EnTT: added new package at v3.5.2 (#19021)

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

@@ -0,0 +1,28 @@
+# 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)
+class Entt(CMakePackage):
+    """EnTT is a header-only, tiny and easy to use library for game
+    programming and much more written in modern C++, mainly known for its
+    innovative entity-component-system (ECS) model.
+    """
+
+    homepage = "https://entt.docsforge.com"
+    url = "https://github.com/skypjack/entt/archive/v3.5.2.tar.gz"
+
+    version('3.5.2', sha256='f9271293c44518386c402c9a2188627819748f66302df48af4f6d08e30661036')
+
+    depends_on('cmake@3.7.0:', type='build')
+    depends_on('doxygen@1.8.0:', type='build')
+
+    # TODO: This list is not comprehensive, we might want to extend it later
+    compiler_warning = 'EnTT requires a compiler with support for C++17'
+    conflicts('%apple-clang@:10.1', msg=compiler_warning)
+    conflicts('%clang@:6', msg=compiler_warning)
+    conflicts('%gcc@:7.1', msg=compiler_warning)
+
+    def cmake_args(self):
+        return [
+            '-DBUILD_DOCS=ON'
+        ]