mumax: new package at v3.10beta (#17398)

This PR creates a new spack package for

mumax: GPU accelerated micromagnetic simulator.

This uses the current beta version because
- it is somewhat dated, ~2018
- it is the only one that supports recent GPU kernels

var/spack/repos/builtin/packages/mumax/package.py

@@ -0,0 +1,62 @@
+# Copyright 2013-2020 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+import os
+import shutil
+
+
+class Mumax(MakefilePackage, CudaPackage):
+    """GPU accelerated micromagnetic simulator."""
+
+    homepage = "http://mumax.github.io"
+    url      = "https://github.com/mumax/3/archive/3.10beta.tar.gz"
+
+    version('3.10beta', sha256='f20fbd90a4b531fe5a0d8acc3d4505a092a5e426f5f53218a22a87d445daf0e9')
+
+    variant('cuda', default=True,
+            description='Use CUDA; must be true')
+    variant('cuda_arch', 'N/A',
+            description='Mumax will build GPU kernels that it supports')
+    variant('gnuplot', default=False,
+            description='Use gnuplot for graphs')
+
+    depends_on('cuda')
+    depends_on('go', type='build')
+    depends_on('gnuplot', type='run', when='+gnuplot')
+
+    conflicts('~cuda', msg='mumax requires cuda')
+
+    patch('https://github.com/mumax/3/commit/2cf5c9a6985c9eb16a124c6bd96aed75b4a30c24.patch',
+          sha256='a43b2ca6c9f9edfb1fd6d916a599f85a57c8bb3f9ee38148b1988fd82feec8ad')
+
+    @property
+    def gopath(self):
+        return self.stage.path
+
+    @property
+    def mumax_gopath_dir(self):
+        return join_path(self.gopath, 'src/github.com/mumax/3')
+
+    def do_stage(self, mirror_only=False):
+        super(Mumax, self).do_stage(mirror_only)
+        if not os.path.exists(self.mumax_gopath_dir):
+            # Need to move source to $GOPATH and then symlink the original
+            # stage directory
+            shutil.move(self.stage.source_path, self.mumax_gopath_dir)
+            force_symlink(self.mumax_gopath_dir, self.stage.source_path)
+
+    # filter out targets that do not exist
+    def edit(self, spec, prefix):
+        filter_file(r'(^ln -sf .*)', r'#\1', 'make.bash')
+        filter_file(r'(^\(cd test)', r'#\1', 'make.bash')
+
+    def setup_build_environment(self, env):
+        env.prepend_path('GOPATH', self.gopath)
+
+    def install(self, spec, prefix):
+        make()
+        with working_dir(self.gopath):
+            install_tree('bin', prefix.bin)