V829. Lifetime of the heap-allocated variable is limited to the current function's scope. Consider allocating it on the stack instead.

This diagnostic rule is based on the R.5 CppCoreGuidelines rule (Prefer scoped objects, don't heap-allocate unnecessarily).

Storage for a local variable is allocated dynamically and deallocated before execution leaves the function. In this case, it is better to stack-allocate the variable to avoid the overhead due to memory allocation and deallocation.

Consider the following example:

class Object { .... };
void DoSomething()
{
  auto obj = new Object;
  ....
  delete obj;
}

Since the variable exists only within the current scope, allocation can be avoided in most cases.

Fixed version:

void DoSomething()
{
  Object obj;
  ....
}

The warning is not issued if the previously allocated storage is not deallocated or if the address leaks outside. The following snippet demonstrates returning a pointer using a function's output parameter:

void DoSomething(Object** ppObj)
{
  auto obj = new Object;
  if (obj->good())
  {
    *ppObj = obj;
    return;
  }
  delete obj;
}