A lot of my coworkers get in this situation where, when a change in direction is made, they feel like we have to stuff the roadmap with work to rewrite everything. That work is... 0 value, in most cases, unless the decision we have made is intended to directly solve an issue in the existing code.
Many times I find that if you just do new work in the new thing, you'll "naturally" prioritize rewriting at the right rate. When we do it that way, we end up replacing, rather than rewriting, those legacy systems, which avoids the pitfall of trying to reproduce prior behavior, down to the bugs it may have had.
This is a general result regardless of what language you're talking about (unless you're really downgrading to assembly or something crazy). This of course presumes that the overall Rust (or other new language) situation is better than the existing one. It's not generally.
As an example, from https://android.googlesource.com/device/generic/trusty/+/c3f...
Many of the files in that commit have a lot of C-style code, yet are classified as C++. C and C++ are very different programming languages, and memory safety is arguably significantly easier to achieve in practice in C++ than in C, yet in the blog post, C++ is blamed for C-style code, and C and C++ are not differentiated.
Compare and contrast with https://android.googlesource.com/device/generic/goldfish/+/d... . That source code file has much more modern C++. Though even then, it contains goto, and modern C++ code reviews would normally not accept goto in my experience. I do not understand what Google Android is doing when its developers are using goto. Could they not have used lambdas in those places where they are using goto? The mixture of std::string_view and goto, modern and yuck, is disconcerting.
On a different topic, how much of the new Rust code is vendored dependencies? Is Fuchsia included?
Maybe the real value for Google Android that Rust holds, is that it mostly prevents C-style code from being written. And Rust does not support goto, and while I think an argument could be made that goto is OK to include in a toolbox, its usage should be very, very, very, very rare. Why does somewhat modern Google Android C++ allow goto?
I am not impressed by Google Android's C++ code quality. Are Google Android developers, independent of language, significantly below average?
C++ does have baggage, cruft and issues. But having strange C++ code (like goto) and also blaming C++ for C-style code, does not help paint an honest and accurate image. And if Google Android's C++ code review process accepts goto willy-nilly, I do not consider Google Android to be at all credible on any subject related to code quality, memory safety and security in any programming language.
Though, I suppose something like C++ profiles, just for modernization, might make it much easier to enforce and track that modern C++ is used.
Or any language with unsafe code blocks, which people keep forgetting also exist, while complaining about Rust, as if there isn't any other memory safe language.
With C++ you need external tooling to disable C like code, that a large part of the community refuses to adopt.
> as if there isn't any other memory safe language.
But Rust is obviously not a memory safe programming language. Unsafe's prevalence and difficulty, no_std, and arguably also the bugs and holes in the type system of Rust that have not been fixed for many years by now, make this clear.
This is not a theoretical exercise. https://materialize.com/blog/rust-concurrency-bug-unbounded-... .
AWS started an initiative to formally verify the Rust standard library, based on volunteer effort and maybe bounties. I think that is interesting, but I looked once at one of the issues for tracking what they had verified, and as I remember, even though they had marked it as fully verified, the main person verifying had called to attention in a post that he had not verified everything that the issue covered.
And even for memory-unsafe languages like Rust, there are trade-offs.
What definition of memory safety are you using where (supposed) "necessity" and "prevalence" are factors, and at what thresholds for those two factors do languages cross from unsafe to safe or vice versa?
> In Java, there would typically AFAIK rarely ever be even a single usage of escape hatches. For Rust, the collection implementations in the Rust standard library are typically riddled with the unsafe keyword, even for simple collections. Java handles performance by generally relying on JIT.
So you have Rust, which uses unsafe code for performant collections, and Java, which uses unsafe code via its JIT for performant collections. I'm not sure I see a substantial difference here.
Everything else aside, why is no_std included here?
And one does not even need esoteric code to trigger stack-overflows, dependent on coding style, a simple recursive call that has bugs like proper lack of constraints relative to resources or bugged infinite recursive calls without tail-call optimization, can do it.
I think you're technically correct, though I also think the picture is a bit more complicated than you paint it. From my understanding, stack overflow protection needs cooperation between (at least) a language, its runtime (if present), and the environment the program is run in. In other words, I'm not sure any language can "protect the stack completely" without knowledge of the environment it's going to be run in, so at least technically speaking I don't think Rust is any different here.
That being said, rustc will insert stack probes even when compiling with no_std, so in environments where stack probes are sufficient to protect against stack overflow/stack clashes no_std is safe with respect to that particular issue.
For example, this short program:
#![no_std]
#[inline(never)]
pub fn f() -> u8 {
let v: [u8; 16384] = [1; 16384];
v.iter().sum()
}
example::f::hb88315ca0b28f303:
sub rsp, 4096
mov qword ptr [rsp], 0
sub rsp, 4096
mov qword ptr [rsp], 0
sub rsp, 4096
mov qword ptr [rsp], 0
sub rsp, 4096
mov qword ptr [rsp], 0
push rax
lea rdi, [rsp + 8]
mov edx, 16384
mov esi, 1
call qword ptr [rip + memset@GOTPCREL]
<further assembly omitted>