[cmake-developers] tll-new-signatures topic

[Brad King]

Steve,

Please add documentation to tll() about the restriction enforced
the signature policy (CMP0023).

Also please extend the RunCMake.target_link_libraries test cases
to cover more combinations:

* Use of PRIVATE and LINK_PRIVATE in separate calls is okay.
* Use of the original plain signature and LINK_PRIVATE triggers
  CMP0023 (you already cover original/PRIVATE).

I think we need to work on the terminology.  Our earlier
discussions on this topic were confused by the terms "old" and
"new" to describe groups of signatures.  Readers of the docs and
messages will have the same confusion.  We need to update the
documentation of tll() to name each signature in a way that we
can refer to each group with a simple name.  For example, the
two groups here:

 http://thread.gmane.org/gmane.comp.programming.tools.cmake.devel/6767/focus=7114

need names that are not "old/new" or "A/B".  Perhaps:

* "plain" signatures:

  target_link_libraries(lhs a b c)
  target_link_libraries(lhs LINK_INTERFACE_LIBRARIES a b c)

* "keyword" signatures:

  target_link_libraries(lhs LINK_PUBLIC a LINK_PRIVATE b)
  target_link_libraries(lhs PUBLIC a PRIVATE b INTERFACE c)

Thanks,
-Brad