New in version 3.16.

Setting this property to true ensures the source file will be skipped by unity builds when its associated target has its UNITY_BUILD property set to true. The source file will instead be compiled on its own in the same way as it would with unity builds disabled.

This property helps with "ODR (One definition rule)" problems where combining a particular source file with others might lead to build errors or other unintended side effects.

Note that sources which are scanned for C++ modules (see cmake-cxxmodules(7)) are not eligible for unity build inclusion and will automatically be excluded.