> Trying to build numpy-1.11.2rc1 wheels for Python 3.6.0b1 on Windows 10 with `python.exe setup.py bdist_wheel`, python36.dll (32 and 64 bit) segfaults in the `find_maxchar_surrogates` function.

I ran "python setup.py bdist_wheel" on numpy-1.11.2rc1 on Linux: no issue.

I compiled Python 3.6 (the default branch in fact, so the future 3.7) in debug mode/64 bit with SSL, but the setup.py command failed with:

   Don't know how to compile Fortran code on platform 'nt'

I don't want to spend too much time to try to reproduce the issue.

Can you please try to get the Python traceback? Try:

   python -X faulthandler setup.py bdist_wheel

It seems like the crash occurs in parse_envlist(), function to parse environment variables in os.spawnve(). Can you try to dump the env parameter of os.spawnve()?

For example, you can put the following lines at the beginning of setup.py:

---
import os
orig_spawnve = os.spawnve

def log_spawnve(*args):
    print("spawnve: %r" % (args,))
    return orig_spawnve(*args)

os.spawnve = log_spawnve
---

My test:
---
>>> import os, sys; args=[sys.executable, "-c", "pass"]; os.spawnve(os.P_WAIT, args[0], args, None)
spawnve: (0, '/home/haypo/prog/python/default/python', ['/home/haypo/prog/python/default/python', '-c', 'pass'], None)
127
---