unresolved import `amiquip`

Question

I've added new amiquip dependency in the cargo.toml

[package]
name = "sender"
version = "0.1.0"
edition = "2021"

[package.metadata.docs.rs]
targets = ["x86_64-unknown-linux-gnu"]

[dependencies]
codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = [
    "derive",
] }
amiquip = { version = "0.4", default-features = false, optional = true }
scale-info = { version = "2.1.1", default-features = false, features = ["derive"] }
frame-benchmarking = { version = "4.0.0-dev", default-features = false, optional = true, git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.32" }
frame-support = { version = "4.0.0-dev", default-features = false, git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.32" }
frame-system = { version = "4.0.0-dev", default-features = false, git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.32" }


[dev-dependencies]
sp-core = { version = "6.0.0", default-features = false, git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.32" }
sp-io = { version = "6.0.0", default-features = false, git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.32" }
sp-runtime = { version = "6.0.0", default-features = false, git = "https://github.com/paritytech/substrate.git", branch = "polkadot-v0.9.32" }


[features]
default = ["std"]
std = ["codec/std", "frame-benchmarking?/std",
"amiquip",
 "frame-support/std", 
 "frame-system/std",
  "scale-info/std"]
runtime-benchmarks = ["frame-benchmarking/runtime-benchmarks"]
try-runtime = ["frame-support/try-runtime"]

But it still showing me this error use of "undeclared crate or module amiquip". I've also tried extern crate amiquip. But it didn't work.

Answer 1

This is intended behavior.

Two major points to notice

1. It's optional dependency

amiquip = { version = "0.4", default-features = false, optional = true }

2. It's will be part of target only when std feature is enabled

[features]
default = ["std"]
std = ["codec/std", "frame-benchmarking?/std",
 "amiquip",
 "frame-support/std", 
 "frame-system/std",
 "scale-info/std"]

What you actually need to do is something like

    #[cfg(feature = "std")]
    use amiquip;

Please adjust your features and dependent features wisely.

For more on cargo features refer https://doc.rust-lang.org/cargo/reference/features.html

Hope it helps! 😊