feat: support no_std

[GZTimeWalker]

This is only a early pr for support no_std.

All tests are passed. Use core and alloc instead of std.

There should be some better ways to disable serialization tests when no_std.

For issue #265

[jf2048]

Instead of having all these separate #[cfg(...)] in the tests, the entire file can be disabled by putting #![cfg(feature = "std")] at the top.

I noticed bytemuck and byteorder are only used for serialization, and serde depends on the serialization. So IMO the Cargo.toml can be changed to this:

[dependencies]
bytemuck = { version = "1.7.3", optional = true }
byteorder = { version = "1.4.3", optional = true }
serde = { version = "1.0.139", optional = true }

[features]
default = ["std"]
serde = ["dep:serde", "std"]
simd = []
std = ["dep:bytemuck", "dep:byteorder"]

So a build with no default features will have no dependencies besides the alloc crate 😃

[GZTimeWalker]

Since no one has responded to this PR for a long time, I wonder if there is any plan to continue support no_std?

[jf2048]

No commit has been made in 5 months, probably the maintainers are busy.

[GZTimeWalker]

No commit has been made in 5 months, probably the maintainers are busy.

ok, I'll take your suggestions, thanks!

[GZTimeWalker]

@Kerollmops Hello! Will no_std support be in the plans?

[Kerollmops]

Hey @jf2048 and @GZTimeWalker 👋

Sorry for the long response time. I was, indeed, swamped working on meilisearch/heed and meilisearch/Meilisearch.

Your changes look good to me overall! However, you'll probably encounter formatting issues in the CI. I advise you to do a small cargo +nightly fmt before pushing to this PR again 😃

Thank you very much 🎉

[GZTimeWalker]

I tested the latest version for all dependencies, all works fine and all tests passed, so I locked them to latest.

note that this pr has already run cargo +nightly fmt

[Kerollmops]

Thank you very much @GZTimeWalker.

I am in the process of bumping the MSRV and fixing the SIMD feature in #267. Would it be possible to rebase on the main once I merge it, please? After that, I will merge yours and #264 to create a new release.

[GZTimeWalker]

Thank you very much @GZTimeWalker.

I am in the process of bumping the MSRV and fixing the SIMD feature in #267. Would it be possible to rebase on the main once I merge it, please? After that, I will merge yours and #264 to create a new release.

Sure.

[Kerollmops]

Can you rebase on main, please? 😃

[GZTimeWalker]

Can you rebase on main, please? 😃

Ok, wait a second

[GZTimeWalker]

Merged main into no_std.

[Kerollmops]

Thank you very much for this addition 🎉