New package: bat (#15345)

* New package: bat

Add package for bat:

     A cat(1) clone with wings.

* Update copyright date

* Embiggen comment re build env settings

Provide a bit more explanatory text about why setup_build_environment
needs to set LLVM_CONFIG_PATH and LIBCLANG_PATH.

Co-authored-by: George Hartzell <ghartzell@audentestx.com>

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

@@ -0,0 +1,29 @@
+# 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 *
+
+
+class Bat(Package):
+    """A cat(1) clone with wings."""
+
+    homepage = "https://github.com/sharkdp/bat"
+    url      = "https://github.com/sharkdp/bat/archive/v0.10.0.tar.gz"
+
+    version('0.12.1', sha256='1dd184ddc9e5228ba94d19afc0b8b440bfc1819fef8133fe331e2c0ec9e3f8e2')
+
+    depends_on('rust')
+
+    def install(self, spec, prefix):
+        cargo = which('cargo')
+        cargo('install', '--root', prefix, '--path', '.')
+
+    # cargo seems to need these to be set so that when it's building
+    # onig_sys it can run llvm-config and link against libclang.
+    def setup_build_environment(self, env):
+        env.append_flags('LLVM_CONFIG_PATH',
+                         join_path(self.spec['llvm'].prefix.libexec.llvm,
+                                   'llvm-config'))
+        env.append_flags('LIBCLANG_PATH', self.spec['llvm'].prefix.lib)