From e664f4aa7b06e1bf78283773c0b1f7dc4cc61674 Mon Sep 17 00:00:00 2001
From: lethosor <lethosor@gmail.com>
Date: Tue, 9 May 2023 21:56:07 -0400
Subject: [PATCH] CMake: fix find_package(Python) when inactive pyenv Python
 installations are present

`find_package(Python)`'s default behavior is to attempt to use any `python3.x`
executables it finds before `python3`. This is problematic when using tools such
as pyenv, where `python3.x` executables may be present in a user's PATH but not
be functional.

Setting the `Python_FIND_UNVERSIONED_NAMES` hint to `FIRST` causes `python3` to
be attempted first, if it exists.

Note that this option was introduced in CMake 3.20:
https://cmake.org/cmake/help/latest/module/FindPython.html#hints
---
 CMakeLists.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4228f45cd..6d1d4c562 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -376,6 +376,9 @@ endif()
 
 #### expose depends ####
 
+# fix for pyenv: default to `python3` before `python3.x`
+set(Python_FIND_UNVERSIONED_NAMES FIRST)
+
 if(UNIX)
     # Rescan for pthread and zlib if the build arch changed
     if(NOT "${DFHACK_BUILD_ARCH}" STREQUAL "${DFHACK_BUILD_ARCH_PREV}")