New in version 3.17.

Setting this variable to true enables showing a context with each line logged by the message() command (see CMAKE_MESSAGE_CONTEXT for how the context itself is specified).

This variable is an alternative to providing the --log-context option on the cmake command line. Whereas the command line option will apply only to that one CMake run, setting CMAKE_MESSAGE_CONTEXT_SHOW to true as a cache variable will ensure that subsequent CMake runs will continue to show the message context.

Projects should not set CMAKE_MESSAGE_CONTEXT_SHOW. It is intended for users so that they may control whether or not to include context with messages.