C++: Give OperatorNewAllocationFunction, OperatorDeleteAllocationFunction proper interfaces.

cpp/ql/src/Critical/NewDelete.qll

@@ -5,8 +5,6 @@
 import cpp
 import semmle.code.cpp.controlflow.SSA
 import semmle.code.cpp.dataflow.DataFlow
-import semmle.code.cpp.models.implementations.Allocation
-import semmle.code.cpp.models.implementations.Deallocation
 
 /**
  * Holds if `alloc` is a use of `malloc` or `new`.  `kind` is

cpp/ql/src/semmle/code/cpp/exprs/Expr.qll

@@ -6,7 +6,6 @@ import semmle.code.cpp.Element
 private import semmle.code.cpp.Enclosing
 private import semmle.code.cpp.internal.ResolveClass
 private import semmle.code.cpp.internal.AddressConstantExpression
-private import semmle.code.cpp.models.implementations.Allocation
 
 /**
  * A C/C++ expression.

cpp/ql/src/semmle/code/cpp/models/implementations/Allocation.qll

@@ -237,12 +237,10 @@ private class SizelessAllocationFunction extends AllocationFunction {
 }
 
 /**
- * An `operator new` or `operator new[]` function that may be associated with `new` or
+ * Implements `OperatorNewAllocationFunction`.
- * `new[]` expressions.  Note that `new` and `new[]` are not function calls, but these
- * functions may also be called directly.
  */
-class OperatorNewAllocationFunction extends AllocationFunction {
+private class OperatorNewAllocationFunctionImpl extends OperatorNewAllocationFunction {
-  OperatorNewAllocationFunction() {
+  OperatorNewAllocationFunctionImpl() {
     exists(string name |
       hasGlobalName(name) and
       (
@@ -259,11 +257,7 @@ class OperatorNewAllocationFunction extends AllocationFunction {
 
   override predicate requiresDealloc() { not exists(getPlacementArgument()) }
 
-  /**
+  override int getPlacementArgument() {
-   * Gets the position of the placement pointer if this is a placement
-   * `operator new` function.
-   */
-  int getPlacementArgument() {
     getNumberOfParameters() = 2 and
     getParameter(1).getType() instanceof VoidPointerType and
     result = 1

cpp/ql/src/semmle/code/cpp/models/implementations/Deallocation.qll

@@ -90,12 +90,10 @@ private class StandardDeallocationFunction extends DeallocationFunction {
 }
 
 /**
- * An `operator delete` or `operator delete[]` function that may be associated
+ * Implements `OperatorDeleteDeallocationFunction`.
- * with `delete` or `delete[]` expressions.  Note that `delete` and `delete[]`
- * are not function calls, but these functions may also be called directly.
  */
-class OperatorDeleteDeallocationFunction extends DeallocationFunction {
+private class OperatorDeleteDeallocationFunctionImpl extends OperatorDeleteDeallocationFunction {
-  OperatorDeleteDeallocationFunction() {
+  OperatorDeleteDeallocationFunctionImpl() {
     exists(string name |
       hasGlobalName(name) and
       (

cpp/ql/src/semmle/code/cpp/models/interfaces/Allocation.qll

@@ -85,3 +85,16 @@ abstract class AllocationExpr extends Expr {
    */
   predicate requiresDealloc() { any() }
 }
+
+/**
+ * An `operator new` or `operator new[]` function that may be associated with
+ * `new` or `new[]` expressions.  Note that `new` and `new[]` are not function
+ * calls, but these functions may also be called directly.
+ */
+abstract class OperatorNewAllocationFunction extends AllocationFunction {
+  /**
+   * Gets the position of the placement pointer if this is a placement
+   * `operator new` function.
+   */
+  int getPlacementArgument() { none()}
+}

cpp/ql/src/semmle/code/cpp/models/interfaces/Deallocation.qll

@@ -30,3 +30,11 @@ abstract class DeallocationExpr extends Expr {
    */
   Expr getFreedExpr() { none() }
 }
+
+/**
+ * An `operator delete` or `operator delete[]` function that may be associated
+ * with `delete` or `delete[]` expressions.  Note that `delete` and `delete[]`
+ * are not function calls, but these functions may also be called directly.
+ */
+abstract class OperatorDeleteDeallocationFunction extends DeallocationFunction {
+}