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Comment by defanor | Hacker News Reader

This is the one I tried to use, but failed to, since one of its dependencies required a rustc version newer than what I have here (1.63.0), and cargo was not able to pick the latest compatible version, but suggested that I do that manually instead. Which surprised me as well, since I keep hearing about it being nice, yet resolving dependencies is something other package managers (and Cabal in particular) tend to do. I tried to find what is the last version of that package supporting my compiler version, failed to do it quickly (how is one supposed to go around such a task, by the way?), and gave up.

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It appears both clap 2 and clap 3 have packages in bookworm. Were you trying to use them from crates.io instead of apt? Clap is on version 4 there.

> how is one supposed to go around such a task, by the way?

There is not great tooling for this, because most people use the latest stable when starting a new project, and then rust being backwards compatible means things Just Work into the future. A vanishingly small number of folks use builds significantly older than that, since upgrading is generally trivial, and newer compilers have faster build times and better error messages.

Oh, I have not tried using it from system repositories: I tried that with another library (in a hobby project) before, had issues with that, been told and generally gathered that it is easier to pull dependencies with cargo, so went straight to that this time. I see that librust-clap-dev would pull 157 other packages with it though, but will look more closely into it: I would actually prefer getting dependencies from system repositories, thanks for pointing it out.

As for newer compilers, I prefer to depend on system repositories and package manager for updates, and to stick to stable branches, so that things do not change too often. I see the appeal of rolling release distributions and cutting edge software, but not feeling comfortable using it for things that are supposed to be reliable.

So to be clear, I do not recommend that you use the rustc provided by Debian for general development. But if that’s what you want to do, by trying to mix a rustc from Debian with packages from the general ecosystem, it is going to be the worst of both worlds. I would ignore crates.io if I were trying to do what you’re trying to do. You’ll have less access to packages overall, and be using older versions, but they’re at least known to work with each other and that specific rustc version.

I'm fascinated by that description since it's the total opposite of my experience using it. I'd love to see what happened if you have a repo. I'm simply intrigued at this point.

They are using a rustc from August of 2022. If you installed that version, made a new project, and asked for the latest clap, it would not shock me at all if rustc were too old.

EDIT: from clap itself:

> We will support the last two minor Rust releases (MSRV, currently 1.70.0)

So yeah, 1.63.0 is going to be quite old.

I see!

Steps to reproduce, once you have cargo and rustc from Debian stable repositories: cargo init && cargo add clap && cargo run. The following happens:

    error: package `anstream v0.6.4` cannot be built because it requires rustc 1.70.0 or newer, while the currently active rustc version is 1.63.0
    Either upgrade to rustc 1.70.0 or newer, or use
    cargo update -p anstream@0.6.4 --precise ver
    where `ver` is the latest version of `anstream` supporting rustc 1.63.0

For what is worth, you can use https://lib.rs to see the earliest version a crate supports. For Rust 1.63.0, you will have to rely on Clap 4.0.32 from December 2022, instead of anything newer (which only support 1.64.0+): https://lib.rs/crates/clap/versions

For anstream, the situation seems more difficult for you, as it doesn't seem that there's any (non-yanked?) release that supports <1.64.0: https://lib.rs/crates/anstream/versions

Thanks! I was looking for a page like that on docs.rs, crates.io, and possibly on lib.rs as well, but missed it; that is likely to be useful in the future. Actually now I see it on crates.io as well, <https://crates.io/crates/anstream/versions>. Or maybe I saw it before, and just have not found versions <= 1.63.

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