[dependencies]
serde = "1.0"              # ^1.0（兼容 1.x）
serde_json = ">=1.0,<2.0"  # 范围
tokio = "~1.20"            # >=1.20.0, <1.21.0
rand = "=0.8.5"            # 精确版本

主版本.次版本.补丁
  ↑      ↑     ↑
  不兼容  新功能  Bug修复

^1.2.3  → >=1.2.3, <2.0.0
~1.2.3  → >=1.2.3, <1.3.0

[dependencies]
my_lib = { git = "https://github.com/user/repo", branch = "main" }
my_lib = { git = "https://github.com/user/repo", tag = "v1.0" }

[dependencies]
my_lib = { path = "../my_lib" }

# 库的 Cargo.toml
[features]
default = ["json"]
json = ["serde", "serde_json"]
full = ["json", "xml", "yaml"]

[dependencies]
serde = { version = "1", optional = true }
serde_json = { version = "1", optional = true }

# 使用方的 Cargo.toml
[dependencies]
my_lib = { version = "1", features = ["full"] }

// 代码中条件编译
#[cfg(feature = "json")]
pub fn parse_json(input: &str) -> serde_json::Value {
    serde_json::from_str(input).unwrap()
}

cargo add serde --features derive    # 添加依赖
cargo remove serde                   # 移除依赖
cargo update                         # 更新依赖
cargo tree                           # 查看依赖树
cargo tree -d                        # 查看重复依赖

# Cargo.toml
[dependencies]
reqwest = { version = "0.12", features = ["json"] }
tokio = { version = "1", features = ["full"] }
serde = { version = "1", features = ["derive"] }

use serde::Deserialize;

#[derive(Deserialize, Debug)]
struct User {
    name: String,
    email: String,
}

#[tokio::main]
async fn main() -> Result<(), reqwest::Error> {
    let user: User = reqwest::get("https://api.example.com/user")
        .await?
        .json()
        .await?;
    println!("{:?}", user);
    Ok(())
}