How to add icon to cmake app in windows

cmake_windows_icon.txt

1. Put app.ico in directory.

2. Create app.rc in same directory with one line:
IDI_ICON1               ICON        DISCARDABLE            "app.ico"

3. Run command (Warning: it's app.o, not app.res, how it is mentioned in other manuals!)
windres app.rc -o app.o

4. add_executable(app
  ...
  app.o
)

5. Proofit!

Generate the object file is not a good way for cross platform, this can add the icon on Windows by my test.

Hi! I was using this method but actually discovered you can simply add the ".rc" file to the sources and it should just work...

how do i use the icon with multiple windows?