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Isn't C++ with RAII reasonably safe? I tried to learn/like Rust but it's against how I use to think. If no friendlier safe high speed programming language appe

Isn't C++ with RAII reasonably safe? I tried to learn/like Rust but it's against how I use to think. If no friendlier safe high speed programming language appears, I rather use C/C++ and trade safety for friendliness.

zaphar 3y ago
If you have no users then go for it. However if you do then you are doing those users a disservice by exposing them to unnecessary risk. Maybe the risk is mitigated in other ways. Your software runs as a cli and not a service. It doesn't process outside input. It is run in an ironclad sandbox. But honestly, if you think the way C++ with RAII want's you to then you should already be following the rules that Rust want's you to follow for the most part.
- binary132 3y ago
  so what you’re saying is proper C++ is fine?
  - zaphar 3y ago
    What I'm saying is that if you are sufficiently smart then you could concievably write perfectly safe C++. But since almost no one in practice has ever been able to be sufficiently smart consistently enough to ship C or C++ code that doesn't have memory safety issues, I don't trust anyone to do so and would rather people stop writing stuff in them when there are better languages to use where I don't have to trust you as much.
    - binary132 3y ago
      Here’s what Stroustrup says: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2687r0.pdf https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p26...
woodruffw 3y ago
RAII is great (especially as a developer’s aid), but I don’t think it’s had a huge effect on memory unsafety: it’s still very easy to UAF in a RAII-only codebase, thanks to all of the flexibility C++ allows in constructors and destructors (and unintuitive behavior in moved-out-of objects). Rust is generally perceived as having many of the same developer kindnesses as C++, while having same-class performance. Learning it has a bit of a curve, but I found that it eventually clicked (I have a C and C++ professional background).
tobias12345 3y ago
RAII is great, but unfortunately it breaks down when the resource it manages leaks out of the RAII type. E.g. Whenever handing out the raw pointer stored in a unique_ptr, the code receiving that raw pointer can delete it, which will very likely lead to a use after free and certainly to a double free issue.
xdavidliu 3y ago
I was shocked to learn that reaching an end of a function without returning is actually UB and the compiler doesn't stop you; only warns. For example: ``` class Foo; Foo get_foo() { std::cout << "whoops, I forgot to return\n"; } int main() { const auto foo = get_foo(); } ```
- jjgreen 3y ago
  (HN weak markdown, indent 2 spaces for code-block)
  - xdavidliu 3y ago
    noted for next time, thanks
- ryao 3y ago
  Serious C/C++ projects build with -Wall -Werror. The compiler definitely stops you then.
trealira 3y ago
Modern C++ can still be unsafe. I recently wrote a comment about it here: https://news.ycombinator.com/item?id=38576681 https://news.ycombinator.com/item?id=38576681

zaphar 3y ago

If you have no users then go for it. However if you do then you are doing those users a disservice by exposing them to unnecessary risk. Maybe the risk is mitigated in other ways. Your software runs as a cli and not a service. It doesn't process outside input. It is run in an ironclad sandbox. But honestly, if you think the way C++ with RAII want's you to then you should already be following the rules that Rust want's you to follow for the most part.

binary132 3y ago
so what you’re saying is proper C++ is fine?
- zaphar 3y ago
  What I'm saying is that if you are sufficiently smart then you could concievably write perfectly safe C++. But since almost no one in practice has ever been able to be sufficiently smart consistently enough to ship C or C++ code that doesn't have memory safety issues, I don't trust anyone to do so and would rather people stop writing stuff in them when there are better languages to use where I don't have to trust you as much.
  - binary132 3y ago
    Here’s what Stroustrup says: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2687r0.pdf https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p26...

woodruffw 3y ago

RAII is great (especially as a developer’s aid), but I don’t think it’s had a huge effect on memory unsafety: it’s still very easy to UAF in a RAII-only codebase, thanks to all of the flexibility C++ allows in constructors and destructors (and unintuitive behavior in moved-out-of objects). Rust is generally perceived as having many of the same developer kindnesses as C++, while having same-class performance. Learning it has a bit of a curve, but I found that it eventually clicked (I have a C and C++ professional background).

tobias12345 3y ago

RAII is great, but unfortunately it breaks down when the resource it manages leaks out of the RAII type. E.g. Whenever handing out the raw pointer stored in a unique_ptr, the code receiving that raw pointer can delete it, which will very likely lead to a use after free and certainly to a double free issue.

xdavidliu 3y ago

I was shocked to learn that reaching an end of a function without returning is actually UB and the compiler doesn't stop you; only warns. For example: ``` class Foo; Foo get_foo() { std::cout << "whoops, I forgot to return\n"; } int main() { const auto foo = get_foo(); } ```

jjgreen 3y ago
(HN weak markdown, indent 2 spaces for code-block)
- xdavidliu 3y ago
  noted for next time, thanks
ryao 3y ago
Serious C/C++ projects build with -Wall -Werror. The compiler definitely stops you then.

trealira 3y ago

Modern C++ can still be unsafe. I recently wrote a comment about it here: https://news.ycombinator.com/item?id=38576681 https://news.ycombinator.com/item?id=38576681