Compilation error on MacOS Sierra

[Andreas Jung]

I am trying to install lxml (3.X) as part of a package dependency on Mac Sierra.
(Out of a sudden) I receive these compilation errors:

Running lxml-3.8.0/setup.py -q bdist_egg --dist-dir /var/folders/vb/sp03lr6n46l4jk2sc5ymv2n00000gn/T/easy_install-suwitwmy/lxml-3.8.0/egg-dist-tmp-mnbvl9ru
Building lxml version 3.8.0.
Building without Cython.
Using build configuration of libxslt 1.1.29
Building against libxml2/libxslt in the following directory: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/lib
clang: warning: argument unused during compilation: '-pthread' [-Wunused-command-line-argument]
Undefined symbols for architecture x86_64:
  "_PyPyArg_UnpackTuple", referenced from:
      ___Pyx_Coroutine_Throw in lxml.etree.o
  "_PyPyBaseObject_Type", referenced from:
      ___pyx_tp_new_4lxml_5etree__Element in lxml.etree.o
      ___pyx_tp_new_4lxml_5etree__ElementTree in lxml.etree.o
      ___pyx_tp_new_4lxml_5etree__ElementTagMatcher in lxml.etree.o
      ___pyx_tp_new_4lxml_5etree__ElementIterator in lxml.etree.o
      ___pyx_tp_new_4lxml_5etree_ElementBase in lxml.etree.o
      ___pyx_tp_new_4lxml_5etree_ElementClassLookup in lxml.etree.o
      ___pyx_tp_new_4lxml_5etree_FallbackElementClassLookup in lxml.etree.o
      ...
  "_PyPyBool_Type", referenced from:
      ___pyx_f_4lxml_5etree__wrapXPathObject in lxml.etree.o
  "_PyPyBytes_AS_STRING", referenced from:
      ___pyx_f_4lxml_5etree__makeElement in lxml.etree.o
      ___pyx_f_4lxml_5etree__makeSubElement in lxml.etree.o
      ___pyx_f_4lxml_5etree__setAttributeValue in lxml.etree.o
      ___pyx_f_4lxml_5etree__delAttribute in lxml.etree.o
      ___pyx_f_4lxml_5etree__utf8 in lxml.etree.o
      ___pyx_f_4lxml_5etree__namespacedNameFromNsName in lxml.etree.o
      ___pyx_f_4lxml_5etree_9_Document__findOrBuildNodeNs in lxml.etree.o

[scoder (scoder)]

Is it intentional that you are building against PyPy? In that case, please use the latest PyPy and the latest lxml.

[Andreas Jung (ajung)]

PyPy?

I have a local Python 3.6 virtualenv running.

There is no PyPy involved on my system...PyPy is somehow installed but actually never used it (intentionally)...I am using Homebrew

[Andreas Jung (ajung)]

But thanks for opening my eyes...somehow the PyPy virtualenv got created by a Makefile. The installed `virtualenv` binary pointed to PyPy.