[cmake] Create FindPythonInterpreter for host information

cmake/modules/FindPython.cmake

@@ -20,7 +20,6 @@
 #
 # PYTHON_FOUND - system has PYTHON
 # PYTHON_VERSION - Python version number (Major.Minor)
-# PYTHON_EXECUTABLE - Python interpreter binary
 # PYTHON_INCLUDE_DIRS - the python include directory
 # PYTHON_LIBRARIES - The python libraries
 # PYTHON_LDFLAGS - Python provided link options
@@ -76,23 +75,12 @@ if(KODI_DEPENDSBUILD)
   endif()
 
   list(APPEND Python3_LIBRARIES ${LZMA_LIBRARY} ${FFI_LIBRARY} ${EXPAT_LIBRARY} ${INTL_LIBRARY} ${GMP_LIBRARY} ${PYTHON_DEP_LIBRARIES})
-else()
-  if(CORE_SYSTEM_NAME STREQUAL linux)
-    if(HOST_CAN_EXECUTE_TARGET)
-      find_package(Python3 ${VERSION} ${EXACT_VER} COMPONENTS Interpreter)
-    else()
-      find_package(Python3 COMPONENTS Interpreter)
-    endif()
-  endif()
 endif()
 
 if(Python3_FOUND)
   list(APPEND PYTHON_DEFINITIONS -DHAS_PYTHON=1)
   # These are all set for easy integration with the rest of our build system
   set(PYTHON_FOUND ${Python3_FOUND})
-  if(NOT PYTHON_EXECUTABLE)
-    set(PYTHON_EXECUTABLE ${Python3_EXECUTABLE} CACHE FILEPATH "Python interpreter" FORCE)
-  endif()
   set(PYTHON_INCLUDE_DIRS ${Python3_INCLUDE_DIRS})
   set(PYTHON_LIBRARIES ${Python3_LIBRARIES})
   set(PYTHON_VERSION "${Python3_VERSION_MAJOR}.${Python3_VERSION_MINOR}" CACHE INTERNAL "" FORCE)

cmake/modules/buildtools/FindPythonInterpreter.cmake

@@ -0,0 +1,56 @@
+# FindPython
+# --------
+# Finds Python3 Interpreter
+#
+# This module will search for a Python3 Interpreter
+#
+# --------
+#
+# the following variables influence behaviour:
+#
+# PYTHON_INTERPRETER_PATH - use external python not found in system paths
+#                           usage: -DPYTHON_INTERPRETER_PATH=/path/to/python3
+#
+# --------
+#
+# This will define the following variable:
+#
+#  PYTHON_EXECUTABLE - The HOST python executable
+#
+
+# We limit search paths to rule out TARGET paths that will populate the default cmake/package paths
+# Note: we do not do a find_package call as it will populate targets based on HOST
+# information and pollute the TARGET python searches when required for actual target platform.
+find_program(PYTHON3_INTERPRETER_EXECUTABLE NAMES python3 python
+                                            HINTS ${PYTHON_INTERPRETER_PATH} ${NATIVEPREFIX}/bin
+                                            NO_CACHE
+                                            NO_PACKAGE_ROOT_PATH
+                                            NO_CMAKE_PATH
+                                            NO_CMAKE_ENVIRONMENT_PATH
+                                            NO_CMAKE_INSTALL_PREFIX)
+
+if(PYTHON3_INTERPRETER_EXECUTABLE)
+  execute_process(COMMAND "${PYTHON3_INTERPRETER_EXECUTABLE}" --version
+                  OUTPUT_VARIABLE PYTHON3_INTERPRETER_VERSION
+                  OUTPUT_STRIP_TRAILING_WHITESPACE)
+  string(REGEX REPLACE "^Python (.*)" "\\1" PYTHON3_INTERPRETER_VERSION "${PYTHON3_INTERPRETER_VERSION}")
+
+  include(FindPackageHandleStandardArgs)
+  find_package_handle_standard_args(PythonInterpreter
+                                    REQUIRED_VARS PYTHON3_INTERPRETER_EXECUTABLE PYTHON3_INTERPRETER_VERSION
+                                    VERSION_VAR PYTHON3_INTERPRETER_VERSION)
+
+  if(PythonInterpreter_FOUND)
+    # We explicitly use a CACHE variable instead of a TARGET as execute_command is not
+    # able to use a TARGET - https://gitlab.kitware.com/cmake/cmake/-/issues/18364
+    set(PYTHON_EXECUTABLE ${PYTHON3_INTERPRETER_EXECUTABLE} CACHE FILEPATH "Host Python interpreter" FORCE)
+  else()
+    if(PythonInterpreter_FIND_REQUIRED)
+      message(FATAL_ERROR "A python3 interpreter was not found. Consider providing path using -DPYTHON_INTERPRETER_PATH=<path/to/python3>")
+    endif()
+  endif()
+else()
+  if(PythonInterpreter_FIND_REQUIRED)
+    message(FATAL_ERROR "A python3 interpreter was not found. Consider providing path using -DPYTHON_INTERPRETER_PATH=<path/to/python3>")
+  endif()
+endif()

cmake/scripts/linux/Install.cmake

@@ -194,6 +194,7 @@ install(FILES ${CMAKE_BINARY_DIR}/${CORE_BUILD_DIR}/scripts/${APP_NAME}Config.cm
         COMPONENT kodi-addon-dev)
 
 if(ENABLE_EVENTCLIENTS)
+  find_package(PythonInterpreter REQUIRED)
   execute_process(COMMAND ${PYTHON_EXECUTABLE} -c "from distutils.sysconfig import get_python_lib; print(get_python_lib(prefix=''))"
                   OUTPUT_VARIABLE PYTHON_LIB_PATH OUTPUT_STRIP_TRAILING_WHITESPACE)
   # Install kodi-eventclients-common BT python files