[Nix-dev] How to build all of nixpkgs?

[Bjørn Forsman]

On 23 May 2017 at 23:31, Bjørn Forsman <bjorn.forsman at gmail.com> wrote:
> Another bit of important information is that the release.nix files map
> over pkgs with builtins.tryEval (with the packagePlatforms function)
> to filter out unsupported packages (among other things). With that
> knowledge I should be able to create my own "release.nix" file that
> builds the world.

I finally have something that seems to be working:

----8<----
let
  pkgs = import <nixpkgs> {
    # ensure we don't get an impure config
    config = { allowUnfree = false; allowBroken = false; };
  };

  lib = pkgs.lib;

  canEval = val: (builtins.tryEval val).success;

  canEvalStrict = val: (builtins.tryEval (builtins.deepSeq val val)).success;

  # myfilter arguments
  recurseYes = true;
  recurseNo = false;

  # Filter out all packages that don't evaluate or have unsupported platform.
  # Attributes of unsupported packages will be set to an empty attrset.
  myfilter = platform: recurse:
    lib.mapAttrs
      (n: v:
        let
          res = builtins.tryEval (
            #builtins.trace ''name=${n}, type=${builtins.typeOf v}${if
v ? name then ", v.name=" + v.name else ""}''
            (
              # for recurseForDerivations and recurseForRelease (bool)
              if builtins.typeOf v == "bool" then
                v
              else if !canEval v then
                {}
              else if lib.isDerivation v && canEval v.drvPath &&
builtins.elem platform (v.meta.platforms or []) then
                v
              else if recurse && (v.recurseForDerivations or false ||
v.recurseForRelease or false) then
                myfilter platform recurse v
              else
                {}
            )
          );
        in
          if res.success then res.value else {}
      );

in
{
  # error: Package
‘Agda-Sheaves-8a06162a8f0f7df308458db91d720cf8f7345d69’ in [...] is
marked as broken, refusing to evaluate.
  inherit pkgs;

  # This shouldn't stop due to eval errors, but expect plenty of build
  # failures. Better run with "--keep-going" if you want to build as much as
  # possible.
  filtered = myfilter "x86_64-linux" recurseYes pkgs;
}
---->8----

Knowing builtins.tryEval wasn't enough, because there are some errors
that are not caught by it. I particularly struggled when applying
recursion to my filter and hit a "error: value is a set while a
Boolean was expected", with no location info or trace back. Luckily
there is builtins.trace.

Best regards,
Bjørn Forsman