pip/manylinux bug

build-wheels.sh

#!/bin/bash
set -e

# Compile wheels
PYTHONS=(
    cp27-cp27m
    cp27-cp27mu
    )

# remove leftovers from previous builds, if any
rm -rf /foo/build

for pydir in "${PYTHONS[@]}"; do
    pybin=/opt/python/$pydir/bin
    echo $pydir

    # if you downgrade to pip==20.0.2, it works
    #"${pybin}/pip" install -U pip==20.0.2

    "${pybin}/python" -V
    "${pybin}/pip" --version
    "${pybin}/python" -c 'import setuptools; print "setuptools", setuptools.__version__'
    echo
    echo "creating wheel"
    "${pybin}/pip" wheel /foo/ -w wheelhouse/

    # if you uncomment the next line and manually remove the build directory
    # between runs, it works
    #rm -rf /foo/build

    whl=/wheelhouse/foo-*-$pydir-*.whl
    echo
    echo "inspecting $whl"
    pushd `mktemp -d`
    unzip -q $whl
    objdump -T foo.so | grep PyUnicode
    "${pybin}/pip" install $whl
    "${pybin}/python" -c 'import foo'
    popd
    echo
    echo
done

foo.c

#include <Python.h>

static PyObject* hello(PyObject* self, PyObject* args)
{
    return PyUnicode_FromString("hello world");
}

static PyMethodDef FooMethods[] = {
    {"hello", (PyCFunction)hello, METH_NOARGS, ""},
    {NULL, NULL, 0, NULL}
};

PyMODINIT_FUNC
initfoo(void)
{
    PyObject* m;
    m = Py_InitModule("foo", FooMethods);
}

setup.py

from setuptools import setup, Extension

setup(name="foo",
      ext_modules = [
          Extension('foo', ['foo.c']),
      ])