0.15 breaks Display about strum

[D4nte]

Fine after a cargo clean...

[Peternator7]

Thanks for reporting this issue! I'm not able to repro it though :( Could you let me know what version of rustc you're using, and potentially try running cargo clean before you build if you've got a little time?

[D4nte]

Oh, actually the issue is when running clippy!

"cargo" "clippy" "--" "-W" "clippy::cast_possible_truncation" "-W" "clippy::cast_sign_loss" "-W" "clippy::fallible_impl_from" "-W" "clippy::cast_precision_loss" "-W" "clippy::cast_possible_wrap" "-W" "clippy::print_stdout" "-W" "clippy::dbg_macro" "-D" "warnings"

▶ rustc --version
rustc 1.35.0-nightly (96d700f1b 2019-04-10)
▶ cargo clippy --version
clippy 0.0.212 (37f5c1ec 2019-04-09)

[D4nte]

To reproduce, check out 864-ethereum-htlc-crate branch of https://github.com/comit-network/comit-rs

Update strum from 0.14 to 0.15 in ./vendor/blockchain_contracts/Cargo.toml

run the clippy command above

[D4nte]

I upgraded to nightly-2019-04-30 and it is fine now. Maybe it's just me...

[D4nte]

Ok so now it fails on travis: https://travis-ci.com/comit-network/comit-rs/builds/110209768

If you checkout https://github.com/comit-network/comit-rs branch strum and run the clippy command: "cargo" "clippy" "--" "-W" "clippy::cast_possible_truncation" "-W" "clippy::cast_sign_loss" you should be able to reproduce the issue.

[Peternator7]

I think I understand what is happening. This seems like a psuedo-diamond-dependency issue.

0.15 added the ability to rename packages using feature flags, and in your repo, this file sets the "verbose-display-name" feature flag which changes the plugin from Display to StrumDisplay. That appears to be changing the name globally across all your crates.

I was able to set up a tiny repro with 2 crates in the same cargo "workspace." One of them set "verbose-display-name" and the other doesn't. If I call cargo build in the root it fails because Display cannot be found. If I cd into each directory individually though, both build separately. Cargo can't seem to use different combinations of feature flags in the same workspace.

This seems to be a cargo issue (by design?).

[D4nte]

@Peternator7 alright, make sense. Any chance you could push the tiny repo somewhere so we can report the issue to cargo?

[thomaseizinger]

That appears to be changing the name globally across all your crates.

I think, this is actually expected behaviour within cargo/rust. As soon as there is a dependency within your dependency tree that enables a certain feature, you cannot depend on the same dependency without that feature. I am not sure but depending on different versions might work because they result in different binary code.

[Peternator7]

I peeked at your code. Macro renaming is mostly for old versions of rustc. If you're importing derives by path, you shouldn't need to use them. You can do this:

#[derive(Clone, Copy, strum_macros::Display, Debug, Serialize)]
#[strum(serialize_all = "snake_case")]
pub enum DataName {
    SecretHash,
    Expiry,
    RedeemIdentity,
    RefundIdentity,
    TokenQuantity,
    TokenContract,
}

Edit: I will also acknowledge that it's perhaps not worth fixing if it works :)

[D4nte]

Thanks!