flatpak: clean up and add comments

pkgs/development/libraries/flatpak/default.nix

@@ -1,7 +1,52 @@
-{ stdenv, fetchurl, autoreconfHook, docbook_xml_dtd_412, docbook_xml_dtd_42, docbook_xml_dtd_43, docbook_xsl, which, libxml2
-, gobject-introspection, gtk-doc, intltool, libxslt, pkgconfig, xmlto, appstream-glib, substituteAll, glibcLocales, yacc, xdg-dbus-proxy, p11-kit
-, bubblewrap, bzip2, dbus, glib, gpgme, json-glib, libarchive, libcap, libseccomp, coreutils, gettext, hicolor-icon-theme, fuse, nixosTests
-, libsoup, lzma, ostree, polkit, python3, systemd, xorg, valgrind, glib-networking, wrapGAppsHook, dconf, gsettings-desktop-schemas, librsvg }:
+{ stdenv
+, fetchurl
+, autoreconfHook
+, docbook_xml_dtd_412
+, docbook_xml_dtd_42
+, docbook_xml_dtd_43
+, docbook_xsl
+, which
+, libxml2
+, gobject-introspection
+, gtk-doc
+, intltool
+, libxslt
+, pkgconfig
+, xmlto
+, appstream-glib
+, substituteAll
+, glibcLocales
+, yacc
+, xdg-dbus-proxy
+, p11-kit
+, bubblewrap
+, bzip2
+, dbus
+, glib
+, gpgme
+, json-glib
+, libarchive
+, libcap
+, libseccomp
+, coreutils
+, gettext
+, hicolor-icon-theme
+, fuse
+, nixosTests
+, libsoup
+, lzma
+, ostree
+, polkit
+, python3
+, systemd
+, xorg
+, valgrind
+, glib-networking
+, wrapGAppsHook
+, dconf
+, gsettings-desktop-schemas
+, librsvg
+}:
 
 stdenv.mkDerivation rec {
   pname = "flatpak";
@@ -16,41 +61,91 @@ stdenv.mkDerivation rec {
   };
 
   patches = [
+    # Hardcode paths used by tests and change test runtime generation to use files from Nix store.
+    # https://github.com/flatpak/flatpak/issues/1460
     (substituteAll {
       src = ./fix-test-paths.patch;
       inherit coreutils gettext glibcLocales;
       hicolorIconTheme = hicolor-icon-theme;
     })
+
+    # Hardcode paths used by Flatpak itself.
     (substituteAll {
       src = ./fix-paths.patch;
       p11 = p11-kit;
     })
+
+    # Adapt paths exposed to sandbox for NixOS.
     (substituteAll {
       src = ./bubblewrap-paths.patch;
       inherit (builtins) storeDir;
     })
-    # patch taken from gtk_doc
+
+    # Allow gtk-doc to find schemas using XML_CATALOG_FILES environment variable.
+    # Patch taken from gtk-doc expression.
     ./respect-xml-catalog-files-var.patch
+
+    # Don’t hardcode flatpak binary path in launchers stored under user’s profile otherwise they will break after Flatpak update.
+    # https://github.com/NixOS/nixpkgs/issues/43581
     ./use-flatpak-from-path.patch
+
+    # Nix environment hacks should not leak into the apps.
+    # https://github.com/NixOS/nixpkgs/issues/53441
     ./unset-env-vars.patch
+
+    # But we want the GDK_PIXBUF_MODULE_FILE from the wrapper affect the icon validator.
     ./validate-icon-pixbuf.patch
   ];
 
   nativeBuildInputs = [
-    autoreconfHook libxml2 docbook_xml_dtd_412 docbook_xml_dtd_42 docbook_xml_dtd_43 docbook_xsl which gobject-introspection
-    gtk-doc intltool libxslt pkgconfig xmlto appstream-glib yacc wrapGAppsHook
+    autoreconfHook
+    libxml2
+    docbook_xml_dtd_412
+    docbook_xml_dtd_42
+    docbook_xml_dtd_43
+    docbook_xsl
+    which
+    gobject-introspection
+    gtk-doc
+    intltool
+    libxslt
+    pkgconfig
+    xmlto
+    appstream-glib
+    yacc
+    wrapGAppsHook
   ];
 
   buildInputs = [
-    bubblewrap bzip2 dbus dconf glib gpgme json-glib libarchive libcap libseccomp
-    libsoup lzma ostree polkit python3 systemd xorg.libXau fuse
-    gsettings-desktop-schemas glib-networking
+    bubblewrap
+    bzip2
+    dbus
+    dconf
+    glib
+    gpgme
+    json-glib
+    libarchive
+    libcap
+    libseccomp
+    libsoup
+    lzma
+    ostree
+    polkit
+    python3
+    systemd
+    xorg.libXau
+    fuse
+    gsettings-desktop-schemas
+    glib-networking
     librsvg # for flatpak-validate-icon
   ];
 
-  checkInputs = [ valgrind ];
+  checkInputs = [
+    valgrind
+  ];
 
-  doCheck = false; # TODO: some issues with temporary files
+  # TODO: some issues with temporary files
+  doCheck = false;
 
   NIX_LDFLAGS = "-lpthread";
 
@@ -65,8 +160,8 @@ stdenv.mkDerivation rec {
   ];
 
   makeFlags = [
-    "installed_testdir=$(installedTests)/libexec/installed-tests/flatpak"
-    "installed_test_metadir=$(installedTests)/share/installed-tests/flatpak"
+    "installed_testdir=${placeholder "installedTests"}/libexec/installed-tests/flatpak"
+    "installed_test_metadir=${placeholder "installedTests"}/share/installed-tests/flatpak"
   ];
 
   postPatch = ''
@@ -82,7 +177,7 @@ stdenv.mkDerivation rec {
 
   meta = with stdenv.lib; {
     description = "Linux application sandboxing and distribution framework";
-    homepage = https://flatpak.org/;
+    homepage = "https://flatpak.org/";
     license = licenses.lgpl21;
     maintainers = with maintainers; [ jtojnar ];
     platforms = platforms.linux;