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cmake: resolve an issue finding main python lib for more corner cases (…
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…#815)

* harden cmake python lib detection logic
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@cyrush
cyrush committed Aug 11, 2021
1 parent 7e6918c commit d01a9c5
Showing 1 changed file with 106 additions and 42 deletions.
148 changes: 106 additions & 42 deletions src/cmake/thirdparty/SetupPython.cmake
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Expand Up @@ -4,14 +4,29 @@

# Find the interpreter first
if(PYTHON_DIR AND NOT PYTHON_EXECUTABLE)
set(PYTHON_EXECUTABLE ${PYTHON_DIR}/bin/python)
if(UNIX)
set(PYTHON_EXECUTABLE ${PYTHON_DIR}/bin/python)
# if this doesn't exist, we may be using python3, which
# in many variants only creates "python3" exe, not "python"
if(NOT EXISTS "${PYTHON_EXECUTABLE}")
set(PYTHON_EXECUTABLE ${PYTHON_DIR}/bin/python3)
endif()
elseif(WIN32)
set(PYTHON_EXECUTABLE ${PYTHON_DIR}/python.exe)
endif()
endif()

find_package(PythonInterp REQUIRED)
if(PYTHONINTERP_FOUND)

MESSAGE(STATUS "PYTHON_EXECUTABLE ${PYTHON_EXECUTABLE}")


execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
"import sys;from distutils.sysconfig import get_config_var; sys.stdout.write(get_config_var('VERSION'))"
OUTPUT_VARIABLE PYTHON_CONFIG_VERSION
ERROR_VARIABLE ERROR_FINDING_PYTHON_VERSION)
MESSAGE(STATUS "PYTHON_CONFIG_VERSION $PYTHON_CONFIG_VERSION}")

execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
"import sys;from distutils.sysconfig import get_python_inc;sys.stdout.write(get_python_inc())"
OUTPUT_VARIABLE PYTHON_INCLUDE_DIR
Expand All @@ -32,20 +47,9 @@ if(PYTHONINTERP_FOUND)
MESSAGE(FATAL_ERROR "Reported PYTHON_SITE_PACKAGES_DIR ${PYTHON_SITE_PACKAGES_DIR} does not exist!")
endif()

execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
"import sys;from distutils.sysconfig import get_config_var; sys.stdout.write(get_config_var('LIBDIR'))"
OUTPUT_VARIABLE PYTHON_LIB_DIR
ERROR_VARIABLE ERROR_FINDING_LIB_DIR)
MESSAGE(STATUS "PYTHON_LIB_DIR ${PYTHON_LIB_DIR}")

# if we are on macOS or linux, expect PYTHON_LIB_DIR to exist
# windows logic does not need PYTHON_LIB_DIR
if(NOT WIN32 AND NOT EXISTS ${PYTHON_LIB_DIR})
MESSAGE(FATAL_ERROR "Reported PYTHON_LIB_DIR ${PYTHON_LIB_DIR} does not exist!")
endif()


# check if we need "-undefined dynamic_lookup" by inspecting LDSHARED flags
execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
"import sys;import sysconfig;sys.stdout.write(sysconfig.get_config_var('LDSHARED'))"
OUTPUT_VARIABLE PYTHON_LDSHARED_FLAGS
ERROR_VARIABLE ERROR_FINDING_PYTHON_LDSHARED_FLAGS)
Expand All @@ -60,45 +64,105 @@ if(PYTHONINTERP_FOUND)
set(PYTHON_USE_UNDEFINED_DYNAMIC_LOOKUP_FLAG OFF)
endif()

# our goal is to find the specific python lib, based on info
# we extract from distutils.sysconfig from the python executable
#
# check for python libs differs for windows python installs
if(NOT WIN32)
# we may build a shared python module against a static python
# check for both shared and static libs cases

# check for shared first
set(PYTHON_GLOB_TEST "${PYTHON_LIB_DIR}/libpython*${CMAKE_SHARED_LIBRARY_SUFFIX}")
FILE(GLOB PYTHON_GLOB_RESULT ${PYTHON_GLOB_TEST})
# then for static if shared is not found
if(NOT PYTHON_GLOB_RESULT)
set(PYTHON_GLOB_TEST "${PYTHON_LIB_DIR}/libpython*${CMAKE_STATIC_LIBRARY_SUFFIX}")
endif()
else()
if(PYTHON_LIB_DIR)
set(PYTHON_GLOB_TEST "${PYTHON_LIB_DIR}/python*.lib")
else()
get_filename_component(PYTHON_ROOT_DIR ${PYTHON_EXECUTABLE} DIRECTORY)
set(PYTHON_GLOB_TEST "${PYTHON_ROOT_DIR}/libs/python*.lib")
# combos to try:
# shared:
# LIBDIR + LDLIBRARY
# LIBPL + LDLIBRARY
# static:
# LIBDIR + LIBRARY
# LIBPL + LIBRARY

execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
"import sys;from distutils.sysconfig import get_config_var; sys.stdout.write(get_config_var('LIBDIR'))"
OUTPUT_VARIABLE PYTHON_CONFIG_LIBDIR
ERROR_VARIABLE ERROR_FINDING_PYTHON_LIBDIR)

execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
"import sys;from distutils.sysconfig import get_config_var; sys.stdout.write(get_config_var('LIBPL'))"
OUTPUT_VARIABLE PYTHON_CONFIG_LIBPL
ERROR_VARIABLE ERROR_FINDING_PYTHON_LIBPL)

execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
"import sys;from distutils.sysconfig import get_config_var; sys.stdout.write(get_config_var('LDLIBRARY'))"
OUTPUT_VARIABLE PYTHON_CONFIG_LDLIBRARY
ERROR_VARIABLE ERROR_FINDING_PYTHON_LDLIBRARY)

execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
"import sys;from distutils.sysconfig import get_config_var; sys.stdout.write(get_config_var('LIBRARY'))"
OUTPUT_VARIABLE PYTHON_CONFIG_LIBRARY
ERROR_VARIABLE ERROR_FINDING_PYTHON_LIBRARY)

message(STATUS "PYTHON_CONFIG_LIBDIR: ${PYTHON_CONFIG_LIBDIR}")
message(STATUS "PYTHON_CONFIG_LIBPL: ${PYTHON_CONFIG_LIBPL}")
message(STATUS "PYTHON_CONFIG_LDLIBRARY: ${PYTHON_CONFIG_LDLIBRARY}")
message(STATUS "PYTHON_CONFIG_LIBRARY: ${PYTHON_CONFIG_LIBRARY}")

set(PYTHON_LIBRARY "")
# look for shared libs first
# shared libdir + ldlibrary
if(NOT EXISTS ${PYTHON_LIBRARY})
if(IS_DIRECTORY ${PYTHON_CONFIG_LIBDIR})
set(_PYTHON_LIBRARY_TEST "${PYTHON_CONFIG_LIBDIR}/${PYTHON_CONFIG_LDLIBRARY}")
message(STATUS "Checking for python library at: ${_PYTHON_LIBRARY_TEST}")
if(EXISTS ${_PYTHON_LIBRARY_TEST})
set(PYTHON_LIBRARY ${_PYTHON_LIBRARY_TEST})
endif()
endif()
endif()
endif()

FILE(GLOB PYTHON_GLOB_RESULT ${PYTHON_GLOB_TEST})
# shared libpl + ldlibrary
if(NOT EXISTS ${PYTHON_LIBRARY})
if(IS_DIRECTORY ${PYTHON_CONFIG_LIBPL})
set(_PYTHON_LIBRARY_TEST "${PYTHON_CONFIG_LIBPL}/${PYTHON_CONFIG_LDLIBRARY}")
message(STATUS "Checking for python library at: ${_PYTHON_LIBRARY_TEST}")
if(EXISTS ${_PYTHON_LIBRARY_TEST})
set(PYTHON_LIBRARY ${_PYTHON_LIBRARY_TEST})
endif()
endif()
endif()

# make sure we found something
if(NOT PYTHON_GLOB_RESULT)
message(FATAL_ERROR "Failed to find main python library using pattern: ${PYTHON_GLOB_TEST}")
endif()
# static: libdir + library
if(NOT EXISTS ${PYTHON_LIBRARY})
if(IS_DIRECTORY ${PYTHON_CONFIG_LIBDIR})
set(_PYTHON_LIBRARY_TEST "${PYTHON_CONFIG_LIBDIR}/${PYTHON_CONFIG_LIBRARY}")
message(STATUS "Checking for python library at: ${_PYTHON_LIBRARY_TEST}")
if(EXISTS ${_PYTHON_LIBRARY_TEST})
set(PYTHON_LIBRARY ${_PYTHON_LIBRARY_TEST})
endif()
endif()
endif()

if(NOT WIN32)
# life is ok on windows, but elsewhere
# the glob result might be a list due to symlinks, etc
# if it is a list, select the first entry as py lib
list(LENGTH PYTHON_GLOB_RESULT PYTHON_GLOB_RESULT_LEN)
if(${PYTHON_GLOB_RESULT_LEN} GREATER 1)
list(GET PYTHON_GLOB_RESULT 0 PYTHON_GLOB_RESULT)
# static: libpl + library
if(NOT EXISTS ${PYTHON_LIBRARY})
if(IS_DIRECTORY ${PYTHON_CONFIG_LIBPL})
set(_PYTHON_LIBRARY_TEST "${PYTHON_CONFIG_LIBPL}/${PYTHON_CONFIG_LIBRARY}")
message(STATUS "Checking for python library at: ${_PYTHON_LIBRARY_TEST}")
if(EXISTS ${_PYTHON_LIBRARY_TEST})
set(PYTHON_LIBRARY ${_PYTHON_LIBRARY_TEST})
endif()
endif()
endif()
else() # windows
get_filename_component(PYTHON_ROOT_DIR ${PYTHON_EXECUTABLE} DIRECTORY)
# Note: this assumes that two versions of python are not installed in the same dest dir
set(_PYTHON_LIBRARY_TEST "${PYTHON_ROOT_DIR}/libs/python${PYTHON_CONFIG_VERSION}.lib")
message(STATUS "Checking for python library at: ${_PYTHON_LIBRARY_TEST}")
if(EXISTS ${_PYTHON_LIBRARY_TEST})
set(PYTHON_LIBRARY ${_PYTHON_LIBRARY_TEST})
endif()
endif()

get_filename_component(PYTHON_LIBRARY "${PYTHON_GLOB_RESULT}" ABSOLUTE)
if(NOT EXISTS ${PYTHON_LIBRARY})
MESSAGE(FATAL_ERROR "Failed to find main library using PYTHON_EXECUTABLE=${PYTHON_EXECUTABLE}")
endif()

MESSAGE(STATUS "{PythonLibs from PythonInterp} using: PYTHON_LIBRARY=${PYTHON_LIBRARY}")
find_package(PythonLibs)
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