cmake: Replace distutils.sysconfig with sysconfig

This commit replaces uses of distutils.sysconfig's get_python_lib()
function with sysconfig's near-equivalent get_path() function to get the
directory for site-specific, platform-specific files. Unfortunately,
get_path() does not have a way to easily modify or strip the prefix
applied to the path like get_python_lib() does, so the code must
manually modify the path to get the same effect:

- First, the platlib path is retrieved from the get_path() call.
- Next, the default base that is used to form the pathlib path is
queried via the get_config_var('base') call.
- Next, the portion of the platlib path that matches the default base is
stripped, and any leading path separator remaining is stripped. This
fundamentally replicates the behavior of get_python_lib() with an empty
prefix (i.e., the prefix positional parameter is specified as '').
- If a different prefix is desired, then the os.path.join() function is
used to combine the new prefix with the stripped pathlib path, ensuring
that the platform-specific path separator is used in crafting the path.

host/python/CMakeLists.txt

@@ -42,7 +42,7 @@ if(WIN32)
 else()
     execute_process(
         COMMAND "${PYTHON_EXECUTABLE}" -c
-        "from distutils.sysconfig import get_config_var; print(get_config_var('EXT_SUFFIX'))"
+        "from sysconfig import get_config_var; print(get_config_var('EXT_SUFFIX'))"
         OUTPUT_VARIABLE PYTHON_EXTENSION_SUFFIX
     )
     string(STRIP ${PYTHON_EXTENSION_SUFFIX} PYTHON_EXTENSION_SUFFIX)
@@ -159,7 +159,7 @@ if(HAVE_PYTHON_VIRTUALENV)
     # In virtualenvs, let setuptools do its thing
     install(CODE "execute_process(COMMAND ${PYTHON_EXECUTABLE} ${SETUP_PY} -q install --force)")
 else()
-    # Otherwise, use distutils to determine the correct relative path for Python
+    # Otherwise, use sysconfig to determine the correct relative path for Python
     # packages, and install to our prefix
     if(NOT DEFINED UHD_PYTHON_DIR)
         if(WIN32)
@@ -168,14 +168,18 @@ else()
             # a blank prefix, which returns only the Python library relative
             # path, and use that in the install step below.
             execute_process(COMMAND ${PYTHON_EXECUTABLE} -c
-                "from distutils import sysconfig;\
-                print(sysconfig.get_python_lib(plat_specific=True, prefix=''));"
+                "import sysconfig;\
+                platlib = sysconfig.get_path(name='platlib');\
+                base = sysconfig.get_config_var('base');\
+                print(platlib.replace(base, '').lstrip('\\\\'));"
                 OUTPUT_VARIABLE UHD_PYTHON_DIR OUTPUT_STRIP_TRAILING_WHITESPACE
             )
         else()
             execute_process(COMMAND ${PYTHON_EXECUTABLE} -c
-                "from distutils import sysconfig;\
-                print(sysconfig.get_python_lib(plat_specific=True, prefix='${CMAKE_INSTALL_PREFIX}'));"
+                "import sysconfig; import os.path; \
+                platlib = sysconfig.get_path(name='platlib');\
+                base = sysconfig.get_config_var('base');\
+                print(os.path.join('${CMAKE_INSTALL_PREFIX}', platlib.replace(base, '').lstrip('/')));"
                 OUTPUT_VARIABLE UHD_PYTHON_DIR OUTPUT_STRIP_TRAILING_WHITESPACE
             )
         endif(WIN32)
@@ -184,9 +188,9 @@ else()
 
     message(STATUS "Utilizing the python install directory: ${UHD_PYTHON_DIR}")
     # CMake will create an up-to-date copy of the entire Python module within
-    # the build directory. Instead of using setuptools, we use distutils (above)
-    # to figure out the destination path, and then we simply copy this module
-    # recursively into its final destination.
+    # the build directory. Use sysconfig (above) to figure out the destination
+    # path, and then we simply copy this module recursively into its final
+    # destination.
     install(DIRECTORY
         ${CMAKE_CURRENT_BINARY_DIR}/uhd
         DESTINATION ${UHD_PYTHON_DIR}

mpm/python/CMakeLists.txt

@@ -101,7 +101,10 @@ add_custom_command(OUTPUT ${OUTPUT}
 add_custom_target(usrp_mpm ALL DEPENDS ${OUTPUT} pyusrp_periphs)
 
 execute_process(COMMAND ${PYTHON_EXECUTABLE} -c
-    "from __future__ import print_function; from distutils import sysconfig; print(sysconfig.get_python_lib(plat_specific=True, prefix=''))"
+    "import sysconfig;\
+    platlib = sysconfig.get_path(name='platlib');\
+    base = sysconfig.get_config_var('base');\
+    print(platlib.replace(base, '').lstrip('/\\\\'))"
     OUTPUT_VARIABLE USRP_MPM_PYTHON_DIR OUTPUT_STRIP_TRAILING_WHITESPACE
 )
 install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/build/lib/usrp_mpm DESTINATION ${USRP_MPM_PYTHON_DIR})

tools/gr-usrptest/cmake/Modules/GrPython.cmake

@@ -105,8 +105,10 @@ endmacro(GR_PYTHON_CHECK_MODULE)
 ########################################################################
 if(NOT DEFINED GR_PYTHON_DIR)
 execute_process(COMMAND ${PYTHON_EXECUTABLE} -c "
-from distutils import sysconfig
-print sysconfig.get_python_lib(plat_specific=True, prefix='')
+import sysconfig
+platlib = sysconfig.get_path(name='platlib')
+base = sysconfig.get_config_var('base')
+print(platlib.replace(base, '').lstrip('/\\\\'))
 " OUTPUT_VARIABLE GR_PYTHON_DIR OUTPUT_STRIP_TRAILING_WHITESPACE
 )
 endif()