Combining many actions in a single C++ expression is a bad practice, as such code is hard to understand, maintain, and it is easy to make mistakes in it. For example, one can instill a bug by reconciling different actions when evaluating function arguments. We agree with the classic recommendation that code should be simple and clear. Now let's look at an interesting case where the PVS-Studio analyzer is technically wrong, but from a practical point of view, the code should still be changed.
by Andrey Karpov
From the article:
As you can see, once upon a time std::make_pair was taking arguments by value. If std::unique_ptr had existed at that time, then the code above would have been indeed incorrect. Whether this code would work or not would be a matter of luck. In practice, of course, this situation would never have occurred, since std::unique_ptr appeared in C++11 as a replacement for std::auto_ptr. Let's go back to our time. Starting with C++11, the constructor started to use move semantics.