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ms-iot / ROSOnWindows

ROS on Windows Documentation Repository
https://aka.ms/ros/docs
MIT License
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catkin_make fails to find proper python env #196

Open mgdelmonte opened 4 years ago

mgdelmonte commented 4 years ago

The setup script c:\opt\ros\melodic\x64\setup.bat properly sets the PYTHONHOME env var, but it does not set PYTHON_EXECUTABLE, which catkin_make references independently. On a system with many python interpreters, this means catkin_make uses the wrong environment entirely (it uses the environment of the first-found interpreter, and not the one in PYTHONHOME).

I'd call this a bug in catkin_make, unless they have a good reason (unlikely) for using a random interpreter. But nevertheless this appears to happen only on Windows.

To reproduce, install two python 2 environments and then ROS using the second environment. Then install any ROS repo and run catkin_make. Unless both python environments have empy It will fail with "python can't find library em..." (meaning empy).

Workaround: manually add that PYTHON_EXECUTABLE env var to the ROS setup. It must have the full path to the python executable. (But you can't add it to setup.bat because it's autogenerated.)

OS: Windows 10 Chocolatey: v0.10.15

AB#509410

ooeygui commented 4 years ago

Thank you for the writeup and investigation. We've been trying to map the ROS environment to a locally installed python path in c:\opt, so that it is isolated from potentially tainted environments outside of the ROS environment.

IoTDan commented 1 year ago

we will consider checking PYTHONHOME in the setup and offer a warning during setup that a previous python environment was detected. the user can still click to continue setup.