# AUTOMOC_COMPILER_PREDEFINES

New in version 3.10.

Boolean value used by `AUTOMOC` to determine if the compiler pre definitions file `moc_predefs.h` should be generated.

CMake generates a `moc_predefs.h` file with compiler pre definitions from the output of the command defined in `CMAKE_CXX_COMPILER_PREDEFINES_COMMAND` when

- `AUTOMOC` is enabled,

- `AUTOMOC_COMPILER_PREDEFINES` is enabled,

- `CMAKE_CXX_COMPILER_PREDEFINES_COMMAND` isn't empty and

- the Qt version is greater or equal 5.8.

The `moc_predefs.h` file, which is generated in `AUTOGEN_BUILD_DIR`, is passed to `moc` as the argument to the `--include` option.

By default `AUTOMOC_COMPILER_PREDEFINES` is initialized from `CMAKE_AUTOMOC_COMPILER_PREDEFINES`, which is ON by default.

See the `cmake-qt(7)` manual for more information on using CMake with Qt.