From 10252e9f66ac87f3903f301b64320d32457f0658 Mon Sep 17 00:00:00 2001 From: Chris Lalancette Date: Fri, 16 Feb 2024 14:43:02 -0500 Subject: [PATCH] Set hints to find the python version we actually want. (#2426) The comment in the commit explains the reasoning behind it. Signed-off-by: Chris Lalancette --- rclcpp/CMakeLists.txt | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/rclcpp/CMakeLists.txt b/rclcpp/CMakeLists.txt index cad17103b7..1f78d03d59 100644 --- a/rclcpp/CMakeLists.txt +++ b/rclcpp/CMakeLists.txt @@ -1,4 +1,4 @@ -cmake_minimum_required(VERSION 3.12) +cmake_minimum_required(VERSION 3.20) project(rclcpp) @@ -127,6 +127,21 @@ set(${PROJECT_NAME}_SRCS src/rclcpp/waitable.cpp ) +# By default, without the settings below, find_package(Python3) will attempt +# to find the newest python version it can, and additionally will find the +# most specific version. For instance, on a system that has +# /usr/bin/python3.10, /usr/bin/python3.11, and /usr/bin/python3, it will find +# /usr/bin/python3.11, even if /usr/bin/python3 points to /usr/bin/python3.10. +# The behavior we want is to prefer the "system" installed version unless the +# user specifically tells us othewise through the Python3_EXECUTABLE hint. +# Setting CMP0094 to NEW means that the search will stop after the first +# python version is found. Setting Python3_FIND_UNVERSIONED_NAMES means that +# the search will prefer /usr/bin/python3 over /usr/bin/python3.11. And that +# latter functionality is only available in CMake 3.20 or later, so we need +# at least that version. +cmake_policy(SET CMP0094 NEW) +set(Python3_FIND_UNVERSIONED_NAMES FIRST) + find_package(Python3 REQUIRED COMPONENTS Interpreter) # "watch" template for changes