nixpkgs/pkgs/stdenv/cross/default.nix
Nicolas B. Pierron f5dfe78a1e Add overlays mechanism to Nixpkgs.
This patch add a new argument to Nixpkgs default expression named "overlays".

By default, the value of the argument is either taken from the environment variable `NIXPKGS_OVERLAYS`,
or from the directory `~/.nixpkgs/overlays/`.  If the environment variable does not name a valid directory
then this mechanism would fallback on the home directory.  If the home directory does not exists it will
fallback on an empty list of overlays.

The overlays directory should contain the list of extra Nixpkgs stages which would be used to extend the
content of Nixpkgs, with additional set of packages.  The overlays, i-e directory, files, symbolic links
are used in alphabetical order.

The simplest overlay which extends Nixpkgs with nothing looks like:

```nix
self: super: {
}
```

More refined overlays can use `super` as the basis for building new packages, and `self` as a way to query
the final result of the fix-point.

An example of overlay which extends Nixpkgs with a small set of packages can be found at:
  https://github.com/nbp/nixpkgs-mozilla/blob/nixpkgs-overlay/moz-overlay.nix

To use this file, checkout the repository and add a symbolic link to
the `moz-overlay.nix` file in `~/.nixpkgs/overlays` directory.
2017-01-16 01:17:33 +01:00

50 lines
1.5 KiB
Nix

{ lib
, system, platform, crossSystem, config, overlays
}:
let
bootStages = import ../. {
inherit lib system platform overlays;
crossSystem = null;
# Ignore custom stdenvs when cross compiling for compatability
config = builtins.removeAttrs config [ "replaceStdenv" ];
};
in bootStages ++ [
# Build Packages.
#
# For now, this is just used to build the native stdenv. Eventually, it
# should be used to build compilers and other such tools targeting the cross
# platform. Then, `forceNativeDrv` can be removed.
(vanillaPackages: {
inherit system platform crossSystem config overlays;
# It's OK to change the built-time dependencies
allowCustomOverrides = true;
stdenv = vanillaPackages.stdenv // {
# Needed elsewhere as a hacky way to pass the target
cross = crossSystem;
overrides = _: _: {};
};
})
# Run packages
(buildPackages: {
inherit system platform crossSystem config overlays;
stdenv = if crossSystem.useiOSCross or false
then let
inherit (buildPackages.darwin.ios-cross {
prefix = crossSystem.config;
inherit (crossSystem) arch;
simulator = crossSystem.isiPhoneSimulator or false; })
cc binutils;
in buildPackages.makeStdenvCross
buildPackages.stdenv crossSystem
binutils cc
else buildPackages.makeStdenvCross
buildPackages.stdenv crossSystem
buildPackages.binutilsCross buildPackages.gccCrossStageFinal;
})
]