How to prevent the entire project from being recompiled due to modifying CMakeLists.txt (IDFGH-13903)

[UradaSources]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

I want to use a library as an idf component but it doesn't come with its own cmake file for idf. There are some cross board files in the library, which I don't need, but I'm not sure which ones I don't need. I can only keep modifying the idf_component_register.SRCS parameters to test, which is a terrible experience. Every time I add even one file to my SOURCE_FILES, it will cause the entire project of more than 1400 source files to be recompiled. I have never hated c++ so much. Is there any way to solve this problem? I also use arduino-esp32 as my component. Maybe there is a way to pre-compile some things as static libraries to reduce compilation time?

set(SOURCE_FILES
    "src/Arduino_DataBus.cpp"
    ...)

idf_component_register(
    INCLUDE_DIRS "src"
    SRCS ${SOURCE_FILES}
    PRIV_REQUIRES "arduino"
)

[dobairoland]

Hi @UradaSources. If I understood your situation correctly then in this case the best and easiest option would be to make sure that you are bulding with ccache enabled. That means it will re-use the previously built source files from the cache if it hasn't been modified.

Depending on your OS and ESP-IDF version, it might be disabled by default. You can force it with the ``--ccache` command line argument:
https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/tools/idf-py.html#global-options