utils: avoid using internal _imp.is_frozen()

imp has been deprecated for a long time, and were removed in Python 3.12 . As a
workaround, we started using the internal _imp. That is ugly and risky.

It seems less risky to get the functionality in some other way. Here, we just
inspect if 'origin' of the '__main__' module is set and 'frozen'. That seems to
work and do the same, and might be better than using the internal _imp
directly.

This way of inspecting module attributes seems to work in some test cases, but
it is a risky change. This level of importlib doesn't have much documentation,
a complicated implementation, and we are dealing with some odd use cases.

mercurial/utils/resourceutil.py

@@ -1,120 +1,122
 # resourceutil.py - utility for looking up resources
 #
 #  Copyright 2005 K. Thananchayan <[e-mail]>
 #  Copyright 2005-2007 Olivia Mackall <[e-mail]>
 #  Copyright 2006 Vadim Gelfer <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 
-import _imp
 import os
 import sys
 
 from .. import pycompat
 
 
 def mainfrozen():
     """return True if we are a frozen executable.
 
     The code supports py2exe (most common, Windows only) and tools/freeze
     (portable, not much used).
     """
     return (
         hasattr(sys, "frozen")  # new py2exe
         or hasattr(sys, "importers")  # old py2exe
-        or _imp.is_frozen("__main__")  # tools/freeze
+        or getattr(
+            getattr(sys.modules.get('__main__'), '__spec__', None),
+            'origin',
+            None,
+        )
+        == 'frozen'  # tools/freeze
     )
 
 
 # the location of data files matching the source code
 if mainfrozen() and getattr(sys, "frozen", None) != "macosx_app":
     # executable version (py2exe) doesn't support __file__
     datapath = os.path.dirname(pycompat.sysexecutable)
     _rootpath = datapath
 
     # The installers store the files outside of library.zip, like
     # C:\Program Files\Mercurial\defaultrc\*.rc.  This strips the
     # leading "mercurial." off of the package name, so that these
     # pseudo resources are found in their directory next to the
     # executable.
     def _package_path(package):
         dirs = package.split(b".")
         assert dirs[0] == b"mercurial"
         return os.path.join(_rootpath, *dirs[1:])
 
-
 else:
     datapath = os.path.dirname(os.path.dirname(pycompat.fsencode(__file__)))
     _rootpath = os.path.dirname(datapath)
 
     def _package_path(package):
         return os.path.join(_rootpath, *package.split(b"."))
 
 
 try:
     # importlib.resources exists from Python 3.7; see fallback in except clause
     # further down
     from importlib import resources  # pytype: disable=import-error
 
     # Force loading of the resources module
     if hasattr(resources, 'files'):
         resources.files  # pytype: disable=module-attr
     else:
         resources.open_binary  # pytype: disable=module-attr
 
     # py2exe raises an AssertionError if uses importlib.resources
     if getattr(sys, "frozen", None) in ("console_exe", "windows_exe"):
         raise ImportError
 
 except (ImportError, AttributeError):
     # importlib.resources was not found (almost definitely because we're on a
     # Python version before 3.7)
 
     def open_resource(package, name):
         path = os.path.join(_package_path(package), name)
         return open(path, "rb")
 
     def is_resource(package, name):
         path = os.path.join(_package_path(package), name)
 
         try:
             return os.path.isfile(pycompat.fsdecode(path))
         except (IOError, OSError):
             return False
 
     def contents(package):
         path = pycompat.fsdecode(_package_path(package))
 
         for p in os.listdir(path):
             yield pycompat.fsencode(p)
 
-
 else:
     from .. import encoding
 
     def open_resource(package, name):
         if hasattr(resources, 'files'):
             return (
                 resources.files(  # pytype: disable=module-attr
                     pycompat.sysstr(package)
                 )
                 .joinpath(pycompat.sysstr(name))
                 .open('rb')
             )
         else:
             return resources.open_binary(  # pytype: disable=module-attr
                 pycompat.sysstr(package), pycompat.sysstr(name)
             )
 
     def is_resource(package, name):
         return resources.is_resource(  # pytype: disable=module-attr
             pycompat.sysstr(package), encoding.strfromlocal(name)
         )
 
     def contents(package):
         # pytype: disable=module-attr
         for r in resources.contents(pycompat.sysstr(package)):
             # pytype: enable=module-attr
             yield encoding.strtolocal(r)