Defer check for sources within a target until generation
The add_library
and add_executable
commands can now be called with
no source-files and won't generate a warning or error message, as long
as source-files will be added later via the target_sources
command.
If during the generation-step still no sources are associated with
targets created by such calls a useful error message will be generated
and generation fails.
Fixes: #16872 (closed)
Topic-rename: defer-target-source-check
Edited by Brad King