nixpkgs/pkgs/top-level/stage.nix

/* This file composes a single bootstrapping stage of the Nix Packages
   collection. That is, it imports the functions that build the various
   packages, and calls them with appropriate arguments. The result is a set of
   all the packages in the Nix Packages collection for some particular platform
   for some particular stage.

   Default arguments are only provided for bootstrapping
   arguments. Normal users should not import this directly but instead
   import `pkgs/default.nix` or `default.nix`. */


{ # The system (e.g., `i686-linux') for which to build the packages.
  system

, # The standard environment to use for building packages.
  stdenv

, # This is used because stdenv replacement and the stdenvCross do benefit from
  # the overridden configuration provided by the user, as opposed to the normal
  # bootstrapping stdenvs.
  allowCustomOverrides ? true

, # Non-GNU/Linux OSes are currently "impure" platforms, with their libc
  # outside of the store.  Thus, GCC, GFortran, & co. must always look for
  # files in standard system directories (/usr/include, etc.)
  noSysDirs ? (system != "x86_64-freebsd" && system != "i686-freebsd"
               && system != "x86_64-solaris"
               && system != "x86_64-kfreebsd-gnu")

, # The configuration attribute set
  config

, crossSystem
, platform
, lib
, nixpkgsFun
}:

let
  stdenvAdapters = self: super:
    let res = import ../stdenv/adapters.nix self; in res // {
      stdenvAdapters = res;
    };

  trivialBuilders = self: super:
    import ../build-support/trivial-builders.nix {
      inherit lib; inherit (self) stdenv stdenvNoCC; inherit (self.xorg) lndir;
    };

  stdenvDefault = self: super:
    { stdenv = stdenv // { inherit platform; }; };

  allPackages = self: super:
    let res = import ./all-packages.nix
      { inherit system noSysDirs config crossSystem platform lib nixpkgsFun; }
      res self;
    in res;

  aliases = self: super: import ./aliases.nix super;

  # stdenvOverrides is used to avoid circular dependencies for building
  # the standard build environment. This mechanism uses the override
  # mechanism to implement some staged compilation of the stdenv.
  #
  # We don't want stdenv overrides in the case of cross-building, or
  # otherwise the basic overridden packages will not be built with the
  # crossStdenv adapter.
  stdenvOverrides = self: super:
    lib.optionalAttrs (crossSystem == null && super.stdenv ? overrides)
      (super.stdenv.overrides super);

  # Allow packages to be overridden globally via the `packageOverrides'
  # configuration option, which must be a function that takes `pkgs'
  # as an argument and returns a set of new or overridden packages.
  # The `packageOverrides' function is called with the *original*
  # (un-overridden) set of packages, allowing packageOverrides
  # attributes to refer to the original attributes (e.g. "foo =
  # ... pkgs.foo ...").
  configOverrides = self: super:
    lib.optionalAttrs allowCustomOverrides
      ((config.packageOverrides or (super: {})) super);

  # The complete chain of package set builders, applied from top to bottom
  toFix = lib.foldl' (lib.flip lib.extends) (self: {}) [
    stdenvDefault
    stdenvAdapters
    trivialBuilders
    allPackages
    aliases
    stdenvOverrides
    configOverrides
  ];

  # Use `overridePackages` to easily override this package set.
  # Warning: this function is very expensive and must not be used
  # from within the nixpkgs repository.
  #
  # Example:
  #  pkgs.overridePackages (self: super: {
  #    foo = super.foo.override { ... };
  #  }
  #
  # The result is `pkgs' where all the derivations depending on `foo'
  # will use the new version.

  # Return the complete set of packages. Warning: this function is very
  # expensive!
in lib.makeExtensibleWithCustomName "overridePackages" toFix