Address feedback

Author: MichaelRFairhurst

change_notes/2026-04-16-alias-parameter-side-effects-in-compond-assignment.md

@@ -0,0 +1,2 @@
+- All queries related to side effects:
+  - Compound assignments of pointer parameters (e.g. `p += 1`) are no longer treated as a modification of the pointed-to object. This was previously only handled for simple assignments (e.g. `p = ...`).

cpp/common/src/codingstandards/cpp/SideEffect.qll

@@ -295,7 +295,7 @@ class AliasParameter extends Parameter {
         this.getUnspecifiedType() instanceof ReferenceType
         or
         // Exclude effects that change the who we point to, since we care about changes to the referenced object.
-        not result.(AssignExpr).getLValue() = va and
+        not result.(Assignment).getLValue() = va and
         not result.(CrementOperation).getOperand() = va
       )
     )

cpp/misra/src/rules/RULE-10-1-1/PointerOrRefParamNotConst.ql

@@ -23,7 +23,7 @@ import codingstandards.cpp.Call
 import codingstandards.cpp.SideEffect
 
 /**
- * Holds if the function is in a template scope and should be excluded.
+ * Holds if `f` is a `Function` in a template scope and should be excluded.
  */
 predicate isInTemplateScope(Function f) {
   f.isFromTemplateInstantiation(_)
@@ -39,9 +39,7 @@ class PointerLikeParam extends Parameter {
 
   PointerLikeParam() {
     pointerLikeType = this.getType() and
-    not pointerLikeType.pointsToConst() and
-    // Exclude pointers to non-object types
-    not pointerLikeType.getInnerType() instanceof RoutineType
+    not pointerLikeType.pointsToConst()
   }
 
   /**
@@ -69,42 +67,6 @@ class PointerLikeParam extends Parameter {
   Expr getAPointerLikeAccess() { result = getAPointerLikeAccessOf(this.getAnAccess()) }
 }
 
-/**
- * A `VariableEffect` whose target variable is a `PointerLikeParam`.
- *
- * Examples of pointer-like effects on a pointer-like parameter `p` would include `p = ...`, `++p`,
- * `*p = ...`, and `++*p`, etc.
- */
-class PointerLikeEffect extends VariableEffect {
-  PointerLikeParam param;
-
-  PointerLikeEffect() { param = this.getTarget() }
-
-  /**
-   * Holds if this effect modifies the pointed-to or referred-to object.
-   *
-   * For example, `*p = 0` modifies the inner type if `p` is a pointer, and `p = 0` affects the
-   * inner type if `p` is a reference.
-   */
-  predicate affectsInnerType() {
-    if param.getPointerLikeType() instanceof ReferenceType
-    then affectsOuterType()
-    else not affectsOuterType()
-  }
-
-  /**
-   * Holds if this effect modifies the pointer or reference itself.
-   *
-   * For example, `p = ...` and `++p` modify the outer type, whether that type is a pointer or
-   * reference, while `*p = 0` does not modify the outer type.
-   */
-  predicate affectsOuterType() {
-    this.(Assignment).getLValue() = param.getAnAccess()
-    or
-    this.(CrementOperation).getOperand() = param.getAnAccess()
-  }
-}
-
 /**
  * A candidate parameter that could have its target type const-qualified.
  */
@@ -119,8 +81,8 @@ class NonConstParam extends PointerLikeParam {
     not exists(AsmStmt a | a.getEnclosingFunction() = this.getFunction()) and
     // Must have a pointer, array, or lvalue reference type with non-const target
     // Exclude pointers to non-object types
-    not pointerLikeType.getInnerType() instanceof RoutineType and
-    not pointerLikeType.getInnerType() instanceof VoidType and
+    not pointerLikeType.getInnerType+().getUnderlyingType() instanceof RoutineType and
+    not pointerLikeType.getInnerType+().getUnderlyingType() instanceof VoidType and
     // Exclude virtual functions
     not this.getFunction().isVirtual() and
     // Exclude functions in template scope
@@ -130,10 +92,7 @@ class NonConstParam extends PointerLikeParam {
     // Exclude deleted functions
     not this.getFunction().isDeleted() and
     // Exclude any parameter whose underlying data is modified
-    not exists(PointerLikeEffect effect |
-      effect.getTarget() = this and
-      effect.affectsInnerType()
-    ) and
+    not exists(AliasParameter alias | alias = this | alias.isModified()) and
     // Exclude parameters passed as arguments to non-const pointer/ref params
     not exists(CallArgumentExpr arg |
       arg = this.getAPointerLikeAccess() and

cpp/misra/test/rules/RULE-10-1-1/test.cpp

@@ -233,4 +233,12 @@ template <typename T> struct A {
   }
 };
 
-template <typename T> void f11(T &l1) {} // COMPLIANT - function template
+template <typename T> void f11(T &l1) {} // COMPLIANT - function template
+
+using func = int(int);
+void f12(void **p1,       // COMPLIANT
+         void *const *p2, // COMPLIANT
+         func *p3,        // COMPLIANT
+         func **p4,       // COMPLIANT
+         func *const *p5  // COMPLIANT
+) {}