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

@@ -19,10 +19,44 @@ import codingstandards.cpp.autosar
 import codingstandards.cpp.SideEffect
 import codingstandards.cpp.sideeffect.DefaultEffects
 
+/**
+ * an operator that does not evaluate its operand
+ * `decltype` also has a non evaluated operand but cannot be used in a `BinaryLogicalOperation`
+ */
+class UnevaluatedOperand extends Expr {
+  Expr operator;
+
+  UnevaluatedOperand() {
+    exists(SizeofExprOperator op | op.getExprOperand() = this |
+      not this.getUnderlyingType().(ArrayType).hasArraySize() and
+      operator = op
+    )
+    or
+    exists(NoExceptExpr e |
+      e.getExpr() = this and
+      operator = e
+    )
+    or
+    exists(TypeidOperator t |
+      t.getExpr() = this and
+      operator = t
+    )
+    or
+    exists(FunctionCall declval |
+      declval.getTarget().hasQualifiedName("std", "declval") and
+      declval.getAChild() = this and
+      operator = declval
+    )
+  }
+
+  Expr getOp() { result = operator }
+}
+
 from BinaryLogicalOperation op, Expr rhs
 where
   not isExcluded(op,
     SideEffects1Package::rightHandOperandOfALogicalAndOperatorsContainSideEffectsQuery()) and
   rhs = op.getRightOperand() and
-  hasSideEffect(rhs)
+  hasSideEffect(rhs) and
+  not exists(UnevaluatedOperand un | un.getOp() = rhs)
 select op, "The $@ may have a side effect that is not always evaluated.", rhs, "right-hand operand"

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

@@ -23,4 +23,14 @@ void f3(bool b) {
 
   if (b || f2()) { // COMPLIANT, f2 has local side-effects
   }
+}
+
+int g1 = 0;
+int f4() { return g1++; }
+int f5() { return 1; }
+
+void f6() {
+  if (noexcept(f5()) &&noexcept(
+          f4())) { // COMPLIANT  - noexcept operands not evaluated
+  }
 }