From 91acf58e953fd6e609788e955d84eab9822d5aa4 Mon Sep 17 00:00:00 2001
From: Sam James <sam@gentoo.org>
Date: Fri, 9 Jun 2023 09:58:11 +0100
Subject: [PATCH 5/6] Respect Gentoo's Python eclasses

[imported from 2.8.10.2-FindPythonLibs.patch]
[imported from 3.9.0_rc2-FindPythonInterp.patch]

Signed-off-by: Sam James <sam@gentoo.org>
--- a/Modules/FindPythonInterp.cmake
+++ b/Modules/FindPythonInterp.cmake
@@ -91,6 +91,11 @@ if(PythonInterp_FIND_VERSION)
 else()
     set(_PYTHON_FIND_OTHER_VERSIONS ${_PYTHON3_VERSIONS} ${_PYTHON2_VERSIONS} ${_PYTHON1_VERSIONS})
 endif()
+
+if (CMAKE_GENTOO_BUILD OR CMAKE_BUILD_TYPE STREQUAL Gentoo)
+    set(_Python_NAMES python)
+endif()
+
 find_program(PYTHON_EXECUTABLE NAMES ${_Python_NAMES})
 
 # Set up the versions we know about, in the order we will search. Always add
@@ -115,12 +120,13 @@ unset(_PYTHON2_VERSIONS)
 unset(_PYTHON3_VERSIONS)
 
 # Search for newest python version if python executable isn't found
-if(NOT PYTHON_EXECUTABLE)
+if(NOT PYTHON_EXECUTABLE AND NOT (CMAKE_GENTOO_BUILD OR CMAKE_BUILD_TYPE STREQUAL Gentoo))
     foreach(_CURRENT_VERSION IN LISTS _Python_VERSIONS)
       set(_Python_NAMES python${_CURRENT_VERSION})
       if(CMAKE_HOST_WIN32)
         list(APPEND _Python_NAMES python)
       endif()
+
       find_program(PYTHON_EXECUTABLE
         NAMES ${_Python_NAMES}
         PATHS
--- a/Modules/FindPythonLibs.cmake
+++ b/Modules/FindPythonLibs.cmake
@@ -130,6 +130,19 @@ if(DEFINED PYTHON_VERSION_MAJOR AND DEFINED PYTHON_VERSION_MINOR)
 endif()
 list(APPEND _Python_VERSIONS ${_PYTHON_FIND_OTHER_VERSIONS})
 
+# Gentoo portage requires that you use exactly the given python version
+if (CMAKE_GENTOO_BUILD OR CMAKE_BUILD_TYPE STREQUAL Gentoo)
+    execute_process(COMMAND python -c "import sys; sys.stdout.write('.'.join([str(x) for x in sys.version_info[:2]]))"
+                    OUTPUT_VARIABLE _Gentoo_Python_VERSION)
+    list(FIND _Python_VERSIONS "${_Gentoo_Python_VERSION}" _Gentoo_Python_INDEX)
+    if (_Gentoo_Python_INDEX EQUAL -1)
+       # the current Gentoo python version is not compatible with what is requested
+       set(_Python_VERSIONS)
+    else ()
+       set(_Python_VERSIONS "${_Gentoo_Python_VERSION}")
+    endif ()
+endif()
+
 unset(_PYTHON_FIND_OTHER_VERSIONS)
 unset(_PYTHON1_VERSIONS)
 unset(_PYTHON2_VERSIONS)
-- 
2.41.0