Conversation

Patrick Walton
@pcwalton
IMO the Chrome article on why borrow checking is impossible in C++ largely misses the point. The biggest issue is simply that virtually no C++ code is written under the invariants that the borrow check enforces, so C++-plus-borrow-check loses compatibility with existing C++.
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indygreg
@indygreg
Replying to
@pcwalton
I agree. But my read of the article is it was to serve as a technical rebuttal for people saying “but C++ can do this too.” As written, it is rather effective at preventing C++ stalwarts from pushing an invalid argument!
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indygreg
@indygreg
Replying to
@indygreg
and
@pcwalton
If you say “you need to change how you write C++,” people will say “then we’ll change how we write C++.” But if you say “you can’t do this if you tried: here’s the proof/code” it cuts off the debate.
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Patrick Walton
@pcwalton
Replying to
@indygreg
Well, I feel like if you modified the language a LOT you could do something that resembles "add borrow checking to C++". But that's my point: such a modification of C++ will by definition have the same restrictions as Rust, including that you can't make mutable shared_ptr.
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Daniel Micay
@DanielMicay
Replying to
@LegNeato
@pcwalton
and
@indygreg
I think most of their engineers have already come to that conclusion a long time ago, but they need to make the case that C++ is a dead end and then to specifically adopt Rust as the solution. They're not going to invest millions of dollars into it without lots of research.
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Daniel Micay
@DanielMicay
Replying to
@DanielMicay
@LegNeato
and 2 others
Android integrated Rust as one of the first-class languages (Kotlin, Java, C++, Rust) and will be moving to using it for most new low-level components. Android 12 has a Rust-based Bluetooth stack. As long as that goes well, you can expect a whole lot more Rust in Android 13+.
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Daniel Micay
@DanielMicay
Replying to
@DanielMicay
@LegNeato
and 2 others
ChromeOS and Fuchsia have been using Rust in certain areas already. Chrome hasn't started using it outside of ChromeOS though. Each of these is essentially a separate sub-organization within Google and makes their own decisions about languages. Each has pretty much rejected Go.
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Daniel Micay
@DanielMicay
Replying to
@DanielMicay
@LegNeato
and 2 others
As far as I know, Google isn't using much Rust outside these 3 sub-organizations. I expect they're replacing a lot of their C++ and Java elsewhere with Go, although they're still likely to start using both Rust and Kotlin as replacements for those. It's a huge decision to make.
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Daniel Micay
@DanielMicay
Replying to
@DanielMicay
@LegNeato
and 2 others
Android is close to the point that they'll start requiring all new low-level userspace components developed internally to be written in Rust rather than C++. They're not going to be rushing to rewrite everything in Rust but adoption is likely going to be very fast nevertheless.
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