`parity-scale-codec/derive` enables `serder/std` even when `std` is not enabled

[recmo]

Simplified example:

serde = { version = "1.0", default_features = false }
parity-scale-codec = { version = '1.3.0', default-features = false, features = ['derive'] }

[features]
default = ["std"]
std = [
    "serde/std",
    "parity-scale-codec/std",
]

Fails to build correctly without the std feature.

This is because parity-scale-codec will force the serde/std feature to be set, even when parity-scale-codec/std is unset.

[recmo]

The dependency path is:

• parity-scale-codec features = ['derive'] (no default features)
• parity-scale-codec-derive (with default features)
• proc-macro-crate (with default features)
• toml (with default features)
• serde (with default features, including std)

This is ultimately caused by rust-lang/cargo#7915

[recmo]

This nightly-only cargo feature solves it for me:

https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#features

Building using it works:

cargo check -Zfeatures=all --lib --bins --no-default-features --target=thumbv7m-none-eabi

[gui1117]

I'm not sure if there is a good way to solve this ? but as we will release 2.0 in some time do you see any fix ?

[bkchr]

This will be solved by: rust-lang/cargo#8997

So with the stable compiler in some weeks.

[Xanewok]

Can this be closed now?

[bkchr]

Probably