问题

问题在我交叉编译rustdesk代码时遇到，错误显示引用的包libsodium-sys在连接时错误，原因发现这个包没有按预期编译出32位版本还是64位版本。

虽然成功编译出了32位版本，但之后测试发现32位release版本仍然存在功能不可正常执行的问题。 还未具体查找到原因。


定位

在libsodium-sys源代码的build.rs中看到:

#[cfg(all(target_env = "msvc", target_pointer_width = "32"))]
fn get_lib_dir() -> PathBuf {
    if is_release_profile() {
        get_crate_dir().join("msvc/Win32/Release/v142/")
    } else {
        get_crate_dir().join("msvc/Win32/Debug/v142/")
    }
}

#[cfg(all(target_env = "msvc", target_pointer_width = "64"))]
fn get_lib_dir() -> PathBuf {
    if is_release_profile() {
        get_crate_dir().join("msvc/x64/Release/v142/")
    } else {
        get_crate_dir().join("msvc/x64/Debug/v142/")
    }
}

配置错误信息发现原因是target_pointer_width不等于”32”而造成。


解决

在github上提交issue#98271得到解决方法

$ rustup toolchain install stable-i686
$ cargo +stable-i686 build


深入

$ cargo --help
Rust's package manager

USAGE:
    cargo [+toolchain] [OPTIONS] [SUBCOMMAND]

OPTIONS:
    -V, --version               Print version info and exit
        --list                  List installed commands
        --explain <CODE>        Run `rustc --explain CODE`
    -v, --verbose               Use verbose output (-vv very verbose/build.rs output)
    -q, --quiet                 Do not print cargo log messages
        --color <WHEN>          Coloring: auto, always, never
        --frozen                Require Cargo.lock and cache are up to date
        --locked                Require Cargo.lock is up to date
        --offline               Run without accessing the network
        --config <KEY=VALUE>    Override a configuration value (unstable)
    -Z <FLAG>                   Unstable (nightly-only) flags to Cargo, see 'cargo -Z help' for
                                details
    -h, --help                  Print help information

Some common cargo commands are (see all commands with --list):
    build, b    Compile the current package
    check, c    Analyze the current package and report errors, but don't build object files
    clean       Remove the target directory
    doc, d      Build this package's and its dependencies' documentation
    new         Create a new cargo package
    init        Create a new cargo package in an existing directory
    run, r      Run a binary or example of the local package
    test, t     Run the tests
    bench       Run the benchmarks
    update      Update dependencies listed in Cargo.lock
    search      Search registry for crates
    publish     Package and upload this package to the registry
    install     Install a Rust binary. Default location is $HOME/.cargo/bin
    uninstall   Uninstall a Rust binary

See 'cargo help <command>' for more information on a specific command.



Common Options
+toolchain
If Cargo has been installed with rustup, and the first argument to cargo begins with +, 
it will be interpreted as a rustup toolchain name (such as +stable or +nightly). 
See the [rustup documentation](https://rust-lang.github.io/rustup/overrides.html) 
for more information about how toolchain overrides work.