Revamp nix flake for nix-tools (#2010)

* Rework static-nix-tool

* Remove buildkite configuration

* Use exeName for packages

* Move nix-tools to its own overlay

* Remove nix-prefetch-git from nix-tools closure

* Uhm....

* Make clear that nix-tools are compiled with a single GHC

* Fix error if attribute is missing

* Restore testing truncate-index

* Add some tests

* Add missing --accept-flake-config

* Update materialisations

* Reword warning

* Fix tests

* WIP

* WIP: move everything nix-tools related to the subflake

* Better name

* Remove unused binding

* Strip compiler name from nix-tools, there's only one

* Almost fix importing nix-tools overlay

* Actually fix importing nix-tools's overlay

* Only one nix-tools-unchecked

* Make sure exes and project are also exposed by nix-tools.${compiler-nix-name}

* Temporarily restore internal-nix-tools

* Fix truncate-index test

* Temporarily disable static tarballs

* Move nix-tools back to ghc 8.10.7

* Update materialized plan after changing the compiler

* ifdLevel 0

* ifdLevel 1

* ifdLevel 2

* Use the same index-state as haskell.nix internal one

* ifdLevel 0

* ifdLevel 1

* Try index-state 2023-07-03T00:00:00Z

* And update the materialisation

* Only check materialization `nix-tools` when told to

* ifdLevel 2

* ifdLevel 3

---------

Co-authored-by: Hamish Mackenzie <Hamish.K.Mackenzie@gmail.com>

Author: andreabedini

.github/workflows/pipeline.yml

@@ -234,9 +234,8 @@ jobs:
       - name: "Check hix -- run github:haskell/cabal/3.10#cabal-install:exe:cabal -- --version"
         run: "HIX_DIR=$(mktemp -d) nix run .#hix --accept-flake-config -- run github:haskell/cabal/3.10#cabal-install:exe:cabal --accept-flake-config --override-input haskellNix . -- --version"
 
-  nix-tools-build:
+  nix-tools:
     runs-on: [self-hosted, linux]
     steps:
       - uses: actions/checkout@v3
-      - name: "nix-tools build"
-        run: cd ./nix-tools && .buildkite/nix-tools-build.sh
+      - run: nix build ./nix-tools#checks.x86_64-linux.truncate-index --accept-flake-config

build.nix

@@ -94,7 +94,7 @@ in rec {
     check-closure-size = pkgs.buildPackages.callPackage ./scripts/check-closure-size.nix {
       # Includes cabal-install since this is commonly used.
       nix-tools = pkgs.linkFarm "common-tools" [
-        { name = "nix-tools";     path = haskell.nix-tools.${compiler-nix-name}; }
+        { name = "nix-tools";     path = haskell.nix-tools; }
         { name = "cabal-install"; path = haskell.cabal-install.${compiler-nix-name}; }
       ];
     };

lib/call-cabal-project-to-nix.nix

@@ -1,4 +1,4 @@
-{ pkgs, runCommand, cacert, index-state-hashes, haskellLib }@defaults:
+{ pkgs, runCommand, cacert, index-state-hashes, haskellLib }:
 { name          ? src.name or null # optional name for better error messages
 , src
 , materialized-dir ? ../materialized
@@ -66,13 +66,13 @@
 let
   inherit (evalPackages.haskell-nix) materialize dotCabal;
 
-  # These defaults are hear rather than in modules/cabal-project.nix to make them
+  # These defaults are here rather than in modules/cabal-project.nix to make them
   # lazy enough to avoid infinite recursion issues.
   # Using null as the default also improves performance as they are not forced by the
   # nix module system for `nix-tools-unchecked` and `cabal-install-unchecked`.
   nix-tools = if args.nix-tools or null != null
     then args.nix-tools
-    else evalPackages.haskell-nix.nix-tools-unchecked.${compiler-nix-name};
+    else evalPackages.haskell-nix.nix-tools-unchecked;
   cabal-install = if args.cabal-install or null != null
     then args.cabal-install
     else evalPackages.haskell-nix.cabal-install-unchecked.${compiler-nix-name};
@@ -148,8 +148,6 @@ in let
     then index-state
     else pkgs.lib.last (builtins.attrNames index-state-hashes);
 
-  pkgconfPkgs = import ./pkgconf-nixpkgs-map.nix pkgs;
-
   # If a hash was not specified find a suitable cached index state to
   # use that will contain all the packages we need.  By using the
   # first one after the desired index-state we can avoid recalculating