Merge pull request #489 from github/lcartey/m5-2-10-arith-only

M5-2-10: Only report the use of `++`/`--` with arithmetic operations

Author: lcartey

change_notes/2024-01-16-m5-2-10-arith-only.md

@@ -0,0 +1,2 @@
+ `M5-2-10` - `IncrementAndDecrementOperatorsMixedWithOtherOperatorsInExpression.ql`:
+   - only report use of the increment and decrement operations in conjunction with arithmetic operators, as specified by the rule. Notably we no longer report the expressions of the form `*p++`, which combine increment and dereferencing operations.

cpp/autosar/src/rules/M5-2-10/IncrementAndDecrementOperatorsMixedWithOtherOperatorsInExpression.ql

@@ -16,8 +16,9 @@
 
 import cpp
 import codingstandards.cpp.autosar
+import codingstandards.cpp.Expr
 
-from CrementOperation cop, Operation op, string name
+from CrementOperation cop, ArithmeticOperation op, string name
 where
   not isExcluded(cop) and
   not isExcluded(op,

cpp/autosar/test/rules/M5-2-10/test.cpp

@@ -6,4 +6,6 @@ void f1() {
   ++l1;             // COMPLIANT
   --l2;             // COMPLIANT
   l3 = l1 * l2;
+  int *p;
+  *p++; // COMPLIANT - * is not an arithmetic operator
 }

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

@@ -2,6 +2,15 @@ import cpp
 private import semmle.code.cpp.valuenumbering.GlobalValueNumbering
 import codingstandards.cpp.AccessPath
 
+/**
+ * A unary or binary arithmetic operation.
+ */
+class ArithmeticOperation extends Operation {
+  ArithmeticOperation() {
+    this instanceof UnaryArithmeticOperation or this instanceof BinaryArithmeticOperation
+  }
+}
+
 /** A full expression as defined in [intro.execution] of N3797. */
 class FullExpr extends Expr {
   FullExpr() {