Support #[no_std]

[dpc]

Job done.

• Basic #![no_std] support as per io::Write as a feature? whitequark/rust-log_buffer#2 (comment)
• Create basic PoC fmt_streamer crate that will be a #[no_std] too, similiar to streamer create but logging to circular buffer. See: https://github.com/dpc/slog-fmtstream

[dpc]

This is awesome.

[dpc]

I have a basic fmt_streamer crate, but I can't decide whatever the logger (in-memory logger) gathered, should be accessed by the rest of the code. fmt_streamer owns some form of io-like datastructre (eg. circular buffer), and it's not obvious how to access it from outside of the drain-hierarchy.

If that logger would just dump it strait to UART, there's no problem. Otherwise some form of Rc<RefCel<..>> will be required?

[tupshin]

Is there an example of using the basic no_std support today?

I have

slog = {version = "1.4", default-features = false}
slog-term = "1.4"

in my Cargo.toml, and

#![no_std]

in my lib.rs

My own code is working fine, any the rest of slog seems ok, but the o! macro fails with

failed to resolve. Maybe a missing `extern crate std;`? (in expansion of `o!`) [E0433]: Maybe a missing `extern crate std;`?

I see that there are two versions of that macro, with the alternate being designed for no_std, but not sure what I'm doing wrong.
Thanks

[dpc]

slog-term is the problem, I believe.

So this is how feature flags in cargo work: If you import any crate that imports slog crate that does not disable default flags, std feature will be implicitly reenabled.

slog-term requires libstd, as most slog crates do. slog crate tiself is known to compile and works without std, but the only current drain that would also work without libstd is https://github.com/slog-rs/fmtstream and it's not finished yet.

You can either help me finish fmtstream or write your own Drain (it's very easy).

[dpc]

No help, no progress. Can be finished in the future.