Added in version 3.18.
CMake provides different algorithms for selecting which sources are grouped together into a bucket. Selection is decided by this property, which has the following acceptable values:
BATCH
When in this mode CMake determines which files are grouped together.
The UNITY_BUILD_BATCH_SIZE
property controls the upper limit on
how many sources can be combined per unity source file.
Example usage:
add_library(example_library
source1.cxx
source2.cxx
source3.cxx
source4.cxx)
set_target_properties(example_library PROPERTIES
UNITY_BUILD_MODE BATCH
UNITY_BUILD_BATCH_SIZE 2
)
GROUP
When in this mode each target explicitly specifies how to group
source files. Each source file that has the same
UNITY_GROUP
value will be grouped together. Any sources
that don't have this property will be compiled individually. The
UNITY_BUILD_BATCH_SIZE
property is ignored when using
this mode.
Example usage:
add_library(example_library
source1.cxx
source2.cxx
source3.cxx
source4.cxx)
set_target_properties(example_library PROPERTIES
UNITY_BUILD_MODE GROUP
)
set_source_files_properties(source1.cxx source2.cxx source3.cxx
PROPERTIES UNITY_GROUP "bucket1"
)
set_source_files_properties(source4.cxx
PROPERTIES UNITY_GROUP "bucket2"
)
If no explicit UNITY_BUILD_MODE
has been specified, CMake will
default to BATCH
.