create a rust-toolchain.toml file with channel="nightly" when the --nightly tag is set

[deerawj]

sorry if the title is a bit too long; but this entire issue is basically title. I have no idea how this could be handled if there is already a rust-toolchain.toml file, but I think it would be nice if a new rust-toolchain.toml file is created atleast when there isn't one present; with

[toolchain]
channel = "nightly"

Also, I would happy to create a pull request for this

[Kobzol]

That's an interesting idea. I agree that it could be useful, but I'm not sure if it's in scope for cargo-wizard. Should every Cargo tool that interacts with nightly features configure toolchain file? 🤔

Have you seen this behavior in other similar tools?

[deerawj]

not really sure; I've never seen a tool that creates a rust-toolchain.toml file before. But, I don't think there's any reason to use the --nightly flag, if someones not using nightly, and I think using rust-toolchain.toml file is the easiest way to do this.

Also, since this is a configuration tool, some people might expect --nightly to actually switch the project to nightly, since just switching to nightly without using any of the nightly specific features could also lead to a compile time or performance improvement.

[Kobzol]

I suppose that using the nightly options without using a nightly compiler is not useful, yeah. That being said, I use nightly in some projects, but I never used rust-toolchain.toml so far, I just use rustup override instead.

[deerawj]

According to the rustup book lists 5 ways to change the toolchain to nightly; out of those 2 are global and 1 is temporary so the remaining options are rustup override and creating a rust-toolchain.toml file. But out of those two think creating the rust-toolchain.toml file seems the simplest option, it doesn't change anything outside of the project directory and reverting is just as simple as deleting the file.

[Kobzol]

Ok. As long as there is a way to opt-out, I'd accept a PR for this :)

[linyihai]

if a new rust-toolchain.toml file is created atleast when there isn't one present

If the rust-toolchain.toml present, could you replace the channel with nightly ？

My problems is using cargo-wizard to generate the fast compile config, which uses mold linker and cranelift backend.

But it failed due to not found the codegen-backends

rust-toolchain.toml:

[toolchain]
channel = "nightly-2024-10-19"

failed log:
error: failed to find a codegen-backends folder in the sysroot candidates:
* /root/.rustup/toolchains/nightly-2024-10-19-x86_64-unknown-linux-gnu
* /root/.rustup/toolchains/nightly-2024-10-19-x86_64-unknown-linux-gnu

Besides，nightly-2024-10-19-x86_64-unknown-linux-gnu had installed.

rustup show
Default host: x86_64-unknown-linux-gnu
rustup home:  /root/.rustup

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu
nightly-2024-03-05-x86_64-unknown-linux-gnu
nightly-2024-04-23-x86_64-unknown-linux-gnu
nightly-2024-07-02-x86_64-unknown-linux-gnu
nightly-2024-08-11-x86_64-unknown-linux-gnu
nightly-2024-09-23-x86_64-unknown-linux-gnu
nightly-2024-10-11-x86_64-unknown-linux-gnu
nightly-2024-10-19-x86_64-unknown-linux-gnu
nightly-2024-11-09-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu (default)
stage1

active toolchain
----------------

nightly-2024-10-19-x86_64-unknown-linux-gnu (overridden by '/root/workspace/greptimedb/rust-toolchain.toml')
rustc 1.84.0-nightly (e92993dbb 2024-10-18)

[Kobzol]

Please create a separate issue about that, thanks!

[linyihai]

Please create a separate issue about that, thanks!

I had opened a new issue here #25.