tendermint crate uses std features in ed25519-dalek

[soareschen]

Part of informalsystems/hermes#1158.

When the Cargo.toml field is set to ed25519-dalek = { version = "1", default-features = false, features = ["serde", "u64_backend"] }, we would get the following compile errors:

error[E0277]: the trait bound `alloc::string::String: DefaultIsZeroes` is not satisfied
   --> tendermint/src/private_key.rs:47:20
    |
47  |     Zeroizing::new(String::from_utf8(Base64::default().encode(&keypair_bytes[..])).unwrap())
    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `DefaultIsZeroes` is not implemented for `alloc::string::String`
    |
    = note: required because of the requirements on the impl of `Zeroize` for `alloc::string::String`
note: required by `Zeroizing::<Z>::new`
   --> /home/ubuntu/.cargo/registry/src/github.com-1ecc6299db9ec823/zeroize-1.1.1/src/lib.rs:428:5
    |
428 |     pub fn new(value: Z) -> Self {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0599]: no method named `serialize` found for struct `Zeroizing` in the current scope
  --> tendermint/src/private_key.rs:48:10
   |
48 |         .serialize(serializer)
   |          ^^^^^^^^^ method not found in `Zeroizing<alloc::string::String>`

[tony-iqlusion]

I don't see anything there using std.

It's using alloc, and it looks like you don't have the zeroize/alloc feature enabled.

[soareschen]

Interesting, didn't realized that it was indirectly caused by zeroized/alloc not enabled. Fixed in 701f028. Thanks!