How do I see a C/C++ source file after preprocessing in STM32CubeIDE

[HPam.1]

I want to check if the preprocessing are correctly adding my function macros

[TDK]

Use the "Preprocess only" checkbox. After that, the converted files will be in the build directory with a "*.o" extension.

[HPam.1]

I checked the "Preprocess only" in all the places , and I open my Debug folder and sub directories ,I could not find the *.o extension. Am I doing it correctly?

EDIT: I found the main.o at last. It's in the sub directory users folder