New in version 3.28.

Semicolon-separated list of base directories of the target's <NAME> C++ module set, which has the set type CXX_MODULES. The property supports generator expressions.

This property is normally only set by target_sources(FILE_SET) rather than being manipulated directly.

See CXX_MODULE_DIRS for the list of base directories in the default C++ module set. See CXX_MODULE_SETS for the file set names of all C++ module sets.