Cargo.lock 的作用

  Cargo.lock(完整内容):
    # This file is automatically @generated by Cargo.
    # It is not intended for manual editing.
    version = 4
    
    [[package]]
    name = "itoa"
    version = "1.0.18"
    source = "registry+https://github.com/rust-lang/crates.io-index"
    checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
    
    [[package]]
    name = "u152"
    version = "0.1.0"
    dependencies = [
     "itoa",
    ]

  Cargo.toml 加了依赖但锁文件没更新,cargo build --locked:
    Updating crates.io index
    error: cannot update the lock file <实验目录>/proj/u152/Cargo.lock because --locked was passed to prevent this
    help: to generate the lock file without accessing the network, remove the --locked flag and use --offline instead.
  不加 --locked 时 cargo 自动更新锁文件:退出码 0;锁文件里的包数:3

  把 itoa 的 checksum 前 8 位改成 deadbeef 后构建:
    error: checksum for `itoa v1.0.18` changed between lock files
    this could be indicative of a few possible errors:
    * the lock file is corrupt
    * a replacement source in use (e.g., a mirror) returned a different checksum
    * the source itself may be corrupt in one way or another
    unable to verify that `itoa v1.0.18` is the same as when the lockfile was generated

  cargo build --locked 退出码 0
  cargo tree --locked:
    u152 v0.1.0 (<实验目录>/proj/u152)
    ├── itoa v1.0.5
    └── semver v1.0.28

  cargo new --bin:.gitignore 内容 ['/target'](是否忽略 Cargo.lock: False)
  cargo new --lib:.gitignore 内容 ['/target'](是否忽略 Cargo.lock: False)