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.

1 files changed, 4 insertions, 1 deletions

diff --git a/mpm/python/CMakeLists.txt b/mpm/python/CMakeLists.txt
index d5106b1b3..260d3bab7 100644
--- a/mpm/python/CMakeLists.txt
+++ b/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})