refactor: Move nixpkgs attribute to `third_party.nixpkgs` r/2470

Please read b/108 to make sense of this.

This gets rid of the explicit list of exposed packages from nixpkgs,
and instead makes the entire package set available at
`third_party.nixpkgs`.

To accommodate this, a LOT of things have to be very slightly shuffled
around. Some of this was done in already submitted CLs, but this
change is unfortunately still quite noisy.

Pay extra attention to:

* overlay-like functionality that was partially moved to actual
  overlays (partially as in, the minimum required to get a green
  build)

* modified uses of the package set path, esp. in NixOS systems

Special notes:

* xanthous has been disabled in CI because of issues with the Haskell
  overlay
* //third_party/nix has been disabled because of other unclear
  dependency issues

Both of these will be tackled in a followup CL.

Change-Id: I2f9c60a4d275fdb5209264be0addfd7e06c53118
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2910
Reviewed-by: glittershark <grfn@gws.fyi>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI

1 files changed, 22 insertions, 72 deletions

diff --git a/third_party/default.nix b/third_party/default.nix
index 774e634f9c..0b1e94c7f8 100644
--- a/third_party/default.nix
+++ b/third_party/default.nix
@@ -1,73 +1,23 @@
-# This file controls the import of external dependencies (i.e.
-# third-party code) into my package tree.
+# This file defines the root of all external dependency imports (i.e.
+# third-party code) in the TVL package tree.
 #
-# This includes *all packages needed from nixpkgs*.
-{ ... }:
-
-let
-  # Tracking nixos-unstable as of 2021-03-25.
-  nixpkgsCommit = "60dd94fb7e01a8288f6638eee71d7cb354c49327";
-  nixpkgsSrc = fetchTarball {
-    url = "https://github.com/NixOS/nixpkgs/archive/${nixpkgsCommit}.tar.gz";
-    sha256 = "0skdwk9bdld295kzrymirs8xrzycqmhsclaz8s18jhcz75hb8sk3";
-  };
-  nixpkgs = import nixpkgsSrc {
-    config.allowUnfree = true;
-    config.allowBroken = true;
-
-    # Lutris depends on p7zip, which is considered insecure.
-    config.permittedInsecurePackages = [
-      "p7zip-16.02"
-    ];
-  };
-
-  # Tracking nixos-20.09 as of 2021-03-25.
-  stableCommit = "223d0d733a66b46504ea6b4c15f88b7cc4db58fb";
-  stableNixpkgsSrc = fetchTarball {
-    url = "https://github.com/NixOS/nixpkgs/archive/${stableCommit}.tar.gz";
-    sha256 = "073327ris0frqa3kpid3nsjr9w8yx2z83xpsc24w898mrs9r7d5v";
-  };
-  stableNixpkgs = import stableNixpkgsSrc {};
-
-  exposed = import ./nixpkgs-exposed/exposed { inherit nixpkgs stableNixpkgs; };
-
-in exposed.lib.fix(self: exposed // {
-  callPackage = nixpkgs.lib.callPackageWith self;
-
-  # Provide the source code of nixpkgs, but do not provide an imported
-  # version of it.
-  inherit nixpkgsCommit nixpkgsSrc stableNixpkgsSrc;
-
-  # Expose upstream attributes so they can be overridden in readTree nodes
-  originals = {
-    inherit (nixpkgs) gtest openldap go grpc notmuch rr;
-    inherit (stableNixpkgs) git tdlib;
-    ffmpeg = nixpkgs.ffmpeg-full;
-    telega = stableNixpkgs.emacsPackages.telega;
-
-  };
-
-  # Use LLVM 11
-  llvmPackages = nixpkgs.llvmPackages_11;
-  clangStdenv = nixpkgs.llvmPackages_11.stdenv;
-  stdenv = nixpkgs.llvmPackages_11.stdenv;
-
-  clang-tools = (nixpkgs.clang-tools.override {
-    llvmPackages = nixpkgs.llvmPackages_11;
-  });
-
-  # Provide Emacs 27
-  #
-  # The assert exists because the name of the attribute is unversioned
-  # (which is different from previous versions).
-  emacs27 = assert ((exposed.lib.versions.major nixpkgs.emacs.version) == "27");
-    nixpkgs.emacs.overrideAttrs(old: {
-      configureFlags = old.configureFlags ++ [ "--with-cairo" ];
-    });
-
-  emacs27-nox = assert ((exposed.lib.versions.major nixpkgs.emacs.version) == "27");
-    nixpkgs.emacs-nox;
-
-  # Make NixOS available
-  nixos = import "${nixpkgsSrc}/nixos";
-})
+# There are two categories of third-party programs:
+#
+# 1) Programs in nixpkgs, the NixOS package set. For these, you might
+#    want to look at //third_party/nixpkgs (for the package set
+#    imports) and //third_party/overlays (for modifications in these
+#    imported package sets).
+#
+# 2) Third-party software packaged in this repository. This is all
+#    other folders below //third_party, other than the ones mentioned
+#    above.
+
+{ pkgs, ... }:
+
+{
+  # Expose a partially applied NixOS, expecting an attribute set with
+  # a `configuration` key. Exposing it like this makes it possible to
+  # modify some of the base configuration used by NixOS. passed to
+  # this.
+  nixos = import "${pkgs.path}/nixos";
+}