Warning C26409

Avoid calling new and delete explicitly, use std::make_unique<T> instead (r.11).

Even if code is clean of calls to malloc and free, we still suggest that you consider better options than explicit use of operators new and delete.

C++ Core Guidelines:
R.11: Avoid calling new and delete explicitly

The ultimate fix is to use smart pointers and appropriate factory functions, such as std::make_unique.


  • The checker warns on calls to any kind of operator new or delete: scalar, vector, overloaded versions (global and class-specific), and placement versions. The placement new case may require some clarifications in the Core Guidelines for suggested fixes, and may be omitted in the future.

Code analysis name: NO_NEW_DELETE


This example shows C26409 is raised for explicit new and delete. Consider using smart pointer factory functions such as std::make_unique instead.

void f(int i)
    int* arr = new int[i]{}; // C26409, warning is issued for all new calls
    delete[] arr;            // C26409, warning is issued for all delete calls

    auto unique = std::make_unique<int[]>(i); // prefer using smart pointers over new and delete

There's a C++ idiom that triggers this warning: delete this. The warning is intentional, because the C++ Core Guidelines discourage this pattern. You can suppress the warning by using the gsl::suppress attribute, as shown in this example:

class MyReferenceCountingObject final
    void AddRef();
    void Release() noexcept
        if (ref_count_ == 0)
            delete this; 
    unsigned int ref_count_{1};