<p dir="auto">Packages that use setup_requires=["numpy"] in their setup.py appear to fail to build on Windows+Py3.8.</p>
<h3 dir="auto">Reproducing code example:</h3>
<p dir="auto"><a href="https://github.com/anntzer/setup_requires-numpy">https://github.com/anntzer/setup_requires-numpy</a> is a minimal repro with just the following setup.py:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="from setuptools import setup

setup(
    name=&quot;testpkg&quot;,
    setup_requires=[&quot;numpy&quot;],
)"><pre class="notranslate"><code class="notranslate">from setuptools import setup

setup(
    name="testpkg",
    setup_requires=["numpy"],
)
</code></pre></div>
<p dir="auto">and is "built" (<code class="notranslate">python setup.py build</code>) on Azure on {linux,mac,windows}+{py3.7,py3.8}.</p>
<p dir="auto">The resulting build is at <a href="https://dev.azure.com/anntzer/setup_requires-numpy/_build/results?buildId=158" rel="nofollow">https://dev.azure.com/anntzer/setup_requires-numpy/_build/results?buildId=158</a><br>
As one can see, all builds succeed except windows+Py3.8, which fails with</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Traceback (most recent call last):
  File &quot;setup.py&quot;, line 3, in &lt;module&gt;
    setup(
  File &quot;C:\hostedtoolcache\windows\Python\3.8.0\x64\lib\site-packages\setuptools\__init__.py&quot;, line 144, in setup
    _install_setup_requires(attrs)
  File &quot;C:\hostedtoolcache\windows\Python\3.8.0\x64\lib\site-packages\setuptools\__init__.py&quot;, line 139, in _install_setup_requires
    dist.fetch_build_eggs(dist.setup_requires)
…distutils.errors.DistutilsError: Setup script exited with error: SandboxViolation: mkd…sers\\VSSADM~1\\AppData\\Local\\Temp\\easy_install-0gx4h9jy\\numpy-1.17.3\\build', 511) {}

The package setup script has attempted to modify files on your system
that are not within the EasyInstall build area, and has been aborted.

This package cannot be safely installed by EasyInstall, and may not
support alternate installation locations even if you run its setup
script by hand.  Please inform the package's author and the EasyInstall
maintainers to find out if a fix or workaround is available."><pre class="notranslate"><code class="notranslate">Traceback (most recent call last):
  File "setup.py", line 3, in &lt;module&gt;
    setup(
  File "C:\hostedtoolcache\windows\Python\3.8.0\x64\lib\site-packages\setuptools\__init__.py", line 144, in setup
    _install_setup_requires(attrs)
  File "C:\hostedtoolcache\windows\Python\3.8.0\x64\lib\site-packages\setuptools\__init__.py", line 139, in _install_setup_requires
    dist.fetch_build_eggs(dist.setup_requires)
…distutils.errors.DistutilsError: Setup script exited with error: SandboxViolation: mkd…sers\\VSSADM~1\\AppData\\Local\\Temp\\easy_install-0gx4h9jy\\numpy-1.17.3\\build', 511) {}

The package setup script has attempted to modify files on your system
that are not within the EasyInstall build area, and has been aborted.

This package cannot be safely installed by EasyInstall, and may not
support alternate installation locations even if you run its setup
script by hand.  Please inform the package's author and the EasyInstall
maintainers to find out if a fix or workaround is available.
</code></pre></div>
<h3 dir="auto">Error message:</h3>
<p dir="auto">see above</p>
<h3 dir="auto">Numpy/Python version information:</h3>
<p dir="auto">numpy 1.17.3, Python 3.8</p>
<p dir="auto">I didn't see this error reported, apologies if it is a duplicate -- my current numpy is 1.6.2.</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="$ sudo easy_install --upgrade numpy
Searching for numpy
Reading http://pypi.python.org/simple/numpy/
Reading http://numpy.scipy.org
Reading http://sourceforge.net/project/showfiles.php?group_id=1369&amp;package_id=175103
Reading http://www.numpy.org
Reading http://sourceforge.net/projects/numpy/files/NumPy/
Reading http://numeric.scipy.org
Best match: numpy 1.7.0
Downloading http://pypi.python.org/packages/source/n/numpy/numpy-1.7.0.zip#md5=ca27913c59393940e880fab420f985b4
Processing numpy-1.7.0.zip
Running numpy-1.7.0/setup.py -q bdist_egg --dist-dir /tmp/easy_install-vw2DNu/numpy-1.7.0/egg-dist-tmp-gJGWkL
Running from numpy source directory.
error: SandboxViolation: open('/dev/null', 'w') {}

The package setup script has attempted to modify files on your system
that are not within the EasyInstall build area, and has been aborted.

This package cannot be safely installed by EasyInstall, and may not
support alternate installation locations even if you run its setup
script by hand.  Please inform the package's author and the EasyInstall
maintainers to find out if a fix or workaround is available."><pre class="notranslate"><code class="notranslate">$ sudo easy_install --upgrade numpy
Searching for numpy
Reading http://pypi.python.org/simple/numpy/
Reading http://numpy.scipy.org
Reading http://sourceforge.net/project/showfiles.php?group_id=1369&amp;package_id=175103
Reading http://www.numpy.org
Reading http://sourceforge.net/projects/numpy/files/NumPy/
Reading http://numeric.scipy.org
Best match: numpy 1.7.0
Downloading http://pypi.python.org/packages/source/n/numpy/numpy-1.7.0.zip#md5=ca27913c59393940e880fab420f985b4
Processing numpy-1.7.0.zip
Running numpy-1.7.0/setup.py -q bdist_egg --dist-dir /tmp/easy_install-vw2DNu/numpy-1.7.0/egg-dist-tmp-gJGWkL
Running from numpy source directory.
error: SandboxViolation: open('/dev/null', 'w') {}

The package setup script has attempted to modify files on your system
that are not within the EasyInstall build area, and has been aborted.

This package cannot be safely installed by EasyInstall, and may not
support alternate installation locations even if you run its setup
script by hand.  Please inform the package's author and the EasyInstall
maintainers to find out if a fix or workaround is available.
</code></pre></div>