expressions have <code>bool</code> type, the fix may instead be of the form <code>a &amp;&amp; !b</code>.</p>
+</example>
 
 <references>
   <li>

cpp/ql/test/query-tests/Likely Bugs/Likely Typos/IncorrectNotOperatorUsage/IncorrectNotOperatorUsage.cpp

@@ -3,7 +3,7 @@
 
 void C6317_positive(int i)
 {
-    if (i & !FLAGS) // BUG 
+    if (i & !FLAGS) // BUG
     {
     }
 }
@@ -71,3 +71,22 @@ void macroUsage(unsigned int arg1, unsigned int arg2)
 
     }
 }
+
+void bool_examples(bool a, bool b)
+{
+    if (a & !b) // dubious (confusing intent, but shouldn't produce a wrong result)
+    {
+    }
+
+    if (a & ~b)
+    {
+    }
+
+    if (a && ~b)
+    {
+    }
+
+    if (a && !b)
+    {
+    }
+}

cpp/ql/test/query-tests/Likely Bugs/Likely Typos/IncorrectNotOperatorUsage/IncorrectNotOperatorUsage.expected

@@ -14,3 +14,4 @@
 | IncorrectNotOperatorUsage.cpp:48:9:48:18 | ... \| ... | Usage of a logical not (!) expression as a bitwise operator. |
 | IncorrectNotOperatorUsage.cpp:49:9:49:20 | ... \| ... | Usage of a logical not (!) expression as a bitwise operator. |
 | IncorrectNotOperatorUsage.cpp:70:10:70:34 | ... \| ... | Usage of a logical not (!) expression as a bitwise operator. |
+| IncorrectNotOperatorUsage.cpp:77:9:77:14 | ... & ... | Usage of a logical not (!) expression as a bitwise operator. |