Is this source file generated as part of the build or CMake process.

Tells the internal CMake engine that a source file is generated by an outside process such as another build step, or the execution of CMake itself. This information is then used to exempt the file from any existence or validity checks. Generated files are created by the execution of commands such as add_custom_command() and file(GENERATE).

When a generated file created by an add_custom_command() command is explicitly listed as a source file for any target in the same directory scope (which usually means the same CMakeLists.txt file), CMake will automatically create a dependency to make sure the file is generated before building that target.

Generated sources may be hidden in some IDE tools, while in others they might be shown. For the special case of sources generated by CMake’s AUTOMOC or AUTORCC functionality, the AUTOGEN_SOURCE_GROUP, AUTOMOC_SOURCE_GROUP and AUTORCC_SOURCE_GROUP target properties may influence where the generated sources are grouped in the project’s file lists.