12:19 <frostie314159[m]> Hi, does anyone know, how I can create an array of static buffers using static_cell?

13:32 <DominicFischer[m> Ehhh, the same way you create anything else with static_cell?

16:01 <frostie314159[m]> I've been trying for sometime now, but it always fails to compile. What I'm trying to achieve is, I want to have an array, with a length controlled by a constant. That array should contain `&'static mut [u8; BUFFER_SIZE]`, i tried using `array::from_fn`, but it fails saying the static cell was already initialized.

16:02 <frostie314159[m]> So the type of the array would be `[&'static mut [u8; BUFFER_SIZE]; BUFFER_COUNT]`

17:13 <DominicFischer[m> You need to do that in two steps I think. One to create a static [[u8; BUFFER_SIZE]; BUFFER_COUNT] and another to split up the buffers. I don't recall a good way to do the seconds step, especially if you want to store that in a static as well.

19:53 <takkaryx[m]> probably a more generic rust question than an embedded specific one, but is there a way to define an environment variable for the build.rs script specifically in the cargo.toml? I'm trying to give it a relative path to a directory to search for some auto-generated code, but the [env] portion of the Cargo seems to only be present in the compilation of the crate, not in the build.rs script where I'm generating some code.

19:53 <takkaryx[m]> * probably a more generic rust question than an embedded specific one, but is there a way to define an environment variable for the build.rs script specifically in the cargo.toml? I'm trying to give it a relative path to a directory to search for some auto-generated code, but the [env] portion of the Cargo seems to only be present in the compilation of the crate, not in the build.rs script where I'm generating some code. ATM

19:53 <takkaryx[m]> I've given it an absolute path, but I'd prefer something a bit safer.

19:56 <Lumpio-> I'm fairly sure [env] should be available in build.rs, what are you using to read the variable?

19:57 <Lumpio-> ttps://doc.rust-lang.org/cargo/reference/config.html#env yeah even the docs give build scripts as the first example

19:57 <Lumpio-> +h

19:57 <takkaryx[m]> std::env::var("ENV_VAR").unwrap

19:58 <Lumpio-> Ooooh you said cargo.toml

19:58 <takkaryx[m]> hmmm, I printed out all the full env with a simple loop, and the [env] variable wasn't present....

19:58 <Lumpio-> It goes in cargo's config.toml not the crate cargo.toml

19:58 <Lumpio-> There is no [env] in cargo.toml

19:58 <takkaryx[m]> wait, it has to be the config.toml....

19:58 <takkaryx[m]> derp, ok, I read it all correctly, and just misread which toml to use XD

19:58 <takkaryx[m]> thanks!

20:51 <dngrs[m]> is there an easy way to figure out which dependency drags in std?

21:11 <vollbrecht[m]> <dngrs[m]> "is there an easy way to figure..." <- cargo tree -e features -i <some top level dep>

21:11 <vollbrecht[m]> that lets you view in reverse how feature come in

21:12 <dngrs[m]> vollbrecht[m]: mmmhm this requires the dep using `std` (or similar) as feature name but yeah I guess that's close enough, thx

21:14 <vollbrecht[m]> ah yeah with std in particular you are right that it can be problematic if a crate doesn't use such a feature explicitly

21:16 <vollbrecht[m]> hmm there exist https://github.com/hobofan/cargo-nono looks interesting :D

21:17 <vollbrecht[m]> it claims to be able to find dependency's that are no_std compatible and name them

21:17 <vollbrecht[m]> s/no_std/no\_std/, s/compatible/incompatible/

21:19 <dngrs[m]> that sounds pretty neat