Translating All C to Rust (TRACTOR) • Hacker News Board

Re: Translating All C to Rust (TRACTOR)

#21

Post by PreInternet01 » Tue, Jul 30, 2024, 4:18 PM UTC

jerf wrote: post #9

calebpeterson wrote: post #6

Earlier quoted context omitted.

Genuine question: Would you mind explaining to a dev that doesn’t know much (anything) about Rust, how does this settle any debate?

I believe it goes something like, "I have constructed a strawman that Rust claims that all code written in it is automatically safe by all conceivable definitions of safe, but look, ha ha, here's something that detects unsafe code in Rust!", and I don't mean "code marked in unsafe blocks". It's a concatenation of several logical fallacies in a row; equivocation, straw manning, binary thinking about safety, several ot…

[flagged]

Re: Translating All C to Rust (TRACTOR)

#22

Post by commodoreboxer » Tue, Jul 30, 2024, 4:19 PM UTC

PreInternet01 wrote: post #18

keybored wrote: post #7

Earlier quoted context omitted.

You linked an interpreter for some kind of internal compiler representation that the Rust compiler uses. What on Earth do you mean?

> What on Earth do you mean? That documented use of safe Rust can easily lead to UB, which this infernal 'internal compiler representation' demonstrates. I'm not even sure what is even remotely confusing about that?

> Miri is an Undefined Behavior detection tool for Rust. It can run binaries and test suites of cargo projects and detect unsafe code that fails to uphold its safety requirements.

> ... detect unsafe code that fails ...

Show me the documented safe Rust code that causes UB without using any unsafe blocks outside of the standard library.

Re: Translating All C to Rust (TRACTOR)

#23

Post by mattgreenrocks » Tue, Jul 30, 2024, 4:19 PM UTC

mike_hearn wrote: post #10

That sounds ... hard. Especially as idiomatic Rust as written by skilled programmers looks nothing like C, and most interesting code is written in C++ anyway. Isn't it equivalent to statically determining the lifetimes of all allocations in the C program, including those that are implemented using custom allocators or which cross into proprietary libraries? There's been a lot of research into this sort of thing over…

Projects are termed DARPA-hard for a reason.

Re: Translating All C to Rust (TRACTOR)

#24

Post by niemandhier » Tue, Jul 30, 2024, 4:19 PM UTC

Is this supposed to be automatic ? And if so wouldn’t any Programm that can automatically port c to rust, by necessity contain all the functionality to make the c code itself safe?

Re: Translating All C to Rust (TRACTOR)

#25

Post by woodruffw » Tue, Jul 30, 2024, 4:20 PM UTC

mike_hearn wrote: post #10

That sounds ... hard. Especially as idiomatic Rust as written by skilled programmers looks nothing like C, and most interesting code is written in C++ anyway. Isn't it equivalent to statically determining the lifetimes of all allocations in the C program, including those that are implemented using custom allocators or which cross into proprietary libraries? There's been a lot of research into this sort of thing over…

It's very hard; DARPA likes to fund hard things[1] :-).

This isn't, however, DARPA's first foray into automatic program translation, or even automatic translation into Rust[2].

[1]: https://www.urbandictionary.com/define.php?term=DARPA%20hard

[2]: https://c2rust.com/

Re: Translating All C to Rust (TRACTOR)

#26

Post by steveklabnik » Tue, Jul 30, 2024, 4:20 PM UTC

commodoreboxer wrote: post #22

PreInternet01 wrote: post #18

Earlier quoted context omitted.

> What on Earth do you mean? That documented use of safe Rust can easily lead to UB, which this infernal 'internal compiler representation' demonstrates. I'm not even sure what is even remotely confusing about that?

> Miri is an Undefined Behavior detection tool for Rust. It can run binaries and test suites of cargo projects and detect unsafe code that fails to uphold its safety requirements. > ... detect unsafe code that fails ... Show me the documented safe Rust code that causes UB without using any unsafe blocks outside of the standard library.

There are some soundness holes in the implementation that can cause this. Just like any project, the compiler can have bugs. They’ll be fixed just like any bug.

Re: Translating All C to Rust (TRACTOR)

#27

Post by nanolith » Tue, Jul 30, 2024, 4:21 PM UTC

I'm personally not a fan of "rewrite the world in Rust" mentality, but that being said, if one is planning to port a project to a new language or platform, mechanical translation is a poor means of doing so. Spend the time planning better architecture and designing a better software system, and find a way to replace it piece by piece. Don't build a castle in the sky, because it will never reach the ground. If you've decided to use Rust for this system, that's fine. But, write Rust. Don't try to back-port C into Rust.

I think a far better and more mature process is to update C to modern C and use a model checker such as CBMC to verify memory, resource, and integer math safety. One gets the same safety as a gradual Rust rewrite, but the code base, knowledge base, and developers can be maintained.

Re: Translating All C to Rust (TRACTOR)

#28

Post by 01HNNWZ0MV43FF » Tue, Jul 30, 2024, 4:21 PM UTC

mike_hearn wrote: post #10

That sounds ... hard. Especially as idiomatic Rust as written by skilled programmers looks nothing like C, and most interesting code is written in C++ anyway. Isn't it equivalent to statically determining the lifetimes of all allocations in the C program, including those that are implemented using custom allocators or which cross into proprietary libraries? There's been a lot of research into this sort of thing over…

Can't most c++ be machine-lowered to C?

Re: Translating All C to Rust (TRACTOR)

#29

Post by TinkersW » Tue, Jul 30, 2024, 4:22 PM UTC

Good luck with that..also shouldn't the target be C++ to Rust? Is there really that much pure C still being written?

Re: Translating All C to Rust (TRACTOR)

#30

Post by steveklabnik » Tue, Jul 30, 2024, 4:23 PM UTC

PreInternet01 wrote: post #15

calebpeterson wrote: post #6

Earlier quoted context omitted.

Genuine question: Would you mind explaining to a dev that doesn’t know much (anything) about Rust, how does this settle any debate?

Well, the general 'Rewrite All in Rust' consensus is that it solves all general programming problems, ever . Yet, the linked repository shows a huge list of cases in which simple, documented use of Rust can cause Undefined Behavior (a.k.a. 'UB') Pretty much every argument of Rust advocates against C/C++ boils down to either 'but memory safety' or 'but UB'. Yet there are many convincing counter-arguments that boil dow…

No serious person claims that Rust solves every problem ever.

Also, many people cite things like Cargo as a reason to prefer Rust over C and C++, as well as other things. UB is a big part of it, of course, but it isn’t the only thing.