CMAKE_UNITY_BUILD_UNIQUE_ID
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Cmake/docs/3.21/variable/cmake unity build unique id
CMAKE_UNITY_BUILD_UNIQUE_ID
New in version 3.20.
This variable is used to initialize the UNITY_BUILD_UNIQUE_ID property of targets when they are created. It specifies the name of the unique identifier generated per file in a unity build.
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https://cmake.org/cmake/help/v3.21/variable/CMAKE_UNITY_BUILD_UNIQUE_ID.html