随手记录 CMake：Could NOT find Python3

前言

其实之前成功过 作死... 安装了一下gtest 然后不止为何python3.8就映射过来了，也可能不是gtest的锅，反正就是突然make不成功了，报错内容：

(missing: Python3_INCLUDE_DIRS Python3_LIBRARIES Python3_NumPy_INCLUDE_DIRS Development NumPy Development.Module Development.Embed) (found version "3.8.12")

暂且直接用test_ws 新建workspace 只有一个cmakelist进行测试：

cmake_minimum_required(VERSION 3.16)
find_package(Python3 COMPONENTS NumPy)# 

if (Python3_FOUND)
  message(STATUS "Python3_EXECUTABLE: ${Python3_EXECUTABLE}")
  message(STATUS "_Python3_EXECUTABLE: ${_Python3_EXECUTABLE}\n")
 
  message(STATUS "Python3_INCLUDE_DIR: ${Python3_INCLUDE_DIR}")
  message(STATUS "_Python3_INCLUDE_DIR: ${_Python3_INCLUDE_DIR}\n")
 
  message(STATUS "Python3_LIBRARY_DEBUG: ${Python3_LIBRARY_DEBUG}")
  message(STATUS "_Python3_LIBRARY_DEBUG: ${_Python3_LIBRARY_DEBUG}\n")
 
  message(STATUS "Python3_LIBRARY_RELEASE: ${Python3_LIBRARY_RELEASE}")
  message(STATUS "_Python3_LIBRARY_RELEASE: ${_Python3_LIBRARY_RELEASE}\n")
 
  message(STATUS "Python3_NumPy_INCLUDE_DIR: ${Python3_NumPy_INCLUDE_DIR}")
  message(STATUS "_Python3_NumPy_INCLUDE_DIR: ${_Python3_NumPy_INCLUDE_DIR}\n")
endif()

相关参考链接

---

1. cmake 官方文档，有关python3

2. Cannot import numpy in Python 3.7 or Python 3.8 - Ubuntu 18.04

3. How to uninstall python 3.8 from Ubuntu after deleting the folder Python-3.8.0 using “rm -rf”?

4. gtest missing方案

错误示意

相关细节性错误复制，基本全都是这个：

CMake Error at xxx/CMakeLists.txt:51 (add_library):
  Target "xxx" links to target "Python3::Python" but the target was
  not found.  Perhaps a find_package() call is missing for an IMPORTED
  target, or an ALIAS target is missing?

心路历程

都… 这么老油条了 还找了近半个小时的解法

1. 首先想到的就是切conda，直接用环境

   然后宣告失败，切完后 有些protobuf，google相关包 路径找不到，摘取错误：

   fatal error: google/protobuf/port_def.inc: No such file or directory
   

2. 安装numpy

   pip3 install numpy

   宣告失败，走了10分钟才发现哦吼，这个怎么找到了python 3.8.12的版本去了，而我系统的python3是链接到python3.6的所以即使这样做也不能有效

3. set好路径

   set(Python3_INCLUDE_DIR /usr/include/python3.6)
   set(Python3_LIBRARIES /usr/lib/x86_64-linux-gnu/libpython3.6m.so)
   set(Python3_NumPy_INCLUDE_DIR /usr/lib/python3/dist-packages/numpy/core/include)
   

   失败，因为… Python3 Find那里 并不会根据set的路径找

4. 直接卸载3.8

   一开始sudo apt remove python-3.8 还不行，非得卸干净了才行（我也不知道为啥我系统上有3.8 正常不走ros我都是conda yyds!!!）

   sudo apt-get -y purge python3.8
   sudo apt-get -y autoremove
   

   随后经过干净的卸载 emmm 然后就找到了

多说一句 记得删除build devel出来的文件夹 再catkin_make