Ed Morley

To support the non-chained form, we'd need to - change the receiver of all of the `BuildPlanBuilder` methods to be `&mut self` not `mut self` - adjust `BuildPlanBuilder::build()` to clone...

@schneems Thoughts on the above? The docs are at: https://docs.rs/libcnb/latest/libcnb/struct.Env.html

> We may also want to consider sprinkling `#![warn(missing_docs)]` in some of the libcnb crates to try and prevent regressions Plus also `#![warn(missing_doc_code_examples)]` - would help prevent things like #406.

#441 helps improve things significantly here for `libcnb-test`.

@Malax Could you add some more items to the list above, based on what you encountered implementing `LayerEnv`?

I've added (2) above, which is about the spec not saying which of the "automatically set env vars" vs "buildpack provided env vars" take precedence.

> 3. Cross-compiling a libcnb buildpack to `x86_64-unknown-linux-musl` is possible on Windows (and is supported by the cross-compile assistance help). Hmm so it seems cross-compiling to `x86_64-unknown-linux-musl` on Windows might...

Hmm though I can now see a bunch of issues with (2), since how can `libcnb-cargo` know in advance which future releases of `libcnb` will/won't be compatible, without making every...

> Have `libcnb-cargo` check for updates from time to time and output an "update available" message. There are a couple of crates than can do this (though neither have very...

I'd be inclined to wontfix this to be honest (if we're going to have to reimplement Go path globs). Usage of slice layers is likely going to be pretty rare,...