Fix false positives in RULE-8-2-6 for implicit conversions

change_notes/2026-10-27-fix-fp-rule-8-2-6-implicit-casts.md

@@ -0,0 +1,2 @@
+- `RULE-8-2-6` - `IntToPointerCastProhibited.ql`:
+  - Remove false positives for implicit conversions, such as the implicit `this` in unevaluated operands (e.g. `sizeof(member)`).

cpp/misra/src/rules/RULE-8-2-6/IntToPointerCastProhibited.ql

@@ -20,6 +20,9 @@ import codingstandards.cpp.misra
 from Cast cast, Type sourceType, PointerType targetType, string typeKind
 where
   not isExcluded(cast, Conversions2Package::intToPointerCastProhibitedQuery()) and
+  // Implicit conversions are not casts, e.g. null pointer constants or the implicit `this` in an
+  // unevaluated operand.
+  not cast.isImplicit() and
   sourceType = cast.getExpr().getType().getUnspecifiedType() and
   targetType = cast.getType().getUnspecifiedType() and
   (

cpp/misra/test/rules/RULE-8-2-6/IntToPointerCastProhibited.expected

@@ -9,3 +9,4 @@
 | test.cpp:35:22:35:57 | reinterpret_cast<int32_t *>... | Cast from pointer to void type 'void *' to pointer type 'int32_t *'. |
 | test.cpp:43:14:43:41 | reinterpret_cast<void *>... | Cast from integral type 'int32_t' to pointer type 'void *'. |
 | test.cpp:44:14:44:41 | reinterpret_cast<void *>... | Cast from integral type 'int64_t' to pointer type 'void *'. |
+| test.cpp:100:12:100:58 | reinterpret_cast<TestStruct *>... | Cast from integral type 'unsigned long' to pointer type 'TestStruct *'. |

cpp/misra/test/rules/RULE-8-2-6/test.cpp

@@ -87,4 +87,16 @@ void test_compliant_regular_pointer_operations() {
   // Regular pointer operations that don't involve forbidden casts
   TestStruct *l4 = l2;   // COMPLIANT
   std::int32_t *l5 = l3; // COMPLIANT
-}
+}
+// The implicit `this` of a member access in an unevaluated operand is
+// extracted as a conversion of 0 to a pointer. It is not a cast.
+struct ImplicitThis {
+  std::int32_t m1;
+  static constexpr unsigned long size() noexcept {
+    return sizeof(m1); // COMPLIANT
+  }
+  TestStruct *nonCompliant(std::int64_t l1) {
+    // The implicit `this` of m1 is compliant, the explicit cast is not
+    return reinterpret_cast<TestStruct *>(l1 + sizeof(m1)); // NON_COMPLIANT
+  }
+};