custom build step after preprocessor with cmake

Question

I'm trying to add a custom build step after the preprocessing using cmake.

After the c++ preprocessor step, I want to call a python script on each preprocessed source files to modify them. Here a Makefile example:

all : prog

#compilation step
prog: main.i
    gcc main.i -g -Wall -o prog 

#custom step
main.i: main.tmp
    ./my_script.py main.tmp > main.i

#only preprocessor step
main.tmp: main.c main.h
    gcc -E main.c > main.tmp

how to achieve this with cmake ? The step should be applied on each c or cpp files of the project.

Answer 1

Indeed, this had to be done manualy : I added a custom target where I generate the preprocessed files:

    add_custom_target(
    start_preprocessor 
    COMMAND make main.cpp.i 
    ..
    )

with another custom target, I make a backup of main.cpp and then rename main.cpp.i into main.cpp. I can then apply my preprocessing process. Afterwards, I restore the source files.