nixpkgs/pkgs/stdenv/default.nix

# This file defines the various standard build environments.
#
# On Linux systems, the standard build environment consists of
# Nix-built instances glibc and the `standard' Unix tools, i.e., the
# Posix utilities, the GNU C compiler, and so on.  On other systems,
# we use the native C library.

{ # Args just for stdenvs' usage
  lib, allPackages
  # Args to pass on to `allPacakges` too
, system, platform, crossSystem, config
} @ args:

let
  # The native (i.e., impure) build environment.  This one uses the
  # tools installed on the system outside of the Nix environment,
  # i.e., the stuff in /bin, /usr/bin, etc.  This environment should
  # be used with care, since many Nix packages will not build properly
  # with it (e.g., because they require GNU Make).
  inherit (import ./native args) stdenvNative;

  stdenvNativePkgs = allPackages {
    inherit system platform crossSystem config;
    allowCustomOverrides = false;
    stdenv = stdenvNative;
    noSysDirs = false;
  };


  # The Nix build environment.
  stdenvNix = assert crossSystem == null; import ./nix {
    inherit config lib;
    stdenv = stdenvNative;
    pkgs = stdenvNativePkgs;
  };

  inherit (import ./freebsd args) stdenvFreeBSD;

  # Linux standard environment.
  inherit (import ./linux args) stdenvLinux;

  inherit (import ./darwin args) stdenvDarwin;

  inherit (import ./cross args) stdenvCross stdenvCrossiOS;

  inherit (import ./custom args) stdenvCustom;

  # Select the appropriate stdenv for the platform `system'.
in
    if crossSystem != null then
      if crossSystem.useiOSCross or false then stdenvCrossiOS
      else stdenvCross else
    if config ? replaceStdenv then stdenvCustom else
    if system == "i686-linux" then stdenvLinux else
    if system == "x86_64-linux" then stdenvLinux else
    if system == "armv5tel-linux" then stdenvLinux else
    if system == "armv6l-linux" then stdenvLinux else
    if system == "armv7l-linux" then stdenvLinux else
    if system == "mips64el-linux" then stdenvLinux else
    if system == "powerpc-linux" then /* stdenvLinux */ stdenvNative else
    if system == "x86_64-darwin" then stdenvDarwin else
    if system == "x86_64-solaris" then stdenvNix else
    if system == "i686-cygwin" then stdenvNative else
    if system == "x86_64-cygwin" then stdenvNative else
    if system == "x86_64-freebsd" then stdenvFreeBSD else
    stdenvNative