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[std-proposals] Float the idea | Safer smart pointers

From: Francesco Scappatura <scappaturafrancesco_at_[hidden]>
Date: Fri, 2 Dec 2022 18:59:05 +0100
Hello everyone,
I would like to collect feedback from you on this proposal.

*Motivation *
With C++ smart pointers there is a lot of space for unexperienced
programmer to run into double free and doing things that are semantically
Some examples:
-You can create a raw pointer and initialize two different unique_pointer.
(double free).
-You can create a raw pointer and initialize two different shared_pointer.
(double free + wrong count).
-You can bind a raw pointer to both a unique and a shared_pointer. (double
free and semantically incorrect).

These bad things of course will not happen if smart_ptr are used correctly,
but I were wondering if it's possible to totally remove this risk managing
smart pointer in a different way.

*Draft solution proposal*
Keep track of the usage of smart pointers in a single unique data-structure.
What if shared_ptr/unique_ptr/weak_ptr class are tracked using a set of
static variable of type map<address, count/bool> for tracking the status
of all the smart pointer of the program?

*Proof of concept*
In these situations, code explains better than words, so I have prepared a
draft repository with the examples I mentioned and how this different
internal implementation can help the programmer.
The repository, of course, also contains a very basic implementation of
smart_ptr using this different approach. There is a lot room for
improvement but I hope it's ok to show the intent.

*POC REPO (Each different couple of functions with the same name shows a
misuse of smart ptr and how a map-based implementation can fix it.)*

*Data structure POC*

This is just a POC but I think there is a lot of space for improvement to
capture further dangerous situation and make the usage of smart pointer
even more secure.
Of course there are also drawbacks, keeping the DS in memory for sure and
probably other thing that I don't see.
Hope it's clear!
Looking forward to receive your feedback and if this has been already
considered understand why this approach has not been used.

Received on 2022-12-02 17:59:17