[buoh/ci-bump: 3/4] nix: Clean up

[Jan Tojnar <jtojnar src gnome org>]

commit 03af8ba16d1dd328d8683ddc9d17c48ad756dd00
Author: Jan Tojnar <jtojnar gmail com>
Date:   Tue Jul 14 01:21:00 2020 +0200

    nix: Clean up
    
    Rewrite the comments to be more understandable, remove some sharp edges like the need to clean build 
directory, and format the expression.

 README.md   |   2 +-
 default.nix | 111 ++++++++++++++++++++++++++++++++++++++----------------------
 shell.nix   |  17 +++++++---
 3 files changed, 85 insertions(+), 45 deletions(-)
---
diff --git a/README.md b/README.md
index 62ef1f6..991a9b7 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ Buoh aims to help the comic lovers by providing an easy way of browsing and read
 * Merge requests: https://gitlab.gnome.org/GNOME/buoh/merge_requests
 
 ## Building
-For building Buoh, you will need `meson`, `ninja` and `pkgconfig`, as well as the following libraries with 
their development headers.
+For building Buoh, you will need `meson`, `ninja` and `pkg-config`, as well as the following libraries with 
their development headers.
 
 * `glib2`
 * `gtk3`
diff --git a/default.nix b/default.nix
index d53b9a5..13dc285 100644
--- a/default.nix
+++ b/default.nix
@@ -1,25 +1,38 @@
-# How to use?
+/*
 
-# If you have Nix installed, you can get in an environment with everything
-# needed to compile buoh by running:
-# $ nix-shell
-# at the root of the buoh repository.
+How to use?
+***********
 
-# How to tweak default arguments?
+If you have Nix installed, you can get an environment with everything
+needed to compile buoh by running:
 
-# nix-shell supports the --arg option (see Nix doc) that allows you for
-# instance to do this:
-# $ nix-shell --arg doCheck false
+    $ nix-shell
 
-# You can also compile buoh and "install" it by running:
-# $ rm -rf build # (only needed if you have left-over compilation files)
-# $ nix-build
-# at the root of the buoh repository.
-# nix-build also supports the --arg option, so you will be able to do:
-# $ nix-build --arg doCheck false
-# if you want to speed up things by not running the test-suite.
-# Once the build is finished, you will find, in the current directory,
-# a symlink to where buoh was installed.
+at the root of the buoh repository.
+
+You can also compile buoh and ‘install’ it by running:
+
+    $ nix-build
+
+at the root of the buoh repository. The command will install
+buoh to a location under Nix store and create a ‘result’ symlink
+in the current directory pointing to the in-store location.
+
+How to tweak default arguments?
+*******************************
+
+Nix supports the ‘--arg’ option (see nix-build(1)) that allows you
+to override the top-level arguments.
+
+For instance, to use your local copy of nixpkgs:
+
+    $ nix-build --arg pkgs "import $HOME/Projects/nixpkgs {}"
+
+Or to speed up the build by not running the test suite:
+
+    $ nix-build --arg doCheck false
+
+*/
 
 { pkgs ?
     (import (fetchTarball {
@@ -28,43 +41,61 @@
     }) {})
 , doCheck ? true
 , shell ? false
-  # We don't use lib.inNixShell because that would also apply
+  # We do not use lib.inNixShell because that would also apply
   # when in a nix-shell of some package depending on this one.
 }:
 
-with pkgs;
-with stdenv.lib;
-
-stdenv.mkDerivation rec {
-
+let
+  inherit (pkgs.stdenv) lib;
+in pkgs.stdenv.mkDerivation rec {
   name = "buoh";
 
-  nativeBuildInputs = [
-    meson ninja pkgconfig gettext python3 xvfb_run libxslt wrapGAppsHook
+  src =
+    let
+      # Do not copy to the store:
+      # - build directory, since Meson will want to use it
+      # - .git directory, since it would unnecessarily bloat the source
+      cleanSource = path: _: !lib.elem (builtins.baseNameOf path) [ "build" ".git" ];
+    in
+      if shell then null else builtins.filterSource cleanSource ./.;
+
+  # Dependencies for build platform
+  nativeBuildInputs = with pkgs; [
+    meson
+    ninja
+    pkg-config
+    gettext
+    python3
+    xvfb_run
+    libxslt
+    wrapGAppsHook
   ];
 
-  buildInputs = [
-    glib gtk3 libsoup libxml2
+  # Dependencies for host platform
+  buildInputs = with pkgs; [
+    glib
+    gtk3
+    libsoup
+    libxml2
   ];
 
-  checkInputs = [
-    desktop-file-utils appstream-glib
+  checkInputs = with pkgs; [
+    desktop-file-utils
+    appstream-glib
   ];
 
-  src =
-    if shell then null
-    else
-      with builtins; filterSource
-        (path: _: !elem (baseNameOf path) [ ".git" "result" ]) ./.;
+  inherit doCheck;
+
+  # Hardening does not work in debug mode
+  hardeningDisable = lib.optionals shell [ "all" ];
 
   checkPhase = ''
+    runHook preCheck
+
     export NO_AT_BRIDGE=1
     xvfb-run -s '-screen 0 800x600x24' \
       meson test --print-errorlogs
-  '';
-
-  # Hardening does not work in debug mode
-  hardeningDisable = optionals shell [ "all" ];
 
-  inherit doCheck;
+    runHook postCheck
+  '';
 }
diff --git a/shell.nix b/shell.nix
index 3cb7758..ae8057f 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,7 +1,16 @@
-# Some developers don't want a pinned nix-shell by default.
-# If you want to use the pin nix-shell or a more sophisticated set of arguments:
-# $ nix-shell default.nix --arg shell true
+/*
+
+Some developers do not want a pinned package set by default.
+If you want to use the pinned nix-shell or a more sophisticated set of arguments:
+
+    $ nix-shell default.nix --arg shell true
+
+*/
+
+{ pkgs ? import <nixpkgs> {}
+, doCheck ? true
+}:
 import ./default.nix {
-  pkgs = import <nixpkgs> {};
+  inherit pkgs doCheck;
   shell = true;
 }