Your English is okay, but let me help clarify your message:
I’ve noticed many similar issue reports, but I haven’t found a solution yet.
When I add a new custom library, I struggle to make it work. I was porting my old EM4100 library from Atmega to ESP32, but I can’t even test it. I can include it, and it gets linked, but no function works:
init_em4100() --> undefined reference.
So, I created a very basic library called test with only one function
test(). The linker/compiler recognizes the library but always ends with an ‘undefined reference’.
What am I overlooking?
please take a look to my ide