build problem about tokio-modbus

[deeptuuk]

This is my Cargo.toml

[package]
name = "test_modbus"
version = "0.1.0"
authors = ["root"]
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
tokio-modbus = { version = "*", default-features = false, features = ["tcp", "server"] }

[features]
tcp = ["tokio-modbus/tcp"]
server = ["tokio-modbus/server"]

[deeptuuk]

This is the error

root@zynq:~/test_modbus# cargo build --features "tcp server"
   Compiling test_modbus v0.1.0 (/root/test_modbus)
error[E0432]: unresolved import `futures`
 --> src/main.rs:4:9
  |
4 |     use futures::future;
  |         ^^^^^^^ use of undeclared type or module `futures`

error[E0433]: failed to resolve: use of undeclared type or module `tokio`
 --> src/main.rs:2:3
  |
2 | #[tokio::main]
  |   ^^^^^ use of undeclared type or module `tokio`

error[E0433]: failed to resolve: could not find `tcp` in `server`
  --> src/main.rs:34:17
   |
34 |         server::tcp::Server::new(socket_addr).serve(|| Ok(MbServer));
   |                 ^^^ could not find `tcp` in `server`

error[E0277]: `main` has invalid return type `impl std::future::Future`
 --> src/main.rs:3:24
  |
3 | pub async fn main() -> Result<(), Box<dyn std::error::Error>> {
  |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `main` can only return types that implement `std::process::Termination`
  |
  = help: consider using `()`, or a `Result`

error[E0752]: `main` function is not allowed to be `async`
 --> src/main.rs:3:1
  |
3 | pub async fn main() -> Result<(), Box<dyn std::error::Error>> {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `main` function is not allowed to be `async`

error: aborting due to 5 previous errors

Some errors have detailed explanations: E0277, E0432, E0433, E0752.
For more information about an error, try `rustc --explain E0277`.
error: could not compile `test_modbus`.

To learn more, run the command again with --verbose.

[deeptuuk]

finally I solve the problem ,below

[dependencies]
tokio-modbus = "*"
tokio = { version = "*", features = ["full"]}
futures = "*"
[features]
tcp = ["tokio-modbus/tcp"]
server = ["tokio-modbus/tcp-server-unstable"]