Fail to install with pip on MacOS 11.5.2 using Python 3.7.9

❯ sudo pip install PyInquirer==1.0.3
WARNING: The directory '/Users/user/Library/Caches/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you should use sudo's -H flag.
Collecting PyInquirer==1.0.3
  Downloading PyInquirer-1.0.3.tar.gz (27 kB)
  Preparing metadata (setup.py) ... error
  ERROR: Command errored out with exit status 1:
   command: /opt/local/Library/Frameworks/Python.framework/Versions/3.7/bin/python3.7 -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/tmp/pip-install-qqqdkx0s/pyinquirer_23b366c6d14e46e1a7f1380c04ab8b8a/setup.py'"'"'; __file__='"'"'/private/tmp/pip-install-qqqdkx0s/pyinquirer_23b366c6d14e46e1a7f1380c04ab8b8a/setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(__file__) if os.path.exists(__file__) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /private/tmp/pip-pip-egg-info-z5j0iug5
       cwd: /private/tmp/pip-install-qqqdkx0s/pyinquirer_23b366c6d14e46e1a7f1380c04ab8b8a/
  Complete output (13 lines):
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/setuptools/__init__.py", line 19, in <module>
      from setuptools.dist import Distribution
    File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/setuptools/dist.py", line 38, in <module>
      from setuptools import windows_support
    File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/setuptools/windows_support.py", line 2, in <module>
      import ctypes
    File "/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/ctypes/__init__.py", line 7, in <module>
      from _ctypes import Union, Structure, Array
  ImportError: dlopen(/opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/lib-dynload/_ctypes.cpython-37m-darwin.so, 2): Library not loaded: /opt/local/lib/libffi.7.dylib
    Referenced from: /opt/local/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/lib-dynload/_ctypes.cpython-37m-darwin.so
    Reason: image not found
  ----------------------------------------
WARNING: Discarding https://files.pythonhosted.org/packages/fb/4c/434b7c454010a284b49d6f1d446fe8dc5960415613d8c0225b9e2efb6724/PyInquirer-1.0.3.tar.gz#sha256=c9a92d68d7727fbd886a7908c08fd9e9773e5dc211bf5cbf836ba90d366dee51 (from https://pypi.org/simple/pyinquirer/). Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.
ERROR: Could not find a version that satisfies the requirement PyInquirer==1.0.3 (from versions: 1.0.0, 1.0.2, 1.0.3)
ERROR: No matching distribution found for PyInquirer==1.0.3

[guedesfelipe]

if it worked, you can close the issue

[douglaslassance]

Found people talking about this here. sudo ln /opt/local/lib/libffi.8.dylib /opt/local/lib/libffi.7.dylib fixed it for me. Not sure how this lib got to be missing in the first place.