Rust 跨平台构建贴士

使用 Nix Flake 搭建基础的 Rust 跨平台构建环境

新增 flake.nix 文件，并执行 git add flake.nix 。

{
  inputs = {
    utils.url = "github:numtide/flake-utils";
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11";
  };

  outputs = {
    nixpkgs,
    utils,
    ...
  }:
    utils.lib.eachDefaultSystem
    (
      system: let
        pkgs = import nixpkgs {inherit system;};
        lib = pkgs.lib;
      in {
        devShells =
          {
            default = pkgs.mkShell {
              nativeBuildInputs = with pkgs; [
                pkg-config
                gcc
              ];
            };
          }
          // builtins.listToAttrs (map (target: {
            name = target;
            value = let
              cross = import nixpkgs {
                inherit system;
                crossSystem = {config = target;};
              };
              cpkgs = cross.pkgsMusl;
            in (cross.mkShell {
              nativeBuildInputs = with pkgs; [
                pkg-config
                gcc # proc macro 等编译过程，需要原架构 toolchians
              ];
              env = let
                normalized = lib.strings.toUpper (builtins.replaceStrings ["-"] ["_"] target);
              in
                with cpkgs; {
                  # https://doc.rust-lang.org/cargo/reference/environment-variables.html#configuration-environment-variables
                  "CARGO_TARGET_${normalized}_LINKER" = "${stdenv.cc.targetPrefix}cc";
                };
            });
          }) ["x86_64-unknown-linux-musl" "aarch64-unknown-linux-musl"]);
      }
    );
}

执行构建

# 本地构建
nix develop .#default --command \
 cargo build

# 跨平台构建
#
# 别忘了先安装对应的 rustup 组件
# rustup target add aarch64-unknown-linux-musl
# rustup target add x86_64-unknown-linux-musl

TARGET=x86_64-unknown-linux-musl nix develop .#$TARGET --command \
 cargo build --target $TARGET

openssl, pq 等 C/C++ 依赖处理

使用静态编译，并使用有 vendor （打包 C/C++ 源码）版本的 bindings 项目，把这些加入依赖管理，确保能稳定的可重复构建。

在 Cargo.toml 文件中增加对应 target 的依赖。

[target.x86_64-unknown-linux-musl.dependencies]
openssl-sys = { version = "0.9", features = ["vendored"] }
pq-sys = { version = "0.7", features = ["bundled"] }

[target.aarch64-unknown-linux-musl.dependencies]
openssl-sys = { version = "0.9", features = ["vendored"] }
pq-sys = { version = "0.7", features = ["bundled"] }

执行构建

# 本地静态编译则需要指定 RUSTFLAGS。经实测，有些架构该配置无效
RUSTFLAGS='-C target-feature=+crt-static' cargo build

# 而 x86_64-unknown-linux-musl 则不需要指定，默认启用
TARGET=x86_64-unknown-linux-musl nix develop .#$TARGET --command \
  cargo build --target $TARGET

CRT means standard C runtime. The default of crt-static will be different depending on the target. For example x86_64-unknown-linux-musl will have it on by default, whereas arm-unknown-linux-musleabi will have it turned off by default. ¹

RFC 1721 crt-static