lazy import of `_sysconfig` in `Lib/ctypes/__init__.py` is eager on android and cygwin

[asottile]

Bug report

(this was found using some recent static analysis capabilities I added to pyflakes -- it searches for lazy imports which are used at the module scope within the module)

$ git grep -El '^lazy (from|import)' -- '*.py' | xargs pyflakes 2> /dev/null | grep ' eager use'
Lib/ctypes/__init__.py:560:23: eager use of lazily imported '_sysconfig' from line 7
Lib/ctypes/__init__.py:562:23: eager use of lazily imported '_sysconfig' from line 7
Lib/test/test_lazy_import/data/basic_used.py:3:1: eager use of lazily imported 'basic2' from line 1
Lib/test/test_lazy_import/data/lazy_import_pkg.py:2:5: eager use of lazily imported 'test' from line 1

(the latter two are test data which makes sense to ignore)

the ctypes one however appears to be valid:

• lazy import:

  cpython/Lib/ctypes/__init__.py

  Line 7 in 1b015e6

  lazy import sysconfig as _sysconfig

• eager module scope accesses:

  cpython/Lib/ctypes/__init__.py

  Lines 560 to 562 in 1b015e6

  	pythonapi = PyDLL(_sysconfig.get_config_var("LDLIBRARY"))
  	elif _sys.platform == "cygwin":
  	pythonapi = PyDLL(_sysconfig.get_config_var("DLLLIBRARY"))

this appears to be the result of #146547

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

Linked PRs

• gh-158684: Remove ineffective lazy import of sysconfig from ctypes #158793

[ZeroIntensity]

Hmm, is there anything we can actually do about this? It seems that we do need _sysconfig eagerly on those platforms. I suppose we could set up a __getattr__ to lazily evaluate it, but that might be overkill and/or have some unintended side effects.

[picnixz]

Isn't this lazy import still correct for other platforms? I don't think it's an issue per se though? many imports can be lazy because a single function uses them but if no one is using the function we still have a lazy pending import so I don't understand why this should be removed.

[DavidCEllis]

Yes, if the import is only eagerly used on some platforms then it's fine for it to be a lazy import. This isn't a bug.

Edit: I don't see a test that checks the import is lazy in the ctypes tests though, perhaps there should be one for the platforms where this is currently lazy?

[picnixz]

Yes, so IMO we don't need to change anything.