[issue12919] Control what module is imported first

[STINNER Victor]

STINNER Victor <vstinner at python.org> added the comment:

I close the issue since I see disagreement on the feature request.

Modules/getpath.c and PC/getpathp.c use Lib/os.py to detect the stdlib directory.

_PyUnicode_InitEncodings() is the first function importing modules: to import the Python codec of the filesystem encoding. If this import fails, Python now dumps the "path configuration" to help users to debug their setup. See bpo-38236.

Example:

$ PYTHONHOME=/xxx ./python -c pass
Python path configuration:
  PYTHONHOME = '/xxx'
  PYTHONPATH = (not set)
  program name = './python'
  isolated = 0
  environment = 1
  user site = 1
  import site = 1
  sys._base_executable = '/home/vstinner/python/master/python'
  sys.base_prefix = '/xxx'
  sys.base_exec_prefix = '/xxx'
  sys.executable = '/home/vstinner/python/master/python'
  sys.prefix = '/xxx'
  sys.exec_prefix = '/xxx'
  sys.path = [
    '/xxx/lib/python39.zip',
    '/xxx/lib/python3.9',
    '/xxx/lib/python3.9/lib-dynload',
  ]
Fatal Python error: init_fs_encoding: failed to get the Python codec of the filesystem encoding
Python runtime state: core initialized
ModuleNotFoundError: No module named 'encodings'

Current thread 0x00007f845ca19740 (most recent call first):
<no Python frame>

----------
nosy: +vstinner
resolution:  -> rejected
stage: patch review -> resolved
status: open -> closed

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue12919>
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