In my project there are some headers which almost using in all files. So, to increase the speed of building I've decided to use Pre-compiled headers. I'm using CMake 3.15 and clang++. In CMake 3.16 we can use target_precompile_headers(). But in 3.15 it is not available.
I will try to explain a sample here. I have common headers such as engine.h, wheel.h, door.h. These files are stored at my_proj/includes/ directory. And these headers are including in all my subprojects.
I would like to know how to make and use them as pre-compiled headers in cmake 3.15 from scartch.