M5-14-1: exclusion unevaluated contexts

change_notes/2024-02-26-exclusion-M5-14-1.md

@@ -0,0 +1,2 @@
+- `M5-14-1` - `RightHandOperandOfALogicalAndOperatorsContainSideEffects.ql`:
+    - Fix FP reported in #375. Addresses incorrect detection of side effects in unevaluated contexts.

cpp/autosar/src/rules/M5-14-1/RightHandOperandOfALogicalAndOperatorsContainSideEffects.ql

@@ -18,11 +18,13 @@ import cpp
 import codingstandards.cpp.autosar
 import codingstandards.cpp.SideEffect
 import codingstandards.cpp.sideeffect.DefaultEffects
+import codingstandards.cpp.Expr
 
 from BinaryLogicalOperation op, Expr rhs
 where
   not isExcluded(op,
     SideEffects1Package::rightHandOperandOfALogicalAndOperatorsContainSideEffectsQuery()) and
   rhs = op.getRightOperand() and
-  hasSideEffect(rhs)
+  hasSideEffect(rhs) and
+  not rhs instanceof UnevaluatedExprExtension
 select op, "The $@ may have a side effect that is not always evaluated.", rhs, "right-hand operand"

cpp/autosar/test/rules/M5-14-1/RightHandOperandOfALogicalAndOperatorsContainSideEffects.expected

@@ -1,3 +1,4 @@
 | test.cpp:15:7:15:14 | ... \|\| ... | The $@ may have a side effect that is not always evaluated. | test.cpp:15:12:15:14 | ... ++ | right-hand operand |
 | test.cpp:18:7:18:21 | ... \|\| ... | The $@ may have a side effect that is not always evaluated. | test.cpp:18:13:18:20 | ... == ... | right-hand operand |
 | test.cpp:21:7:21:15 | ... \|\| ... | The $@ may have a side effect that is not always evaluated. | test.cpp:21:12:21:13 | call to f1 | right-hand operand |
+| test.cpp:40:7:40:41 | ... \|\| ... | The $@ may have a side effect that is not always evaluated. | test.cpp:40:26:40:26 | call to operator== | right-hand operand |

cpp/autosar/test/rules/M5-14-1/test.cpp

@@ -23,4 +23,20 @@ void f3(bool b) {
 
   if (b || f2()) { // COMPLIANT, f2 has local side-effects
   }
+}
+
+int g1 = 0;
+int f4() { return g1++; }
+int f5() { return 1; }
+
+#include <typeinfo>
+
+void f6() {
+  if (1 && sizeof(f4())) {
+  } // COMPLIANT  - sizeof operands not evaluated
+  if (1 &&noexcept(f4()) &&noexcept(f4())) {
+  } // COMPLIANT  - noexcept operands not evaluated
+
+  if (1 || (typeid(f5()) == typeid(f4()))) {
+  } // NON_COMPLIANT  - typeid operands not evaluated, but the ==operator is
 }

cpp/common/src/codingstandards/cpp/Expr.qll

@@ -189,3 +189,17 @@ module MisraExpr {
     CValue() { isCValue(this) }
   }
 }
+
+/**
+ * an operator that does not evaluate its operand
+ */
+class UnevaluatedExprExtension extends Expr {
+  UnevaluatedExprExtension() {
+    this.getAChild().isUnevaluated()
+    or
+    exists(FunctionCall declval |
+      declval.getTarget().hasQualifiedName("std", "declval") and
+      declval.getAChild() = this
+    )
+  }
+}

cpp/common/test/includes/standard-library/typeinfo.h

@@ -4,5 +4,6 @@ namespace std {
 struct type_info {
   const char *name() const noexcept;
   std::size_t hash_code() const noexcept;
+  bool operator==(const type_info &rhs) const;
 };
 } // namespace std