No, not even remotely. ABI-stability in C++ means that C++ is stuck with suboptimal implementations of stdlib functions, whereas Rust only stabilizes the exposed interface without stabilizing implementation details.
> Unfortunately editions don't allow breaking changes in the standard library
Surprisingly, this isn't true in practice either. The only thing that Rust needs to guarantee here is that once a specific symbol is exported from the stdlib, that symbol needs to be exported forever. But this still gives an immense amount of flexibility. For example, a new edition could "remove" a deprecated function by completely disallowing any use of a given symbol, while still allowing code on an older edition to access that symbol. Likewise, it's possible to "swap out" a deprecated item for a new item by atomically moving the deprecated item to a new namespace and making the existing item an alias to that new location, then in the new edition you can change the alias to point to the new item instead while leaving the old item accessible (people are exploring this possibility for making non-poisoning mutexes the default in the next edition).
One business domain that Rust currently doesn't have an answer for, is selling commercial SDKs with binary libraries, which is exactly the kind of customers that get pissed off when C and C++ compilers break ABIs.
Microsoft mentions this in the adoption issues they are having with Rust, see talks from Victor Ciura, and while they can work around this with DLLs and COM/WinRT, it isn't optimal, after all Rust's safety gets reduced to the OS ABI for DLLs and COM.
ISO C++ standard is silent on how the ABI actually looks like, the ABI not being broken in most C and C++ compilers is a consequence of customers of those compilers not being happy about breakages.
It's a straightjacket that has application in few select cases.
Things ABI prevents in C++:
- better shared_ptr
- adding UTF8 to regex
- int128_t standardisation
- make most of <cstring> constexpr
And so on: https://cor3ntin.github.io/posts/abi/
I get you might have particular criteria on this. But it's a feature that comes with huge, massive downsides.
In theory. In practice the standards committee, consisting of compiler vendors and some of their users, shape the standard, and thus the standard just so happens to conspire to avoid ABI breakages.
This is in part why Google bowed out of C++ standardization years ago.
