Docker: global build directory doesn't match CMake convention

[chopikus]

CMake expects 1-to-1 mapping of a source directory to the build directory. Since our build directory is constant, some errors are possible:

-- west build: generating a build system
CMake Error: The source "/zephyr/samples/basic/blinky/CMakeLists.txt" does not match the source "/workspace/CMakeLists.txt" used to generate cache.  Re-run cmake with a different source directory.
FATAL ERROR: command exited with status 1: /usr/bin/cmake -DWEST_PYTHON=//.venv/bin/python3 -B/build -GNinja -DBOARD=reel_board -S/zephyr/samples/basic/blinky

Command:

west build -p always -b nucleo_h753zi apps/pay

Right now, a user has to do rm -rf /build before building a different app to fix the issue.

Here are a few options to proceed with this:

1. Keep everything as is
2. Use per-app build directory, like /build/pay, /build/blinky. But then the flash and debug scripts have to know what path is zephyr.elf under.
3. Add steps to west build to remove the build directory (not sure if that's possible)

[mshinjo]

Do you have a procedure on how to reproduce this issue?
Running west build -p always -b nucleo_h753zi apps/pay and then west build -p always -b nucleo_h753zi apps/obc didn't have issues.
I think running rm -rf build/ is fine. I do that instead of -p every time and believe it's a standard practice everywhere. I use rm -rf instead of make clean for example.

[alexapostolu]

I'm not sure, but I think the issue arose from trying to build in the /zephyr/ directory