nix: provide package in release tarballs

.gitignore

@@ -82,3 +82,4 @@ GTAGS
 *.dsc
 *.gcov
 spot.spec
+default.nix

Makefile.am

@@ -65,7 +65,8 @@ EXTRA_DIST = HACKING ChangeLog.1 tools/gitlog-to-changelog	\
 	     tools/help2man tools/man2html.pl			\
 	     tools/test-driver-teamcity $(UTF8) $(DEBIAN)	\
 	     m4/gnulib-cache.m4 .dir-locals.el			\
-	     spot.spec spot.spec.in README.ltsmin
+	     spot.spec spot.spec.in README.ltsmin		\
+	     default.nix default.nix.in
 
 dist-hook: gen-ChangeLog
 
@@ -111,3 +112,6 @@ deb: dist
 
 spot.spec: configure.ac spot.spec.in
 	sed 's/[@]VERSION[@]/$(VERSION)/;s/[@]GITPATCH[@]/@@@$(GITPATCH)/;s/@@@\.//' spot.spec.in > $@.tmp && mv $@.tmp $@
+
+default.nix: configure.ac default.nix.in
+	sed 's/[@]VERSION[@]/$(VERSION)/' default.nix.in > $@.tmp && mv $@.tmp $@

default.nix.in

@@ -0,0 +1,35 @@
+# -*- mode: nix; coding: utf-8 -*-
+# Copyright (C) 2022 Laboratoire de Recherche et Développement de l'Epita
+# (LRDE).
+#
+# This file is part of Spot, a model checking library.
+#
+# Spot is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Spot is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+{ pkgs ? import <nixpkgs> {} }:
+let
+  version = "@VERSION@";
+in
+pkgs.stdenv.mkDerivation {
+  inherit version;
+  pname = "spot";
+
+  buildInputs = [
+    pkgs.python3
+  ];
+
+  src = ./.;
+
+  enableParallelBuilding = true;
+}