nixpkgs/pkgs/build-support/rust/lib/default.nix

{ lib }:

rec {
  # https://doc.rust-lang.org/reference/conditional-compilation.html#target_arch
  toTargetArch = platform:
    if platform.isAarch32 then "arm"
    else platform.parsed.cpu.name;

  # https://doc.rust-lang.org/reference/conditional-compilation.html#target_os
  toTargetOs = platform:
    if platform.isDarwin then "macos"
    else platform.parsed.kernel.name;

  # Returns the name of the rust target, even if it is custom. Adjustments are
  # because rust has slightly different naming conventions than we do.
  toRustTarget = platform: let
    inherit (platform.parsed) cpu vendor kernel abi;
    cpu_ = platform.rustc.platform.arch or {
      "armv7a" = "armv7";
      "armv7l" = "armv7";
      "armv6l" = "arm";
      "armv5tel" = "armv5te";
      "riscv64" = "riscv64gc";
    }.${cpu.name} or cpu.name;
    vendor_ = platform.rustc.platform.vendor or {
      "w64" = "pc";
    }.${vendor.name} or vendor.name;
  in platform.rustc.config
    or "${cpu_}-${vendor_}-${kernel.name}${lib.optionalString (abi.name != "unknown") "-${abi.name}"}";

  # Returns the name of the rust target if it is standard, or the json file
  # containing the custom target spec.
  toRustTargetSpec = platform:
    if (platform.rustc or {}) ? platform
    then builtins.toFile (toRustTarget platform + ".json") (builtins.toJSON platform.rustc.platform)
    else toRustTarget platform;
}