# 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.

{ system, allPackages ? import ../top-level, platform, config, crossSystem, lib }:


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 { inherit system allPackages config; }) stdenvNative;

  stdenvNativePkgs = allPackages {
    allowCustomOverrides = false;
    stdenv = stdenvNative;
    noSysDirs = false;
  };


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

  inherit (import ./freebsd { inherit system allPackages platform config; }) stdenvFreeBSD;

  # Linux standard environment.
  inherit (import ./linux { inherit system allPackages platform config lib; }) stdenvLinux;

  inherit (import ./darwin { inherit system allPackages platform config; }) stdenvDarwin;

  inherit (import ./cross { inherit system allPackages platform crossSystem config lib; }) stdenvCross stdenvCrossiOS;

  inherit (import ./custom { inherit system allPackages platform crossSystem config lib; }) 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