Issue #1761 - Enable use of Tauthon instead of Python 2.7 at build

Make essential Tauthon's builtins and modules available in sandboxes, without
disrupting building with Python 2.7.

1. Allow new builtins and modules. "__build_class__" is for
building... new-style classes (to handle the new metaclass syntax imported from
3.x). "_oserror" is necessary because of internal changes to raise errors
deriving from OSError (which are reported as IOError if not caught).
2. Look for modules and packages in the right places.

This was tested on FreeBSD, and should work out of the box on Linux.

4 files changed, 30 insertions, 16 deletions

diff --git a/python/mozbuild/mozbuild/configure/__init__.py b/python/mozbuild/mozbuild/configure/__init__.py
index 0fe640caee..a59876fcae 100644
--- a/python/mozbuild/mozbuild/configure/__init__.py
+++ b/python/mozbuild/mozbuild/configure/__init__.py
@@ -192,8 +192,9 @@ class ConfigureSandbox(dict):
         b: __builtins__[b]
         for b in ('None', 'False', 'True', 'int', 'bool', 'any', 'all', 'len',
                   'list', 'tuple', 'set', 'dict', 'isinstance', 'getattr',
-                  'hasattr', 'enumerate', 'range', 'zip')
-    }, __import__=forbidden_import, str=unicode)
+                  'hasattr', 'enumerate', 'range', 'zip', '__build_class__')
+        if b in __builtins__},
+    __import__=forbidden_import, str=unicode)
 
     # Expose a limited set of functions from os.path
     OS = ReadOnlyNamespace(path=ReadOnlyNamespace(**{
diff --git a/python/mozbuild/mozbuild/frontend/sandbox.py b/python/mozbuild/mozbuild/frontend/sandbox.py
index 0bf1599f20..3638ec807c 100644
--- a/python/mozbuild/mozbuild/frontend/sandbox.py
+++ b/python/mozbuild/mozbuild/frontend/sandbox.py
@@ -115,7 +115,10 @@ class Sandbox(dict):
     def __init__(self, context, builtins=None, finder=default_finder):
         """Initialize a Sandbox ready for execution.
         """
-        self._builtins = builtins or self.BUILTINS
+        self._builtins = ReadOnlyDict(
+            (builtins or self.BUILTINS).viewitems() |
+            {b: __builtins__[b] for b in ('__build_class__',)
+             if b in __builtins__}.viewitems())
         dict.__setitem__(self, '__builtins__', self._builtins)
 
         assert isinstance(self._builtins, ReadOnlyDict)
diff --git a/python/virtualenv/site.py b/python/virtualenv/site.py
index 4e426cdb66..bf23c19204 100644
--- a/python/virtualenv/site.py
+++ b/python/virtualenv/site.py
@@ -65,6 +65,7 @@ ImportError exception, it is silently ignored.
 
 import sys
 import os
+import platform
 
 try:
     import __builtin__ as builtins
@@ -85,11 +86,14 @@ USER_SITE = None
 USER_BASE = None
 
 _is_64bit = (getattr(sys, 'maxsize', None) or getattr(sys, 'maxint')) > 2**32
+_is_tauthon = platform.python_implementation() == "Tauthon"
 _is_pypy = hasattr(sys, 'pypy_version_info')
 _is_jython = sys.platform[:4] == 'java'
 if _is_jython:
     ModuleType = type(os)
 
+_python_libdir = "tauthon" if _is_tauthon else "python"
+
 def makepath(*paths):
     dir = os.path.join(*paths)
     if _is_jython and (dir == '__classpath__' or
@@ -228,16 +232,16 @@ def addsitepackages(known_paths, sys_prefix=sys.prefix, exec_prefix=sys.exec_pre
 
                 else: # any other Python distros on OSX work this way
                     sitedirs = [os.path.join(prefix, "lib",
-                                             "python" + sys.version[:3], "site-packages")]
+                                             _python_libdir + sys.version[:3], "site-packages")]
 
             elif os.sep == '/':
                 sitedirs = [os.path.join(prefix,
                                          "lib",
-                                         "python" + sys.version[:3],
+                                         _python_libdir + sys.version[:3],
                                          "site-packages"),
                             os.path.join(prefix, "lib", "site-python"),
-                            os.path.join(prefix, "python" + sys.version[:3], "lib-dynload")]
-                lib64_dir = os.path.join(prefix, "lib64", "python" + sys.version[:3], "site-packages")
+                            os.path.join(prefix, _python_libdir + sys.version[:3], "lib-dynload")]
+                lib64_dir = os.path.join(prefix, "lib64", _python_libdir + sys.version[:3], "site-packages")
                 if (os.path.exists(lib64_dir) and
                     os.path.realpath(lib64_dir) not in [os.path.realpath(p) for p in sitedirs]):
                     if _is_64bit:
@@ -252,15 +256,15 @@ def addsitepackages(known_paths, sys_prefix=sys.prefix, exec_prefix=sys.exec_pre
                     pass
                 # Debian-specific dist-packages directories:
                 sitedirs.append(os.path.join(prefix, "local/lib",
-                                             "python" + sys.version[:3],
+                                             _python_libdir + sys.version[:3],
                                              "dist-packages"))
                 if sys.version[0] == '2':
                     sitedirs.append(os.path.join(prefix, "lib",
-                                                 "python" + sys.version[:3],
+                                                 _python_libdir + sys.version[:3],
                                                  "dist-packages"))
                 else:
                     sitedirs.append(os.path.join(prefix, "lib",
-                                                 "python" + sys.version[0],
+                                                 _python_libdir + sys.version[0],
                                                  "dist-packages"))
                 sitedirs.append(os.path.join(prefix, "lib", "dist-python"))
             else:
@@ -583,9 +587,9 @@ def virtual_install_main_packages():
     elif sys.platform == 'win32' and os.sep == '\\':
         paths = [os.path.join(sys.real_prefix, 'Lib'), os.path.join(sys.real_prefix, 'DLLs')]
     else:
-        paths = [os.path.join(sys.real_prefix, 'lib', 'python'+sys.version[:3])]
+        paths = [os.path.join(sys.real_prefix, 'lib', _python_libdir + sys.version[:3])]
         hardcoded_relative_dirs = paths[:] # for the special 'darwin' case below
-        lib64_path = os.path.join(sys.real_prefix, 'lib64', 'python'+sys.version[:3])
+        lib64_path = os.path.join(sys.real_prefix, 'lib64', _python_libdir + sys.version[:3])
         if os.path.exists(lib64_path):
             if _is_64bit:
                 paths.insert(0, lib64_path)
@@ -602,7 +606,7 @@ def virtual_install_main_packages():
             # This is a non-multiarch aware Python.  Fallback to the old way.
             arch = sys.platform
         plat_path = os.path.join(sys.real_prefix, 'lib',
-                                 'python'+sys.version[:3],
+                                 _python_libdir + sys.version[:3],
                                  'plat-%s' % arch)
         if os.path.exists(plat_path):
             paths.append(plat_path)
diff --git a/python/virtualenv/virtualenv.py b/python/virtualenv/virtualenv.py
index e363021cc1..655e25cf01 100755
--- a/python/virtualenv/virtualenv.py
+++ b/python/virtualenv/virtualenv.py
@@ -44,13 +44,14 @@ if sys.version_info < (2, 6):
     print('ERROR: this script requires Python 2.6 or greater.')
     sys.exit(101)
 
+import platform
+
 try:
     basestring
 except NameError:
     basestring = str
 
-py_version = 'python%s.%s' % (sys.version_info[0], sys.version_info[1])
-
+is_tauthon = platform.python_implementation() == "Tauthon"
 is_jython = sys.platform.startswith('java')
 is_pypy = hasattr(sys, 'pypy_version_info')
 is_win = (sys.platform == 'win32' and os.sep == '\\')
@@ -59,6 +60,9 @@ is_msys2 = (sys.platform == 'win32' and os.sep == '/')
 is_darwin = (sys.platform == 'darwin')
 abiflags = getattr(sys, 'abiflags', '')
 
+py_version = '%s%s.%s' % ("tauthon" if is_tauthon else "python",
+                          sys.version_info[0], sys.version_info[1])
+
 user_dir = os.path.expanduser('~')
 if is_win:
     default_storage_dir = os.path.join(user_dir, 'virtualenv')
@@ -121,7 +125,7 @@ REQUIRED_MODULES = ['os', 'posix', 'posixpath', 'nt', 'ntpath', 'genericpath',
                     'fnmatch', 'locale', 'encodings', 'codecs',
                     'stat', 'UserDict', 'readline', 'copy_reg', 'types',
                     're', 'sre', 'sre_parse', 'sre_constants', 'sre_compile',
-                    'zlib']
+                    'zlib', 'platform', 'string']
 
 REQUIRED_FILES = ['lib-dynload', 'config']
 
@@ -131,6 +135,8 @@ if majver == 2:
         REQUIRED_MODULES.extend(['warnings', 'linecache', '_abcoll', 'abc'])
     if minver >= 7:
         REQUIRED_MODULES.extend(['_weakrefset'])
+    if is_tauthon:
+        REQUIRED_MODULES.extend(['_oserror'])
     if is_msys2:
         REQUIRED_MODULES.extend(['functools'])
 elif majver == 3: