M5-0-20: Exclude pointer assign from bitwise assign

This query was erroneously reporting pointer assign as a bitwise assign
operator.

Author: lcartey

change_notes/2023-10-04-m5-0-20-exclude-pointer-bitwise.md

@@ -0,0 +1 @@
+ * `M5-0-20` - exclude pointer assignment operators as bitwise operators.

cpp/autosar/src/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.ql

@@ -22,7 +22,16 @@ predicate isBinaryBitwiseOperation(Operation o, VariableAccess l, VariableAccess
     l = bbo.getLeftOperand() and r = bbo.getRightOperand()
   )
   or
-  exists(AssignBitwiseOperation abo | abo = o | l = abo.getLValue() and r = abo.getRValue())
+  exists(AssignBitwiseOperation abo |
+    abo = o and
+    // exclude += and -= on pointers, which seem to be erroneously included
+    // in the database schema
+    not abo instanceof AssignPointerAddExpr and
+    not abo instanceof AssignPointerSubExpr
+  |
+    l = abo.getLValue() and
+    r = abo.getRValue()
+  )
 }
 
 from Operation o, Variable left, Variable right

cpp/autosar/test/rules/M5-0-20/test.cpp

@@ -71,3 +71,8 @@ void test463_2_instantiations() {
   char shift2 = 2;
   test463_2(val, shift2);
 }
+
+void test_add(char *val) {
+  int add = 2;
+  val += add; // COMPLIANT
+}