FindPython3Alt.cmake

# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

# This module finds the libraries corresponding to the Python 3 interpreter
# and the NumPy package, and sets the following variables:
# - PYTHON_EXECUTABLE
# - PYTHON_INCLUDE_DIRS
# - PYTHON_LIBRARIES
# - PYTHON_OTHER_LIBS
# - NUMPY_INCLUDE_DIRS

if(Python3Alt_FOUND)
  return()
endif()

set(Python3Alt_FIND_PACKAGE_OPTIONS)
set(Python3Alt_NumPy_FIND_PACKAGE_OPTIONS)
if(Python3Alt_FIND_VERSION)
  list(APPEND Python3Alt_FIND_PACKAGE_OPTIONS ${Python3Alt_FIND_VERSION})
endif()
if(Python3Alt_FIND_REQUIRED)
  list(APPEND Python3Alt_FIND_PACKAGE_OPTIONS REQUIRED)
  list(APPEND Python3Alt_NumPy_FIND_PACKAGE_OPTIONS REQUIRED)
endif()
if(Python3Alt_FIND_QUIETLY)
  list(APPEND Python3Alt_FIND_PACKAGE_OPTIONS QUIET)
  list(APPEND Python3Alt_NumPy_FIND_PACKAGE_OPTIONS QUIET)
endif()

if(CMAKE_VERSION VERSION_LESS 3.18.0)
  # We need libpython to be present, so ask for the full "Development"
  # component on CMake < 3.18, where "Development.Module" is not
  # available.
  find_package(Python3 ${Python3Alt_FIND_PACKAGE_OPTIONS} COMPONENTS Interpreter
                                                                     Development NumPy)
else()
  find_package(Python3 ${Python3Alt_FIND_PACKAGE_OPTIONS}
               COMPONENTS Interpreter Development.Module NumPy)
endif()

if(NOT Python3_FOUND)
  return()
endif()

set(PYTHON_EXECUTABLE ${Python3_EXECUTABLE})
set(PYTHON_INCLUDE_DIRS ${Python3_INCLUDE_DIRS})
set(PYTHON_LIBRARIES ${Python3_LIBRARIES})
set(PYTHON_OTHER_LIBS)

get_target_property(NUMPY_INCLUDE_DIRS Python3::NumPy INTERFACE_INCLUDE_DIRECTORIES)

# CMake's python3_add_library() doesn't apply the required extension suffix,
# detect it ourselves.
# (https://gitlab.kitware.com/cmake/cmake/issues/20408)
execute_process(COMMAND "${PYTHON_EXECUTABLE}" "-c"
                        "import sysconfig; print(sysconfig.get_config_var('EXT_SUFFIX'))"
                RESULT_VARIABLE _PYTHON_RESULT
                OUTPUT_VARIABLE _PYTHON_STDOUT
                ERROR_VARIABLE _PYTHON_STDERR)

if(NOT _PYTHON_RESULT MATCHES 0)
  if(Python3Alt_FIND_REQUIRED)
    message(FATAL_ERROR "Python 3 config failure:\n${_PYTHON_STDERR}")
  endif()
endif()

string(STRIP ${_PYTHON_STDOUT} _EXT_SUFFIX)

function(PYTHON_ADD_MODULE name)
  python3_add_library(${name} MODULE ${ARGN})
  set_target_properties(${name} PROPERTIES SUFFIX ${_EXT_SUFFIX})
endfunction()

find_package_handle_standard_args(
  Python3Alt REQUIRED_VARS PYTHON_EXECUTABLE PYTHON_INCLUDE_DIRS NUMPY_INCLUDE_DIRS)