Fix build scripts for python3 (#1823)

python/CMakeLists.txt

@@ -18,7 +18,7 @@ else(Boost_MINOR_VERSION GREATER 66)
   endif(PY_VERSION_STRIPPED_FIRST_CHAR STREQUAL "2")
 endif(Boost_MINOR_VERSION GREATER 66)
 
-find_package(PythonInterp REQUIRED)
+find_package(PythonInterp ${PY_VERSION} REQUIRED)
 find_package(PythonLibs ${PY_VERSION} REQUIRED)
 find_package(Boost REQUIRED COMPONENTS system python${BOOST_PY_VERSION_SUFFIX})
 

python/pylibvw.cc

@@ -11,7 +11,7 @@
 
 // see http://www.boost.org/doc/libs/1_56_0/doc/html/bbv2/installation.html
 #define BOOST_PYTHON_STATIC_LIB
-
+#define BOOST_PYTHON_USE_GCC_SYMBOL_VISIBILITY 1
 #include <boost/make_shared.hpp>
 #include <boost/python.hpp>
 #include <boost/python/suite/indexing/vector_indexing_suite.hpp>
@@ -701,9 +701,6 @@ void my_set_condition_range(predictor_ptr P, ptag hi, ptag count, char name0) {
 void my_set_learner_id(predictor_ptr P, size_t id) { P->set_learner_id(id); }
 void my_set_tag(predictor_ptr P, ptag t) { P->set_tag(t); }
 
-//We need to forward declare this here to be able to add VW_DLL_MEMBER as BOOST_PYTHON_MODULE doesn't help
-extern "C" VW_DLL_MEMBER void initpylibvw();
-
 BOOST_PYTHON_MODULE(pylibvw)
 { // This will enable user-defined docstrings and python signatures,
   // while disabling the C++ signatures

python/setup.py

@@ -22,8 +22,32 @@ class CMakeExtension(Extension):
     def __init__(self, name):
         # don't invoke the original build_ext for this special extension
         Extension.__init__(self, name, sources=[])
-
+
+def get_ext_filename_without_platform_suffix(filename):
+    from distutils.sysconfig import get_config_var
+    ext_suffix = get_config_var('EXT_SUFFIX')
+    name, ext = os.path.splitext(filename)
+
+    if not ext_suffix:
+        return filename
+
+    if ext_suffix == ext:
+        return filename
+
+    ext_suffix = ext_suffix.replace(ext, '')
+    idx = name.find(ext_suffix)
+
+    if idx == -1:
+        return filename
+    else:
+        return name[:idx] + ext
+
 class BuildPyLibVWBindingsModule(_build_ext):
+    def get_ext_filename(self, ext_name):
+        # don't append the extension suffix to the binary name
+        # see https://stackoverflow.com/questions/38523941/change-cythons-naming-rules-for-so-files/40193040#40193040
+        filename = _build_ext.get_ext_filename(self, ext_name)
+        return get_ext_filename_without_platform_suffix(filename)
 
     def run(self):
         for ext in self.extensions: