Fix issue with detecting ternary expressions.

Author: lcartey

c/misra/src/rules/RULE-11-9/MacroNullNotUsedAsIntegerNullPointerConstant.ql

@@ -34,9 +34,9 @@ where
     // ?: operator
     exists(ConditionalExpr parent |
       (
-        parent.getThen().getAChild*() = zero and parent.getElse().getType() instanceof PointerType
+        parent.getThen() = zero and parent.getElse().getType() instanceof PointerType
         or
-        parent.getElse().getAChild*() = zero and parent.getThen().getType() instanceof PointerType
+        parent.getElse() = zero and parent.getThen().getType() instanceof PointerType
       ) and
       // exclude a common conditional pattern used in macros such as 'assert'
       not parent.isInMacroExpansion() and

c/misra/test/rules/RULE-11-9/MacroNullNotUsedAsIntegerNullPointerConstant.expected

@@ -2,3 +2,4 @@
 | test.c:17:8:17:8 | 0 | $@ uses zero-value integer constant expression as null pointer constant. | test.c:17:3:17:8 | ... = ... | Assignment to pointer |
 | test.c:23:13:23:13 | 0 | $@ uses zero-value integer constant expression as null pointer constant. | test.c:23:3:23:13 | ... ? ... : ... | Ternary operator |
 | test.c:24:8:24:8 | 0 | $@ uses zero-value integer constant expression as null pointer constant. | test.c:24:3:24:13 | ... ? ... : ... | Ternary operator |
+| test.c:31:14:31:14 | 0 | $@ uses zero-value integer constant expression as null pointer constant. | test.c:31:9:31:14 | ... = ... | Assignment to pointer |

c/misra/test/rules/RULE-11-9/test.c

@@ -26,5 +26,9 @@ void *f1(void *p1, int p2) {
   p2 ? p1 : (void*) 0;     // COMPLIANT
   p2 ? p2 : 0;     // COMPLIANT - p2 is not a pointer type
   p2 ? 0 : p2;     // COMPLIANT - p2 is not a pointer type
+  int x;
+  int *y;
+  p2 ? (p1 = 0) : p1;     // NON_COMPLIANT - p1 is a pointer type
+  p2 ? (p2 = 0) : p1;     // COMPLIANT - p2 is not a pointer type
   return 0;                             // COMPLIANT
 }

change_notes/2023-07-28-rule-11-4-improvements.md

@@ -7,4 +7,6 @@
  - `RULE-11-5` - `ConversionFromPointerToVoidIntoPointerToObject.ql`:
     - Fixed issue #331 - consider `0` a null pointer constant.
  - `RULE-11-6` - `CastBetweenPointerToVoidAndArithmeticType.ql`:
-    - Fixed issue #331 - accept integer constant expressions with value `0` instead of null pointer constants.
+    - Fixed issue #331 - accept integer constant expressions with value `0` instead of null pointer constants.
+ - `RULE-11-9` - `MacroNullNotUsedAsIntegerNullPointerConstant.ql`:
+    - Remove false positives in branches of ternary expressions, where `0` was used correctly.