add emscripten package

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

@@ -0,0 +1,74 @@
+# Copyright 2013-2022 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)
+
+import os
+import re
+import sys
+from textwrap import dedent
+
+from spack import *
+
+
+class Emscripten(Package):
+    """An LLVM-to-WebAssembly Compiler"""
+
+    homepage = "https://emscripten.org"
+    git      = "https://github.com/emscripten-core/emscripten.git"
+    url      = "https://github.com/emscripten-core/emscripten/archive/refs/tags/3.0.0.tar.gz"
+
+    version('latest', branch='main')
+    version('3.0.0', sha256='c5524755b785d8f4b83eb3214fdd3ac4b2e1b1a4644df4c63f06e5968f48f90e')
+
+    executables = ['emcc', 'em\+\+', 'emconfigure', 'emcmake']
+
+    # Need f-strings to run emcc, so 3.7+.
+    depends_on('python@3.7:')
+    depends_on('npm', type='build')
+    depends_on('llvm@14:+lld+clang targets=webassembly')
+    depends_on('binaryen')
+    depends_on('openjdk')
+
+    phases = ['install']
+
+    @classmethod
+    def determine_version(cls, exe_path):
+        try:
+            exe = Executable(exe_path)
+            output = exe('--version', output=str, error=str).splitlines()[0]
+            m = re.search(r' ([0-9]+\.[0-9]+\.[0-9]+(?:\-git)?)$', output)
+            if m is None:
+                return None
+            (v,) = m.groups()
+            return Version(v)
+        except spack.util.executable.ProcessError:
+            pass
+
+        return None
+
+    def install(self, spec, prefix):
+        npm = which('npm')
+        npm('install')
+
+        with open('.emscripten', 'w') as f:
+            f.write(dedent("""\
+            NODE_JS = '{node_js}'
+            LLVM_ROOT = '{llvm}'
+            BINARYEN_ROOT = '{binaryen}'
+            EMSCRIPTEN_ROOT = '{emscripten}'
+            JAVA = '{java}'
+            COMPILER_ENGINE = NODE_JS
+            JS_ENGINES = [NODE_JS]
+            """.format(
+                node_js=str(which('node')),
+                llvm=os.path.dirname(str(which('lld'))),
+                binaryen=str(self.spec['binaryen'].prefix),
+                emscripten=str(prefix),
+                java=str(which('java')),
+            )))
+
+        install_tree('.', str(prefix))
+
+    def setup_run_environment(self, env):
+        env.prepend_path('PATH', self.prefix)