Rust has explicit provision for C-style ABI if you want that and are willing to pay for it. The provision could be improved, and valuable work on that has taken place and is ongoing, but I think the harsh lesson in this space isn't for Rust but for C++ which fell into just delivering absolute ABI freeze years ago out of terrorized panic rather than any coherent policy or strategy.
Plenty of people told WG21 (the C++ committee) that they need to fix this, P1863R0 ("ABI: Now or Never") is five years old on Friday. If you bet "Never" when that paper was written, you're ahead by five years, if you understand how this actually works you know that you have much longer. When Titus wrote that he estimated 5-10% perf left on the table. That's a thin margin, on its own it would not justify somebody to come in and pick that up. But it isn't on its own, there are a long list of problems with C++.
Plenty of people told WG21 (the C++ committee) that they need to fix this, P1863R0 ("ABI: Now or Never") is five years old on Friday. If you bet "Never" when that paper was written, you're ahead by five years, if you understand how this actually works you know that you have much longer. When Titus wrote that he estimated 5-10% perf left on the table. That's a thin margin, on its own it would not justify somebody to come in and pick that up. But it isn't on its own, there are a long list of problems with C++.