I can think of two reasons. First, achieving the same level of correctness could be cheaper using a better language. And second, you have to assume that your testing is not 100% correct and complete either. I think starting from a better baseline can only be helpful.
That said, I have never used formal verification tools for C or C++. Maybe they make up for the deficiencies of the language.
If Ada was "better" than C++, why did Ada not perform much better than C++, both in regards to safety and correctness (Ariane 5), and commercially regarding its niche and also generally? Lots of companies out there could have gotten a great competitive edge with a "better" programming language. Why did the free market not pick Ada?
You could then argue that C++ had free compilers, but that should have been counter-weighed somewhat by the Ada mandate. Why did businesses not pick up Ada?
Rust is much more popular than Ada, at least outside Ada's niche. Some of that is organic, for instance arguably due to Rust's nice pattern matching and modules and crates. And some of that is inorganic, like how Rust evangelists through force, threats[0], harassment[1] and organized and paid media spam force Rust.
I also tried Ada some time ago, trying to write a tiny example, and it seemed worse than C++ in some regards. Though I only spent a few hours or so on it.
[0]: https://github.com/microsoft/typescript-go/discussions/411#d...
[1]: https://lkml.org/lkml/2025/2/6/1292
> Technical patches and discussions matter. Social media brigading - no than\k you.
> Linus
Ariane 5 is a nice anti-ada catchphrase, but ada is probably the most used language for war machines in the United States.
now the argument can be whether or not the US military is superior to X; but the fact that the largest military in the world is filled to the brim with warmachines running ada code is testament itself to the effectiveness of the language/dod/grant structure around the language.
would it be better off in c++? I don't know about that one way or the other , but it's silly pretend ada isn't successful.
Ada is almost non-existent outside its niche.
The main companies arguing for Ada appear to be the ones selling Ada services, meaning they have a horse in the race.
I barely have any experience at all with Ada. My main impression is that it, like C++, is very old.
[0]: https://www.militaryaerospace.com/communications/article/167...
> The Defense Department`s chief of computers, Emmett Paige Jr., is recommending a rescission of the DOD`s mandate to use the Ada programming language for real-time, mission-critical weapons and information systems.